Historically, open vascular surgical approaches were required for all critically advanced atherosclerotic disease. An  endarterectomy  is a large operation, where blood flow is temporarily stopped using clamps, the vessel is cut open, the plaque removed and then the vessel resealed. If an occlusion is too dense or complex, a bypass could also be performed, where two segments of vessel are bridged by an additional vein or synthetic graft.
Modern endovascular approaches to treating atherosclerosis can include combinations of angioplasty, stenting, and atherectomy (removal of plaque).


There are several systems for staging PAD, but an often used scale is the revised Rutherford classification. [ 75 ] [ 88 ]  Plaque and blood flow can be evaluated using  ultrasound ,  CT angiography , MR angiography, and catheter-based angiography to establish anatomic segments of disease. The severity of ischemia can be evaluated by correlating symptoms and non-invasive physiologic vascular studies including toe pressures, TCPO2, and skin perfusion studies.


Certain monitored exercises, such as walking regimens, have been shown to significantly improve walking distance especially when used consistently for at least six months. When medical management fails, vascular interventional radiologists can attempt to restore blood flow to extremities using angioplasty and stenting. Sometimes repeat interventions are required. The goal of therapy is to maintain perfusion, avoid amputation and preserve the limb structure and function.


Aneurysm  refers to pathologic dilation of an artery to greater than 1.5 times its normal size.  True vascular aneurysms are due to degenerative processes in the wall of the artery. Aneurysms can be solitary or multiple and are sometimes found in association with various clinical syndromes, including forms of vasculitis or connective tissue diseases. Aneurysms are typically classified by major shapes, either fusiform (tubular) or saccular (eccentric).  Ectasia  is another broad term for an enlarged vessel, but is not necessarily pathological. Rupture is a dreaded complication of aneurysms that can lead to extensive, difficult to control bleeding. Aneurysms can also clot, or  thrombose , and rapidly occlude the involved vessel, leading to acute distal ischemia.


A variety of endovascular grafts are available, and each has advantages and disadvantages depending on the characteristics of the aneurysm and patient. [ 89 ]


Dissection refers to a tear in the inner layer of the arterial wall. Blood pumps into this defect and dissects its way between the layers in the wall of an artery, creating a false channel separate from the true arterial lumen. Dissections can develop due to trauma, spontaneously due to high blood pressure and native vascular disease, or in some cases as a complication of prior surgical or endovascular treatment.


When an arterial dissection expands, it can restrict normal flow through the affected artery or potentially block the origin of a branch vessel—this can compromise distal perfusion in either case. When acute and symptomatic, this is an emergency that requires prompt treatment.


However, as medical imaging has improved, chronic, asymptomatic dissections have also been discovered, and in some cases these may be safely managed with blood pressure control, follow-up imaging and proper counseling for the warning signs of potential ischemia.


Dissections can occur in any artery and are named for their vessel of origin.  Aortic dissections  can be further classified and treated depending on whether they involve the thoracic aorta, the abdominal aorta or both. Classic pain related to acute aortic dissections is described as "tearing" or "ripping" and possibly radiating to a patient's back. Acute aortic dissection can be difficult to diagnose but is more common than aortic aneurysm rupture.


Thoracic aortic dissections are further characterized with the Stanford classification. [ 92 ]  Type A dissections involve the root and ascending aorta. These require prompt treatment, which currently is mostly surgical in nature.  Type B dissections begin in the distal aortic arch beyond the left subclavian artery origin, and may often be addressed with pain medication and blood pressure control. If the type B aortic dissection results in poor circulation to the intestines, kidneys or legs it often requires urgent endovascular repair with endografts and/or fenestrations. If a type B aortic dissection has ruptured, or has features that indicate impending rupture, they are urgently repaired too.


Dissections can also arise in virtually any other artery. Carotid artery dissection, for example, places patients at increased risk for stroke and may extend further into the blood vessels within the brain.  Vertebral artery dissection  are less common but also dangerous for similar reasons. Mesenteric artery dissection may limit the blood supply to the intestines. Renal artery dissections can decrease blood flow to the kidneys and contribute to hypertension. [ 93 ]  Peripheral arterial dissections can be found elsewhere in the arms and legs. These dissections can occur primarily due to focal traumas, underlying vascular disease, or as an extension of a larger, complex aortic dissection that tears further into these smaller branches.


Treatment of dissections depends on several factors, including the location, extent, how long it has been developing (acute or chronic) and whether it is limiting perfusion. Surgical approaches to dissections can include reconstructing the aorta, surgical bypass and surgical fenestration.  Like other arterial disorders, endovascular approaches to dissection such as stent-grafting [ 94 ]  and percutaneous fenestration [ 95 ]  can be utilized, either primarily or in combination with surgery depending on the complexity of the dissection.


Penetrating aortic ulcer (PAU) is an advanced focal form of atherosclerosis, most often encountered in the aorta. [ 96 ]  It starts as a small plaque in the inner-most layer of the aorta called the intima, but the inflammatory process ulcerates and penetrates through this layer into the media. While PAU is considered a distinct entity, many think this is a precursor lesion to dissection or aneurysm. [ citation needed ]  Along with intramural hematoma, aneurysm and dissection, PAU is recognized as one of several  acute aortic syndromes —a spectrum of related conditions correlated to potential aortic rupture. They thus have a high potential morbidity and mortality, and should at least be followed closely.


Acute or active bleeding can occur throughout the human body due to a variety of causes. Interventional radiologists can address bleeding with embolization, usually with small plastic particles, glues or coils. Traumatic rupture of a blood vessel, for example, may be addressed this way if a patient is at risk of fatal bleeding. This has revolutionized medicine and interventional radiologists commonly treat refractory nose bleeds, excessive coughing of blood, intestinal bleeding, post-pregnancy bleeding, spontaneous intra-abdominal on intra-thoracic bleeding, bleeding related to trauma and post-surgical bleeding. In some instances where severe bleeding is anticipated, such as in complex surgery or the excision of a highly vascular tumor, interventional radiologists may embolize certain target blood vessels prior to the operation to prevent major blood loss.


Transplant organs rely on healthy blood supply to survive. In some instances, the arteries that feed a transplant may narrow, typically where the donor vessel is sewn to the recipient. Interventional radiologists evaluate the blood supply of these patient's and may use balloons or stents to open narrowed vessels and keep the transplant organ functional.


The  veins  of the human body are responsible for returning de-oxygenated blood back to the heart. Like a rock rolling down a hill, blood flows from the highest pressure (the blood in the aorta) to the lower venous pressure (the blood in the vena cava as it empties back to the heart.) Unlike arteries, veins are thin walled and distensible, allowing them to accommodate large volumes of blood without significant changes in pressure. In fact, the venous system is so low pressure that veins have valves to keep blood from flowing backward. The motion of the human body helps pump blood through the veins—squeezing leg muscles while walking, for instance, helps push venous blood back up to the heart against the pull of gravity. Unfortunately, without this extra push some blood can sit stagnant in veins, leading to a multitude of clinical problems. The largest vein in the body is the vena cava. The superior vena cava (SVC) drains blood from the top half of the body while the inferior vena cava (IVC) drains blood from below the diaphragm. Elsewhere in the body, veins can be categorized into superficial, primarily associated with the skin and soft tissues, or deep veins, which drain muscles and organs.


Chronic kidney disease  (CKD or chronic renal disease) is a condition in which there is a progressive loss of kidney function. It has numerous recognized causes and risk factors. CKD affects approximately 14% of the world population, and over 600,000 people in the United States alone.  There are five recognized stages of CKD; the fifth stage is also called end-stage renal disease (ESRD) and invariably requires some form of  renal replacement therapy .


Around the turn of the 20th century, breakthroughs in understanding of renal physiology led many to believe that dialysis using  artificial kidneys  was a potential cure for renal disease. Over 100 years later, the only available curative, renal replacement therapy for CKD is kidney transplantation. However, many patients can live for decades utilizing dialysis.


Dialyzer technology initially outpaced the ability of clinicians to apply it to patients. In the 1920s, the first dialysis catheter was created using thin fragile glass tubes. Early methods required surgical incision to reach large vessels, which carried a large risk of major bleeding. The first somewhat permanent, reliable dialysis access, the  Scribner Teflon shunt , was invented nearly 40 years later and allowed a patient with  kidney failure  to survive 11 more years. As medicine and surgery have grown more sophisticated, more patients now live with chronic renal disease than ever before. The most common type of dialysis in the United States is hemodialysis, which can be performed through several types of vascular access. The arteriovenous fistula (AVF) is the preferred method.  Arteriovenous fistula are created surgically by directly connecting an artery and a vein, most commonly in the arm. An arteriovenous graft (AVG) relies on the same principle but bridges the gap between the artery and vein with a medical-grade prosthetic shunt. Over time, altered flow mechanics can result in changes within the involved vessels.  Vascular narrowing, thrombosis, aneurysms and pseudoaneurysms are commonly encountered complications over the life of an AVF or AVG. Interventional radiologists can use angiography to evaluate these structures (commonly called a istulogram) and treat dysfunctional access with angioplasty, stenting, and thrombectomy. Most patients require regular evaluation and treatment to keep their access working.  When possible, AVFs are preferred to AVGs due to their relatively lower complication rate and longer patency. The Fistula First initiative works to promote physician and patient awareness about the benefits of first attempting hemodialysis through a fistula. [ 97 ]   There are a few devices (endo AVF) that are being utilized by interventional radiologists to percutaneously create fistulas in a minimally invasive fashion.


Dialysis catheters include temporary and tunneled large-bore central venous access lines placed for administering hemodialysis. When possible, these catheters are placed in the right internal jugular vein, but the left internal jugular and femoral veins may also be utilized. Temporary dialysis lines may be placed when patients are hospitalized and either too sick or at a high risk of bleeding. Permanent hemodialysis catheters are longer overall but a segment is tunneled through the skin of the chest, which lets the catheter lie flat and lowers the risk of infection.


Central venous access refers to a variety of intravenous catheters placed in patients requiring certain long-term medications. These are much smaller in diameter than dialysis lines, but are larger and longer than a standard intravenous line (IV.) Examples include Hickman catheters, peripherally inserted central cathethers (or PICCs), tunneled small bore central venous catheters, and mediports. These lines differ in where they are inserted but are all placed under imaging guidance and adjusted so the end of the catheter sits in the vena cava adjacent to the heart. These catheters are designed to deliver strong medications, such as chemotherapy or prolonged courses of antibiotics, which are either dosed too frequently to keep placing new IVs or are too irritating to small veins be injected through a standard IV.


