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20,300 | Most MIs occur due to coronary artery disease. Risk factors include high blood pressure, smoking, diabetes, lack of exercise, obesity, high blood cholesterol, poor diet and excessive alcohol intake. The complete blockage of a coronary artery caused by a rupture of an atherosclerotic plaque is usually the underlying mec... | https://en.wikipedia.org/wiki?curid=20556798 |
20,301 | Treatment of an MI is time-critical. Aspirin is an appropriate immediate treatment for a suspected MI. Nitroglycerin or opioids may be used to help with chest pain; however, they do not improve overall outcomes. Supplemental oxygen is recommended in those with low oxygen levels or shortness of breath. In a STEMI, treat... | https://en.wikipedia.org/wiki?curid=20556798 |
20,302 | Worldwide, about 15.9 million myocardial infarctions occurred in 2015. More than 3 million people had an ST elevation MI, and more than 4 million had an NSTEMI. STEMIs occur about twice as often in men as women. About one million people have an MI each year in the United States. In the developed world, the risk of deat... | https://en.wikipedia.org/wiki?curid=20556798 |
20,303 | Myocardial infarction (MI) refers to tissue death (infarction) of the heart muscle (myocardium) caused by ischaemia, the lack of oxygen delivery to myocardial tissue. It is a type of acute coronary syndrome, which describes a sudden or short-term change in symptoms related to blood flow to the heart. Unlike the other t... | https://en.wikipedia.org/wiki?curid=20556798 |
20,304 | The phrase "heart attack" is often used non-specifically to refer to myocardial infarction. An MI is different from—but can cause—cardiac arrest, where the heart is not contracting at all or so poorly that all vital organs cease to function, thus might lead to death. It is also distinct from heart failure, in which the... | https://en.wikipedia.org/wiki?curid=20556798 |
20,305 | Chest pain that may or may not radiate to other parts of the body is the most typical and significant symptom of myocardial infarction. It might be accompanied by other symptoms such as sweating. | https://en.wikipedia.org/wiki?curid=20556798 |
20,306 | Chest pain is one of the most common symptoms of acute myocardial infarction and is often described as a sensation of tightness, pressure, or squeezing. Pain radiates most often to the left arm, but may also radiate to the lower jaw, neck, right arm, back, and upper abdomen. The pain most suggestive of an acute MI, wit... | https://en.wikipedia.org/wiki?curid=20556798 |
20,307 | Typically, chest pain because of ischemia, be it unstable angina or myocardial infarction, lessens with the use of nitroglycerin, but nitroglycerin may also relieve chest pain arising from non-cardiac causes. | https://en.wikipedia.org/wiki?curid=20556798 |
20,308 | Chest pain may be accompanied by sweating, nausea or vomiting, and fainting, and these symptoms may also occur without any pain at all. In women, the most common symptoms of myocardial infarction include shortness of breath, weakness, and fatigue. Women are more likely to have unusual or unexplained tiredness and nause... | https://en.wikipedia.org/wiki?curid=20556798 |
20,309 | "Silent" myocardial infarctions can happen without any symptoms at all. These cases can be discovered later on electrocardiograms, using blood enzyme tests, or at autopsy after a person has died. Such silent myocardial infarctions represent between 22 and 64% of all infarctions, and are more common in the elderly, in t... | https://en.wikipedia.org/wiki?curid=20556798 |
20,310 | The most prominent risk factors for myocardial infarction are older age, actively smoking, high blood pressure, diabetes mellitus, and total cholesterol and high-density lipoprotein levels. Many risk factors of myocardial infarction are shared with coronary artery disease, the primary cause of myocardial infarction, wi... | https://en.wikipedia.org/wiki?curid=20556798 |
20,311 | Many risk factors for myocardial infarction are potentially modifiable, with the most important being tobacco smoking (including secondhand smoke). Smoking appears to be the cause of about 36% and obesity the cause of 20% of coronary artery disease. Lack of physical activity has been linked to 7–12% of cases. Less comm... | https://en.wikipedia.org/wiki?curid=20556798 |
