Ventricular fibrillation ( V-fib or VF ) is an abnormal heart rhythm in which the ventricles of the heart quiver . It is due to disorganized electrical activity . Ventricular fibrillation results in cardiac arrest with loss of consciousness and no pulse . This is followed by sudden cardiac death in the absence of treatment. Ventricular fibrillation is initially found in about 10% of people with cardiac arrest.
149-675: Ventricular fibrillation can occur due to coronary heart disease , valvular heart disease , cardiomyopathy , Brugada syndrome , long QT syndrome , electric shock , or intracranial hemorrhage . Diagnosis is by an electrocardiogram (ECG) showing irregular unformed QRS complexes without any clear P waves . An important differential diagnosis is torsades de pointes . Treatment is with cardiopulmonary resuscitation (CPR) and defibrillation . Biphasic defibrillation may be better than monophasic. The medication epinephrine or amiodarone may be given if initial treatments are not effective. Rates of survival among those who are out of hospital when
298-411: A blood test for biomarkers (the cardiac protein troponin ). When there is evidence of an MI, it may be classified as an ST elevation myocardial infarction (STEMI) or Non-ST elevation myocardial infarction (NSTEMI) based on the results of an ECG . 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
447-475: A coronary artery caused by a rupture of an atherosclerotic plaque is usually the underlying mechanism of an MI. MIs are less commonly caused by coronary artery spasms , which may be due to cocaine , significant emotional stress (often known as Takotsubo syndrome or broken heart syndrome ) and extreme cold, among others. Many tests are helpful to help with diagnosis, including electrocardiograms (ECGs), blood tests and coronary angiography . An ECG, which
596-417: A coronary care unit for possible complications (such as cardiac arrhythmias – irregularities in the heart rate). Depending on the risk assessment, stress testing or angiography may be used to identify and treat coronary artery disease in patients who have had an NSTEMI or unstable angina. There are various risk assessment systems for determining the risk of coronary artery disease, with various emphasis on
745-619: A healthy diet , regularly exercising , maintaining a healthy weight, and not smoking. Medications for diabetes, high cholesterol, or high blood pressure are sometimes used. There is limited evidence for screening people who are at low risk and do not have symptoms. Treatment involves the same measures as prevention. Additional medications such as antiplatelets (including aspirin ), beta blockers , or nitroglycerin may be recommended. Procedures such as percutaneous coronary intervention (PCI) or coronary artery bypass surgery (CABG) may be used in severe disease. In those with stable CAD it
894-474: A benefit of 15 to 45%. 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 cardiovascular disease. Substituting unsaturated fats such as olive oil and rapeseed oil instead of saturated fats may reduce
1043-487: A build-up of atheromatous plaque in the arteries of the heart . It is the most common of the cardiovascular diseases . CAD can cause stable angina , unstable angina , myocardial ischemia, and myocardial infarction . A common symptom is angina, which is chest pain or discomfort which may travel into the shoulder, arm, back, neck, or jaw. Occasionally it may feel like heartburn . In stable angina , symptoms occur with exercise or emotional stress , last less than
1192-656: A combination of genetic predisposition and environmental factors. Organizations such as the Indian Heart Association are working with the World Heart Federation to raise awareness about this issue. Coronary artery disease is the leading cause of death for both males and females and accounts for approximately 600,000 deaths in the United States every year. According to present trends in the United States, half of healthy 40-year-old males will develop CAD in
1341-428: A common, and sometimes the only symptom, occurring when damage to the heart limits the output of the left ventricle , with breathlessness arising either from low oxygen in the blood or pulmonary edema . Other less common symptoms include weakness, light-headedness , palpitations , and abnormalities in heart rate or blood pressure . These symptoms are likely induced by a massive surge of catecholamines from
1490-705: A few minutes, and improve with rest. Shortness of breath may also occur and sometimes no symptoms are present. In many cases, the first sign is a heart attack . Other complications include heart failure or an abnormal heartbeat . Risk factors include high blood pressure , smoking , diabetes , lack of exercise, obesity , high blood cholesterol , poor diet, depression , and excessive alcohol consumption. A number of tests may help with diagnosis including: electrocardiogram , cardiac stress testing , coronary computed tomographic angiography , biomarkers ( high-sensitivity cardiac troponins ) and coronary angiogram , among others. Ways to reduce CAD risk include eating
1639-405: A given age also decreased between 1990 and 2010. In the United States in 2010, about 20% of those over 65 had CAD, while it was present in 7% of those 45 to 64, and 1.3% of those 18 to 45; rates were higher among males than females of a given age. The most common symptom is chest pain or discomfort that occurs regularly with activity, after eating, or at other predictable times; this phenomenon