Angioplasty , also known as  balloon angioplasty  and  percutaneous transluminal angioplasty  ( PTA ), is a  minimally invasive   endovascular   procedure  used to widen narrowed or obstructed arteries or veins, typically to treat arterial  atherosclerosis . [ 1 ]


A deflated balloon attached to a catheter (a  balloon catheter ) is passed over a guide-wire into the  narrowed   vessel  and then inflated to a fixed size. [ 1 ]  The balloon forces expansion of the blood vessel and the surrounding muscular wall, allowing an improved blood flow. [ 1 ]  A  stent  may be inserted at the time of ballooning to ensure the vessel remains open, and the balloon is then deflated and withdrawn. [ 2 ]  Angioplasty has come to include all manner of  vascular  interventions that are typically performed  percutaneously .


A coronary angioplasty is a therapeutic procedure to treat the  stenotic  (narrowed)  coronary arteries  of the  heart  found in  coronary heart disease . [ 1 ]  These stenotic segments of the coronary arteries arise due to the buildup of  cholesterol -laden  plaques  that form in a condition known as  atherosclerosis . [ 3 ]   A  percutaneous coronary intervention  (PCI), or coronary angioplasty with stenting, is a non-surgical procedure used to improve the blood flow to the heart. [ 1 ]


Coronary angioplasty is indicated for coronary artery diseases such as  unstable angina ,  NSTEMI ,  STEMI  and spontaneous coronary artery perforation. [ 1 ]  PCI for stable coronary disease has been shown to significantly relieve symptoms such as  angina , or chest pain, thereby improving functional limitations and quality of life. [ 4 ]


Peripheral angioplasty refers to the use of a balloon to open a blood vessel outside the coronary arteries.  It is most commonly done to treat  atherosclerotic  narrowings of the abdomen, leg and  renal  arteries caused by  peripheral artery disease . Often, peripheral angioplasty is used in conjunction with guide wire, peripheral  stenting  and an  atherectomy . [ 5 ]


Angioplasty can be used to treat advanced  peripheral artery disease  to relieve the  claudication , or leg pain, that is classically associated with the condition. [ 6 ]


The bypass versus angioplasty in severe ischemia of the leg (BASIL) trial investigated infrainguinal  bypass surgery  first compared to angioplasty first in select patients with severe lower limb ischemia who were candidates for either procedure. The BASIL trial found that angioplasty was associated with less short term morbidity compared with bypass surgery, however long term outcomes favor bypass surgery. [ 7 ]


Based on the BASIL trial, the ACCF/AHA guidelines recommend balloon angioplasty only for patients with a life expectancy of 2 years or less or those who do not have an  autogenous vein  available. For patients with a life expectancy greater than 2 of years life, or who have an autogenous vein, a bypass surgery could be performed first. [ 8 ]


Renal artery stenosis  is associated with  hypertension  and loss of  renal function . [ 9 ]  Atherosclerotic obstruction of the  renal artery  can be treated with angioplasty with or without  stenting  of the renal artery. [ 10 ]  There is a weak recommendation for renal artery angioplasty in patients with renal artery stenosis and flash edema or congestive heart failure. [ 10 ]


Carotid artery stenosis  can be treated with angioplasty and  carotid stenting  for patients at high risk for undergoing  carotid endarterectomy  (CEA). [ 11 ]   Although carotid endarterectomy is typically preferred over carotid artery stenting, stenting is indicated in select patients with radiation-induced stenosis or a carotid lesion not suitable for surgery. [ 12 ]


Angioplasty is used to treat venous stenosis affecting  dialysis  access, with drug-coated balloon angioplasty proving to have better 6 month and 12 month patency than conventional balloon angioplasty. [ 13 ]  Angioplasty is occasionally used to treat residual  subclavian vein  stenosis following  decompression surgery  for  thoracic outlet syndrome . [ 14 ]  There is a weak recommendation for deep venous stenting to treat obstructive chronic venous disease. [ 15 ]


Angioplasty requires an access vessel, typically the  femoral  or  radial artery  or  femoral vein , to permit access to the vascular system for the wires and  catheters  used. If no access vessel of sufficient size and quality is available, angioplasty is contraindicated. A small vessel diameter, the presence of posterior calcification, occlusion, hematoma, or an earlier placement of a  bypass origin , may make access to the vascular system too difficult. [ citation needed ]


Percutaneous transluminal coronary angioplasty (PTCA) is contraindicated in patients with left main coronary artery disease, due to the risk of spasm of the left main coronary artery during the procedure. [ 16 ]  Also, PTCA is not recommended if there is less than 70% stenosis of the coronary arteries, as the stenosis it is not deemed to be hemodynamically significant below this level. [ 16 ]


Access to the vascular system is typically gained  percutaneously  (through the skin, without a large surgical incision). An  introducer sheath  is inserted into the blood vessel via the  Seldinger technique . [ 17 ]   Fluoroscopic guidance  uses magnetic resonance or X-ray fluoroscopy and  radiopaque   contrast dye  to guide angled wires and  catheters  to the region of the body to be treated in real time. [ 18 ]  Tapered guidewire is chosen for small occlusion, followed by intermediate type guidewires for tortuous arteries and difficulty passing through extremely narrow channels, and stiff wires for hard, dense, and blunt occlusions. [ 19 ]


To treat a narrowing in a blood vessel, a wire is passed through the  stenosis  in the vessel and a  balloon on a catheter  is passed over the wire and into the desired position. [ 20 ]  The positioning is verified by fluoroscopy and the balloon is inflated using water mixed with contrast dye to 75 to 500 times normal  blood pressure  (6 to 20 atmospheres), with most coronary angioplasties requiring less than 10 atmospheres. [ 21 ]  A  stent  may or may not also be placed.


At the conclusion of the procedure, the balloons, wires and catheters are removed and the vessel puncture site is treated either with direct pressure or a  vascular closure device . [ 22 ]


Transradial artery access (TRA) and transfemoral artery access (TFA) are two techniques for percutaneous coronary intervention. [ 23 ]  TRA is the technique of choice for management of acute coronary syndrome (ACS) as it has significantly lower incidence of bleeding and vascular complications compared with the TFA approach. [ 23 ]  TRA also has a mortality benefit for high risk ACS patients and high risk bleeding patients. [ 23 ]  TRA was also found to yield improved quality of life, as well as decreased healthcare costs and resources. [ 23 ]


Relative to  surgery , angioplasty is a lower-risk option for the treatment of the conditions for which it is used, but there are unique and potentially dangerous risks and complications associated with angioplasty:


Angioplasty may also provide a less durable treatment for atherosclerosis and be more prone to  restenosis  relative to  vascular bypass  or  coronary artery bypass grafting . [ 28 ]  Drug-eluting balloon angioplasty has significantly less restenosis, late lumen loss and target lesion revascularization at both short term and midterm follow-up compared to uncoated balloon angioplasty for femoropopliteal arterial occlusive disease. [ 29 ]   Although angioplasty of the femoropopliteal artery with paclitaxel-coated stents and balloons significantly reduces rates of vessel restenosis and target lesion revascularization, it was also found to have increased risk of death. [ 30 ]


After angioplasty, most patients are monitored overnight in the hospital, but if there are no complications, patients are sent home the following day. [ 26 ]


The catheter site is checked for bleeding and swelling and the heart rate and blood pressure are monitored to detect late rupture and hemorrhage. [ 26 ]  Post-procedure protocol also involves monitoring urinary output, cardiac symptoms, pain and other signs of systemic problems. [ 26 ]  Usually, patients receive medication that will relax them to protect the arteries against  spasms . Patients are typically able to walk within two to six hours following the procedure and return to their normal routine by the following week. [ 31 ]


Angioplasty recovery consists of avoiding physical activity for several days after the procedure. Patients are advised to avoid heavy lifting and strenuous activities for a week. [ 32 ] [ 33 ]  Patients will need to avoid physical stress or prolonged sport activities for a maximum of two weeks after a delicate balloon angioplasty. [ 34 ]


After the initial two week recovery phase, most angioplasty patients can begin to safely return to low-level exercise. A graduated exercise program is recommended whereby patients initially perform several short bouts of exercise each day, progressively increasing to one or two longer bouts of exercise. [ 35 ]   As a precaution, all structured exercise should be cleared by a cardiologist before commencing. Exercise-based rehabilitation following percutaneous coronary intervention has shown improvement in recurrent angina, total exercise time, ST-segment decline, and maximum exercise tolerance. [ 36 ]


Patients who experience swelling, bleeding or pain at the insertion site, develop  fever , feel faint or weak, notice a change in temperature or color in the arm or leg that was used or have  shortness of breath  or chest pain should immediately seek medical advice.


Patients with stents are usually prescribed dual antiplatelet therapy (DAPT) which consists of a  P2Y12 inhibitor , such as  clopidogrel , which is taken at the same time as  acetylsalicylic acid  (aspirin). [ 37 ]  Dual antiplatelet therapy (DAPT) is recommended for 1 month following bare metal stent placement, for 3 months following a second generation drug-eluting stent placement, and for 6–12 months following a first generation  drug-eluting stent  placement. [ 1 ]  DAPT's antiplatelet properties are intended to prevent blood clots, however they also increase the risk of bleeding, so it is important to consider each patient's preferences, cardiac conditions, and bleeding risk when determining the duration of DAPT treatment. [ 37 ]  Another important consideration is that concomitant use of  Clopidogrel  and  Proton Pump Inhibitors  following coronary angiography is associated with significantly higher adverse cardiovascular complications such as major adverse cardiovascular events (MACE), stent thrombosis and myocardial infarction. [ 38 ]


Angioplasty was first described by the US  interventional radiologist   Charles Dotter  in 1964. [ 39 ]  Dotter pioneered modern medicine with the invention of angioplasty and the catheter-delivered stent, which were first used to treat peripheral arterial disease. On January 16, 1964, Dotter percutaneously dilated a tight, localized stenosis of the  subsartorial artery  in an 82-year-old woman with painful leg ischemia and gangrene who refused leg amputation. After successful dilation of the stenosis with a guide wire and coaxial Teflon catheters, the circulation returned to her leg. The dilated artery stayed open until her death from pneumonia two and a half years later. [ 40 ]  Charles Dotter is commonly known as the "Father of  Interventional Radiology " and was nominated for the  Nobel Prize  in medicine in 1978.


The first percutaneous coronary angioplasty on an awake patient was performed in Zurich by the German cardiologist  Andreas Gruentzig  on September 16, 1977. [ 41 ]


The first percutaneous coronary angioplasties in the United States were performed on the same day (March 1, 1978) by Simon H. Stertzer at Lenox Hill Hospital in New York and Richard K. Myler at St. Mary's Hospital in San Francisco. During the previous year, also at St. Mary's Hospital in San Francisco, Myler and Gruentzig had performed dilatations in the setting of bypass surgery to test the catheter concept before Gruentzig performed the first PTCA in his catheterization lab in Zurich.