20,312 | There is varying evidence about the importance of saturated fat in the development of myocardial infarctions. Eating polyunsaturated fat instead of saturated fats has been shown in studies to be associated with a decreased risk of myocardial infarction, while other studies find little evidence that reducing dietary sat... | https://en.wikipedia.org/wiki?curid=20556798 |
20,313 | Family history of ischemic heart disease or MI, particularly if one has a male first-degree relative (father, brother) who had a myocardial infarction before age 55 years, or a female first-degree relative (mother, sister) less than age 65 increases a person's risk of MI. | https://en.wikipedia.org/wiki?curid=20556798 |
20,314 | Genome-wide association studies have found 27 genetic variants that are associated with an increased risk of myocardial infarction. The strongest association of MI has been found with chromosome 9 on the short arm "p" at locus 21, which contains genes CDKN2A and 2B, although the single nucleotide polymorphisms that are... | https://en.wikipedia.org/wiki?curid=20556798 |
20,315 | The risk of having a myocardial infarction increases with older age, low physical activity, and low socioeconomic status. Heart attacks appear to occur more commonly in the morning hours, especially between 6AM and noon. Evidence suggests that heart attacks are at least three times more likely to occur in the morning t... | https://en.wikipedia.org/wiki?curid=20556798 |
20,316 | Women who use combined oral contraceptive pills have a modestly increased risk of myocardial infarction, especially in the presence of other risk factors. The use of non-steroidal anti inflammatory drugs (NSAIDs), even for as short as a week, increases risk. | https://en.wikipedia.org/wiki?curid=20556798 |
20,317 | Air pollution is also an important modifiable risk. Short-term exposure to air pollution such as carbon monoxide, nitrogen dioxide, and sulfur dioxide (but not ozone) have been associated with MI and other acute cardiovascular events. For sudden cardiac deaths, every increment of 30 units in Pollutant Standards Index c... | https://en.wikipedia.org/wiki?curid=20556798 |
20,318 | A number of acute and chronic infections including "Chlamydophila pneumoniae", influenza, "Helicobacter pylori", and "Porphyromonas gingivalis" among others have been linked to atherosclerosis and myocardial infarction. As of 2013, there is no evidence of benefit from antibiotics or vaccination, however, calling the as... | https://en.wikipedia.org/wiki?curid=20556798 |
20,319 | Calcium deposits in the coronary arteries can be detected with CT scans. Calcium seen in coronary arteries can provide predictive information beyond that of classical risk factors. High blood levels of the amino acid homocysteine is associated with premature atherosclerosis; whether elevated homocysteine in the normal ... | https://en.wikipedia.org/wiki?curid=20556798 |
20,320 | In people without evident coronary artery disease, possible causes for the myocardial infarction are coronary spasm or coronary artery dissection. | https://en.wikipedia.org/wiki?curid=20556798 |
20,321 | The most common cause of a myocardial infarction is the rupture of an atherosclerotic plaque on an artery supplying heart muscle. Plaques can become unstable, rupture, and additionally promote the formation of a blood clot that blocks the artery; this can occur in minutes. Blockage of an artery can lead to tissue death... | https://en.wikipedia.org/wiki?curid=20556798 |
20,322 | The gradual buildup of cholesterol and fibrous tissue in plaques in the wall of the coronary arteries or other arteries, typically over decades, is termed atherosclerosis. Atherosclerosis is characterized by progressive inflammation of the walls of the arteries. Inflammatory cells, particularly macrophages, move into a... | https://en.wikipedia.org/wiki?curid=20556798 |
20,323 | Atherosclerotic disease is not the only cause of myocardial infarction, but it may exacerbate or contribute to other causes. A myocardial infarction may result from a heart with a limited blood supply subject to increased oxygen demands, such as in fever, a fast heart rate, hyperthyroidism, too few red blood cells in t... | https://en.wikipedia.org/wiki?curid=20556798 |
20,324 | If impaired blood flow to the heart lasts long enough, it triggers a process called the ischemic cascade; the heart cells in the territory of the blocked coronary artery die (infarction), chiefly through necrosis, and do not grow back. A collagen scar forms in their place. When an artery is blocked, cells lack oxygen, ... | https://en.wikipedia.org/wiki?curid=20556798 |
