The word  cardioplegia  combines the Greek  cardio  meaning the "heart", and  plegia  "paralysis". [ 1 ]  Technically, this means arresting or stopping the heart so that surgical procedures can be done in a still and bloodless field. Most commonly, however, the word  cardioplegia  refers to the solution used to bring about  asystole  of the heart, or heart paralysis. One of the first physicians to use the term cardioplegia was Dr. Lam in 1957. However his work on the myocardial protection was preceded serendipitously by  Sydney Ringer  in the late 1800s. At that time Ringer and colleagues noticed that tap water had the ability to increase contractility of the heart, likely due to its high calcium content. Sydney Ringer also commented on the importance of potassium ion concentration on depressing intrinsic heart rhythm. Through a series of experiments performed on frog and canine hearts, reversible arrest was achieved with potassium ions with the consequence of ventricular fibrillation and observed  myocardial   necrosis . These early experiments started nearly 50 years of work that has led to variety of  perfusion  strategies available today.


The main goals of hypothermic cardioplegia are:


The most common procedure for accomplishing asystole is infusing cold cardioplegic solution into the  coronary circulation . This process protects the  myocardium , or heart muscle, from damage during the period of ischemia. [ 3 ]


To achieve this, the patient is first placed on  cardiopulmonary bypass . This device, otherwise known as the heart-lung machine, takes over the functions of gas exchange by the lung and blood circulation by the heart. Subsequently, the heart is isolated from the rest of the blood circulation by means of an occlusive cross-clamp placed on the  ascending aorta  proximal to the  innominate artery .  During this period of heart isolation, the heart is not receiving any blood flow, thus no oxygen for metabolism.  As the cardioplegia solution distributes to the entire myocardium, the ECG will change and eventually asystole will ensue. Cardioplegia lowers the metabolic rate of the heart muscle, thereby preventing cell death during the ischemic period of time.


Cardioplegic solution is the means by which the ischemic myocardium is protected from cell death. This is achieved by reducing myocardial metabolism through a reduction in cardiac work load and by the use of hypothermia.


Chemically, the high potassium concentration present in most cardioplegic solutions decreases the membrane resting potential of cardiac cells. The normal  resting potential  of ventricular myocytes is about -90 mV. [ 4 ]  When extracellular cardioplegia displaces blood surrounding myocytes, the membrane voltage becomes less negative and the cell depolarizes more readily. The depolarization causes contraction, intracellular calcium is sequestered by the sarcoplasmic reticulum via ATP-dependent Ca 2+  pumps, and the cell relaxes (diastole).  However, the high potassium concentration of the cardioplegia extracellular prevents repolarization.
The resting potential on ventricular myocardium is about −84 mV at an extracellular K +  concentration of 5.4 mmol/L. Raising the K +  concentration to 16.2 mmol/L raises the resting potential to −60 mV, a level at which muscle fibers are inexcitable to ordinary stimuli.  When the resting potential approaches −50 mV,  sodium channels are inactivated, resulting in a diastolic arrest of cardiac activity. [ 5 ]  Membrane inactivation gates, or  h   Na +  gates, are voltage dependent. The less negative the membrane voltage, the more  h  gates that tend to close. If partial depolarization is produced by a gradual process such as elevating the level of extracellular K + , then the gates have ample time to close and thereby inactivate some of the Na +  channels.  When the cell is partially depolarized, many of the Na +  channels are already inactivated, and only a fraction of these channels is available to conduct the inward Na +  current during phase 0 depolarization. [ 6 ]


The use of two other cations, Na +  and Ca 2+ , also can be used to arrest the heart.  By removing extracellular Na +  from perfusate, the heart will not beat because the action potential is dependent upon extracellular Na +  ions.  However, the removal of Na +  does not alter the resting membrane potential of the cell.  Likewise, removal of extracellular Ca 2+  results in a decreased contractile force, and eventual arrest in diastole. An example of a low [K + ] low [Na + ] solution is  histidine-tryptophan-ketoglutarate .  Conversely, increasing extracellular Ca 2+  concentration enhances contractile force.  Elevating Ca 2+  concentration to a high enough level results in cardiac arrest in systole.  This unfortunate irreversible event is referred to as "stone-heart" or rigor.


Hypothermia is the other key component of most cardioplegic strategies.  It is employed as another means to further lower myocardial metabolism during periods of  ischemia . The  Van 't Hoff equation  allows calculation that oxygen consumption will drop by 50% for every 10 °C reduction in temperature. This  Q 10  effect combined with a chemical cardiac arrest can reduce myocardial oxygen consumption (MVO 2 ) by 97%. [ 7 ]


Cold cardioplegia is given into the heart through the aortic root. Blood supply to the heart arises from the aortic root through  coronary arteries . Cardioplegia in diastole ensures that the heart does not use up the valuable energy stores ( adenosine triphosphate ). Blood is commonly added to this solution in varying amounts from 0 to 100%. Blood acts a buffer and also supplies nutrients to the heart during ischemia.


Once the procedure on the heart vessels ( coronary artery bypass grafting ) or inside the heart such as  valve replacement  or correction of  congenital heart defect , etc. is over, the cross-clamp is removed and the isolation of the heart is terminated, so normal blood supply to the heart is restored and the heart starts beating again.


The cold fluid (usually at 4 °C)  ensures that the heart cools down to a temperature of around 15–20 °C, thus slowing down the metabolism of the heart and thereby preventing damage to the heart muscle. This is further augmented by the cardioplegia component which is high in potassium.


When solution is introduced into the  aortic root  (with an  aortic cross-clamp  on the distal aorta to limit systemic circulation), this is called antegrade cardioplegia.  When introduced into the  coronary sinus , it is called retrograde cardioplegia. [ 8 ]


Whilst there are several cardioplegic solutions commercially available; there are no clear advantages of one cardioplegic solution over another. Some cardioplegias, such as del Nido or Histidine-Tryptophan-Ketoglutamate solutions, offer an advantage over blood and other crystalloid cardioplegia as they only require one administration during short cardiac surgeries, compared to multiple doses required by blood and other crystalloid. [ 9 ]


In coronary surgery, there are various alternatives to cardioplegia to perform the operation. One is  off-pump  coronary surgery where the surgery is done without the need of a cardiopulmonary bypass machine. Another is to use cross-clamp fibrillation whereby the heart fibrillates whilst on cardiopulmonary bypass in order to perform the distal anastomoses. [ 10 ]


Cardiac surgical cases were performed with the aid of a cardiopulmonary pump, without cardioplegia or other means of protecting the heart. High mortality rates due to cardiac injury though, made surgeons to look on how to protect the heart. In 1955  D.G. Melrose  suggested ‘’elective cardiac arrest’’, a technique already used for other purposes, in order to protect the heart from ischemia- since cardiac muscle is not working, oxygen demands should be low. In the 1960’s other groups introduced ice slur applied all over the heart’s surface. The rationale was to decrease the temperature of the heart, thus to reduce oxygen demands further. [ 11 ]


The next decades many investigators (Bretschneider, Kirch and others)  came up with various solutions that could pause the heart without damaging cardiac muscle. In the same period, surgeons found out delivery roots for cardioplegia, other than the commonly used antegrade. Buckberg in North America and Menasche in Europe, introduced retrograde cardioplegia method, via a catheter inserted in Coronary Sinus and thus perfusing the heart in a retrograde fashion. [ 11 ]


Cardiothoracic anesthesiology  is a subspeciality of the medical practice of  anesthesiology , devoted to the preoperative, intraoperative, and postoperative care of adult and pediatric patients undergoing cardiothoracic surgery and related invasive procedures.


It deals with the  anesthesia  aspects of care related to  surgical  cases such as  open heart surgery ,  lung  surgery, and other operations of the human  chest . These aspects include  perioperative  care with expert manipulation of patient cardiopulmonary physiology through precise and advanced application of  pharmacology , resuscitative techniques, critical care medicine, and invasive procedures. This also includes management of the  cardiopulmonary bypass  (heart-lung) machine, which most cardiac procedures require intraoperatively while the heart undergoes surgical correction. [ 1 ] [ 2 ]


All anesthesiologists obtain either a  Doctor of Medicine  (MD) or  Doctor of Osteopathic Medicine  (DO) degree prior to entering post-medical school graduate medical education. After satisfactory completion of an  Accreditation Council for Graduate Medical Education  (ACGME) or  American Osteopathic Association  (AOA) accredited one year  internship  in either  internal medicine  or  surgery  and a three-year  residency  program in all subspecialties of  anesthesiology ,  formal advanced training in Cardiothoracic Anesthesiology is available via a one-year  fellowship . Cardiothoracic Anesthesia Fellowship - Department of Anesthesiology - Miller School of Medicine at the University of Miami   Society of Cardiovascular Anesthesiologists .


The first Cardiothoracic Anesthesiology fellowship was formed at Harvard Medical School and the Massachusetts General Hospital in 1971.  Massachusetts General Hospital Department of Anesthesia, Critical Care and Pain Medicine - Fellowships  Since then, Cardiothoracic Anesthesiology has become an  ACGME  approved fellowship (2007), and there are 64 ACGME accredited programs and 212 match positions for the 2017-2018 application year. [ citation needed ]


This fellowship consists of at least eight months of adult Cardiothoracic Anesthesiology, one month dedicated to transesophageal echocardiography, one month in cardiothoracic intensive care unit and two months of elective rotation which includes inpatient or outpatient cardiology or pulmonary medicine, invasive cardiology, medical or surgical critical care and extracorporeal perfusion technology. [ citation needed ]


Fellows are offered the opportunity to participate in clinical research and encouraged to present at national or international conferences after completion of a research project. The arenas of research can be as diverse as neuroprotection, [ 3 ]  myocardial protection, [ 4 ]  blood conservation strategies, [ 5 ]  and port access surgery.


Fellows are trained to provide perioperative anesthetic management for patients with severe cardiopulmonary pathology. Some of the cardiac surgeries they train for include the following:  coronary artery bypass surgery  (CABG) both on cardiopulmonary bypass as well as on a beating heart,  heart valve  surgery, aortic reconstruction requiring deep hypothermic arrest, mechanical ventricular assist device (VAD) placement, thoracic  aortic aneurysm  repair,  aortic dissection  repair, heart transplants, lung transplants, heart/lung transplants, and adult congenital heart surgery. [ citation needed ]


Adequate exposure and experience provided in the management of adult patients for cardiac pacemaker and automatic implantable cardiac defibrillator placement, surgical treatment of cardiac arrhythmias, and the complete gamut of invasive cardiologic (catheter-based) and electrophysiological procedures is expected as well.