The initial form of angioplasty was 'plain old balloon angioplasty' (POBA) without stenting, until the invention of bare metal stenting in the mid-1980s to prevent the abrupt closure sometimes seen with POBA. [ 1 ]


Bare metal stents were found to cause in-stent restenosis as a result of  neointimal hyperplasia  and stent thrombosis, which led to the invention of drug-eluting stents with anti-proliferative drugs to combat in-stent restenosis. [ 1 ]


The first coronary angioplasty with a drug delivery stent system was performed by Stertzer and Luis de la Fuente, at the Instituto Argentino de Diagnóstico y Tratamiento (English: Argentina Institute of Diagnosis and Treatment [ 42 ] ) in Buenos Aires, in 1999.


Ingemar Henry Lundquist  invented the over-the-wire balloon catheter that is now used in the majority of angioplasty procedures in the world. [ 43 ]


A subset of angioplasty, known as excimer laser coronary angioplasty (ELCA), uses  excimer lasers  to remove small amounts of tissue, including undilatable and uncrossable lesions, in the artery in order to allow the balloon to more effectively compress plaque into the artery walls. [ 44 ]  Such work was first developed in 1984 following earlier work in 1980–1983, when  Rangaswamy Srinivasan ,  Samuel Blum  and  James J. Wynne  at  IBM 's  T. J. Watson Research Center  observed the effect of the ultraviolet excimer laser on biological materials. Intrigued, they investigated further, finding that the laser made clean, precise cuts that would be ideal for delicate surgeries.  This resulted in a fundamental patent [ 45 ]  and Srinivasan, Blum and Wynne were elected to the  National Inventors Hall of Fame  in 2002. In 2012, the team members were honored with  National Medal of Technology and Innovation  by the  President   Barack Obama  for their work related to the excimer laser. [ 46 ]  Robert Ginsburg deployed the first used of ELCA in 1984 on a patient with severe stenosis of the deep femoral artery and a threatened limb. [ 47 ]


An  angiosome  is a three-dimensional unit of  skin  and  underlying tissues  vascularized by a source  artery , termed an  arteriosome  and drained by a vein termed a  venosome . It is a concept that is used by  plastic surgeons , and other medical disciplines like CMF,  ENT , etc., for the design and harvesting of  free flap  transplants (e.g. fibula free-flap transplant [ 1 ] ), and by  vascular surgeons  and  interventional radiologists  for the  endovascular treatment  of critical  limb ischemia .  It is an alternative model to the traditional "best vessel" model. [ 2 ]


An example is the angiosome of the  fibular artery  (also called the  peroneal artery ), that primarily vascularizes the skin of the distal two-thirds of the  lateral-posterior  aspect of the leg. Furthermore, also the underlying  fibula bone  and parts of the local muscles, like the  flexor hallucis longus muscle .


Small arteries, called  arterial perforators , branch off from the larger arteries below the deep body  fascia . These arterial perforators penetrate the deep body fascia in their course towards the skin and further ramify in the  subcutaneous tissue . A three-dimensional unit of tissue, only encompassing skin and the subcutaneous tissue – but not the tissue from below the body fascia (like muscle and bone) – primarily supplied by a dominant arterial perforator, is called a  perforasome . Although multiple other arterial perforators may also supply this unit of tissue with arterial blood, it is the dominant arterial perforator that is essential for the survival of the perforasome.


Arterial perforators can be further defined by their path, in three categories: direct-cutaneous perforator, septo-cutaneous perforator and musculo-cutaneous perforator, depending on what anatomical structure the perforator progresses through, after branching from the deep source artery.


Therefore, generally speaking, one “big” angiosome can contain multiple “smaller” perforasomes.


Atherectomy  is a  minimally invasive  technique for removing  atherosclerosis  from blood vessels within the body. It is an alternative to  angioplasty  for the treatment of  peripheral artery disease , but the studies that exist are not adequate to determine whether it is superior to angioplasty. [ 1 ]  It has also been used to treat  coronary artery disease , albeit without evidence of superiority to angioplasty. [ 2 ]


Atherectomy is used to treat  narrowing  in  arteries  caused by  peripheral artery disease  and  coronary artery disease . [ 1 ] [ 2 ]


The use of atherectomy instead of or in addition to angioplasty remains an area of controversy, as atherectomy typically involves the use of more costly disposable devices, and clear evidence to justify its use is lacking. [ 1 ]  Atherectomy has high physician reimbursement relative to angioplasty alone. [ 3 ]  According to the New York Times, ‘Medical device makers have bankrolled a cottage industry of doctors and clinics that perform artery-clearing procedures that can lead to amputations.’ [ 4 ]


Unlike  angioplasty  and  stents , which push plaque into the vessel wall, atherectomy cuts plaque from the wall of the artery. While atherectomy is usually employed to treat  arteries  it can be used in  veins  and  vascular bypass  grafts as well.


Atherectomy falls under the general category of  percutaneous   revascularization , which implies re-canalizing blocked vasculature via a needle puncture in the skin. The most common access point is near the groin through the  common femoral artery  (CFA). Other common places are the  brachial artery ,  radial artery ,  popliteal artery ,  dorsalis pedis , and others.


There are four types of atherectomy devices: orbital, rotational, laser, and directional.


The decision to use which type of device is made by the interventionist, based on a number of factors. They include the type of lesion being treated, the physician's experience with each device, and interpretation of the devices' risks and effectiveness, based on a review of the medical literature.


Directional atherectomy is an intravascular procedure guided by  optical coherence tomography  termed as  lumivascular atherectomy . [ 5 ]


Balloon-occluded retrograde transvenous obliteration  ( BRTO ) is an  endovascular procedure  used for the treatment of  gastric varices . When performing the procedure, an  interventional radiologist  accesses blood vessels using a catheter, inflates a balloon (e.g. balloon occlusion) and injects a substance into the variceal blood vessels that causes blockage of those vessels. To prevent the flow of the agent out of the intended site (variceal blood vessels), a balloon is inflated during the procedure, which occludes.


BRTO is used for the treatment of bleeding from gastric varices. In addition to  transjugular intrahepatic portosystemic shunt  (TIPS), BRTO is a first line treatment for the prevention of recurrent bleeding from gastric varices (GOV2 or IGV1). [ 1 ]  BRTO may be used for the treatment of ectopic varices. [ 1 ]


As BRTO results in a blockage of a portosystemic shunt, the procedure may result in increased portal hypertension, which may worsen esophageal varices or ascites. [ 2 ] [ 1 ]


BRTO was developed as a procedure in the early 1990s. [ 2 ]  Initially, the procedure was performed using  ethanolamine oleate  as a sclerosant. [ 2 ] [ 3 ]  Between 2006 and 2007, American physicians began using  sodium tetradecyl sulfate  (3% STS) as an alternative sclerosing agent. [ 2 ] [ 3 ]


Suvro Banerjee  is a consultant interventional  cardiologist , practicing in  Kolkata . He has worked at various hospitals in the  United Kingdom , and is a Fellow of the  Royal College of Physicians  of  London  as well as  Edinburgh . His procedural skills, among others, include coronary and peripheral  angioplasty ,  pacemaker , ICD and CRT implantation. He is the first doctor in Kolkata to successfully use the  ICD  which is the  Implantable Carvioverter Defibrillatorto  to treat a patient's abnormal heart rhythm. [ 1 ] [ 2 ]


Banerjee is a clinical examiner for the MRCP (UK) examinations in  India . He is also a postgraduate teacher in  Indira Gandhi Open University  (IGNOU). He was the Steering Committee member for The Indian Consensus Guidance on Stroke Prevention in Atrial Fibrillation (2015) and Joint Convener for the Cardiological Society of India (CSI) Guideline Committee position statement on the management of heart failure (2017). He is a member of the Editorial Advisory Board for Indian Heart Journal Interventions. Currently, he is the Overseas Regional Adviser for East Region of India and West Bengal. [ 3 ]  He has also been involved as Principal Investigator in epidemiological studies with  University of Calgary ,  Canada  and Coventry & Warwickshire NHS Trust, UK. His work on the "Prevalence, awareness and control of hypertension in the slums of Kolkata" was carried out in collaboration with Kolkata Municipal Corporation. He has been conferred the fellowship of European Society of Cardiology and the American College of Cardiology. [ 4 ]


He was the Honorary Treasurer of West Bengal Academy of Echocardiography, a post which he has held since 2013. Additionally, he was the Secretary of the Cardiological Society of India, West Bengal Branch (2017-2018).


For his philanthropic and social work, Dr. Banerjee was recognized by Rotary International as a Paul Harris Fellow in 2004. [ 5 ]  He regularly contributes to newspapers on matters of health and heart related diseases. [ 6 ]


A  biopsy  is a  medical test  commonly performed by a  surgeon ,  an interventional radiologist , or an  interventional cardiologist . The process involves the extraction of  sample   cells  or  tissues  for examination to determine the presence or extent of a disease. The tissue is then  fixed, dehydrated, embedded, sectioned, stained and mounted [ 1 ]  before it is generally examined under a  microscope  by a  pathologist ; it may also be analyzed chemically. When an entire lump or suspicious area is removed, the procedure is called an  excisional biopsy . An  incisional biopsy  or  core biopsy  samples a portion of the abnormal tissue without attempting to remove the entire lesion or tumor. When a sample of tissue or fluid is removed with a needle in such a way that cells are removed without preserving the histological architecture of the tissue cells, the procedure is called a  needle aspiration biopsy . Biopsies are most commonly performed for insight into possible  cancerous  or inflammatory conditions.


The  Arab  physician  Abulcasis  (1013–1107) developed one of the earliest diagnostic biopsies. He used a needle to puncture the  thyroid  and then characterized many types of  goiter . [ 2 ] [ 3 ]


The term  biopsy  reflects the  Greek  words  βίος   bios , "life," and  ὄψις   opsis , "a sight." [ 4 ]


The French dermatologist  Ernest Besnier  introduced the word  biopsie  to the medical community in 1879. [ 5 ]


When cancer is suspected, a variety of biopsy techniques can be applied. An  excisional biopsy  is an attempt to remove an entire lesion. When the specimen is evaluated, in addition to diagnosis, the amount of uninvolved tissue around the lesion, the  surgical margin  of the specimen is examined to see if the disease has spread beyond the area biopsied. "Clear margins" or "negative margins" means that no disease was found at the edges of the biopsy specimen. "Positive margins" means that disease was found, and a wider excision may be needed, depending on the diagnosis. [ citation needed ]


When intact removal is not indicated for a variety of reasons, a wedge of tissue may be taken in an  incisional biopsy . In some cases, a sample can be collected by devices that "bite" a sample. A variety of sizes of needles can collect tissue in the lumen ( core biopsy ). Smaller diameter needles collect cells and cell clusters,  fine needle aspiration biopsy . [ 6 ]


Pathologic  examination of a biopsy can determine whether a lesion is  benign  or  malignant , and can help differentiate between different types of cancer. In contrast to a biopsy that merely samples a lesion, a larger excisional specimen called a resection may come to a pathologist, typically from a surgeon attempting to eradicate a known lesion from a patient. For example, a pathologist would examine a  mastectomy  specimen, even if a previous nonexcisional breast biopsy had already established the diagnosis of breast cancer. Examination of the full mastectomy specimen would confirm the exact nature of the cancer (subclassification of tumor and histologic "grading") and reveal the extent of its spread ( pathologic "staging" ).