20,325 | Cells in the area with the worst blood supply, just below the inner surface of the heart (endocardium), are most susceptible to damage. Ischemia first affects this region, the "subendocardial" region, and tissue begins to die within 15–30 minutes of loss of blood supply. The dead tissue is surrounded by a zone of poten... | https://en.wikipedia.org/wiki?curid=20556798 |
20,326 | Tissue death and myocardial scarring alter the normal conduction pathways of the heart, and weaken affected areas. The size and location puts a person at risk of abnormal heart rhythms (arrhythmias) or heart block, aneurysm of the heart ventricles, inflammation of the heart wall following infarction, and rupture of the... | https://en.wikipedia.org/wiki?curid=20556798 |
20,327 | Injury to the myocardium also occurs during re-perfusion. This might manifest as ventricular arrhythmia. The re-perfusion injury is a consequence of the calcium and sodium uptake from the cardiac cells and the release of oxygen radicals during reperfusion. No-reflow phenomenon—when blood is still unable to be distribut... | https://en.wikipedia.org/wiki?curid=20556798 |
20,328 | A myocardial infarction, according to current consensus, is defined by elevated cardiac biomarkers with a rising or falling trend and at least one of the following: | https://en.wikipedia.org/wiki?curid=20556798 |
20,329 | A myocardial infarction is usually clinically classified as an ST-elevation MI (STEMI) or a non-ST elevation MI (NSTEMI). These are based on ST elevation, a portion of a heartbeat graphically recorded on an ECG. STEMIs make up about 25–40% of myocardial infarctions. A more explicit classification system, based on inter... | https://en.wikipedia.org/wiki?curid=20556798 |
20,330 | There are many different biomarkers used to determine the presence of cardiac muscle damage. Troponins, measured through a blood test, are considered to be the best, and are preferred because they have greater sensitivity and specificity for measuring injury to the heart muscle than other tests. A rise in troponin occu... | https://en.wikipedia.org/wiki?curid=20556798 |
20,331 | Other tests, such as CK-MB or myoglobin, are discouraged. CK-MB is not as specific as troponins for acute myocardial injury, and may be elevated with past cardiac surgery, inflammation or electrical cardioversion; it rises within 4–8 hours and returns to normal within 2–3 days. Copeptin may be useful to rule out MI rap... | https://en.wikipedia.org/wiki?curid=20556798 |
20,332 | Electrocardiograms (ECGs) are a series of leads placed on a person's chest that measure electrical activity associated with contraction of the heart muscle. The taking of an ECG is an important part of the workup of an AMI, and ECGs are often not just taken once but may be repeated over minutes to hours, or in response... | https://en.wikipedia.org/wiki?curid=20556798 |
20,333 | ECG readouts product a waveform with different labelled features. In addition to a rise in biomarkers, a rise in the ST segment, changes in the shape or flipping of T waves, new Q waves, or a new left bundle branch block can be used to diagnose an AMI. In addition, ST elevation can be used to diagnose an ST segment myo... | https://en.wikipedia.org/wiki?curid=20556798 |
20,334 | Noninvasive imaging plays an important role in the diagnosis and characterisation of myocardial infarction. Tests such as chest X-rays can be used to explore and exclude alternate causes of a person's symptoms. Echocardiography may assist in modifying clinical suspicion of ongoing myocardial infarction in patients that... | https://en.wikipedia.org/wiki?curid=20556798 |
20,335 | Echocardiography, an ultrasound scan of the heart, is able to visualize the heart, its size, shape, and any abnormal motion of the heart walls as they beat that may indicate a myocardial infarction. The flow of blood can be imaged, and contrast dyes may be given to improve image. Other scans using radioactive contrast ... | https://en.wikipedia.org/wiki?curid=20556798 |
20,336 | Medical societies and professional guidelines recommend that the physician confirm a person is at high risk for Chronic Coronary Syndrome before conducting diagnostic non-invasive imaging tests to make a diagnosis, as such tests are unlikely to change management and result in increased costs. Patients who have a normal... | https://en.wikipedia.org/wiki?curid=20556798 |