Fellows also gain experience in perioperative medical (anesthetic) management of the cardiac patient, including management of intra-aortic balloon pumps (IABP) and ventricular assist devices (VAD), post-operative ICU care, blood transfusion medicine, electrophysiology, and transthoracic echocardiography.  Massachusetts General Hospital Department of Anesthesia, Critical Care and Pain Medicine - Fellowships


Many fellowships also offer opportunity to become familiar with anesthetic techniques for pediatric cardiac surgery and minimally invasive cardiac surgery, however no formal case numbers for ACGME accreditation are required. [ 6 ]


In addition to the focused cardiac training, additional clinical experience within the full one-year fellowship includes anesthetic management of adult patients undergoing thoracic and vascular surgery. Fellows are trained to manage all type of thoracic surgeries which include  video-assisted thoracoscopic surgery  (VATS), [ 7 ]  open  thoracotomy , and advanced airway procedures involving the trachea. Fellows achieve expertise in different techniques of lung isolation and ventilation
including double-lumen endotracheal tubes, bronchial blockers, Univent tubes under guidance of fiber optic bronchoscopy, and advanced jet ventilation. [ 8 ]


The complex nature of cardiothoracic surgery necessitates extra training to acquire the skills needed to be a cardiothoracic anesthesiology consultant. Fellows are trained to achieve expertise in the advanced monitoring techniques including invasive blood pressure, arterial blood gas analysis, cardiac output monitoring, jugular venous oxygen saturation, cerebral oximetry, Bispectral Index (BIS), [ 9 ]  Transcranial doppler (TCD), [ 10 ]  and Near infrared spectroscopy (NIRS). [ 11 ]


Finally, invasive procedures completed by the cardiothoracic anesthesiology fellows include but are not limited to arterial line placement (femoral, axillary, brachial, radial), central venous cannulation (internal jugular, femoral, subclavian), pulmonary artery catheter placement, transvenous pacemaker placement, thoracic epidural analgesia, fiberoptic endotracheal tube placement, 2D/3D transesophageal echocardiography, intraspinal drainage placement, and advanced ultrasound guidance of vascular access. [ citation needed ]


Echocardiography  produces a real-time image of the heart via ultrasound imaging, and can be performed in two or three dimensions. There are two ways of performing echocardiography depending on placement of echocardiography probe: transthoracic or transesophageal. [ citation needed ]


In transthoracic echocardiography (TTE), the probe is placed over the patient's chest wall, while in transesophageal  echocardiography (TEE or TOE  in the UK), the probe is placed into the esophagus. [ citation needed ]


Regardless of technique, each probe contains a transducer. While transmitting signals, it converts electrical energy to acoustic energy. When receiving signals, it converts acoustic energy to electrical energy, which is processed by the machine to form an image. Various techniques are employed to manipulate the data, including Doppler imaging. [ 12 ] [ 13 ]


Transesophageal echocardiography  has rapidly become the most powerful monitoring technique and diagnostic tool for the management of cardiac surgical patients, primarily due to the  transesophageal echocardiogram  probe location and ability to be used intraoperatively.  It provides the detailed information about the structure and function of the heart/great vessels in real time, allowing the cardiothoracic anesthesiologist to precisely manage patient physiology while providing updates and direction to members of the surgical team throughout the pre, intra, and post operative time frame of patient care. [ 14 ]


After successful completion of the fellowship with subspecialty training in TEE, cardiothoracic anesthesiology fellows may sit for examination leading to board certification in echocardiography.  The examination, also known as the  Advanced PTEeXAM , is administered by  the National Board of Echocardiography (NBE).
 National Board of Echocardiography - PTEeXAM . In addition to passing the test, fellows can become board certified only after performing 150 exams as well as reviewing an additional 150 exams with a board certified cardiologist/cardiothoracic anesthesiologist.


Cardiopulmonary bypass (CPB) is a technique in which heart-lung machine temporarily takes over the function of the heart and lungs during surgery. The CPB is operated by the  perfusionist . During the heart operation, the perfusionist takes over the heart function. The perfusionist works in close relation with the anesthesiologist and the surgeon.


Blood is drained from the venous (deoxygenated) circulation, and is cycled through the CPB machine. While in the machine, the blood is filtered, heated or cooled, and infused with oxygen. Subsequently, it is pumped back into the arterial (oxygenated) circulation, thereby bypassing the heart and lungs and maintaining the  perfusion  of the vital organs.


While the step by step process for preparation and initiation of CPB can vary between institution and type of surgery, a typical scenario is as follows.


After a  median sternotomy , a surgical retractor is placed by the surgeon to optimize exposure of the  heart . At this time,  heparin  is given to thin the blood to prevent  thrombus  from forming while on CPB. The surgeon places a  cannula  in the right atrium, vena cava, or femoral vein to withdraw blood from the venous circulation. The perfusionist uses gravity to drain the venous blood into the CPB machine, and a separate cannula, usually placed in the aorta or femoral artery, is used to return blood to the arterial circulation.


The process of preparation, initiation, and separation of cardiopulmonary bypass is a critical time during cardiac surgery. Some studies have even considered formalizing this period of time, much like the "sterile cockpit" process in critical steps of aviation  Is the "sterile cockpit" concept applicable to cardiovascular surgery critical intervals or critical events? The impact of protocol-driven communication during cardiopulmonary bypass . The communication, while a team effort, is led and directed by the cardiothoracic anesthesiologist, as the surgeon is focused  on acquiring and maintaining adequate exposure. This can even extend to placement of the cannulae for CPB preparation, as the cardiothoracic anesthesiologist often directs the surgical placement via real-time TEE data. As such, this responsibility demands that the cardiothoracic anesthesiologist have a thorough knowledge of the advanced physiology, principles, practical application and management of CPB.


After completion of the "on bypass" surgical correction, preparations are made to separate the patient from CPB. In other words, the heart and lung are prepared to receive, oxygenate, and pump the blood which had immediately previous been done by the CPB machine. Separation can be complicated by the CPB machine, the patient's inherent pathology/physiology, surgical correction, and the dynamic interaction of all three. Cardiopulmonary bypass has effects on the patient's hematology, physiology, and immunology, which must be acutely managed by the cardiothoracic anesthesiologist in order to ensure effective separation from CPB.


Patients with cardiothoracic pathology who present for non-cardiothoracic surgery are at increased risk for serious perioperative complications. Cardiothoracic anesthesiologists are often consulted by their colleagues to provide expert management during intraoperative hemodynamic instability or  cardiac arrest  by evaluating heart function with the aid of TEE and placement of other invasive advanced hemodynamic monitors, such as pacing swans. [ 14 ]


A  cardiotomy  is a  surgical procedure  where an  incision  is made in the  heart . It can be used for  suction  during  heart surgery . [ 1 ]


A  catheterization laboratory , commonly referred to as a  cath lab , is an examination room in a hospital or clinic with  diagnostic imaging  equipment used to visualize the arteries of the heart and the chambers of the  heart  and treat any  stenosis  or abnormality found.


Most catheterization laboratories are "single plane" facilities, those that have a single  X-ray  generator source and an  X-ray image intensifier  for  fluoroscopic  imaging. [ 1 ]  Older cath labs used  cine film  to record the information obtained, but since 2000, most new facilities are  digital . The latest digital cath labs are biplane (have two X-ray sources) and use  flat panel detectors . [ 2 ]


Cardiac catheterization laboratories are usually staffed by a multidisciplinary team. This may include a medical practitioner (normally either a consultant  cardiologist  or  radiologist ), cardiac  physiologist ,  radiographer  and  nurse . [ 3 ] [ 4 ]


The consultant cardiologist is responsible for gaining arterial access, inserting a sheath into either the  radial  or  femoral artery , passing a wire and  catheter  into the coronary artery and selectively injecting  contrast media  into the coronary arteries. They then interpret the images taken to ascertain where the narrowed or blocked artery has the problem. They use a variety of techniques and imaging tools to measure the size of things such as balloons and  stents .


Cardiac physiologists usually set up what is known as a  transducer  to monitor pressure in the arteries. They also have a live view of the patients  ECG  so they can tell whether or not there is a problem caused by the insertion of the catheter into the heart to the electrical pathways. [ 5 ] [ 6 ]  The physiologist will also set up a temporary pacemaker if the procedure is an angioplasty or a  percutaneous coronary intervention  (PCI). Finally, they also set up  defibrillators  on to the patient for emergency use if needed. In some locations, some of these responsibilities may be carried out by other personnel, such as trained nurses or technologists. [ 7 ]


Cardiac catheterization  is a general term for a group of procedures that are performed in the cath lab, such as  coronary angiography . Once a catheter is in place, it can be used to perform a number of procedures including  angioplasty , PCI ( percutaneous coronary intervention ) angiography,  transcatheter aortic valve replacement ,  balloon septostomy , and an  electrophysiology study  or  catheter ablation . Devices such as  pacemakers  may be fitted or  rotablation  to remove plaque can be performed. [ 8 ] [ 9 ]


A  commissurotomy  ( / ˌ k ɒ m ə ʃ ər ˈ ɒ t ə m i / ) is a  surgical  incision of a  commissure  in the body, as one made in the heart at the edges of the commissure formed by  cardiac valves , or one made in the brain to treat certain psychiatric disorders.


Patients with  scleroderma , a disease that thickens and hardens the skin, sometimes require oral commissurotomy to open the corners of the mouth, the commissures, to allow dental treatment. This procedure often leaves characteristic scars.


Commissurotomy of  cardiac valves  is called  valvulotomy , [ 1 ]  and consists of making one or more incisions at the edges of the commissure formed between two or three valves, in order to relieve constriction such as occurs in  valvular stenosis , especially  mitral valve stenosis . [ citation needed ]


In  neurosurgery , as a treatment for severe epilepsy, the corpus callosum, or the area of the brain that connects the two hemispheres, would be completely bisected. By eliminating the connection between the two hemispheres of a patient's brain, electrical communication would be cut off greatly diminishing the amount and severity of the epileptic seizures. For some, seizures would be completely eliminated. [ 2 ]


Though no effect on behavior was observed after commissurotomy was performed on monkeys, it gave peculiar effects on human perception. Different functions of cognition are predominantly located on one of the hemispheres. For example, Brocas area, crucial for forming sentences, is on most people situated in the left hemisphere ventral to the facial motor cortex. The left hemisphere is referred to as the "talking" hemisphere and the right the "silent". A commisurotomy prevents any sensory input to the silent hemisphere from reaching the talking hemisphere. Since the left visual field is processed in the right hemisphere, a person with a commissurotomy is unable to describe objects to the left, because the "talking" hemisphere has not seen anything. It appears as though the person had not seen anything at all, and it does not bother him either. It can be demonstrated that stimuli to the right hemisphere for example give emotional response, but because of the severed corpus callosum it cannot be verbalized. [ 3 ]


Coronary artery bypass surgery , also known as  coronary artery bypass graft  ( CABG , pronounced "cabbage"), is a surgical procedure to treat  coronary artery disease  (CAD), the buildup of plaques in the arteries of the heart. It can relieve  chest pain  caused by CAD, slow the progression of CAD, and increase life expectancy. It aims to bypass  narrowings  in heart arteries by using arteries or veins  harvested  from other parts of the body, thus restoring adequate blood supply to the previously  ischemic  (deprived of blood) heart.