There are two types of liquid biopsy (which is not really a biopsy as they are blood tests that do not require a biopsy of tissue): circulating tumor cell assays or cell-free circulating tumor DNA tests. [ 7 ]  These methods provide a non-invasive alternative to repeat invasive biopsies to monitor cancer treatment, [ 8 ]  test available drugs against the circulating tumor cells, [ 9 ]  evaluate the mutations in cancer and plan individualized treatments. In addition, because cancer is a heterogeneous genetic disease, and excisional biopsies provide only a snapshot in time of some of the rapid, dynamic genetic changes occurring in tumors, liquid biopsies provide some advantages over tissue biopsy-based genomic testing. [ 10 ]  In addition, excisional biopsies are invasive, cannot be used repeatedly, and are ineffective in understanding the dynamics of tumor progression and metastasis. [ 11 ] [ 12 ]  By detecting, quantifying and characterisation vital circulating tumor cells or genomic alterations in CTCs and cell-free DNA in blood, liquid biopsy can provide real-time information on the stage of tumor progression, treatment effectiveness, and cancer metastasis risk. [ 13 ]  This technological development could make it possible to diagnose and manage cancer from repeated blood tests rather than from a traditional biopsy. [ 13 ] [ 14 ] [ 15 ] [ 16 ]


Circulating tumor cell tests are already available but not covered by insurance yet at  maintrac  and under development by many pharmaceutical companies. Those tests analyze  circulating tumor cells  (CTCs) [ 14 ] [ 17 ]  Analysis of individual CTCs demonstrated a high level of heterogeneity seen at the single cell level [ 18 ]  for both protein expression and protein localization and the CTCs reflected both the primary biopsy and the changes seen in the metastatic sites. [ citation needed ]


Analysis of cell-free circulating tumor DNA (cfDNA) has an advantage over circulating tumor cells assays in that there is approximately 100 times more cell-free DNA than there is DNA in circulating tumor cells. [ 7 ]  These tests analyze fragments of tumor-cell DNA that are continuously shed by tumors into the bloodstream. Companies offering cfDNA next generation sequencing testing include Personal Genome Diagnostics and  Guardant Health . [ 10 ]  These tests are moving into widespread use when a tissue biopsy has insufficient material for DNA testing or when it is not safe to do an invasive biopsy procedure, according to a recent report of results on over 15,000 advanced cancer patients sequenced with the Guardant Health test. [ 19 ]


A 2014 study of the blood of 846 patients with 15 different types of cancer in 24 institutions was able to detect the presence of cancer DNA in the body. They found tumor DNA in the blood of more than 80 percent of patients with metastatic cancers and about 47 percent of those with localized tumors. The test does not indicate the tumor site(s) or other information about the tumor. The test did not produce false positives. [ 20 ]


Such tests may also be useful to assess whether malignant cells remain in patients whose tumors have been surgically removed. [ 21 ]  Up to 30 percent are expected to relapse because some tumor cells remain. [ 22 ]  Initial studies identified about half the patients who later relapsed, again without false positives. [ 20 ]


Another potential use is to track the specific DNA mutations driving a tumor. Many new cancer medications block specific molecular processes. Such tests could allow easier targeting of therapy to tumors. [ 20 ]


For easily detected and accessed sites, any suspicious lesions may be assessed. Originally, this was skin or superficial masses.  X-ray , then later  CT ,  MRI , and  ultrasound  along with  endoscopy  extended the range. [ citation needed ]


A biopsy of the  temporal arteries  is often performed for suspected  vasculitis .
In  inflammatory bowel disease  ( Crohn's disease  and  ulcerative colitis ), frequent biopsies are taken to assess the activity of the disease and to assess changes that precede malignancy. [ 23 ]


Biopsy specimens are often taken from part of a  lesion  when the cause of a disease is uncertain or its extent or exact character is in doubt.  Vasculitis , for instance, is usually diagnosed on biopsy.


Needle core biopsies or aspirates of the pancreas may be made through the duodenum or stomach. [ 29 ]


In the case of  Wilson's disease , clinicians use biopsies to determine the  quantitative   copper  level.


After the biopsy is performed, the sample of tissue that was removed from the patient is sent to the  pathology   laboratory . A  pathologist  specializes in diagnosing  diseases  (such as  cancer ) by examining tissue under a  microscope . When the laboratory (see  Histology ) receives the biopsy sample, the tissue is processed and an extremely thin slice of  tissue  is removed from the sample and attached to a glass slide. Any remaining tissue is saved for use in later studies, if required. [ citation needed ]


The slide with the tissue attached is treated with dyes that stain the tissue, which allows the individual  cells  in the tissue to be seen more clearly. The slide is then given to the pathologist, who examines the tissue under a microscope, looking for any abnormal findings. The pathologist then prepares a report that lists any abnormal or important findings from the biopsy. This report is sent to the  surgeon  who originally performed the biopsy on the patient. [ citation needed ]


Bronchial artery  embolization  is a treatment for  hemoptysis , abbreviated as  BAE . It is a kind of catheter intervention to control hemoptysis (airway bleeding) by embolizing the  bronchial artery , which is a bleeding source. Embolic agents are particulate embolic material such as gelatin sponge or polyvinyl alcohol (PVA), and liquid embolic material such as NBCA, or metallic coils. [ 1 ]


It is said that  hemoptysis  is caused by the formation of anomalous anastomosis (bronchial artery-pulmonary artery shunt) between the  bronchial artery  and the pulmonary artery, and if the bronchial artery is embolized, hemorrhage will cease. [ 1 ]  This is a fundamental concept of BAE. Traditionally, BAE was mostly performed as an emergency hemostatic procedure. Recently, it is often performed as an elective catheter treatment to prevent recurrence after massive hemoptysis, or control chronic repetitive hemoptysis. [ 2 ]  Although it is termed bronchial artery embolization, various systemic arteries other than the bronchial artery (non-bronchial arteries) also form a shunt with the pulmonary artery and cause hemoptysis. Therefore, it is common to embolize such non-bronchial arteries, but the expression of bronchial artery embolization, BAE, rather than the universal expression "arterial embolization" is more common. [ 3 ]  The therapeutic outcomes are improving, due to the combined approach such as spreading the treatment target to non-bronchial arteries, development of 3D-CT angiography following the development of MDCT, the advancement of devices such as coils and micro-catheters, and the evolution of therapeutic strategies. BAE has become the gold standard for hemoptysis for its dramatic improvement. [ 4 ] [ 1 ]  Although the hemostatic effect is greatly affected by the underlying disease, some high-volume centers report a hemostatic rate of about 90.4% within one year of treatment, and 85.9% even in two years after treatment. [ 2 ]  The occlusion of the blood vessels in the brain, heart, and kidneys, which are supplied by the end arteries, can cause cerebral, myocardial, and renal infarctions. In BAE, both bronchial mucosal necrosis and pulmonary infarction seldom occur. [ 1 ]  It is presumed that this is because the pulmonary circulation is dually controlled by the bronchial artery and the pulmonary artery; and even if the blood flow in the bronchial artery is lost, blood flow from the pulmonary artery is slightly maintained. [ 1 ]  With non-bronchial arteries, it is empirically known that some collateral circulations also develop. [ 5 ]  In addition, direct hemorrhage from the pulmonary artery is rare (less than 5%), which requires embolization of the pulmonary artery. [ citation needed ]


BAE is effective for hemoptysis in most underlying diseases such as  bronchiectasis ,  nontuberculous mycobacterial disease  (NTM), cryptogenic hemoptysis, pulmonary  aspergillosis , and  pulmonary tuberculosis  sequelae. [ 1 ]  According to Ishikawa who reported long-term treatment results of BAE for 489 hemoptysis patients, each underlying disease's ratio is 34.0%, 23.5%, 18.4%, 13.3%, 6.8%, respectively. [ 2 ]  Other diseases for which BAE is effective include  lung abscess  and pulmonary actinomycosis. [ 6 ]


As for lung cancer, hemoptysis is caused mostly by bleeding from the tumor itself, and not by the bronchial-pulmonary artery shunt mechanism; embolism of the feeding vessels for the tumor causes necrosis of the cancer which may evoke massive hemoptysis. In addition, subsequent chemotherapy and endovascular treatment cannot be performed if the route of anticancer drugs is permanently obstructed. Lung cancer needs a different strategy. Seki et al. reported the usefulness of endovascular treatment for lung cancer hemoptysis. [ 7 ]  Kichang et al. reported BAE for hemoptysis in 84 lung cancer patients, and demonstrated that massive hemoptysis and cavity formation were significantly poor prognosis factors; re-hemoptysis rate was 23.8% in their follow-up period. [ 8 ]


Even though BAE is currently considered the gold standard treatment for hemoptysis, Ishikawa et al. [ 9 ]  found that only 9065 patients (8.4%) out of 107,389 patients hospitalized for hemoptysis between 2010 and 2018 in Japan were treated with BAE. According to Ishikawa basically, all patients with hemoptysis who are admitted to the hospital are eligible for BAE, and the reason why BAE has been performed only in such a small number of patients is that there are still few facilities that can perform BAE,


Besides, among the 660 hospitals that performed BAE, half of them (334 centers) experienced less than one case per year. [ 9 ]  Centralization of hemoptysis treatment facilities will be necessary to increase the performance rate of BAE and to improve the quality of BAE.