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#17330844963361788-490: A heart attack or myocardial infarction, and immediate emergency medical services are crucial. With advanced disease, the narrowing of coronary arteries reduces the supply of oxygen-rich blood flowing to the heart, which becomes more pronounced during strenuous activities during which the heart beats faster and has an increased oxygen demand. For some, this causes severe symptoms, while others experience no symptoms at all. Symptoms in females can differ from those in males, and
1937-429: A high metabolic rate of the myocardium , produces no useful beats. As a result, the arterial pressure falls abruptly to very low levels, and death results within six to eight minutes from anemia [ischemia] of the brain and spinal cord ". Spontaneous conversion of ventricular fibrillation to a more benign rhythm is rare in all but small animals. Defibrillation is the process that converts ventricular fibrillation to
2086-480: A late consequence of Kawasaki disease . 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 range is causal is controversial. In people without evident coronary artery disease , possible causes for
2235-415: A layperson can look like normal spontaneous breathing, but is a sign of hypoperfusion of the brainstem . It has an appearance on electrocardiography of irregular electrical activity with no discernable pattern. It may be described as "coarse" or "fine" depending on its amplitude, or as progressing from coarse to fine V-fib. Coarse V-fib may be more responsive to defibrillation, while fine V-fib can mimic
2384-402: A more benign rhythm. This is usually by application of an electric shock to the myocardium and is discussed in detail in the relevant article. Coronary heart disease Coronary artery disease ( CAD ), also called coronary heart disease ( CHD ), or ischemic heart disease ( IHD ), is a type of heart disease involving the reduction of blood flow to the cardiac muscle due to
2533-431: 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. 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
2682-431: A myocardial infarction but does not change the overall risk of death. Aspirin therapy to prevent heart disease is thus recommended only in adults who are at increased risk for cardiovascular events, which may include postmenopausal females, males above 40, and younger people with risk factors for coronary heart disease, including high blood pressure , a family history of heart disease, or diabetes . The benefits outweigh
2831-463: 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 than in the late evening. Shift work is also associated with a higher risk of MI. One analysis has found an increase in heart attacks immediately following
2980-406: A myocardial infarction. Spasm of coronary arteries, such as Prinzmetal's angina may cause blockage. 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
3129-543: A myocardial infarction. The flow of blood can be imaged, and contrast dyes may be given to improve image. Other scans using radioactive contrast include SPECT CT-scans using thallium , sestamibi ( MIBI scans ) or tetrofosmin ; or a PET scan using Fludeoxyglucose or rubidium-82 . These nuclear medicine scans can visualize the perfusion of heart muscle. SPECT may also be used to determine viability of tissue, and whether areas of ischemia are inducible. Medical societies and professional guidelines recommend that
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#17330844963363278-404: A neuropsychological assessment. There are a number of treatment options for coronary artery disease: It is recommended that blood pressure typically be reduced to less than 140/90 mmHg. The diastolic blood pressure however should not be lower than 60 mmHg. Beta-blockers are recommended first line for this use. In those with no previous history of heart disease, aspirin decreases the risk of
3427-637: A person localizes the chest pain by clenching one or both fists over their sternum , has classically been thought to be predictive of cardiac chest pain, although a prospective observational study showed it had a poor positive predictive value . 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. Chest pain may be accompanied by sweating , nausea or vomiting, and fainting , and these symptoms may also occur without any pain at all. Dizziness or lightheadedness
3576-407: A previous heart attack is also suggestive. The pain associated with MI is usually diffuse, does not change with position, and lasts for more than 20 minutes. It might be described as pressure, tightness, knifelike, tearing, burning sensation (all these are also manifested during other diseases). It could be felt as an unexplained anxiety, and pain might be absent altogether. Levine's sign , in which
3725-469: A reputed incidence of approximately 1% of all cases of out-of-hospital arrest, as well as 3–9% of the cases of ventricular fibrillation unrelated to myocardial infarction , and 14% of all ventricular fibrillation resuscitations in patients under the age of 40. It follows then that, on the basis of the fact that ventricular fibrillation itself is common, idiopathic ventricular fibrillation accounts for an appreciable mortality. Recently described syndromes such as
3874-554: 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 myocardial infarction (STEMI). A rise must be new in V2 and V3 ≥2 mm (0,2 mV) for males or ≥1.5 mm (0.15 mV) for females or ≥1 mm (0.1 mV) in two other adjacent chest or limb leads . ST elevation