There are two main approaches. The first uses a  cardiopulmonary bypass machine , a machine which takes over the functions of the heart and lungs during surgery by circulating blood and oxygen. With the heart in   cardioplegic arrest , harvested arteries and veins are used to connect across problematic regions—a construction known as  surgical anastomosis . In the second approach, called the  off-pump coronary artery bypass  (OPCAB), these anastomoses are constructed while the heart is still beating. The anastomosis supplying the  left anterior descending branch  is the most significant one and usually, the  left internal mammary artery  is harvested for use. Other commonly employed sources are the right internal mammary artery, the  radial artery , and the  great saphenous vein .


Effective ways to treat chest pain (specifically,  angina , a common symptom of CAD) have been sought since the beginning of the 20th century. In the 1960s, CABG was introduced in its modern form and has since become the main treatment for significant CAD. Significant complications of the operation include bleeding, heart problems ( heart attack ,  arrhythmias ),  stroke , infections (often  pneumonia ) and  injury to the kidneys .


Coronary artery bypass surgery aims to prevent death from  coronary artery disease  and improve quality of life by relieving  angina , the associated feeling of chest pain. [ 1 ]  The decision to perform surgery is informed by studies of CABG's efficacy in different patient subgroups, based on the lesions' anatomy or how well the heart is functioning. These results are compared with that of other strategies, most importantly  percutaneous coronary intervention  (PCI). [ 2 ] [ 3 ]


Coronary artery disease is caused when  coronary arteries  of the heart accumulate  atheromatous plaques , causing  stenosis  (narrowing) in one or more arteries and risking  myocardial infarction , the interruption of blood supply to the heart. CAD can occur in any of the major vessels of the  coronary circulation : the left main stem, left ascending artery, circumflex artery, and right coronary artery, and branches thereof. CAD symptoms vary from none, to chest pain only when exercising (stable angina), to chest pain even at rest (unstable angina). It can even manifest as a myocardial infarction; if blood flow to the heart is not restored within a few hours, whether spontaneously or by medical intervention, the blood-deprived part of the heart becomes  necrotic  (dies) and is scarred. It may lead to other complications such as  arrhythmias , rupture of the  papillary muscles of the heart , or sudden death. [ 4 ]


There are various methods of detecting and assessing CAD. Apart from history and clinical examination, noninvasive methods include  electrocardiography  (ECG) at rest or during exercise, and  X-ray of the chest .  Echocardiography  can quantify heart functioning by measuring, for example, enlargement of the  left ventricle , the  ejection fraction , and the situation of the  heart valves . The most accurate ways to detect CAD are the  coronary angiogram  and the  coronary CT angiography . [ 4 ]  An angiogram can provide detailed anatomy of coronary circulation and lesions. The significance of each lesion is determined by the diameter loss. A diameter loss of 50% translates to a 75% cross-sectional area loss, considered moderate by most groups. Severe stenosis constitutes a diameter loss of 2/3 or more—a greater-than-90% loss of cross-sectional area. [ 5 ]  To more accurately determine the severity of stenosis, interventional cardiologists may also employ  intravascular ultrasound , which can determine the severity and provide information on the composition of the atheromatous plaque. With the technique of  fractional flow reserve , the pressure after the stenosis is compared to mean aortic pressure. If the ratio is less than 0.80, then the stenosis is deemed significant. [ 5 ]


People with angina during exercise are usually first treated with medical therapy. Noninvasive tests help estimate which patients might benefit from undergoing coronary angiography. Generally, if portions of cardiac wall are receiving less blood than normal, coronary angiography is indicated; then, lesions are identified and inform a decision to undergo PCI or CABG. [ 6 ]


CABG is generally preferred over PCI when there is a significant burden of plaque on the coronary arteries, that is extensive and complex, due to survival benefit. Other indicators that a patient will benefit more from CABG rather than PCI include: decreased left-ventricle function;  left main disease ;  diabetes ; and complex triple system disease (including LAD, Cx and RCA), especially when the lesion in the LAD is at its proximal part. [ 2 ] [ 3 ]


During an acute heart event, known as  acute coronary syndrome , it is paramount to quickly restore blood flow to heart tissue. Typically, patients arrive at the hospital with chest pain. They are first treated with drugs, particularly the strongest drugs that prevent clots within vessels (dual anti-platelet therapy:  aspirin  and  clopidogrel ). Patients at risk of ongoing ischemia undergo PCI to restore blood flow and thus oxygen delivery to the struggling heart. [ 7 ]  If PCI failed to restore blood flow because of anatomical considerations or other technical problems, urgent CABG is indicated to save heart tissue. The timing of the operation plays a role in survival: It is preferable to delay the surgery if possible (three days if the infarction affecting the total thickness of the cardiac muscle, and six hours if it does not). [ 2 ]


CABG is also indicated when there are  mechanical complications of an infarction  ( ventricular septal defect ,  papillary muscle  rupture or myocardial rupture). [ 8 ]  There are no absolute contraindications of CABG, but severe disease of other organs such as the liver or brain, limited life expectancy, and patient fragility are considered. [ 8 ]


CABG is also performed when a patient is to undergo another cardiac surgical procedure, most commonly for  valve disease , and angiography reveals a significant lesion of the coronary arteries. [ 9 ]  CABG can also address  dissection  of coronary arteries, where a rupture of the coronary layers creates a pseudo- lumen  (cavity) and diminishes blood delivery to the heart. Such a dissection may be caused by pregnancy, tissue diseases like  Ehlers–Danlos syndromes  and  Marfan syndrome , cocaine abuse, or PCI. A coronary aneurysm may also indicate CABG: A  blood clot  might develop within the vessel and travel downstream. [ 10 ]


CABG and percutaneous coronary intervention (PCI) are the two methods to restore blood flow caused by stenotic lesions of the coronary arteries. The choice of method is still a matter of debate, but it is clear that in the presence of complex lesions, significant left main disease, or diabetes, CABG yields better long-term survival and outcomes. [ 11 ] [ 10 ]  Strong indications for CABG also include symptomatic patients and impaired left ventricle function. [ 10 ]  CABG offers better results than PCI in left main disease and in CAD that affects multiple vessels, because of the protection arterial conduits offer to the native arteries of the heart, by producing  vasodilator  factors and preventing the advancement of plaques. Studies published in 2023 show that CABG in patients with left main disease is associated with lower mortality and fewer adverse events compared to PCI. [ 12 ] [ 13 ]


Patients with unprotected left main disease—when the runoff of the left main artery is not protected by a patent graft since a previous CABG operation—have been studied as a group. A 2016 European study found that in these patients, CABG outperforms PCI in the long run (5 years). Another 2016 study found that PCI has similar results to CABG at 3 years, but that CABG becomes better than PCI after 4 years. [ 14 ] [ 15 ]


A 2012 trial and followup in diabetic patients demonstrated a significant advantage to CABG over PCI. The relative advantage remained evident at 3.8-year and 7.5-year follow ups, which found particular benefits in smokers and younger patients. [ 16 ]  A 2015 trial compared CABG and the latest technological advancement of PCI, second-generation  drug-eluting stents  in multivessel disease. Their results indicated that CABG is a better option for CAD patients. [ 17 ]  A trial published in 2021, comparing results after one year, also concluded that CABG is a safer option than PCI. [ 18 ]  A large study published in 2023 showed that PCI patients had higher mortality than CABG patients with left main coronary artery disease. [ 19 ]


Routine preoperative examination aims to check the status of systems and organs besides the heart. The examination typically includes a chest X-ray to check the lungs, a  complete blood count , and kidney and liver function tests. Physical examination to determine the quality of the grafts or the safety of removing them, such as  varicosities in the legs , or the  Allen test  in the arm is performed to be sure that blood supply to the arm will not be critically disturbed. [ 20 ]


A patient taking anticoagulants— aspirin ,  clopidogrel ,  ticagrelol  and others—will stop taking them several days before, to prevent excessive bleeding during and after the operation. Warfarin is also stopped for the same reason and the patient starts taking  heparin products  after the  INR  falls below 2.0. [ 20 ] [ 21 ]


After the angiogram is reviewed by the surgical team, targets are selected (that is, which native arteries will be bypassed and where the anastomosis should be placed). Ideally, all major lesions in significant vessels should be addressed. Most commonly, the left internal thoracic artery (LITA; formerly, left internal mammary artery, LIMA) is anastomosed to the left anterior descending artery (LAD) because the LAD is the most significant artery of the heart and supplies blood to a larger portion of myocardium than other arteries. [ 21 ]


A conduit can be used to graft one or more native arteries. In the latter case, an end-to-side anastomosis is performed. In the former, using a sequential anastomosis, a graft can then deliver blood to two or more native vessels of the heart. [ 21 ]  Also, the proximal part of a conduit can be anastomosed to the side of another conduit. It is preferred not to harvest too much conduit because it might necessitate re-operation. [ 21 ]


The intubated patient is brought to the  operating theater . Lines (e.g., peripheral IV cannulae, central lines such as internal jugular cannulae) are inserted for drug administration and monitoring. A description of a traditional CABG follows. [ 21 ]


An  incision in the sternum  is made while  vessels  are being  harvested , either from the arms or chest or from the leg, usually from the internal mammary artery or the saphenous vein. The LITA is harvested through the sternotomy. There are two common ways of mobilizing the LITA: the pedicle (i.e., a pedicle consisting of the artery plus surrounding fat and veins) and the skeletonized (i.e., freed of other tissues). Before the LITA is divided in its more distal part, the anticoagulant heparin is administered to the patient via a peripheral line, to prevent clots. [ 21 ]


After harvesting, the  pericardium —the sac that surrounds the heart—is opened and stay sutures are placed to keep it open.  Purse string  sutures are placed in the aorta to prepare the insertions of the cannula into the aorta, and a catheter which  temporarily arrests the heart  using a solution high in potassium. Another purse string is placed in the right atrium for the venous cannula. Once the cannulas and the catheter are placed, cardiopulmonary bypass (CPB) is commenced. Deoxygenated blood arriving to the heart from veins is forwarded to the CPB machine to get oxygenated, then delivered to the aorta to keep the rest of the body saturated. The blood is often cooled to 32–34 °C (90–93 °F) to slow  metabolism  and minimize the demand for oxygen. A clamp is placed on the aorta between the cardioplegic catheter and aortic cannula, so that the flow of cardioplegic solution may be controlled by adjusting the clamp. Within minutes, the heart stops beating. [ 21 ] [ 22 ]