A  catheter  with a diameter of less than 2 mm is inserted at the base of the foot ( femoral artery ) or the artery in the wrist ( radial artery ). [ 2 ]  The tip of the catheter is inserted into the orifice of the bronchial artery (normally smaller than 1 mm) or other non-bronchial hemoptysis-related arteries. Contrast agent is injected through the catheter, and when abnormal findings are observed, such as systemic–pulmonary shunts, proliferations of the capillary vessels, or extravasation of the contrast medium to the lung tissues, they were super selectively embolized using the 3 Fr microcatheter system. [ 5 ]  A thinner microcatheter (about 0.8 mm) is passed through the catheter into the blood vessel, and then, embolic material is injected into the appropriate site. Thus, hemostasis is performed by ceasing or reducing the pressure applied to a bronchial (or non-bronchial)-pulmonary shunt (abnormal anastomosis). BAE is performed under local anesthesia, and the required time is about 1 hour to 3 hours. [ 2 ]


In the past, BAE was mostly considered a palliative or a bridge therapy to surgical operation owing to the high rate of re-hemoptysis with BAE. But with the improvement in treatment strategy and devices, it is regarded as a permanent therapy for hemoptysis nowadays. [ 1 ] [ 4 ]


There are few facilities in which sophisticated BAE is feasible, and there are significant disparities between hospitals in the treatment quality and their experience. In most of the facilities, BAE is operated by interventional vascular radiology doctors, [ 10 ]  but in recent years, specialized high volume centers where a trained pulmonologist performs BAE are emerging. [ 11 ] [ 2 ]  It is particularly effective for cryptogenic hemoptysis. Ando, Masuda et al. reported in their article that the hemostatic rate is 97% at 20 months, [ 12 ]  which is equivalent to the results of the article by Ishikawa. [ 2 ]  Ando, Masuda et al. state that micro bronchial aneurysms are involved in 22.9% of cryptogenic hemoptysis [ 12 ]


For pulmonary aspergillosis, BAE was relatively less effective and was once thought to be contraindicated, but hemostatic rates have improved in recent years. Ando, Masuda et al. demonstrated that the re-hemoptysis rate was significantly higher in cases of disease progression. [ 11 ]


The hemostatic rate in each underlying disease by Ishikawa is shown below. [ 2 ]  In this paper, both re-hemoptysis and death are defined as composite endpoints, and among these, only re-hemoptysis free rate is shown in the following table. It is originally a long-term performance data for 3 years; In the third year, the 95% confidence interval was too wide except for cryptogenic hemoptysis; hence, they are regarded as statistically unreliable figures. Therefore, the third year result is not posted here except for idiopathic hemoptysis. [ 2 ]  The poorest hemostatic rate after 2 years was observed in nontuberculous mycobacterial disease (NTM). The result shown by Okuda, Masuda et al. was similar (73.8%). [ 13 ]  It is considered to reflect the progressive nature of the disease. [ citation needed ]


Below are the treatment results summarized according to underlying diseases based on peer-reviewed papers published by Eishinkai Kishiwada Rehabilitation Hospital Hemoptysis and Pulmonary Circulation Center (EHPC), and The National Hospital Organization Tokyo Hospital Pulmonary Circulation and Hemoptysis Center (Tokyo Hp) ; the top two representatives of high-volume centers in Japan.


In cases of recurrence, re-BAE is possible to perform several times.


Furthermore, Takeda et al. showed that the 1, 2, 3, and 5-year hemostatic rates of bronchiectasis (without nontuberculous mycobacteriosis or pulmonary aspergillosis) were 91.3, 84.2, 81.5, and 78.9%, respectively. [ 15 ]  This paper is valuable for its long-term results of 5 years.


These include polyvinyl alcohol (PVA), n-butyl-2-cyanoacrylate (NBCA), gelatin sponge, metallic coil, etc. [ 1 ] [ 4 ]


PVA  - Woo et al. reported 406 cases of BAE long-term results, including 293 cases of PVA and 113 cases of NBCA. [ 16 ]


NBCA  - This is a kind of medical instant adhesive. Generally, there are many complications such as non-target blood vessel embolization and adhesion of catheter and vessel wall. However, in the article by Woo et al., major complication rate was 0%. [ 16 ]


This kind has many advantages, such as low cost, instantaneous embolization, and very low recanalization rate since it does not depend on the patient's thrombus formation. It appears to be the best indication for traumatic bleeding control, particularly, in the peripheral bronchial aneurysms that the micro-catheter cannot access in BAE procedures, is a very good indication, and Mine, Hasebe et al. reported a technique called B-glue; NBCA combined with a balloon. [ 10 ]


Gelatin sponge  (GS) is a transient embolic material, and in most cases, it dissolves within one to two weeks, and blood flow resumes. For this reason, it is important for emergency hemostatic purposes such as palliative treatment until surgery, which was the former positioning of BAE. GS is not suitable for the prevention of recurrence after massive hemoptysis or elective BAE for chronic repetitive hemoptysis. Wada et al. demonstrated that hemostatic rate was 24% (median follow-up time was 15 months) in their retrospective analysis of BAE for 33 patients using GS. [ 17 ]


There are three kinds of platinum vascular embolic coil. One is a detachable coil, which is expensive, but can be deployed repetitively until electric detach. This enables safest and fully controlled embolization. The second one is pushable coil, which is affordable, and allows for only one deployment. The third one is mechanical detachable coil; it has a moderate price range, and repetitive deployment is feasible. Ishikawa termed BAE with metallic coil as ssBACE, and published the world's largest number of cases of ssBACE long-term results in 2017. [ 2 ]  As described below, there are no reports on spinal cord ischemia in ssBACE, [ 2 ] [ 11 ]  which is considered the most serious complication of BAE. This is one of the strongest merit of ssBACE. [ citation needed ]


Despite a rumor that it cannot be re-treated if ssBACE is performed once, Ryuge demonstrated in their article on "the mechanism of re-hemoptysis" that the technical success rate in re-BAE was at least 97.7%. [ 18 ]


Ryuge classified the re-hemoptysis mechanism after ssBACE into four as shown below. They also demonstrated that for the improvement of the long-term results in ssBACE in the future, suppressing recanalization is necessary. [ 18 ]


Some readers misunderstand that 45.2% of the embolized coils recanalized. This, in fact, is the ratio of re-hemoptysis mechanism occurring in 9.6% cases in 1 year, and in 14.1% of those in 2 years. [ 18 ]


Recanalization was the main cause of re-hemoptysis, and the suppression of new hemoptysis-related vessels, which is the second cause, cannot be controlled by the BAE procedure itself. It was shown that suppression of the recanalization was the key to improvement in ssBACE result in future. [ 18 ]


Chest pain is the most common complication for who had undergone BAE, ranging from 24 to 91%. However, the symptom is temporary due to accidental embolisation of  coronary artery  supplying the heart. [ 19 ]
In the past,  paraplegia  caused by spinal cord ischemia due to erroneous embolization of the  anterior spinal artery  was well known as a rare, but serious complication. [ 1 ] [ 20 ]  Super selective BAE using microcatheter reduced the incidence of the spinal ischemia. [ 1 ]


However, according to Ishikawa et al., spinal cord infarction still occurs, with an incidence of 0.19% (16/8563). [ 9 ]


They also compared it between three embolic agents (GS, NBCA, Coil) and demonstrated that the incidence of spinal cord infarction was significantly lower in coils: 0.06% (1/1577) compared with GS 0.18% (12/6561) and NBCA 0.71% (3/425) (p=0,04).


Major complications reported by Ishikawa et al. are presented below. [ 2 ]


Mediastinal hematoma occurs by injury of hemoptysis-related vessel, mainly by wire, and can easily bail out by proximal coil embolization. [ citation needed ]


The majority of research on BAE was the single-center retrospective observational studies. Descriptive epidemiological studies using French medical big data is precious in that aspect. [ 21 ]  From the fall of 2020 to January 2021, a collaborative study led by the Yasunaga Laboratory of the University of Tokyo published two landmark papers using the Japanese medical database. [ 22 ] [ 9 ]  One of them is a study by Ando et al. of the Department of Respiratory Medicine, University of Tokyo, which demonstrated for the first time in the world that early BAE (within three days after endotracheal intubation) significantly reduced in-hospital mortality in patients with severe hemoptysis on ventilators (30 days): 7.5% in the early BAE group vs. 16.8% in the non-early BAE group. (odds ratio, 0.45; 95% CI, 0.28-0.73; p = 0.001). [ 11 ]


Omachi et al. of the Hemoptysis and Pulmonary Circulation Center, Kishiwada Rehabilitation Hospital, demonstrated for the first time in the world that elective BAE with coils significantly improved the quality of life of hemoptysis patients(single-center prospective observational study). In this study, both physical and mental QOL improved significantly after BAE, especially the latter. [ 23 ]


Cholecystostomy  or ( cholecystotomy ) is a medical procedure used to drain the  gallbladder  through either a percutaneous or endoscopic approach. The procedure involves creating a  stoma  in the gallbladder, which can facilitate placement of a tube or stent for  drainage , first performed by American surgeon, Dr.  John Stough Bobbs , in 1867. [ 1 ] [ 2 ] [ 3 ]  It is sometimes used in cases of  cholecystitis  or other gallbladder disease where the person is ill, and there is a need to delay or defer  cholecystectomy . [ 4 ]  The first endoscopic cholecystostomy was performed by Drs.  Todd Baron  and Mark Topazian in 2007 using ultrasound guidance to puncture the stomach wall and place a plastic biliary catheter for gallbladder drainage. [ 5 ]


Cholecystostomy finds its application when the patient has cholecystitis and is not a good candidate for surgery. [ 6 ]  Some indications include:


Contraindications to cholecystostomy include:


Percutaneous cholecystostomy is performed under sedation and guided by  ultrasound  (US) or  computed tomography  (CT) imaging. [ 7 ]  There are 3 major considerations when deciding the approach for this procedure.


There are numerous studies comparing the trans-hepatic and trans-peritoneal approaches and their associated complications. Some studies have shown that there is no statistically significant difference in complications between the two approaches and recommend operator preference. A more recent study, however, did suggest greater incidence of hemorrhage with the trans-hepatic approach. [ 8 ]


Before the procedure, a thorough review of the patient's imaging is conducted to evaluate the anatomy of the  gallbladder  and surrounding structures. [ 9 ]  The patient's clinical status, medications, and laboratory values (i.e.  white blood cell count ,  coagulation studies ,  inflammatory markers ,  anticoagulation  therapy, etc.) are reviewed to ensure the patient is stable for the procedure. [ 9 ]


Once the patient is ready, the surgical site is cleaned with an  antiseptic  solution to minimize the risk of infection. [ 9 ]  Local anesthesia, in the form of a topical 1%  lidocaine  injection, is administered. A small incision is made in the right upper quadrant (RUQ) directly above the gallbladder, using a #11 blade. [ 9 ]  At this point, there are 2 main techniques to perform the cholecystostomy.