4023-427: A role. The diagnosis of CAD depends largely on the nature of the symptoms and imaging. The first investigation when CAD is suspected is an electrocardiogram (ECG/EKG), both for stable angina and acute coronary syndrome. An X-ray of the chest , blood tests and resting echocardiography may be performed. For stable symptomatic patients, several non-invasive tests can diagnose CAD depending on pre-assessment of
4172-558: A safe and feasible procedure that may offer some advantages over conventional CABG though it is more expensive. As of 2010, CAD was the leading cause of death globally resulting in over 7 million deaths. This increased from 5.2 million deaths from CAD worldwide in 1990. It may affect individuals at any age but becomes dramatically more common at progressively older ages, with approximately a tripling with each decade of life. Males are affected more often than females. The World Health Organization reported that: "The world's biggest killer
4321-409: 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 to changes in signs or symptoms. ECG readouts produce a waveform with different labeled features. In addition to
4470-406: A significant effect on blood cholesterol and thus recommendations about its consumption may not be needed. Trans fats do appear to increase risk. Acute and prolonged intake of high quantities of alcoholic drinks (3–4 or more daily) increases the risk of a heart attack. Family history of ischemic heart disease or MI, particularly if one has a male first-degree relative (father, brother) who had
4619-416: A significant role in stiffening the arteries and inducing the early phase of coronary arteriosclerosis . This can be seen in a so-called metastatic mechanism of calciphylaxis as it occurs in chronic kidney disease and hemodialysis . Although these people have kidney dysfunction, almost fifty percent of them die due to coronary artery disease. Plaques can be thought of as large "pimples" that protrude into
Ventricular fibrillation - Misplaced Pages Continue
4768-438: A single shock to a frog heart. The concept of "R on T ectopics" was further brought out by Katz in 1928. This was called the "vulnerable period" by Wiggers and Wegria in 1940, who brought to attention the concept of the danger of premature ventricular beats occurring on a T wave . Another definition of VF was produced by Wiggers in 1940. He described ventricular fibrillation as "an incoordinate type of contraction which, despite
4917-434: A tail. The length of the refractory period and the time taken for the dipole to travel a certain distance—the propagation velocity—will determine whether such a circumstance will arise for re-entry to occur. Factors that promote re-entry would include a slow-propagation velocity, a short refractory period with a sufficient size of ring of conduction tissue. These would enable a dipole to reach an area that had been refractory and
5066-554: A waveform can be expressed as a power spectrum in which the contribution of different waveform frequencies to the waveform under analysis is measured. This can be expressed as either the dominant or peak frequency, i.e., the frequency with the greatest power or the median frequency, which divides the spectrum in two halves. Frequency analysis has many other uses in medicine and in cardiology, including analysis of heart rate variability and assessment of cardiac function, as well as in imaging and acoustics. Myofibre break-up, abbreviated MFB,
5215-601: Is a known risk factor, particularly high low-density lipoprotein , low high-density lipoprotein , and high triglycerides . 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 common causes include stress-related causes such as job stress , which accounts for about 3% of cases, and chronic high stress levels. There
5364-454: Is a recording of the heart's electrical activity, may confirm an ST elevation MI ( STEMI ), if ST elevation is present. Commonly used blood tests include troponin and less often creatine kinase MB . 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
5513-490: Is advanced and death is near." A book authored by Jo Miles suggests that it may even go back farther. Tests done on frozen remains found in the Himalayas seemed fairly conclusive that the first known case of ventricular fibrillation dates back to at least 2500 BC. Whether this is a description of ventricular fibrillation is debatable. The next recorded description occurs 3000 years later and is recorded by Vesalius , who described
5662-795: Is also an important modifiable risk. Short-term exposure to air pollution such as carbon monoxide , nitrogen dioxide , and sulfur dioxide (but not ozone ) has been associated with MI and other acute cardiovascular events. For sudden cardiac deaths, every increment of 30 units in Pollutant Standards Index correlated with an 8% increased risk of out-of-hospital cardiac arrest on the day of exposure. Extremes of temperature are also associated. 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. Myocardial infarction can also occur as
5811-452: Is also seen in those with cardiomyopathy , myocarditis , and other heart pathologies. In addition, it is seen with electrolyte imbalance , overdoses of cardiotoxic drugs, and following near drowning or major trauma . It is also notable that ventricular fibrillation occurs where there is no discernible heart pathology or other evident cause, the so-called idiopathic ventricular fibrillation. Idiopathic ventricular fibrillation occurs with