20,337 | There are many causes of chest pain, which can originate from the heart, lungs, gastrointestinal tract, aorta, and other muscles, bones and nerves surrounding the chest. In addition to myocardial infarction, other causes include angina, insufficient blood supply (ischemia) to the heart muscles without evidence of cell ... | https://en.wikipedia.org/wiki?curid=20556798 |
20,338 | There is a large crossover between the lifestyle and activity recommendations to prevent a myocardial infarction, and those that may be adopted as secondary prevention after an initial myocardial infarction, because of shared risk factors and an aim to reduce atherosclerosis affecting heart vessels. The influenza vacci... | https://en.wikipedia.org/wiki?curid=20556798 |
20,339 | Physical activity can reduce the risk of cardiovascular disease, and people at risk are advised to engage in 150 minutes of moderate or 75 minutes of vigorous-intensity aerobic exercise a week. Keeping a healthy weight, drinking alcohol within the recommended limits, and quitting smoking reduce the risk of cardiovascul... | https://en.wikipedia.org/wiki?curid=20556798 |
20,340 | Substituting unsaturated fats such as olive oil and rapeseed oil instead of saturated fats may reduce the risk of myocardial infarction, although there is not universal agreement. Dietary modifications are recommended by some national authorities, with recommendations including increasing the intake of wholegrain starc... | https://en.wikipedia.org/wiki?curid=20556798 |
20,341 | Public health measures may also act at a population level to reduce the risk of myocardial infarction, for example by reducing unhealthy diets (excessive salt, saturated fat, and trans fat) including food labeling and marketing requirements as well as requirements for catering and restaurants, and stimulating physical ... | https://en.wikipedia.org/wiki?curid=20556798 |
20,342 | Most guidelines recommend combining different preventive strategies. A 2015 Cochrane Review found some evidence that such an approach might help with blood pressure, body mass index and waist circumference. However, there was insufficient evidence to show an effect on mortality or actual cardio-vascular events. | https://en.wikipedia.org/wiki?curid=20556798 |
20,343 | Statins, drugs that act to lower blood cholesterol, decrease the incidence and mortality rates of myocardial infarctions. They are often recommended in those at an elevated risk of cardiovascular diseases. | https://en.wikipedia.org/wiki?curid=20556798 |
20,344 | Aspirin has been studied extensively in people considered at increased risk of myocardial infarction. Based on numerous studies in different groups (e.g. people with or without diabetes), there does not appear to be a benefit strong enough to outweigh the risk of excessive bleeding. Nevertheless, many clinical practice... | https://en.wikipedia.org/wiki?curid=20556798 |
20,345 | There is a large crossover between the lifestyle and activity recommendations to prevent a myocardial infarction, and those that may be adopted as secondary prevention after an initial myocardial infarct. Recommendations include stopping smoking, a gradual return to exercise, eating a healthy diet, low in saturated fat... | https://en.wikipedia.org/wiki?curid=20556798 |
20,346 | Following a heart attack, nitrates, when taken for two days, and ACE-inhibitors decrease the risk of death. Other medications include: | https://en.wikipedia.org/wiki?curid=20556798 |
20,347 | Aspirin is continued indefinitely, as well as another antiplatelet agent such as clopidogrel or ticagrelor ("dual antiplatelet therapy" or DAPT) for up to twelve months. If someone has another medical condition that requires anticoagulation (e.g. with warfarin) this may need to be adjusted based on risk of further card... | https://en.wikipedia.org/wiki?curid=20556798 |
20,348 | Beta blocker therapy such as metoprolol or carvedilol is recommended to be started within 24 hours, provided there is no acute heart failure or heart block. The dose should be increased to the highest tolerated. Contrary to what was long believed, the use of beta blockers does not appear to affect the risk of death, po... | https://en.wikipedia.org/wiki?curid=20556798 |