Cholecystostomy is a medical procedure and carries its share of complications and adverse effects. Complications occur in approximately 10% of cases. [ 7 ]  The most common issues encountered are catheter dislodgement, blockage, or a bile leak, which, while frequent, are considered minor complications. [ 10 ]  Major complications, although rare, encompass  sepsis , significant  hemorrhage ,  pneumothorax , and bowel injury. [ 10 ]  Notably, the transhepatic approach offers advantages by reducing the risk of both organ perforation and bile leaks. [ 10 ]


Once the cholecystostomy tube is placed, it is recommended to keep the tube for 3–6 weeks to allow the tract to mature. [ 11 ]  Studies have shown that premature removal (before 21 days) is associated with a higher incidence of bile leaks. [ 11 ]  Once the cholecystitis is resolved and adequate time has passed for tract maturation, a clamp trial can be conducted for 24 hours to assess drainage from the gallbladder. [ 9 ]  If the patient passes the clamp trial (minimal to no drainage after unclamping), the tube is removed. Future management consists of performing a  cholecystectomy  to prevent future episodes of cholecystitis once the patient is stable for surgery. [ 9 ]


An alternative to the percutaneous cholecystostomy is to use the  endoscopic  route. There are 2 primary techniques: endoscopic transpapillary gallbladder drainage (ET-GBD) and endoscopic ultrasound-guided gallbladder drainage (EUS-GBD). These techniques are considered when the patient is a poor candidate for surgical cholecystectomy but can tolerate anesthesia for an endoscopic procedure and does not have a gallbladder perforation. [ 3 ]


This procedure is performed during an  endoscopic retrograde cholangiopancreatography (ERCP) . The  cystic duct  is cannulated and a plastic  stent  is deployed to relieve the blockage and allow for drainage. ET-GBD can be considered when the patient is already undergoing an ERCP for another medical condition (i.e.  choledocholithiasis ). Some drawbacks include an increased risk of  pancreatitis  from the ERCP procedure and a lower success rate compared to EUS-GBD or percutaneous cholecystostomy, particularly when there is evidence of cystic duct obstruction (i.e.  stones ,  adhesions ,  strictures ,  cancer , or other masses). [ 3 ]


EUS-GBD allows for internal drainage by placing a  lumen-apposing metal stent  (LAMS) into the gallbladder from either the  stomach  or the  duodenum .  The procedure involves using a cautery-powered LAMS to puncture through the gastric wall and enter the gallbladder. Two flanges on either side of the LAMS are deployed, tethering the stent on the inside walls of the gallbladder and gastric lumen. An important consideration is that the gallbladder must be within 10mm of the gastric puncture site. EUS-GBD is a good option for patients who are unlikely to undergo a future surgical cholecystectomy. It may also be used in patients with a cystic duct occlusion, or a pre-existing uncovered metal biliary stent. Some advantages include a high success rate with few complications and a reduced need for reinterventions. The primary drawback is the risk of stent occlusion with food or gastric contents. This risk is lowered when entering through the duodenum. EUS-GBD also complicates a future surgical cholecystectomy because the patient's anatomy is modified, requiring an additional repair of the choleycystoenteric  fistula . [ 3 ]


Cryoablation  is a process that uses extreme  cold  to destroy  tissue . Cryoablation is performed using hollow needles (cryoprobes) through which cooled, thermally conductive fluids are circulated. Cryoprobes are positioned adjacent to the target in such a way that the freezing process will destroy the diseased tissue. Once the probes are in place, the attached cryogenic freezing unit removes heat from ("cools") the tip of the probe and by extension from the surrounding tissues.


Ablation occurs in tissue that has been frozen by at least three mechanisms:


The most common application of cryoablation is to ablate solid tumors found in the lung, liver, breast, kidney and prostate. The use in prostate and renal cryoablation are the most common. Although sometimes applied in  cryosurgery  through  laparoscopic  or open surgical approaches, most often cryoablation is performed percutaneously (through the skin and into the target tissue containing the tumor) by a medical specialist, such as an  interventional radiologist . The term is from  cryo-  +  ablation .


Prostate  cryoablation is moderately effective but, as with any prostate removal process, also can result in impotence. Prostate cryoablation is used in three patient categories:


Cryoablation has been explored as an alternative to  radiofrequency ablation  in the treatment of moderate to severe pain in people with  metastatic bone disease . The area of tissue destruction created by this technique can be monitored more effectively by CT than RFA, a potential advantage when treating tumors adjacent to critical structures. [ 1 ]


Cryoablation has similar outcomes to radiofrequency ablation when treating  renal cell carcinoma . [ 2 ]


Cryoablation for breast cancer is typically only possible for small tumors. [ 3 ]  Often surgery is used following cryoablation. [ 3 ]  As of 2014 more research is required before it can replace  lumpectomy . [ 3 ]


Another type of cryoablation is used to restore normal electrical conduction by freezing tissue or heart pathways that interfere with the normal distribution of the heart’s electrical impulses. Cryoablation is used in two types of intervention for the treatment of  arrhythmias : (1)  catheter -based procedures and (2) surgical operations.


A catheter is a very thin tube that is inserted into a vein in the patient’s leg and threaded to the heart where it delivers energy to treat the patient’s arrhythmia. In surgical procedures, a flexible probe is used directly on an exposed heart to apply the energy that interrupts the arrhythmia. By cooling the tip of a cryoablation catheter ( cardiology ) or probe ( heart surgery ) to sub-zero temperatures, the cells in the heart responsible for conducting the arrhythmia are altered so that they no longer conduct electrical impulses.


Cryoablation is also currently being used to treat  fibroadenomas  of the breast. Fibroadenomas are  benign  breast tumors that are found in approximately 10% of women (primarily ages 15–30). [ 4 ]


In this procedure which has been approved by the U.S.  Food and Drug Administration  (FDA), an ultrasound-guided probe is inserted into the fibroadenoma and extremely cold temperatures are then used to destroy the abnormal cells. [ 5 ]  Over time the cells are reabsorbed into the body. The procedure can be performed in a doctor's office setting with  local anesthesia  and leaves very little scarring compared to open surgical procedures. [ 5 ]


Different catheter-based ablation techniques may be used and they generally fall into two categories: (1) cold-based procedures where tissue cooling is used to treat the arrhythmia, and (2) heat-based procedures where high temperature is used to alter the abnormal conductive tissue in the heart.


Cold temperatures are used in cryoablation to chill or freeze cells that conduct abnormal heart rhythms. The catheter removes heat from the tissue to cool it to temperatures as low as -75 °C. This causes localized scarring, which cuts undesired conduction paths.


This is a much newer treatment for  supraventricular tachycardia  (SVT) involving the atrioventricular (AV) node directly. SVT involving the AV node is often a contraindication for using radiofrequency ablation because of the risk of injuring the AV node, forcing patients to receive a permanent pacemaker. With cryoablation, areas of tissue can be mapped by limited, reversible, freezing (e.g., to -10 C). If the result is undesirable, the tissue can be rewarmed without permanent damage. Otherwise, the tissue can be permanently ablated by freezing it to a lower temperature (e.g., -73 C).


This therapy has revolutionized  AV nodal reentrant tachycardia  (AVNRT) and other AV nodal tachyarrhythmias. It has allowed people who were otherwise not a candidate for radiofrequency ablation to have a chance at having their problem cured. This technology was developed at The Montreal Heart Institute in the late 1990s. The therapy was successfully adopted in Europe in 2001, and in the US in 2004 following the "Frosty Trial". [ 6 ]


In 2004, the technology was pioneered in the midwest United States at Miami Valley Hospital in Dayton, Ohio, by Mark Krebs, MD, FACC, Matthew Hoskins, RN, BSN and Ken Peterman, RN, BSN.  These electrophysiology experts were successful in curing the first 12 candidates in their facility. [ citation needed ]


Cryoablation for AVNRT and other arrhythmias do have some drawbacks. A recent study [ 7 ]  concluded that procedure times are slightly higher on average for cryoablation than for traditional radio-frequency (heat-based) ablations. Also, higher rate of equipment failures were recorded using this technique. Finally, even though short term success rate is equivalent to RF treatments, cryoablation appears to have a significantly higher long term recurrence rate.


Cryotherapy  is able to produce a temporary electrical block by cooling down the tissue believed to be conducting the arrhythmia. This allows the physician to make sure this is the right site before permanently disabling it. The ability to test a site in this way is referred to as site testing or  cryomapping .


When ablating tissue near the  AV node  (a special conduction center that carries electrical impulses from the atria to the ventricles), there is a risk of producing heart block – that is, normal conduction from the atria cannot be transmitted to the ventricles. Freezing tissue near the AV node is less likely to provoke irreversible heart block than ablating it with heat.


As in catheter-based procedures, techniques using heating or cooling temperatures may be used to treat arrhythmias during heart surgery. Techniques also exist where incisions are used in the open heart to interrupt abnormal electrical conduction ( Maze procedure ).  Cryosurgery  involves the use of freezing techniques for the treatment of arrhythmias during surgery.


A physician may recommend cryosurgery being used during the course of heart surgery as a secondary procedure to treat any arrhythmia that was present or that may appear during the primary open-chest procedure. The most common heart operations in which cryosurgery may be used in this way are  mitral valve repairs  and  coronary artery bypass grafting . During the procedure, a flexible cryoprobe is placed on or around the heart and delivers cold energy that disables tissue responsible for conducting the arrhythmia.


Cryoablation has recently been used to treat low-flow  vascular malformations  such as  venous malformations  (VM) and  fibroadipose vascular anomalies  (FAVA). Cryoablation has proved effective for treating these disorders both as primary treatment and after  sclerotherapy . [ 8 ]


Cryoimmunotherapy  is an oncological treatment for various cancers that combines cryoablation of tumor with  immunotherapy  treatment. [ 9 ]  In-vivo cryoablation of a tumor alone can induce an immunostimulatory, systemic anti-tumor response, resulting in a cancer vaccine – the  abscopal effect . [ 10 ]  However, cryoablation alone may produce an insufficient immune response, depending on various factors, such as high freeze rate. Combining cryotherapy with immunotherapy enhances the immunostimulating response and has synergistic effects for cancer treatment. [ 11 ]


The use of cold for pain relief and as an anti-inflammatory has been known since the time of  Hippocrates  (460–377 BC). [ 12 ]  Since then there have been numerous accounts of ice used for pain relief including from the Ancient Egyptians and Avicenna of Persia (AD 982–1070). [ 13 ]  Since 1899, Dr. Campbell White used refrigerants for treating a variety of conditions, including: lupus erythematosus, herpes zoster, chancroid, naevi, warts, varicose leg ulcers, carbuncles, carcinomas and epitheliomas. De Quervain successfully used of carbonic snow to treat bladder papillomas and bladder cancers in 1917. Dr. Irving S. Cooper, in 1913, progressed the field of cryotherapy by designing a liquid nitrogen probe capable of achieving temperatures of -196 °C, and utilizing it to treat of Parkinson's disease and previously inoperable cancer. Cooper's cryoprobe advanced the practice of cryotherapy, which led to growing interest and practice of cryotherapy. In 1964, Dr. Cahan successfully used his liquid nitrogen probe invention to treat uterine fibroids and cervical cancer. Cryotherapy continued to advance with Dr. Amoils developing a liquid nitrogen probe capable of achieving cooling expansion, in 1967. [ 14 ] [ 15 ] [ 16 ]


With the technological cryoprobe advancements in the 1960s came wider acceptance and practice of cryotherapy. Since the 1960s, liver, prostate, breast, bone, and other cancers have been treated with cryoablation in many parts of the world. Japanese physician Dr. Tanaka began treating metastatic  breast cancer  with cryoablation in 1968. [ 17 ]   For the next three decades, Dr. Tanaka successfully treated small and localized as well as advanced and unresectable breast cancer with minimally invasive cryoablation.  All of Dr. Tanaka's breast cancer cases were considered incurable: advanced, unresectable, and resistant to radiotherapy, chemotherapy, and endocrine therapy. [ 17 ]  At the same time, physicians, including Dr. Ablin and Dr. Gage, started utilizing cryoablation for the treatment of prostate and  bone cancer . [ 18 ] [ 19 ]  Dr. Paul J. Wang MD and Dr. Peter L. Friedman MD, PhD invented cryoablation for the heart and cardiac arrhythmia in 1988. Their patents were for the cryoablation catheter and cryogenic mapping (US Patents 5147355A and 5423807A).