5960-570: Is another way of risk assessment. In one study the relative risk of incident coronary events was 91% higher among participants at high genetic risk than among those at low genetic risk. Up to 90% of cardiovascular disease may be preventable if established risk factors are avoided. Prevention involves adequate physical exercise , decreasing obesity , treating high blood pressure , eating a healthy diet , decreasing cholesterol levels, and stopping smoking . Medications and exercise are roughly equally effective. High levels of physical activity reduce
6109-499: Is associated with infarction, and may be preceded by changes indicating ischemia, such as ST depression or inversion of the T waves. Abnormalities can help differentiate the location of an infarct, based on the leads that are affected by changes. Early STEMIs may be preceded by peaked T waves. Other ECG abnormalities relating to complications of acute myocardial infarctions may also be evident, such as atrial or ventricular fibrillation . Noninvasive imaging plays an important role in
Ventricular fibrillation - Misplaced Pages Continue
6258-421: Is associated with ventricular fibrillation leading to death. Histomorphologically , MFB is characterized by fractures of the cardiac myofibres perpendicular to their long axis, with squaring of the myofibre nuclei . Defibrillation is the definitive treatment of ventricular fibrillation, whereby an electrical current is applied to the ventricular mass either directly or externally through pads or paddles, with
6407-410: Is available. In the absence of ST-segment elevation, heart damage is detected by cardiac markers (blood tests that identify heart muscle damage). If there is evidence of damage ( infarction ), the chest pain is attributed to a "non-ST elevation MI" (NSTEMI). If there is no evidence of damage, the term "unstable angina" is used. This process usually necessitates hospital admission and close observation on
6556-511: Is blocked, cells lack oxygen , needed to produce ATP in mitochondria . ATP is required for the maintenance of electrolyte balance, particularly through the Na/K ATPase . This leads to an ischemic cascade of intracellular changes, necrosis and apoptosis of affected cells. 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,
6705-507: Is called a myocardial infarction (commonly referred to as a heart attack). It leads to damage, death, and eventual scarring of the heart muscle without regrowth of heart muscle cells. Chronic high-grade narrowing of the coronary arteries can induce transient ischemia which leads to the induction of a ventricular arrhythmia , which may terminate into a dangerous heart rhythm known as ventricular fibrillation , which often leads to death. Typically, coronary artery disease occurs when part of
6854-503: Is characterized by heart problems that result from atherosclerosis. Atherosclerosis is a type of arteriosclerosis which is the "chronic inflammation of the arteries which causes them to harden and accumulate cholesterol plaques (atheromatous plaques) on the artery walls". CAD has several well-determined risk factors that contribute to atherosclerosis. These risk factors for CAD include "smoking, diabetes, high blood pressure (hypertension), abnormal (high) amounts of cholesterol and other fat in
7003-433: Is common and occurs due to reduction in oxygen and blood to the brain. In females, the most common symptoms of myocardial infarction include shortness of breath, weakness, and fatigue . Females are more likely to have unusual or unexplained tiredness and nausea or vomiting as symptoms. Females having heart attacks are more likely to have palpitations, back pain, labored breath, vomiting, and left arm pain than males, although
7152-415: Is found in cardiac muscle; it is a 'cytolinker' that connects actin and desmin to facilitate cytoskeletal function and vesicular movement. The endocytic pathway is further modulated by changes in tubulin , a key microtubule protein, and fidgetin , a tubulin-severing enzyme that is a marker for cardiovascular risk identified by genome-wide association study . Protein recycling would be modulated by changes in
7301-491: Is inferior to non-invasive imaging methods due to the risk of false negative and false positive test results. The use of non-invasive imaging is not recommended on individuals who are exhibiting no symptoms and are otherwise at low risk for developing coronary disease. Invasive testing with coronary angiography (ICA) can be used when non-invasive testing is inconclusive or show a high event risk. The diagnosis of microvascular angina (previously known as cardiac syndrome X –
7450-453: Is ischemic heart disease, responsible for 13% of the world's total deaths. Since 2000, the largest increase in deaths has been for this disease, rising by 2.7 million to 9.1 million deaths in 2021." It is estimated that 60% of the world's cardiovascular disease burden will occur in the South Asian subcontinent despite only accounting for 20% of the world's population. This may be secondary to
7599-687: Is linked to an increased risk of coronary disease. The consumption of different types of fats including trans fat (trans unsaturated), and saturated fat , in a diet "influences the level of cholesterol that is present in the bloodstream". Unsaturated fats originate from plant sources (such as oils). There are two types of unsaturated fats, cis and trans isomers. Cis unsaturated fats are bent in molecular structure and trans are linear in structure. Saturated fats originate from animal sources (such as animal fats) and are also molecularly linear in structure. The linear configurations of unsaturated trans and saturated fats allow them to easily accumulate and stack at