With the heart still, the tip of the heart is taken out of pericardium so that native arteries lying on the posterior side of the heart are accessible. Usually, distal anastomoses are constructed first (first to the right coronary system, then to the circumflex) and then the sequential anastomosis if necessary. Surgeons check the anastomosis for patency (whether it is sufficiently open) or leaking. They then insert the graft within the pericardium, sometimes attached to the cardioplegic catheter. The anastomosis of the LIMA to the LAD is usually the last distal anastomosis to be constructed; while it is being constructed the blood rewarming process starts (by the CPB). [ 21 ]  After the anastomosis is completed and checked for leaks, the proximal anastomoses of the conduits, if any, are next. They can be done either with the clamp still on, or after removing the aortic clamp and isolating a small segment of the aorta by placing a partial clamp. That said, aortas burdened by plaques might be damaged or release atheromatous debris by being overhandled. [ 21 ] [ 23 ]


After the proximal anastomoses are done, the clamp is removed and the aorta and conduits de-aired. Pacing wires, which supply a current to assist the heartbeat, might be placed. If the heart and other systems are functioning, CPB is discontinued and cannulae are removed.  Protamine  is administered to reverse the effect of the anticoagulant heparin. After possible bleeding sites are checked,  chest tubes  are placed and the sternum is closed. [ 21 ] [ 23 ]


Off-pump coronary artery bypass  (OPCAB) surgery avoids using the CPB machine by stabilizing small segments of the heart at a time. The surgical team and anesthesiologists must coordinate and take great care to not manipulate the heart too much, lest they compromise the stability of blood flow. Compromise should be detected immediately and appropriate action taken. [ 24 ]


Keeping a healthy heartbeat may involve maneuvers like placing atrial wires to protect from  bradycardia , or by placing stitches or incisions into the pericardium to help exposure. Snares and tapes are used to facilitate exposure. The aim is to avoid distal ischemia caused by blockage of the vessel supplying distal portions of the left ventricle, so usually LITA to LAD is the first to be anastomosed and others follow. For the anastomosis, a fine tube blowing humidified CO 2  keeps the surgical field clean of blood. Also, a shunt might be used so the blood can travel past the site of anastomosis. After the distal anastomoses are completed, proximal anastomoses to the aorta are constructed with a partially closed aortic clamp. The rest of the process is similar to on-pump CABG. [ 24 ]


When CABG is performed as an emergency because of a myocardial infarction, the highest priority is to salvage the struggling myocardium. Before operation, an  intra-aortic balloon pump  (IABP) might be inserted to relieve some of the burden of pumping blood, effectively reducing the amount of oxygen needed by myocardium. During operation, the standard practice is to place the patient on CPB as soon as possible and revascularize the heart with three saphenous veins. A calcified aorta also poses a problem because it is very dangerous to clamp. In this case, the operation can be done as an off-pump CAB using both  inferior mesenteric arteries  (IMA) or Y, T and sequential grafts. Deep arrest may be induced with  hypothermia , lowering the temperature of the body to slightly above 20 °C (68 °F). [ 25 ]  In cases where a significant artery is totally blocked, it may be possible to remove the plaque and use the same hole in the artery to perform an anastomosis. This technique is called endarterectomy and is usually performed at the right coronary system. [ 26 ]


Re-operations of CABG (another CABG operation after a previous one) pose difficulties. The heart may be positioned too close to the sternum and thus at risk when cutting the sternum again, so an  oscillating saw  is used. The heart may be covered with strong adhesions to adjusting structures. Doctors must decide whether aging grafts should be replaced. Manipulation of vein grafts is avoided because it risks dislodgement of plaque. [ 27 ]


Minimally invasive direct coronary artery bypass  (MIDCAB) strives to avoid a large incision in the sternum. It utilizes off-pump techniques to place a graft, usually of the LIMA at the LAD. The LIMA is freed through an  incision between the left ribs  (thoractomy), or even using an endoscope placed in the left chest. [ 28 ]  Robot-assisted coronary revascularization, which is not yet widely used, avoids the sternum incision to prevent infections and bleeding. Both conduit harvesting and the anastomosis are performed with the aid of a robot, through a thoracotomy. Usually, the procedure is combined with  hybrid coronary revascularization , in which methods of CABG and PCI are both employed. Anastomosis of the LIMA to the LAD is performed in the operating theater and other lesions are treated with PCI—either at the operating room immediately following the anastomosis, or several days later. [ 29 ]


After the procedure, the patient is usually transferred to the  intensive care unit  (ICU), where intubations are removed if not already done in the operating theater. They usually exit the ICU by the following day, and four days later, if no complications occur, the patient is discharged from the hospital. [ 30 ]


A series of drugs are commonly used in early post-operative care.  Dobutamine , a beta agent, can increase the cardiac output and is administered some hours after the operation. Beta blockers are used to prevent atrial fibrillation and other supraventricular arrhythmias. Pacing wires attached to both atria, inserted during the operation, may help prevent atrial fibrillation. Aspirin (80 mg) is used to prevent graft failure. [ 30 ]   Angiotensin-converting enzyme (ACE) inhibitors  and  angiotensin receptor blockers (ARBs)  are used to control blood pressure, especially in patients with low cardiac function (<40%).  Amlodipine , a calcium channel blocker, is used for patients whose radial artery was used as a graft. [ 2 ]


After the discharge, patients may experience insomnia, low appetite, decreased sex drive, and memory problems. This effect is usually transient and lasts 6 to 8 weeks. [ 30 ]  A tailored exercise plan is usually beneficial. [ 30 ]


CABG is the best procedure to reduce mortality from severe CAD and improve quality of life. [ 31 ] [ 32 ] : 153   Operative mortality strongly relates to the patient's age. According to a study by Eagle  et al ., patients 50–59 years old have an operative mortality rate of 1.8%, while patients older than 80 have a rate of 8.3%. [ 33 ]  Other factors that increase mortality are being female, re-operation, dysfunction of the left ventricle, and  left main disease . [ 33 ]  CABG usually relieves angina, but in some patients it reoccurs. Around 60% of patients will be angina-free 10 years after their operation. [ 33 ]  Myocardial infarction is rare five years after a CABG, but its risk increases with time. [ 34 ]  The risk of sudden death for CABG patients is low. [ 34 ]  Quality of life is also high for at least five years, then can slowly start to decline. [ 35 ]  However,  the use of bilateral mammary artery in patients of younger age and those without specific comorbidities (diabetes, obesity, steroid use) can provide excellent long-term survival and quality of life. [ 36 ]


The beneficial effects of CABG are clear at the cardiac level. Left-ventricle function is improved and malfunctioning segments of the heart—dyskinetic (moving inefficiently) or even akinetic (not moving)—can show signs of improvement. Both systolic and diastolic functions are improved and keep improving for up to five years in some cases. [ 37 ]  Left-ventricle function and myocardial perfusion during exercise also improves after CABG. When the left ventricle is severely impaired before operation (ejection fraction below 30%), however, benefits are less impressive in terms of segmental wall movement but still significant because other parameters might improve as LV function improves; the pulmonary hypertension might be relieved and lengthen survival. [ 37 ] [ 38 ]


Determining the total risk of the procedure is difficult because of the diversity of patients undergoing CABG; different subgroups have different risk, but younger patients see better results than older ones. A CABG using two, rather than one,  internal mammary arteries  (IMAs) may offer greater protection from CAD, but results are not yet conclusive. [ 33 ] [ 39 ]


Conduits that can be used for CABG may be arteries or veins. Arteries have a superior long-term patency (expandedness), but veins are more commonly used due to their practicality. [ 40 ]


Arterial grafts originate from the part of the internal thoracic artery (ITA) that runs near the edge of  sternum , and can easily be mobilized and anastomosed to the native target vessel of the heart. The left artery is most often used because it is closer to the heart, but the right artery is sometimes used, depending on patient and surgeon preferences. The ITAs  are advantageous because of their endothelial cells, which produce  endothelium-derived relaxing factor  and  prostacyclin , protecting the artery from atherosclerosis and thus stenosis or occlusion. Disadvantages include a high rate of complications, such as deep sternal wound infections, in some subgroups of patients—mainly obese and diabetic ones. The  left radial artery  and  left gastroepiploic artery  can be also used. Long-term patency is influenced by the type of artery used and intrinsic factors of the cardiac arterial circulation. [ 41 ]


Veins used are mostly  great saphenous veins  and, in some cases, the  lesser saphenous vein . Their patency rate is lower than that of arteries.  Aspirin  protects grafts from occlusion; adding  clopidogrel  does not improve rates. [ 41 ]


CABG and PCI are the two methods to revascularize stenotic lesions of the cardiac arteries. The preferences for each patient is still a matter of debate but in the presence of complex lesions and significant Left Main Disease, and in diabetic patients, CABG seems to offer better results in patients than PCI. [ 11 ] [ 10 ]  Strong indications for CABG also include symptomatic patients and those with impaired LV function. [ 10 ]


The most common complications of CABG are postoperative bleeding, heart failure,  atrial fibrillation  (a form of arrhythmia),  stroke , kidney dysfunction, and infection of the wound near the sternum. [ 38 ]


Postoperative bleeding occurs in 2–5% of cases and may require returning to the operating room; [ 42 ]  the most common indicator is the amount of blood being drained by  chest tubes , which are inserted during the operation to drain fluid or air from the chest. Bleeding may originate from the  aorta , the anastomosis, an insufficiently sealed branch of the conduit, or from the sternum. Other causes include platelet abnormalities or  their failure to clot —perhaps due to the bypass or to the rebound  heparin  effect, which occurs when the anti-coagulant heparin is administered at the beginning of surgery and reappears in the blood after its neutralization by  protamine . [ 43 ]