The 1980s and 1990s saw dramatic advancement in apparatus and imaging techniques, with the introduction of CMS Cryoprobe, and Accuprobe. [ 20 ]   CT -,  MRI -, and  ultrasound -guided cryoprobes became available and improved the capabilities of cryoprobes in treatment. Excited by the latest advancements in cryotherapy, China embraced cryotherapy in the 1990s to treat many oncological conditions. [ 21 ]  With the benefits well-established, the FDA approved the treatment of prostate cancer with cryoablation in 1998. [ 22 ]


Electromagnetic navigation bronchoscopy  ( ENB ) is a medical procedure utilizing  electromagnetic technology  designed to localize and guide  endoscopic  tools or  catheters  through the  bronchial pathways  of the lung.  Using a virtual, three-dimensional (3D) bronchial map from a recently  computed tomography  (CT) chest scan and disposable catheter set, physicians are able to navigate to a desired location within the lung to  biopsy   lesions , stage  lymph nodes , insert markers to guide  radiotherapy  or guide  brachytherapy  catheters.  [ 1 ] [ 2 ]


The ENB system consists of four essential components:


Electromagnetic navigation bronchoscopy consists of two primary phases: planning and navigation. In the planning phase previously acquired CT scans are utilized to mark and plan pathways to targets within the lung. In the navigation phase these previously planned targets and pathways are displayed and can be utilized for navigation and access deep within the lung. Upon arriving at the target ENB enables multiple applications all within the same procedure. [ 3 ]


CT scans of the patient’s chest are loaded into proprietary software that reconstructs the patient’s airways in multiple 3D images. The physician utilizes these images to mark target locations and plan pathways to these target locations within the lungs. [ 1 ] [ 3 ]


Using the planned pathway created in the Planning Phase and real-time guidance, the physician navigates the steerable sensor probe and extended working channel to the desired target location(s). Once at the desired location, the physician locks the extended working channel in place and the steerable sensor probe is removed. The extended working channel provides access to the target lesion for standard bronchoscopic tools or catheters. [ 1 ] [ 3 ]


According to the Aetna Clinical Policy Bulletin on ENB, "In 2004, the FDA cleared for marketing through the 510(k) process the  Medtronic  superDimension/Bronchus system, also known as the inReach system (superDimension, Ltd, Israel), a minimally invasive image-guidance localization and navigation system that uses electromagnetic guidance for the management of peripheral lung lesions. [ 1 ]   The system consists of several components: a guide catheter, a steerable navigation catheter, and planning and navigation software and hardware (i.e., computer and monitor).  Navigation is facilitated by an electromagnetic tracking system that detects a position sensor incorporated into a flexible catheter advanced through a bronchoscope.  Information obtained during bronchoscopy is super-imposed on previously acquired computed tomography (CT) data and 3-dimensional virtual images.  The system was designed to solve the clinical problem of reaching small suspected lesions in the peripheral lung airways and mediastinal lymph nodes and is being proposed as an alternative to open surgical biopsy of distant lung lesions and as an alternative to transthoracic implantation of radiosurgical markers." [ 4 ]


Despite the medical advances of detection, diagnosis and treatment methods throughout the past 50 years, lung cancer causes more deaths than any other cancer in both men and women. [ 5 ]  Currently, lung cancer is the most common form of cancer diagnosed in the United States and a major cause of death, accounting for 14% of all cancers. [ 6 ]


The most effective way of stopping cancer comes at diagnosis and treatment in the early stages. Lung cancer diagnosed in the early stages yields an 88% survival rate at ten years versus 16% at five years when found in the later stages, [ 7 ] [ 8 ]  although 88% rate has only been achieved once. [ 1 ]


Although 1 in 500 chest X-rays show a peripheral lesion, [ 9 ]  65% of traditional bronchoscopes fail to reach these distant lesions. [ 10 ]  More invasive diagnostic techniques are then necessary, posing a greater potential for complications such as pneumothorax. [ 11 ]
Patients with poor lung function may not tolerate more invasive procedures, leaving them with "watchful waiting" as their only option.


There are four publications that show that peripheral lung lesions can be diagnosed successfully in 69% to 86% of cases using the  Medtronic   superDimension system. [ 3 ] [ 12 ] [ 13 ] [ 14 ]


According to the American Journal of Respiratory and Critical Care Medicine, a prospective ... study was conducted to determine the ability of electromagnetic navigation bronchoscopy to sample peripheral lung lesions and mediastinal lymph nodes with standard bronchoscopic instruments and demonstrate safety the ENB."  The results provided a "yield/procedure [rate at] 74% and 100% for peripheral lesions and lymph nodes, respectively." Additionally, "a diagnosis was obtained in 80.4% of bronchoscopic procedures." The study concluded that ENB "is a safe method for sampling peripheral and mediastinal lesions with high diagnostic yield independent of lesion size and location". [ 15 ]


A similar study of 40 patients issued in the  European Respiratory Journal  resulted in an overall 62.5% diagnostic yield and concluded;
"electromagnetic navigation bronchoscopy without additional fluoroscopic guidance is a safe and efficient technique for the diagnosis of peripheral pulmonary nodules. The overall diagnostic yield found in the present study is superior to rates reported in most previous studies performed for small peripheral pulmonary nodules with bronchoscopy". [ 16 ]


Virtual bronchoscopy continues to be an active subject for basic engineering research. The Bioelectromagnetics group at  University College Cork  has developed a novel low-cost tracking system for use in electromagnetic navigation bronchoscopy. [ 17 ]  The group is also collaborating with the Surgical Planning Laboratory at  Harvard Medical School  to develop the world's first open-source virtual bronchoscopy module to be implemented in the  3DSlicer  environment. [ 18 ]


Embolectomy  is the emergency  interventional  or  surgical  removal of  emboli  which are blocking blood circulation. It usually involves removal of  thrombi  (blood clots), and is then referred to as  thromboembolectomy  or  thrombectomy . Embolectomy is an emergency procedure often as the last resort because permanent occlusion of a significant blood flow to an organ leads to  necrosis . Other involved therapeutic options are  anticoagulation  and  thrombolysis .


Surgical embolectomy for massive pulmonary embolism (PE) has become a rare procedure and is often viewed as a last resort.  Thrombolytic therapy  has become the treatment of choice. [ 1 ]


Surgical or catheter embolectomy is a procedure performed in patients with pulmonary embolism, which is a blockage of an artery in the lung caused by a blood clot. This procedure is typically used for patients who are in a critical condition, such as those who are experiencing persisting shock despite receiving supportive care, and who have an absolute contraindication for thrombolytic therapy. During the procedure, a catheter is inserted into the affected artery, and the clot is removed using a variety of techniques such as mechanical fragmentation or suction. However, it's important to note that there is a risk of complications such as bleeding, infection, and damage to the artery or surrounding tissue. This procedure is done under general anesthesia and with the help of imaging technology like angiography, and it's performed by interventional radiologists or cardiothoracic surgeons. [ 2 ]  And although other treatments have improved urgent surgical embolectomy or catheter embolectomy may be a life saving procedure in severe pulmonary embolism. [ 3 ]


Embolectomies are performed as  limb-sparing techniques  for arterial embolisms in  acute limb ischemia . However, there are also other options, such as  catheter-directed thrombolysis  and  anticoagulation  with observation. [ 4 ]  It can also be used for other ischemias due to embolism for example mesenteric ischemia and  stroke . [ 5 ] [ 6 ]


Typically this is done by inserting a  catheter  with an inflatable balloon attached to its tip into an artery, passing the catheter tip beyond the clot, inflating the balloon, and removing the clot by withdrawing the catheter. The catheter is called Fogarty, named after its inventor  Thomas J. Fogarty . [ citation needed ]


Possible complications of balloon embolectomy include intimal lesions, which can lead to another thrombosis. [ 7 ]  The vessel may also be affected by a  dissection  or rupture. The  procedure may lead to  cholesterol embolism  from atherosclerotic plaques. [ 7 ]


Catheter embolectomy is also used for aspiration embolectomy, where the thrombus is removed by suction rather than pushing with a balloon. [ 8 ]  It is a rapid and effective way of removing thrombi in thromboembolic occlusions of the limb arteries below the inguinal ligament, [ 8 ]  as in  leg infarction .


Surgical embolectomy is the simple surgical removal of a clot following incision into a vessel by open surgery on the artery. [ 9 ]


Outcome of embolectomy varies with size and location of the embolus. [ citation needed ]


In pulmonary embolism recent data shows mortality as being approximately 20%. Although this is a high mortality, it may have life-saving potential in some instances. [ 10 ]


Emboli  are abnormal masses of material (which can be solid, liquid or gas) that are carried in the blood stream from one part of the circulation to another causing a blockage ( occlusion ) of a  blood vessel  that leads to lack of oxygen supply ( ischemia ) and finally  infarction  of  tissue  downstream of the embolus. [ citation needed ]


The most common type of emboli are a blood clot generated by  thrombosis  which has then broken off and is then transported in the blood stream  [ citation needed ]


There are two areas where emboli can form and therefore impact: [ citation needed ]


Embolization  refers to the passage and lodging of an  embolus  within the bloodstream. It may be of natural origin ( pathological ), in which sense it is also called  embolism , for example a  pulmonary embolism ; or it may be artificially induced ( therapeutic ), as a  hemostatic  treatment for bleeding or as a treatment for some types of cancer by deliberately blocking blood vessels to starve the  tumor  cells.


In the  cancer management  application, the embolus, besides blocking the blood supply to the tumor, also often includes an ingredient to attack the tumor chemically or with  irradiation . When it bears a  chemotherapy  drug, the process is called chemoembolization.  Transcatheter arterial chemoembolization  (TACE) is the usual form. When the embolus bears a  radiopharmaceutical  for  unsealed source radiotherapy , the process is called radioembolization or  selective internal radiation therapy  (SIRT).