20,349 | ACE inhibitor therapy should be started within 24 hours, and continued indefinitely at the highest tolerated dose. This is provided there is no evidence of worsening kidney failure, high potassium, low blood pressure, or known narrowing of the renal arteries. Those who cannot tolerate ACE inhibitors may be treated with... | https://en.wikipedia.org/wiki?curid=20556798 |
20,350 | Statin therapy has been shown to reduce mortality and subsequent cardiac events and should be commenced to lower LDL cholesterol. Other medications, such as ezetimibe, may also be added with this goal in mind. | https://en.wikipedia.org/wiki?curid=20556798 |
20,351 | Aldosterone antagonists (spironolactone or eplerenone) may be used if there is evidence of left ventricular dysfunction after an MI, ideally after beginning treatment with an ACE inhibitor. | https://en.wikipedia.org/wiki?curid=20556798 |
20,352 | A defibrillator, an electric device connected to the heart and surgically inserted under the skin, may be recommended. This is particularly if there are any ongoing signs of heart failure, with a low left ventricular ejection fraction and a New York Heart Association grade II or III after 40 days of the infarction. Def... | https://en.wikipedia.org/wiki?curid=20556798 |
20,353 | A myocardial infarction requires immediate medical attention. Treatment aims to preserve as much heart muscle as possible, and to prevent further complications. Treatment depends on whether the myocardial infarction is a STEMI or NSTEMI. Treatment in general aims to unblock blood vessels, reduce blood clot enlargement,... | https://en.wikipedia.org/wiki?curid=20556798 |
20,354 | The pain associated with myocardial infarction is often treated with nitroglycerin, a vasodilator, or opioid medications such as morphine. Nitroglycerin (given under the tongue or injected into a vein) may improve blood supply to the heart. It is an important part of therapy for its pain relief effects, though there is... | https://en.wikipedia.org/wiki?curid=20556798 |
20,355 | Aspirin, an antiplatelet drug, is given as a loading dose to reduce the clot size and reduce further clotting in the affected artery. It is known to decrease mortality associated with acute myocardial infarction by at least 50%. P2Y12 inhibitors such as clopidogrel, prasugrel and ticagrelor are given concurrently, also... | https://en.wikipedia.org/wiki?curid=20556798 |
20,356 | There is varying evidence on the mortality benefits in NSTEMI. A 2014 review of P2Y12 inhibitors such as clopidogrel found they do not change the risk of death when given to people with a suspected NSTEMI prior to PCI, nor do heparins change the risk of death. They do decrease the risk of having a further myocardial in... | https://en.wikipedia.org/wiki?curid=20556798 |
20,357 | Primary percutaneous coronary intervention (PCI) is the treatment of choice for STEMI if it can be performed in a timely manner, ideally within 90–120 minutes of contact with a medical provider. Some recommend it is also done in NSTEMI within 1–3 days, particularly when considered high-risk. A 2017 review, however, did... | https://en.wikipedia.org/wiki?curid=20556798 |
20,358 | PCI involves small probes, inserted through peripheral blood vessels such as the femoral artery or radial artery into the blood vessels of the heart. The probes are then used to identify and clear blockages using small balloons, which are dragged through the blocked segment, dragging away the clot, or the insertion of ... | https://en.wikipedia.org/wiki?curid=20556798 |
20,359 | If PCI cannot be performed within 90 to 120 minutes in STEMI then fibrinolysis, preferably within 30 minutes of arrival to hospital, is recommended. If a person has had symptoms for 12 to 24 hours evidence for effectiveness of thrombolysis is less and if they have had symptoms for more than 24 hours it is not recommend... | https://en.wikipedia.org/wiki?curid=20556798 |
20,360 | In the past, high flow oxygen was recommended for everyone with a possible myocardial infarction. More recently, no evidence was found for routine use in those with normal oxygen levels and there is potential harm from the intervention. Therefore, oxygen is currently only recommended if oxygen levels are found to be lo... | https://en.wikipedia.org/wiki?curid=20556798 |
20,361 | If despite thrombolysis there is significant cardiogenic shock, continued severe chest pain, or less than a 50% improvement in ST elevation on the ECG recording after 90 minutes, then rescue PCI is indicated emergently. | https://en.wikipedia.org/wiki?curid=20556798 |