Low cardiac output syndrome  (LCOS) can occur in up to 14% of CABG patients. According to its severity, LCOS is treated with  inotropes , an intra-aortic balloon pump (IABP), optimization of pre-load and afterload, or correction of blood gauzes and electrolytes. The aim is to maintain a systolic blood pressure above 90   mmHg  and a  cardiac index  of more than 2.2 L/min/m 2 . [ 38 ]  LCOS is often transient. [ 42 ]  Myocardial infarction can occur after the operation because of either technical or patient-specific factors. Its incidence is difficult to estimate due to varying definitions, but most studies place its occurrence at between 2% and 5%. The incidence is also dependent on whether it is isolated CABG (average, 4%, range, 0.3%–10%) or a combined operation (average, 2.0%, range, 0.7%–12%). [ 44 ]  New electrocardiogram features, such as Q waves or ultrasound-documented alternation of cardiac wall motions, are indicative. Ongoing ischemia might prompt emergency angiography and PCI or re-operation. [ 45 ] [ 42 ]  Immediate coronary angiography offers the most expeditious modality not only for diagnosis but also for potential reintervention. [ 46 ]  Echocardiography is less valuable for the detection or confirmation of postoperative myocardial ischemia. [ 47 ]  Arrhythmias can also occur, most-commonly  atrial fibrillation  (incidence of 20–40%) that is treated with correcting electrolyte balance, and rate and rhythm control. [ 42 ] [ 38 ]  However, arrhythmia such as ventricular tachycardia or fibrillation can be a sign of postoperative myocardial ischemia that is treated depending on the cause. [ 48 ]


Adverse neurological effects occur after CABG in about 1.5% of patients. [ 42 ]  They can manifest as type-1 deficits—focal deficits such as stroke or  coma —or type-2 global deficits such as delirium caused by CPB, hypoperfusion, or cerebral embolism. [ 38 ]  Cognitive impairment has been reported in up to 80% cases after CABG at discharge and lasts for a year in up to 40% of cases. The cause remains unclear; CPB is an unlikely cause because even in CABG patients without CPB, as in off-pump CABG, and PCI patients, the incidence is the same. [ 38 ] [ 39 ]


Infections, such as wound infections in the sternum (superficial or deep) are most commonly caused by  Staphylococcus aureus , and may complicate the post-operation process. The harvesting of both two thoracic arteries is a risk factor because it significantly impairs the perfusion of blood through the sternum. [ 38 ]   Pneumonia  can also occur. [ 42 ]  Complications in the  gastrointestinal tract  have been described and are most commonly due to medications administered during the operation. [ 39 ]


In the early 20th century, surgical interventions aiming to relieve angina and prevent death were either sympathectomy — a cut on the  sympathetic chain  that supplies the heart—or pericardial abrasion, with the hope adhesions would create significant collateral circulation. Sympathectomy produced disappointing and inconsistent results. [ 50 ]  French surgeon  Alexis Carrel  was the first to anastomose a vessel—a branch of the  carotid artery —to a native artery in the heart of a dog, but the experiment could not be reproduced. [ 51 ]  In the mid-20th century, revascularization efforts continued. Beck C. S. used a carotid conduit to connect the descending aorta to the  coronary sinus , the biggest vein of the heart. In the "Vineberg Procedure",  Arthur Vineberg  used skeletonized LITA, placing it in a small tunnel he created next to the LAD and hoping spontaneous collateral circulation would form. This occurred in canine experiments but not in humans. Goetz RH was the first to perform an anastomosis of the ITA to LAD in the 1960 using a sutureless technique. [ 50 ]


The development of coronary angiography in 1962 by  Mason Sones  helped medical doctors to identify patients in need of operation, and which native heart vessels should be bypassed. [ 52 ]  In 1964, Soviet cardiac surgeon  Vasilii Kolesov  performed the first successful internal thoracic artery–coronary artery anastomosis, followed by  Michael DeBakey  in the United States. Argentine surgeon  René Favaloro  standardized the procedure. Their advances made CABG the standard of care of CAD patients. [ 53 ]


The modern era of the CABG began in 1964 when Soviet cardiac surgeon  Vasilii Kolesov  performed the first successful internal thoracic artery–coronary artery anastomosis. The same year, American surgeon  Michael DeBakey  used a saphenous vein to create an aorta-coronary artery bypass. Argentinean surgeon  René Favaloro  advanced and standardized the CABG technique using the patient's saphenous vein. [ 53 ]


The introduction of arresting the heart during operation (cardioplegia) made CABG much less risky. A major obstacle of CABG was ischemia and infarction occurring while the heart was stopped to allow surgeons to construct the distal anastomosis. In the 1970s, potassium-based cardioplegia was used. Cardioplegia minimized the oxygen demands of the heart, thus reducing the effects of ischemia. Refinement of cardioplegia in the 1980s made CABG less risky, lowering mortality during operation. [ 54 ]


In the late 1960s, after the work of René Favaloro, the operation was performed in only a few centers, but was anticipated to more broadly change the outcome of coronary artery disease. By 1979, there were 114,000 procedures per year in the US. The introduction of percutaneous coronary intervention (PCI) did not obsolesce CABG; rates of both procedures continued to increase, but PCIs grew more rapidly. In the following decades, CABG was extensively studied and compared to PCI. The absence of a clear advantage of CABG over PCI led to a small decrease in numbers of CABGs in some countries (like the US) by 2000. In Europe—mainly Germany—CABG was increasingly performed. As of 2023 [update] , research comparing the two techniques is continuing. [ 55 ]  Meta-analysis published in 2023 suggests that CABG provides a consistent survival benefit over PCI with drug-eluting stents (DES). [ 56 ]


Favaloro's work is fundamental to the history of graft selection. He established the use of bilateral ITAs as superior to vein grafts. Surgeons examined the use of other arterial grafts—splenic, gastroepiploic mesenteric, subscapular and others—but none matched the patency rates of ITA. In 1971, Carpentier introduced the use of the radial artery, which was initially prone to failure, but the development of harvesting techniques in the following 20 years significantly improved patency. [ 57 ]


Pigs, sheep, and dogs have been used as experimental models, for the development of CABG. [ 58 ]  Performing CABG to treat a sick animal though is extremely rare.  [ 59 ]


The  Damus–Kaye–Stansel (DKS) procedure  is a cardiovascular surgical procedure used as part of the repair of some  congenital heart defects . [ 1 ]  This procedure joins the  pulmonary artery  and the  aorta  in situations where the  systemic circulation  is obstructed. It is commonly used when a patient has the combination of a small  left ventricle  and a  transposition of the great arteries  (TGA); in this case, the procedure allows blood to flow from the  left ventricle  to the aorta.


The DKS procedure is named for three physicians – Paul Damus,  Michael Peter Kaye , and H. C. Stansel – who independently reported the procedure in the literature in the 1970s. At that time, the procedure was used for patients who had TGA with a  ventricular septal defect  (VSD). By the late 2000s, the procedure was employed in situations where the right ventricle is bigger than the left ventricle and the left ventricle connects to the  pulmonary artery  instead of the  aorta ; examples include  double inlet left ventricle , TGA with  tricuspid atresia  and TGA with  hypoplastic left heart syndrome . [ 2 ]


In the original DKS procedure, surgeons separated the  main pulmonary artery  (MPA) just below the point where it divides into the right and left pulmonary arteries. The end of the MPA was then joined to the side of the  ascending aorta , allowing blood from the left heart to communicate directly with the aorta. The procedure was later accomplished via a "double-barrel" technique that resulted in a new aorta with two valves. Later, a modified DKS was reported in which an aortic flap technique was utilized. [ 3 ]


Arthur DeBoer , (July 2, 1917-July 31, 2007), was an American  cardiologist  specializing in  cardiac surgery  at  Northwestern University 's  Feinberg School of Medicine . DeBoer was one of the pioneer cardiac surgeons in  Chicago  and was on staff at Wesley Memorial Hospital (later called  Northwestern University Hospital ).  DeBoer was the hospital's first chief of cardiothoracic surgery, and performed the first  open heart operation  at Wesley Memorial Hospital in 1958. [ citation needed ]  He served as Chair of Northwestern's Department of Cardiovascular Surgery until 1975.  [ 1 ]  He was also a pioneer in research on  congenital heart defects .


He was born to John and Lucy DeBoer in  Gallatin County, Montana , and was a graduate of Montana Normal School (now  University of Montana Western ) earning his B.E. Degree in 1938.  He earned a B.S. Degree from  University of Montana  while teaching school. He graduated from  Northwestern University Medical School  in 1946 and after serving his internship at Wesley Hospital he served in the U.S. Army Medical Corps in Asia. [ 1 ]


This biographical article related to a physician in the United States is a  stub . You can help Wikipedia by  expanding it .


Decellularized homografts  are  donated  human  heart valves  which have been modified via  tissue engineering . Several techniques exist for  decellularization  with the majority based on detergent or enzymatic protocols which aim to eliminate all donor cells while preserving the mechanical properties of the remaining matrix. [ 1 ]


Aortic valve  disease affects the valve between the  left ventricle  and the  aorta , and can be present as a  congenital condition  at birth or caused by other factors. Several therapeutic options are open to patients once the indication for  aortic valve replacement  has been confirmed. One option is replacement using a  mechanical valve . [ citation needed ]


This, however, necessitates a strict lifelong  anticoagulation  regime to avoid cerebral  thromboembolism . These blood thinners hold an inherent risk for severe bleeding episodes, which affects both professional and leisure activities and the majority of patients opt to not use mechanical valves for this reason. [ citation needed ]


Biological  prostheses , i.e.  pericardial heart valves  of animal origin ( xenogenic ), offer a viable alternative. However, in particular for young patients, it has been found that xenogenic valves do not provide satisfactory durability and rapid valve degeneration can occur within months. [ 2 ]


A further avenue open to patients is a so-called  Ross operation , an extensive surgical procedure in which the diseased aortic valve is replaced by the patient's  pulmonary valve  ( autograft ). The pulmonary valve then needs to be replaced by a heart valve prosthesis. A drawback of this method is that it can frequently result in a "two-valve" diseased heart, as almost all autografts are impaired by progressive dilatation in the long term, and the pulmonary valve prosthesis, often a conventional  cryopreserved   homograft , is subject to the same rate of degeneration as all biological valves. This can thereby lead to frequent reoperations [ 3 ]  which have a substantially higher mortality rate due to postoperative adhesions. [ 4 ]


The lack of durable heart valve prostheses for young patients has driven forward research in  tissue engineering  approaches for valve replacement. Current tissue-engineering concepts are based on either artificial  polymeric  or biological scaffolds, derived from donated human tissue ( allogeneic ) or animals (xenogenic). While more readily available, there have been reports of dramatic failure in the use of xenogeneic matrices in  paediatric  patients, leading to scepticism regarding their application. [ 5 ]


Total artificial tissue-engineered heart valve concepts are currently under development and would solve many unmet clinical demands, such as the permanent availability of different sizes and lengths. These concepts have shown good results in the technical implementation of valved polymeric conduit production and have successfully been used for  in vitro  and  in vivo  seeding of different (stem) cell lines. However,  preclinical  testing in long-term animal models has yet to deliver satisfactory results due to a lack of mechanical, leading to early failure of the valvular function. [ 6 ]


Aortic valve replacement using a  homograft  in orthotopic position was first performed over 50 years ago on 24 July 1962 by  Donald Ross  at  Guy's Hospital ,  London  and has been assessed in prospective randomized studies, e.g. in comparison to the Ross procedure. [ 7 ]  Aortic valve replacement using conventional  cryopreserved  homografts is currently performed only in about 3% of all patients, mostly to treat acute aortic valve  endocarditis .1 Severe  calcification  of conventional homografts frequently occurs and is the main reason for its restrictive use, however, current guidelines confirm homografts as a valid alternative for young patients requiring anatomical reconstruction of the outflow tract. [ citation needed ]


DPH have been clinically implanted since 2002 in paediatric patients. [ 8 ]  The indications mainly include patients with pulmonary diseases such as pulmonary valve stenosis, atresia or insufficiency. They have shown excellent early to midterm clinical performance, challenging conventional  cryopreserved  homografts as the "gold standard" for pulmonary valve replacement in congenital heart disease. [ 9 ] [ 10 ]  Compared to cryopreserved homograft, decellularized pulmonary homografts have shown less degeneration and had to be explanted less. [ 11 ]  The main limitation is the low availability of such homografts and the higher costs.