Embolization involves the selective  occlusion  of  blood vessels  by purposely introducing  emboli , in other words deliberately blocking a blood vessel. Embolization is used to treat a wide variety of conditions affecting different organs of the human body.


Embolization is commonly used to treat active arterial bleeding. Embolization is rarely used to treat venous bleeding as venous bleeding can stop on its own or with packing or compression. [ 1 ] [ 2 ]


The treatment is used to occlude:


The treatment is used to slow or stop blood supply thus reducing the size of the tumour:


It could be useful for managing  malignant hypertension  due to end stage  kidney failure . [ 6 ]


First developed by  Sadek Hilal  in 1968, embolization is a minimally invasive surgical technique. [ 8 ]  The purpose is to prevent blood flow to an area of the body, which can effectively shrink a tumor or block an aneurysm.


The procedure is carried out as an endovascular procedure by an  interventional radiologist  in an interventional suite. It is common for most patients to have the treatment carried out with little or no sedation, although this depends largely on the organ to be embolized. Patients who undergo cerebral embolization or portal vein embolization are usually given a  general anesthetic .


Access to the organ in question is acquired by means of a guidewire and catheter(s). Depending on the organ this can be very difficult and time-consuming. The position of the correct artery or vein supplying the pathology in question is located by  digital subtraction angiography  (DSA). These images are then used as a map for the radiologist to gain access to the correct vessel by selecting an appropriate  catheter  and or wire, depending on the 'shape' of the surrounding anatomy.


Once in place, the treatment can begin. The artificial embolus used is usually one of the following:


Once the artificial emboli have been successfully introduced, another set of DSA images are taken to confirm a successful deployment.


Liquid embolic agents  – Used for AVM, these agents can flow through complex vascular structures so the surgeon does not need to target the catheter to every single vessel.


Sclerosing agents  – These will harden the endothelial lining of vessels. They require more time to react than the liquid embolic agents. Therefore, they cannot be used for large or high-flow vessels.


Particulate embolic agents  – These are only used for precapillary arterioles or small arteries. These are also very good for AVM deep within the body. The disadvantage is that they are not easily targeted in the vessel. None of these are radioopaque, so they are difficult to view with radiologic imaging unless they are soaked in contrast prior to injection.


Mechanical occlusion devices  – These fit in all vessels. They also have the advantage of accuracy of location; they are deployed exactly where the catheter ends.


Endovascular aneurysm repair  ( EVAR ) is a type of minimally-invasive  endovascular surgery  used to treat  pathology  of the  aorta , most commonly an  abdominal aortic aneurysm  (AAA). When used to treat  thoracic aortic  disease, the procedure is then specifically termed  TEVAR  for "thoracic endovascular aortic/aneurysm repair." EVAR involves the placement of an expandable  stent graft  within the aorta to treat aortic disease without operating directly on the aorta. In 2003, EVAR surpassed  open aortic surgery  as the most common technique for repair of AAA, [ 1 ]  and in 2010, EVAR accounted for 78% of all intact AAA repair in the United States. [ 2 ]


Standard EVAR is appropriate for aneurysms that begin below the  renal arteries , where there exists an adequate length of normal  aorta  (the  "proximal aortic neck" ) for reliable attachment of the endograft without leakage of blood around the device (" endoleak "). [ 3 ]  If the proximal aortic neck is also involved with the aneurysm, the patient may be a candidate for complex visceral EVAR with a fenestrated or branched EVAR.


Patients with aneurysms require elective repair of their aneurysm when it reaches a diameter large enough (typically greater than 5.5 cm) such that the risk of rupture is greater than the risk of surgery. Repair is also warranted for aneurysms that rapidly enlarge or those that have been the source of  emboli  (debris from the aneurysm that dislodges and travel into other arteries). Lastly, the repair is also indicated for aneurysms that are the source of  pain  and  tenderness , which may indicate impending rupture. The options for repair include traditional  open aortic surgery  or endovascular repair. [ citation needed ]


Endovascular procedures aim to reduce the morbidity and mortality of treating arterial disease in a patient population that is increasingly older and less fit than when major open repairs were developed and popularized. Even in the early days, significant risks were accepted in the understanding that the large open operation was the only option. That is not the case in most patients today. [ citation needed ]


Studies that assign aneurysm patients to treatment with EVAR or traditional open surgery have demonstrated fewer early complications with the minimally invasive approach. Some studies have also observed a lower mortality rate with EVAR. [ 4 ] [ 5 ]  The reduction in death, however, does not persist long-term. After a few years, the survival after repair is similar to EVAR or open surgery. This observation may be the result of durability problems with early endograft, with a corresponding need for additional procedures to repair endoleaks and other device-related issues. Newer, improved technology may reduce the need for such secondary procedures. If so, the results of EVAR may improve to the point where long-term survival benefit becomes evident. [ citation needed ]


EVAR is also used for  rupture  of the abdominal and descending thoracic aorta, and in rare cases used to treat pathology of the  ascending aorta . [ 6 ]


Endografts have been used in patients with  aortic dissection , noting the extremely complex nature of open surgical repair in these patients. In uncomplicated aortic dissections, no benefit has been demonstrated over medical management alone.
In uncomplicated type B aortic dissection, TEVAR does not seem either to improve or compromise 2-year survival and adverse event rates. [ 7 ]  Its use in complicated aortic dissection is under investigation. In the Clinical Practice Guidelines of the European Society for Vascular Surgery, it is recommended that in patients with complicated acute type B aortic dissection, endovascular repair with thoracic endografting should be the first line intervention. [ 8 ]


Before people are deemed to be suitable candidates for this treatment, they have to go through a rigorous set of tests.  These include a CT scan of the complete thorax/abdomen/pelvis and blood tests.  The CT scan gives precise measurements of the aneurysm and the surrounding anatomy. In particular, the calibre/tortuosity of the iliac arteries and the relationship of the neck of the aneurysm to the renal arteries are important determinants of whether the aneurysm is amenable to endoluminal repair. In certain occasions where the renal arteries are too close to the aneurysm, the custom-made fenestrated graft stent is now an accepted alternative to doing open surgery. [ citation needed ]


A patient's anatomy can be unsuitable for EVAR in several ways. Most commonly, in an infrarenal aneurysm, a potential EVAR candidate lacks adequate length of the normal-diameter aorta between the aneurysm and the takeoff of the renal arteries, the "infra-renal neck". Another relative  contraindications  include prohibitively small  iliac arteries , aneurysmal iliac arteries, prohibitively small  femoral arteries , or circumferential calcification of the femoral or iliac arteries. [ citation needed ]


In addition to a short proximal aortic neck, the neck may be angulated, large in diameter, or shaped like a funnel (conical) where the neck diameter at the top is larger than the neck diameter at the bottom. Along with a short proximal aortic neck, necks with any of these characteristics are called "hostile necks" and endovascular repair can be either contraindicated or associated with early-late complications of endoleak, or endograft migration, or both. [ citation needed ]


Many of the advances in EVAR technique aim to adapt EVAR for these situations, and advanced techniques allow EVAR to be employed in patients who previously were not candidates. [ citation needed ]


The procedure is carried out in a sterile environment under  fluoroscopic  guidance.  It is usually carried out by a  vascular surgeon ,  interventional radiologist  or  cardiac surgeon , and occasionally,  general surgeon  or  interventional cardiologist . [ 9 ] [ 10 ] [ 11 ] [ 12 ]  The procedure can be performed under  general ,  regional (spinal or epidural)  or even  local anesthesia . [ 13 ]


Access to the patient's femoral arteries can be with surgical incisions or  percutaneously  in the groin on both sides. Vascular sheaths are introduced into the patient's femoral arteries, through which guidewires, catheters, and the endograft are passed. [ citation needed ]


Diagnostic angiography images are captured of the aorta to determine the location of the patient's renal arteries, so the stent-graft can be deployed without blocking these. Failure to achieve this will cause  kidney failure . With most devices, the "main body" of the endograft is placed first, followed by the "limbs" which join the main body and extend to the iliac arteries, effectively protecting the aneurysm sac from blood pressure. [ citation needed ]


The abdominal aneurysm extends down to the common iliac arteries in about 25%-30% of patients. In such cases, the iliac limbs can be extended into the external iliac artery to bypass a common iliac aneurysm. Alternatively, a specially designed endograft, (an iliac branch device) can be used to preserve flow to the  internal iliac arteries . The preservation of the hypogastric (internal iliac) arteries is important to prevent buttock  claudication  and  impotence , and every effort should be made to preserve flow to at least one hypogastric artery. [ citation needed ]


The endograft acts as an artificial lumen for blood to flow through, protecting the surrounding aneurysm sac. This reduces the pressure in the aneurysm, which itself will usually thrombose and shrink in size over time. [ 14 ]


Staging such procedures is common, particularly to address aortic branch points near the diseased aortic segment. One example in the treatment of thoracic aortic disease is revascularization of the left common carotid artery and/or the left subclavian artery from the innominate artery or the right common carotid artery to allow treatment of a thoracic aortic aneurysm that encroaches proximally into the aortic arch. These "extra-anatomic bypasses" can be performed without an invasive  thoracotomy . Another example in the abdominal aorta is the embolization of the internal iliac artery on one side prior to coverage by an iliac limb device. Continued improvement in stent-graft design, including branched endografts, will reduce but not eliminate multi-stage procedures. [ citation needed ]


Standard EVAR involves a surgical cut-down on either the femoral or iliac arteries, with the creation of a 4–6 cm incision. Like many surgical procedures, EVAR has advanced to a more  minimally invasive  technique, by accessing the femoral arteries  percutaneously  In percutaneous EVAR ( PEVAR ), small, sub-centimeter incisions are made over the femoral artery, and endovascular techniques are used to place the device over a wire. Percutaneous EVAR has been systematically compared to the standard EVAR cut-down femoral artery approach. [ 15 ]  Moderate quality evidence suggests that there are no differences in short-term mortality, aneurysm sealing, long and short-term complications, or infections at the wound site. [ 15 ]  Higher quality evidence suggests that there are no differences in post-repair bleeding complications or haematoma between the two approaches. [ 15 ]  The percutaneous approach may have reduced surgical time. [ 15 ]


Fenestrated endovascular aortic/aneurysm repair (FEVAR) is performed in the cases where the aneurysm extends near or involves the visceral vessels (such as juxta-renal, para-renal, thoraco-abdominal aortic aneurysms). A custom-made graft with fenestrations (holes on the graft body to maintain the patency of the visceral arteries) is used for the procedure. When the aneurysm involves the visceral arteries, standard EVAR is  contraindicated  due to the lack of suitable infra-aortic segment for the endograft attachment; FEVAR achieves seal between the stent graft and para-visceral segment and/or more proximal segment while preserving the flow of the visceral arteries. FEVAR has been in use in the United Kingdom for over a decade and early results were published in Jun 2012.
 [ 16 ]