20,362 | Those who have had cardiac arrest may benefit from targeted temperature management with evaluation for implementation of hypothermia protocols. Furthermore, those with cardiac arrest, and ST elevation at any time, should usually have angiography. Aldosterone antagonists appear to be useful in people who have had an STE... | https://en.wikipedia.org/wiki?curid=20556798 |
20,363 | Cardiac rehabilitation benefits many who have experienced myocardial infarction, even if there has been substantial heart damage and resultant left ventricular failure. It should start soon after discharge from the hospital. The program may include lifestyle advice, exercise, social support, as well as recommendations ... | https://en.wikipedia.org/wiki?curid=20556798 |
20,364 | In the short-term, exercise-based cardiovascular rehabilitation programs may reduce the risk of a myocardial infarction, reduces a large number of hospitalizations from all causes, reduces hospital costs, improves health-related quality of life, and has a small effect on all-cause mortality. Longer-term studies indicat... | https://en.wikipedia.org/wiki?curid=20556798 |
20,365 | The prognosis after myocardial infarction varies greatly depending on the extent and location of the affected heart muscle, and the development and management of complications. Prognosis is worse with older age and social isolation. Anterior infarcts, persistent ventricular tachycardia or fibrillation, development of h... | https://en.wikipedia.org/wiki?curid=20556798 |
20,366 | It is unusual for babies to experience a myocardial infarction, but when they do, about half die. In the short-term, neonatal survivors seem to have a normal quality of life. | https://en.wikipedia.org/wiki?curid=20556798 |
20,367 | Complications may occur immediately following the myocardial infarction or may take time to develop. Disturbances of heart rhythms, including atrial fibrillation, ventricular tachycardia and fibrillation and heart block can arise as a result of ischemia, cardiac scarring, and infarct location. Stroke is also a risk, ei... | https://en.wikipedia.org/wiki?curid=20556798 |
20,368 | Heart failure may develop as a long-term consequence, with an impaired ability of heart muscle to pump, scarring, and an increase in the size of the existing muscle. Aneurysm of the left ventricle myocardium develops in about 10% of MI and is itself a risk factor for heart failure, ventricular arrhythmia, and the devel... | https://en.wikipedia.org/wiki?curid=20556798 |
20,369 | Risk factors for complications and death include age, hemodynamic parameters (such as heart failure, cardiac arrest on admission, systolic blood pressure, or Killip class of two or greater), ST-segment deviation, diabetes, serum creatinine, peripheral vascular disease, and elevation of cardiac markers. | https://en.wikipedia.org/wiki?curid=20556798 |
20,370 | Myocardial infarction is a common presentation of coronary artery disease. The World Health Organization estimated in 2004, that 12.2% of worldwide deaths were from ischemic heart disease; with it being the leading cause of death in high- or middle-income countries and second only to lower respiratory infections in low... | https://en.wikipedia.org/wiki?curid=20556798 |
20,371 | Rates of death from ischemic heart disease (IHD) have slowed or declined in most high-income countries, although cardiovascular disease still accounted for one in three of all deaths in the US in 2008. For example, rates of death from cardiovascular disease have decreased almost a third between 2001 and 2011 in the Uni... | https://en.wikipedia.org/wiki?curid=20556798 |
20,372 | In contrast, IHD is becoming a more common cause of death in the developing world. For example, in India, IHD had become the leading cause of death by 2004, accounting for 1.46 million deaths (14% of total deaths) and deaths due to IHD were expected to double during 1985–2015. Globally, disability adjusted life years (... | https://en.wikipedia.org/wiki?curid=20556798 |
20,373 | Social determinants such as neighborhood disadvantage, immigration status, lack of social support, social isolation, access to health services play an important role in myocardial infarction risk and survival. Studies have shown that low socioeconomic status is associated with an increased risk of poorer survival. Ther... | https://en.wikipedia.org/wiki?curid=20556798 |