DAH developed at  Hannover Medical School  (MHH) have shown sufficient mechanical stability for the systemic circulation at the greatest possible extent of antigen elimination and have been validated in long-term animal models. [ 12 ]  The first DAH was implanted in human in the year 2008. [ 13 ]


A multicenter european study of aortic valve replacement with the use of DAH in 106 pediatric patients published in 2020 showed outcome data comparable to Ross procedure and mechanical aortic valve implantation and better results compared to cryopreserved homografts. In comparison to Ross procedure, early mortality rates were lower in DAH patients (2,2% versus 4,2%), however this trend was not statistically significant. Complications due to coronary reimplantation during DAH implantation occurred in 3.8% and progressive valve degeneration in 10%. [ 14 ]


A multicenter european study in both pediatric and adult patients compared DAH with Ross procedure and showed almost identical results regarding valve degeneration and freedom from explantation. [ 13 ]


The  Dor procedure  is a medical technique used as part of  heart surgery  and originally introduced by the French cardiac surgeon Vincent Dor (b.1932). [ 1 ]  It is also known as endoventricular circular patch plasty (EVCPP).


In 1985, Dor introduced EVCPP as a viable method for restoring a dilated left  ventricle  (LV) to its normal, elliptical geometry. The Dor procedure uses a circular suture and a  Dacron  patch to correct LV  aneurysms  and exclude scarred parts of the  septum  and ventricular wall and would prove to be the best option amongst the other methods of ventricular remodeling, i.e. Cooley’s linear suturing and Jatene’s circular external suturing. [ citation needed ]  EVCPP is a relatively easy procedure that covers all aspects of successful heart restoration—restores ventricular shape, increases ejection fraction, decreases the left ventricular end systolic volume index (LVESVI), and allows for complete coronary revascularization.


The  myocardium  consists of a single, vascular, continuous tissue that wraps around itself, spiraling up from the apex of the heart, to form a helix with elliptically shaped ventricles. [ 2 ]  This spiral produces an oblique muscle fiber orientation, meaning that the fibers form a more ventricle ‘x’ shape, so that when fibers shorten 15%, it produces a 60% ejection fraction. Because of its elliptical shape and defined apex, the ventricle is subjected to a relatively low level of lateral stress.


A dilated left  ventricle  is generally due to the effects of a myocardial infarction. An occlusion, or blockage, results in either akinetic (non-beating) or dyskinetic (irregular beating) tissue downstream from the occlusion. This tissue is virtually useless. However, the volume of blood that fills the ventricle prior to contraction, or end-diastolic volume, remains constant, so the tissue that still functions has to do more work to eject the blood, as the Frank-Starling Laws demand.


The tension on the functioning tissue increases as it compensates for the work of the necrotic tissue, so, as per  Laplace's law , the radius of the ventricle increases and the thickness of the ventricular wall decreases. The apex of the heart becomes circular,  hypertrophy  ensues in the viable myocardial tissue, and the valve opening widens. As the ventricle dilates, the muscle fiber orientation, which is critical to a good ejection fraction, becomes transverse, or more horizontal. Subsequently, the ejection fraction decreases; a 15% shortening produces only a 30% ejection fraction. The lateral stress on the ventricle increases. Overall, the dilated left ventricle cannot produce a strong enough contraction.
Nonviable myocardial muscle mass (NVMMM) implies a distinct, inexpensively reproduced  signature (electrocardiography and echocardiography) of several contemporary myocardial performance determinants when compared to viable myocardial muscle mass (VMMM). Ratio between the two in heart failure on a time curve is a determinate of compensatory geometric remodeling of the myocardium.
Fick/Frank/Starling describes gas diffusion, fluid and compliance relationships of the myocardium, primarily in systole. Geometric derangement induced by nonviable myocardium (see myocardial infarction) is exponentially impacted and proportional to the weight of the performance determinant measured.  Viable/Nonviable myocardial mass fraction is substantially  reduced by surgical interventions such as Dor and Batista.


Doctors take a cardiac  MRI  to determine extent and location of the damage. Occasionally this reveals that the patient may be better suited for biventricular pacing or a  defibrillator , but if the  cardiologist  determines that the Dor procedure is necessary, then the patient must display other symptoms to indicate that they would be a good candidate, including:  angina ,  heart failure ,  arrhythmias  or a combination of the three, large areas of akinesis or dyskensis, ejection fraction of less than forty percent


Contraindications include: dysfunctional right ventricle,  pulmonary hypertension , dysfunction at the base of the heart,  systolic  pulmonary artery pressure greater than 60mmHg (in the absence of severe mitral regurgitation)


Surgeons usually perform the Dor procedure following a  coronary artery bypass graft  (CABG). EVCPP consumes only approximately twenty minutes of the three- to four-hour procedure.


To begin a basic remodeling, the surgeon makes an incision at the center of the depressed area on the LV wall and removes blood clots and endocardial scar tissue. To restore the heart to its elliptical shape, an endoventricular suture is put in place and a longitudinal tuck is made to return the cardiac apex from the posterior to the front. The suture also serves as guidance for the patch location. The surgeon then inserts a balloon into the ventricular cavity to ensure correct size and sutures a Dacron patch, deflating the balloon and removing it before complete closure. The non-viable fibrous tissue is pulled over the patch, and surgical glue is occasionally used to complete the closure.
When the  lesion  is placed on the anteroseptoapical wall of the heart, it will include the  septum  and apex more extensively than the lateral wall. As a result, the suture is placed deeply within the septum, and the new neck of the suture, which holds the Dacron patch, extends from the septum. Dor explicates this procedure in detail.
When the lesion is placed on the posterolateral wall of the heart, a triangular patch is used and stabilized by the posterior  mitral annulus . This placement of the lesion allows for mitral valve replacement to be easily conducted by the transventricular approach. (The surgeon does not have to incise the atrium, rather can replace the valve through the already incised ventricle.)


It is recommended that the patient be placed on a mild anti-coagulant post operation to reduce the risk of blood clots. Some surgeons suggest the use of stronger anti-coagulants.


The disadvantage to the Dor procedure is that it places synthetic tissue inside the LV cavity. However, it is possible to replace the Dacron patch with autologous tissue. The surgeon can make a semicircular patch, mobilized with a septal hinge, out of the endocardial scar or use autologous patches of the  pericardium .


The Dor procedure requires a hospital stay of approximately 8 days, which is only one day longer than CABG, and the early mortality rate is about 5.6%. Post-operation, the patient does not have any lifestyle constraints other than those associated with CABG.  There is a 4% chance the patient will require another cardiac operation: 18% of patients who underwent CABG had recurrent heart failure. [ 3 ]  Because the Dor procedure restores the left ventricle to its correct, elliptical orientation, it results in a mean ejection fraction increase of 12.5%. This number continues to improve over the patient’s lifetime, and patients can expect to live an extra 4–10 years, which is 3.3% longer than CABG alone with virtually no extra risk. [ 3 ]


Vessel harvesting  is a  surgical technique  that may be used in conjunction with a  coronary artery bypass graft  (CABG). For patients with  coronary artery disease , a  vascular bypass  may be recommended to reroute blood around blocked arteries to restore and improve  blood flow  and  oxygen  to the heart. To create the  bypass graft , a surgeon will remove or "harvest" healthy blood vessels from another part of the body, either  arteries  from an arm or the chest, or  veins  from a leg. [ 1 ]  This vessel becomes a  graft , with one end attaching to a blood source above and the other end below the blocked area, creating a "conduit" channel or new blood flow connection across the heart.


The success of a coronary artery bypass graft may be influenced by the quality of the conduit and how it is handled or treated during the vessel harvest and preparation steps prior to grafting.


Success can be measured in terms of:


Coronary artery bypass graft surgery has been in practice since the 1960s. Historically, vessels—such as the  great saphenous vein  in the leg or the  radial artery  in the arm—were obtained using a traditional "open" procedure that required a single, long incision from groin to ankle, or a "bridging" technique that used three or four smaller incisions. [ citation needed ]


The most minimally invasive technique is known as  endoscopic vessel harvesting  (EVH), often described as  endoscopic vein harvesting  when a  saphenous vein  is used. This type of procedure requires a single 2 cm incision plus one or two smaller incisions of 2–3 mm in length.


Each method involves carefully cutting and sealing off smaller blood vessels that branch off the main vessel conduit prior to removal from the body. This practice does not harm the remaining blood vessel network, which heals and maintains sufficient blood flow to the  extremities , allowing the patient to return to normal function without noticeable effects. [ citation needed ]


There is no evidence on the risk of surgical site infection and wound dehiscence when using staples or sutures to close the wound after vein graft harvesting. [ 2 ]


Endovascular vessel harvesting (EVH) uses small incisions and specialized  minimally invasive  instruments to internally view, cut and seal side branches and remove the healthy blood vessel with minimal trauma to the vessel or surrounding tissues. In  clinical studies , EVH has shown important benefits, including a reduced risk of infection [ 3 ] [ 4 ]  and wound complications; [ 3 ] [ 5 ] [ 6 ] [ 7 ] [ 8 ] [ 9 ] [ 10 ] [ 11 ] [ 12 ] [ 13 ] [ 14 ]  less postoperative pain and swelling; [ 5 ] [ 15 ] [ 16 ]  and faster recovery [ 8 ] [ 11 ] [ 17 ] [ 18 ] [ 19 ]  with minimal scarring. [ 16 ] [ 17 ]  The reduction in pain allows patients to get back on their feet and return to normal mobility much sooner, [ 11 ] [ 17 ] [ 18 ] [ 19 ]  and have a reduced length of hospital stay. Thus they may be able to begin their cardiac rehabilitation program sooner.