20,374 | Race: In the U.S. African Americans have a greater burden of myocardial infarction and other cardiovascular events. On a population level, there is a higher overall prevalence of risk factors that are unrecognized and therefore not treated, which places these individuals at a greater likelihood of experiencing adverse ... | https://en.wikipedia.org/wiki?curid=20556798 |
20,375 | Socioeconomic status: Among individuals who live in the low-socioeconomic (SES) areas, which is close to 25% of the US population, myocardial infarctions (MIs) occurred twice as often compared with people who lived in higher SES areas. | https://en.wikipedia.org/wiki?curid=20556798 |
20,376 | Immigration status: In 2018 many lawfully present immigrants who are eligible for coverage remain uninsured because immigrant families face a range of enrollment barriers, including fear, confusion about eligibility policies, difficulty navigating the enrollment process, and language and literacy challenges. Uninsured ... | https://en.wikipedia.org/wiki?curid=20556798 |
20,377 | Health care access: Lack of health insurance and financial concerns about accessing care were associated with delays in seeking emergency care for acute myocardial infarction which can have significant, adverse consequences on patient outcomes. | https://en.wikipedia.org/wiki?curid=20556798 |
20,378 | Education: Researchers found that compared to people with graduate degrees, those with lower educational attainment appeared to have a higher risk of heart attack, dying from a cardiovascular event, and overall death. | https://en.wikipedia.org/wiki?curid=20556798 |
20,379 | Depictions of heart attacks in popular media often include collapsing or loss of consciousness which are not common symptoms; these depictions contribute to widespread misunderstanding about the symptoms of myocardial infarctions, which in turn contributes to people not getting care when they should. | https://en.wikipedia.org/wiki?curid=20556798 |
20,380 | At common law, in general, a myocardial infarction is a disease, but may sometimes be an injury. This can create coverage issues in the administration of no-fault insurance schemes such as workers' compensation. In general, a heart attack is not covered; however, it may be a work-related injury if it results, for examp... | https://en.wikipedia.org/wiki?curid=20556798 |
20,381 | Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale blue liquid that is slightly more viscous than water. It is used as an oxidizer, bleaching agent, and antiseptic, usually as a dilute solution (3%–6% by weight) in water for consumer use, and in higher concentrations for ind... | https://en.wikipedia.org/wiki?curid=14403 |
20,382 | Hydrogen peroxide is a reactive oxygen species and the simplest peroxide, a compound having an oxygen–oxygen single bond. It decomposes slowly when exposed to light, and rapidly in the presence of organic or reactive compounds. It is typically stored with a stabilizer in a weakly acidic solution in a dark bottle to blo... | https://en.wikipedia.org/wiki?curid=14403 |
20,383 | The boiling point of has been extrapolated as being , approximately higher than water. In practice, hydrogen peroxide will undergo potentially explosive thermal decomposition if heated to this temperature. It may be safely distilled at lower temperatures under reduced pressure. | https://en.wikipedia.org/wiki?curid=14403 |
20,384 | Hydrogen peroxide () is a nonplanar molecule with (twisted) C symmetry; this was first shown by Paul-Antoine Giguère in 1950 using infrared spectroscopy. Although the O−O bond is a single bond, the molecule has a relatively high rotational barrier of 386 cm (4.62 kJ/mol) for rotation between enantiomers via the "trans"... | https://en.wikipedia.org/wiki?curid=14403 |
20,385 | The approximately 100° dihedral angle between the two O–H bonds makes the molecule chiral. It is the smallest and simplest molecule to exhibit enantiomerism. It has been proposed that the enantiospecific interactions of one rather than the other may have led to amplification of one enantiomeric form of ribonucleic acid... | https://en.wikipedia.org/wiki?curid=14403 |
20,386 | The molecular structures of gaseous and crystalline are significantly different. This difference is attributed to the effects of hydrogen bonding, which is absent in the gaseous state. Crystals of are tetragonal with the space group "D" or "P"422. | https://en.wikipedia.org/wiki?curid=14403 |
20,387 | In aqueous solutions, hydrogen peroxide differs from the pure substance due to the effects of hydrogen bonding between water and hydrogen peroxide molecules. Hydrogen peroxide and water form a eutectic mixture, exhibiting freezing-point depression down as low as -56 °C; pure water has a freezing point of 0 °C and pure ... | https://en.wikipedia.org/wiki?curid=14403 |
20,388 | Hydrogen peroxide has several structural analogues with bonding arrangements (water also shown for comparison). It has the highest (theoretical) boiling point of this series (X = O, S, N, P). Its melting point is also fairly high, being comparable to that of hydrazine and water, with only hydroxylamine crystallising si... | https://en.wikipedia.org/wiki?curid=14403 |
20,389 | Alexander von Humboldt is sometimes said to have been the first to report the first synthetic peroxide, barium peroxide, in 1799 as a by-product of his attempts to decompose air, although this is disputed due to von Humboldt's ambiguous wording. Nineteen years later Louis Jacques Thénard recognized that this compound c... | https://en.wikipedia.org/wiki?curid=14403 |
20,390 | An improved version of Thénard's process used hydrochloric acid, followed by addition of sulfuric acid to precipitate the barium sulfate byproduct. This process was used from the end of the 19th century until the middle of the 20th century. | https://en.wikipedia.org/wiki?curid=14403 |
20,391 | The bleaching effect of peroxides and their salts on natural dyes had been known since Thénard's experiments in the 1820s, but early attempts of industrial production of peroxides failed. The first plant producing hydrogen peroxide was built in 1873 in Berlin. The discovery of the synthesis of hydrogen peroxide by elec... | https://en.wikipedia.org/wiki?curid=14403 |
20,392 | Early attempts failed to produce neat hydrogen peroxide. Anhydrous hydrogen peroxide was first obtained by vacuum distillation. | https://en.wikipedia.org/wiki?curid=14403 |
20,393 | Determination of the molecular structure of hydrogen peroxide proved to be very difficult. In 1892, the Italian physical chemist Giacomo Carrara (1864–1925) determined its molecular mass by freezing-point depression, which confirmed that its molecular formula is . At least half a dozen hypothetical molecular structures... | https://en.wikipedia.org/wiki?curid=14403 |
20,394 | which was itself obtained by the electrolysis of a solution of ammonium bisulfate () in sulfuric acid: | https://en.wikipedia.org/wiki?curid=14403 |
20,395 | Today, hydrogen peroxide is manufactured almost exclusively by the anthraquinone process, which was originally developed by BASF in 1939. It begins with the reduction of an anthraquinone (such as 2-ethylanthraquinone or the 2-amyl derivative) to the corresponding anthrahydroquinone, typically by hydrogenation on a pall... | https://en.wikipedia.org/wiki?curid=14403 |
20,396 | The economics of the process depend heavily on effective recycling of the extraction solvents, the hydrogenation catalyst and the expensive quinone. | https://en.wikipedia.org/wiki?curid=14403 |
20,397 | Small, but detectable, amounts of hydrogen peroxide can be formed by several methods. Small amounts are formed by electrolysis of dilute acid around the cathode where hydrogen evolves if oxygen is bubbled around it. It is also produced by exposing water to ultraviolet rays from a mercury lamp, or an electric arc while ... | https://en.wikipedia.org/wiki?curid=14403 |
20,398 | A commercially viable process to produce hydrogen peroxide directly from the environment has been of interest for many years. Efficient direct synthesis is difficult to achieve, as the reaction of hydrogen with oxygen thermodynamically favours production of water. Systems for direct synthesis have been developed, most ... | https://en.wikipedia.org/wiki?curid=14403 |
20,399 | Hydrogen peroxide is most commonly available as a solution in water. For consumers, it is usually available from pharmacies at 3 and 6 wt% concentrations. The concentrations are sometimes described in terms of the volume of oxygen gas generated; one milliliter of a 20-volume solution generates twenty milliliters of oxy... | https://en.wikipedia.org/wiki?curid=14403 |
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