Developed in 1995, adoption of EVH accelerated in 2005 after the International Society for Minimally Invasive Cardiothoracic Surgery (ISMICS) concluded that EVH should be the standard of care for vessel harvest. [ 20 ] [ 21 ]  EVH is now the de facto standard of care, and is performed at most hospitals in the United States. However, a 2009 study published by Dr. Renato Lopes et al. in the  New England Journal of Medicine  concluded that the clinical outcomes of EVH were inferior to open vessel harvesting (OVH), [ 22 ]  prompting a flurry of articles in mainstream media. This study was performed between 2002 and 2007. Some clinicians challenged the study's conclusion, while others questioned the  methodology  of the study. Other seasoned clinicians wondered if EVH adoption and practitioners' experience have affected the data, as practitioners' experiences, techniques and technologies have evolved since the study began in 2002. Many clinicians called for more long-term studies to be conducted.


In randomized clinical trials as well as other studies looking specifically at EVH, [ 6 ] [ 16 ] [ 17 ] [ 18 ] [ 23 ] [ 24 ] [ 25 ] [ 26 ]  the endoscopic harvesting technique has been found to offer comparable graft patency at six months—meaning that, in these studies, EVH did not compromise the grafted vessel's ability to remain open and unblocked.


In 2011, a large study by Dr. Lawrence Dacey et al. was published in  Circulation  supporting the use of endoscopic vessel harvesting in  cardiac surgery . [ 27 ]  The study compared more than 8,500  propensity-adjusted  patients and revealed that EVH significantly reduced wound complications without compromising long-term survival or freedom from repeat revascularization. These findings contradicted the conclusion drawn by Lopes et al. that EVH is inferior to OVH with respect to long-term survival. EVH was not associated with increased mortality or need for repeat revascularization at four years follow up. [ 27 ]  An accompanying editorial in  Circulation  further concluded that "EVH is here to stay" and predicted that "OVH will be obsolete in a few years."  [ citation needed ]  Dacey's study supported the findings of two other large, observational studies and reaffirmed the significant benefits of EVH in reducing wound complications. [ 28 ] [ 29 ]  Totaling more than 16,000 patients tracked, these three studies provide strong evidence that EVH is a safe and viable technique to use to obtain a saphenous vein conduit for CABG surgery. Additional support that EVH does not adversely affect the integrity of the conduit and has equivalent clinical outcomes has recently been published by Krishnamoorthy et al. in  Circulation . [ 30 ]


As mentioned above, the success of  CABG  surgery may be influenced by the quality of the "conduit" vessel and how it is handled or treated during the harvest and preparation steps prior to grafting.


The harvested blood vessel used in coronary artery bypass graft surgery must be free from damage to ensure proper long-term function and good patient outcomes. [ 31 ]  Conduit quality is a significant factor in long-term patient results. Conduit quality is not always visibly evident when looking at the exterior of the harvested vessel. Damage to the  endothelium , the interior of the vessel, has been shown to increase the likelihood of graft occlusion or blockage. [ 32 ] [ 33 ]  Specifically, damage can be caused during the procedure by:


To preserve and optimize conduit quality, clinical specialists take care to avoid unnecessary thermal injury, overhandling and overdistension, and ensure proper storage conditions for the harvested vessel.


Thermal Injury


Comprehensive training and a careful approach are needed when cutting and removing side branches from the main vessel being harvested. As branches are cut, they must be sealed, or cauterized, to prevent bleeding after disconnection from the main vessel. In surgical practice it is common to use a form of heat or electrical energy to  cauterize , or seal tissues in order to stop bleeding. If not properly controlled, the application of heat or energy to seal off the branch vessels can cause unintended thermal injury to the surrounding cells including the  endothelium  of the main vessel or conduit.


There are two main forms of electrical energy used for cutting and sealing off branch vessels during harvesting: bipolar radio frequency (RF) and direct current (DC).


Bipolar RF


Bipolar RF tools pass  alternating electric current  (AC) through the tissue – in this case, the branch vessel – located between two electrodes. As the energy passes through the vessel tissue, water molecules within the cells begin to vibrate rapidly, creating heat, resulting in tissue  vaporization  and  coagulation . The amount of cutting (vaporization) and sealing (coagulations) is defined by the wave form of the RF energy passed through the tissue.


Direct Current


With  direct current  devices, current flows to the heating elements contained within a set of "jaws" that clamp down on the branch vessel. The amount of heat generated by the heating elements defines the cutting and sealing. The combination of the heat and pressure results in a single, simultaneous cut-and-seal motion.


The distance between the location at which the side branch is cut and the main conduit is especially critical to minimize thermal injury to the main vessel during dissection. On some devices, a mechanical feature is used to physically distance the main conduit from the cautery device.


Overhandling


It is important to minimize handling, which may damage or cause strain on the internal endothelial layer of the conduit. Harvester training and experience reduce the likelihood of damage. The risk of damage can also be lessened with techniques such as EVH (rather than bridging), or by using EVH devices that minimize the amount of torque or stretch to the main conduit during harvesting.


Overdistension


When a vessel is prepared for use as a bypass graft, a standard syringe is typically used to flush the vessel and check for leaks. Using uncontrolled pressure to flush or clear the vessel can result in damage to the internal cellular lining of the vessel, known as the endothelium. [ 34 ]  Limiting the maximum pressure that can be applied to the vessel may prevent injury and improve the overall quality and long term patency of the graft. Pressure-limiting syringes are available, and they have been clinically shown to protect against overdistension. [ 35 ]


Storage Conditions


Studies have indicated that endothelium and  smooth muscle  cells are affected by the type of storage solution, and may play a role in long-term vessel  patency . [ 36 ]


EuroSCORE  (European System for Cardiac Operative Risk Evaluation) is a risk  model  which allows the calculation of the risk of death after a heart operation. The model asks for 17 items of information about the patient, the state of the heart and the proposed operation, [ 1 ]  and uses logistic regression to calculate the risk of death. [ 2 ]  It is free to use online.


First published in 1999, [ 3 ]  the model has been adopted worldwide, becoming the most widely used risk index for  cardiac surgery , [ 4 ]  and its use is believed to have contributed substantially to the improvement in the results of heart surgery seen at the beginning of the millennium. The original models are now aging, [ 5 ]  and a new model - EuroSCORE II - was announced at the EACTS meeting in Lisbon in 2011 and published in the  European Journal of Cardiothoracic Surgery  in April 2012. The updated calculator is available online at the official EuroSCORE website.


EuroSCORE II has substantially improved the calibration of the older models and at least maintained and perhaps further improved on their  discriminatory  power. It has largely replaced the two older models of EuroSCORE and is now the predominant worldwide heart surgery risk model. [ citation needed ]


Risk models are used for two main reasons. The first is that a risk model such as EuroSCORE allows the calculation of the risk of death before undertaking a heart operation. This is important as it serves to guide the clinician and the patient about the advisability of an operation by helping to weigh the risk against the benefits. The second is as a method of quality control. By calculating the expected risk of death for a population of patients having heart operations, this can be compared with the number of actual deaths. This comparison can be used as a measure of the quality of the performance of the hospital, unit or surgeon in question. [ citation needed ]


The statistical basis for EuroSCORE and EuroSCORE II is the well-established  logistic regression . The available EuroSCORE papers supply logistic regression coefficients but without any measure of uncertainty and the raw data from which the calculations have been made are not available to the public.


The  Fontan procedure  or  Fontan–Kreutzer procedure  is a  palliative  surgical procedure used in children with univentricular hearts. It involves diverting the  venous   blood  from the  inferior vena cava  (IVC) and  superior vena cava  (SVC) to the  pulmonary arteries . The procedure varies for differing congenital heart pathologies. For example, in  tricuspid atresia , the procedure can be done where the blood does not pass through the morphologic  right ventricle ; i.e., the systemic and pulmonary circulations are placed in series with the functional single ventricle. By contrast, in  hypoplastic left heart syndrome , the heart is more reliant on the more functional right ventricle to provide blood flow to the systemic circulation. The procedure was initially performed in 1968 by  Francis Fontan  and Eugene Baudet from Bordeaux, France, published in 1971, simultaneously described in July 1971 by Guillermo Kreutzer from Buenos Aires, Argentina, presented at the Argentinean National Cardilogy meeting of that year and finally published in 1973. [ 1 ] [ 2 ]


The Fontan Kreutzer procedure is used in pediatric patients who possess only a single functional ventricle, either due to lack of a heart valve (e.g.  tricuspid  or  mitral atresia ), an abnormality of the pumping ability of the heart (e.g.  hypoplastic left heart syndrome  or  hypoplastic right heart syndrome ), or a complex congenital  heart disease  where a bi-ventricular repair is impossible or inadvisable. The surgery allows blood to be delivered to the lungs via central venous pressure rather than via the right ventricle. [ 3 ]  Patients typically present as neonates with cyanosis or congestive heart failure. [ 4 ]  Fontan completion is usually carried out when the patient is 2–5 years of age, but is also performed before 2 years of age. [ 5 ] [ 6 ]


There are four variations of the Fontan procedure: [ 7 ]


The  Fontan-Kreutzer  procedure is the third procedure in the staged surgical palliation. [ 8 ]  It is performed in children born with congenital heart disease without two functional ventricles and an effective parallel blood flow circuit. [ 9 ]


The first stage is known as the  Norwood  procedure. This stage generally involves combining the pulmonary artery and aorta to form a larger vessel for blood to get to the body. An artificial tube or shunt can be placed from this larger vessel to the pulmonary arteries so that blood can get from the heart to the lungs. The wall between the left and right atrium can be removed to allow the mixing of oxygenated and de-oxygenated blood. [ 10 ] [ 11 ] [ 12 ]


The second stage is called the  hemi-Fontan  or the  Bidirectional Glenn  procedure . This intermediary stage incorporates the shifting of oxygen-poor blood from the top of the body to the lungs. [ 13 ]  The  superior vena cava  (SVC), which carries blood returning from the upper parts of the body, is disconnected from the heart and instead redirects the blood into the pulmonary arteries. [ 13 ]  The  inferior vena cava  (IVC), which carries blood returning from the lower body, continues to connect to the  right atrium . [ 14 ] [ 12 ]


The third stage is called the  Fontan-Kreutzer  procedure  which involves redirecting the blood from the  inferior vena cava  to the lungs. [ 8 ]  At this point, the oxygen-poor blood from upper and lower body flows through the lungs without being pumped (driven only by the pressure that builds up in the veins or central venous pressure). This improves the lower than normal oxygen levels and results in one functional ventricle that is responsible  for supplying blood to the rest of the body. There are currently three various modern techniques for the Fontan procedure which include: Atriopulmonary connection, lateral tunnel total cavopulmonary connection, and extracardiac conduit.


After Fontan Kreutzer completion, blood must flow through the lungs without being pumped by the heart.  Therefore, children with high  pulmonary vascular resistance  may not tolerate a Fontan procedure.  Often,  cardiac catheterization  is performed to check the resistance before proceeding with the surgery.  This is also the reason a Fontan procedure cannot be done immediately after birth; the pulmonary vascular resistance is high  in utero  and takes months to drop.
Fontan procedure is also contraindicated in those with pulmonary artery hypoplasia and significant mitral insufficiency. [ citation needed ]


In the short term, children can have trouble with  pleural effusions  (fluid building up around the lungs).  This can require a longer stay in the hospital for drainage with  chest tubes .  To address this risk, some surgeons make a fenestration from the venous circulation into the atrium.  When the pressure in the veins is high, some of the oxygen-poor blood can escape through the fenestration to relieve the pressure.  However, this results in  hypoxia , so the fenestration may eventually need to be closed by an  interventional cardiologist .


In a 2016 review, Dr. Jack Rychik, head of the Single Ventricle Survivorship Program at  Children's Hospital of Philadelphia  summarized the long-term consequences of Fontan circulation as an "indolent and progressive state of heart failure" with predictable long-term consequences on several organ systems. [ 15 ]  Chronic  venous hypertension  from the stasis and lowered cardiac output are assumed to be at the root of lymphatic complications such as  chylothorax ,  protein losing enteropathy  and  plastic bronchitis . These complications may occur in the immediate post-operative period as well as in the medium and long term. New interventional and surgical strategies have been investigated to relieve the lymphatic complications associated with the Fontan circulation. [ 16 ]  Concerns about damage to the liver have emerged more recently, as the Fontan circulation produces congestion and  lymphedema  in this organ. This can lead towards progressive  hepatic fibrosis  and other complications of  Fontan-associated liver disease . [ 17 ]  Screening protocols and treatment standards are emerging in the light of these discoveries. [ 15 ]


Because of structural and electrochemical changes related to scarring after the procedure,  arrhythmias  are common.  Pacemakers  are placed in as many as 7% of patients who undergo the Fontan procedure. [ 18 ]  While the need for pacemakers may be related to the underlying cardiac anomaly, there is sufficient evidence that the surgery itself lead to the need for cardiac pacing.


The Fontan procedure is  palliative  — not curative — but more than 80% of the cases  can result in normal or near-normal growth, development, exercise tolerance, and good quality of life. [ 19 ]  However, 10% or more of patients may eventually require  heart transplantation , [ 20 ]  and given the long-term consequences of chronic venous hypertension and insidious organ damage, freedom from morbidity is unlikely in the long term. New approaches to the management of failing Fontans or other clinical deterioration have included lymphatic decompression surgical procedures & intervention,  Ventricular assist devices  or other mechanical support therapies as either bridge to transplantation or destination therapies. [ 21 ]


Renal complications may occur. This is attributed to the circulatory changes in blood flow as well as possible exposure to nephrotoxic medications, iodine contrast agents, and long term cyanotic and ischemic nephropathy. Abnormalities including chronic kidney disease and impaired renal function have been shown with measured renal function. [ 22 ]  Popular markers, such as proteinuria and microalbuminuria, are used in the measurement renal function.


It is estimated in 2018 there was an 85% for a survival rate of thirty years following a Fontan procedure and there are approximately 50,000 to 70,000 people in the world with Fontan circulation. [ 23 ]  It is approximated that 40% of people with Fontan circulation are ≥18 years of age. [ 22 ]


A normal heart system has a series circuit with the right ventricle pumping blood into the pulmonary circulation. After exchanging gases, the blood is delivered to the left ventricle (and systemic arteries) through the pulmonary veins. In Fontan circulation, the right ventricle does not exist (or is bypassed), and the venae cavae are attached directly to the pulmonary artery. [ 24 ]  After oxygenation, the blood is pumped into the aorta by the unique, single ventricle. Because of the missing right ventricle, the force driving blood through the lungs is strongly reduced. This causes engorgement of the venous circulation, the most frequent complication of the Fontan procedure.


Fontan circulation can influence the  peripartum  or pregnant physiologic states. Pregnancy has historically been discouraged in Fontan patients due to high rates of miscarriage, cardiovascular compromise, or increased mortality. Many complications have been attributed to flawed placental function. However, improvements of the Fontan operation have resulted in pregnancies with lower incidence of heart and vascular compromise in the mother. [ 25 ]  Complications that may occur in the fetus may include, but are not limited to: oligohydramnios, preterm birth, low birth weight, small size for gestational age, or still birth. Maternal complications can include, but are not limited to: heart failure, thromboembolism, arrhythmias, and preeclampsia. [ 22 ]


The Fontan procedure was initially described in 1971 by  Dr. Francis Fontan  (1929–2018) from Bordeaux, France.  Prior to this, the surgical treatment for tricuspid atresia consisted of creating a  shunt  between a systemic artery and the  pulmonary artery  ( Blalock-Taussig shunt ) or the  superior vena cava  and the pulmonary artery (Glenn shunt).  These procedures were associated with high mortality rates, commonly leading to death before the age of one year. [ 26 ]    In an attempt to improve this, Fontan was engaged in research between 1964 and 1966 endeavouring to fully redirect flow from the superior and inferior vena cavae to the pulmonary artery. [ 27 ]  His initial attempts in dogs were unsuccessful and all experimental animals died within a few hours; however, despite these failures, he successfully performed this operation in a young woman with  tricuspid atresia  in 1968 with Dr. Eugene Baudet. [ 26 ]  The operation was completed on a second patient in 1970, and after a third case the series was published in the international journal  Thorax  in 1971. [ 28 ]  Dr. Guillermo Kreutzer from Buenos Aires, Argentina (b. 1934), without any knowledge of Fontan's experience, performed a similar procedure in July, 1971 without placing a valve in the Inferior Vena Cava inlet and introduced the concept of "fenestration" – leaving a small atrial septal defect to serve as a pop-off valve for the circulation. [ 29 ] [ 26 ]  Techniques have been improved to include the lateral tunnel and use of an extracardiac conduit for congenital heart diseases beyond tricuspid atresia (hypoplastic left heart syndrome, etc). [ 30 ]


Glenn procedure  is a  palliative   surgical procedure  performed for patients with  Tricuspid atresia . It is also part of the surgical treatment path for  hypoplastic left heart syndrome  and  hypoplastic right heart syndrome .  [ 1 ] [ 2 ] [ 3 ]  This procedure has been largely replaced by  Bidirectional Glenn procedure . [ citation needed ]


It connects the superior  vena cava  to the right pulmonary artery. [ 4 ]


Bartley P. Griffith  (born 1949) is an American  heart surgeon . [ 2 ]


Griffith joined Muhammad Mohiuddin's MD Xenoheart laboratory in 2018. Together, they were able to demonstrate that the heart of a genetically altered pig could support life when transplanted into an orthotopic position in the chest for up to 9 months. Griffith and Mohiuddin performed the first successful  xenotransplantation  of a  genetically modified  pig heart to a human on January 7, 2022. [ 3 ]  The recipient was 57-year-old David Bennett Sr. The procedure occurred at the  University of Maryland Medical Center . [ 4 ]  Due to complications, David Bennett Sr died on March 8, 2022. [ 5 ]


On September 20, 2023, Bartley P. Griffith performed his second pig heart transplant. [ 6 ]


This biographical article related to medicine in the United States is a  stub . You can help Wikipedia by  expanding it .


A  heart transplant , or a  cardiac transplant , is a  surgical   transplant  procedure performed on patients with end-stage  heart failure  or severe  coronary artery disease  when other medical or surgical treatments have failed. As of 2018 [update] , the most common procedure is to take a functioning  heart , with or without both lungs, from a recently deceased  organ donor  ( brain death  is the standard [ 1 ] ) and implant it into the patient. The patient's own heart is either removed and replaced with the donor heart ( orthotopic procedure ) or, much less commonly, the recipient's diseased heart is left in place to support the donor heart (heterotopic, or "piggyback", transplant procedure).


Approximately 3,500 heart transplants are performed each year worldwide, more than half of which are in the US. [ 2 ]  Post-operative survival periods average 15 years. [ 3 ]  Heart transplantation is not considered to be a cure for heart disease; rather it is a life-saving treatment intended to improve the quality and duration of life for a recipient. [ 4 ]


American medical researcher  Simon Flexner  was one of the first people to mention the possibility of heart transplantation. In 1907, he wrote the paper "Tendencies in Pathology," in which he said that it would be possible one day by surgery to  replace diseased human organs  – including arteries, stomach,  kidneys  and heart. [ 5 ]


Not having a human donor heart available,  James D. Hardy  of the  University of Mississippi Medical Center  transplanted the heart of a chimpanzee into the chest of dying  Boyd Rush  in the early morning of Jan. 24, 1964. Hardy used a defibrillator to shock the heart to restart beating. This heart did beat in Rush's chest for 60 to 90 minutes (sources differ), and then Rush died without regaining consciousness. [ 6 ] [ 7 ] [ 8 ]  Although Hardy was a respected surgeon who had performed the world's first human-to-human lung transplant a year earlier, [ 9 ] [ 10 ]  author Donald McRae states that Hardy could feel the "icy disdain" from fellow surgeons at the Sixth International Transplantation Conference several weeks after this attempt with the chimpanzee heart. [ 11 ]  Hardy had been inspired by the limited success of  Keith Reemtsma  at  Tulane University  in transplanting chimpanzee kidneys into human patients with kidney failure. [ 12 ]  The consent form Hardy asked Rush's stepsister to sign did not include the possibility that a chimpanzee heart might be used, although Hardy stated that he did include this in verbal discussions. [ 7 ] [ 12 ] [ 13 ]  A  xenotransplantation  is the technical term for the transplant of an organ or tissue from one species to another.


Dr Dhaniram Baruah  of  Assam , India was the first heart surgeon to transplant a pig's heart in human body. [ 14 ]  However the recipient died subsequently. The world's first successful pig-to-human heart transplant was performed in January 2022 by surgeon  Bartley P. Griffith  of USA. [ 15 ]


The world's first human-to-human heart transplant was performed by  South African  cardiac surgeon  Christiaan Barnard  utilizing the techniques developed by American surgeons  Norman Shumway  and  Richard Lower . [ 16 ] [ 17 ]  Patient  Louis Washkansky  received this transplant on December 3, 1967, at the  Groote Schuur Hospital  in  Cape Town , South Africa. Washkansky, however, died 18 days later from  pneumonia . [ 16 ] [ 18 ] [ 19 ]