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#17330844963367748-411: Is lost and therefore there can be activation of funny current even in myocardial cells (which is normally suppressed by the hyperpolarizing effect of coexisting potassium currents). This can lead to the instauration of automaticity in ischemic tissue. The role of re-entry or circus motion was demonstrated separately by G. R. Mines and W. E. Garrey . Mines created a ring of excitable tissue by cutting
7897-465: Is more effective than hemoglobin A1c (HbA1c) for detecting dysglycemia in patients with coronary artery disease. The study highlighted that 2-hour post-load glucose levels of at least 9 mmol/L were strong predictors of cardiovascular outcomes, while HbA1c levels of at least 5.9% were also significant but not independently associated when combined with OGTT results. A diet high in fruits and vegetables decreases
8046-489: Is most commonly used to provide rapid relief for acute angina attacks and as a complement to anti-anginal treatments in patients with refractory and recurrent angina. When nitroglycerine enters the bloodstream, it forms free radical nitric oxide, or NO, which activates guanylate cyclase and in turn stimulates the release of cyclic GMP. This molecular signaling stimulates smooth muscle relaxation, ultimately resulting in vasodilation and consequently improved blood flow to regions of
8195-533: Is no evidence that they change mortality, the risk of revascularization procedures, or the rate of non-fatal myocardial infarction. Antibiotics for secondary prevention of coronary heart disease Early studies suggested that antibiotics might help patients with coronary disease to reduce the risk of heart attacks and strokes. However, a 2021 Cochrane meta-analysis found that antibiotics given for secondary prevention of coronary heart disease are harmful for people with increased mortality and occurrence of stroke. So,
8344-477: 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 the bloodstream , or low blood pressure . Damage or failure of procedures such as percutaneous coronary intervention (PCI) or coronary artery bypass grafts (CABG) may cause
8493-575: Is now able to be depolarised with continuation of the wavefront . In clinical practice, therefore, factors that would lead to the right conditions to favour such re-entry mechanisms include increased heart size through hypertrophy or dilatation, drugs which alter the length of the refractory period and areas of cardiac disease. Therefore, the substrate of ventricular fibrillation is transient or permanent conduction block. Block due either to areas of damaged or refractory tissue leads to areas of myocardium for initiation and perpetuation of fibrillation through
8642-430: 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, with the highest likelihood ratio , is pain radiating to the right arm and shoulder. Similarly, chest pain similar to
8791-626: Is preventing further sequelae of already established disease. Effective lifestyle changes include: Aerobic exercise , like walking, jogging, or swimming, can reduce the risk of mortality from coronary artery disease. Aerobic exercise can help decrease blood pressure and the amount of blood cholesterol (LDL) over time. It also increases HDL cholesterol. Although exercise is beneficial, it is unclear whether doctors should spend time counseling patients to exercise. The U.S. Preventive Services Task Force found "insufficient evidence" to recommend that doctors counsel patients on exercise but "it did not review
8940-402: Is rapidly fatal as the vital organs of the body, including the heart, are starved of oxygen, and as a result patients in this rhythm will not be conscious or responsive to stimuli. Coma and persistent vegetative state may also result. Prior to cardiac arrest, patients may complain of varying symptoms depending on the underlying cause . Patients may exhibit signs of agonal breathing , which to
9089-414: Is recommended in those with low oxygen levels or shortness of breath. In a STEMI, treatments attempt to restore blood flow to the heart and include percutaneous coronary intervention (PCI), where the arteries are pushed open and may be stented , or thrombolysis , where the blockage is removed using medications. People who have a non-ST elevation myocardial infarction ( NSTEMI ) are often managed with
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#17330844963369238-412: Is still unable to be distributed to the affected myocardium despite clearing the occlusion—also contributes to myocardial injury. Topical endothelial swelling is one of many factors contributing to this phenomenon. 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: A myocardial infarction
9387-541: Is termed stable angina and is associated with narrowing of the arteries of the heart . Angina also includes chest tightness, heaviness, pressure, numbness, fullness, or squeezing. Angina that changes in intensity, character or frequency is termed unstable. Unstable angina may precede myocardial infarction . In adults who go to the emergency department with an unclear cause of pain, about 30% have pain due to coronary artery disease. Angina, shortness of breath, sweating, nausea or vomiting, and lightheadedness are signs of
9536-556: Is the leading cause of death in the industrialised world. It exacts a significant mortality with approximately 70,000 to 90,000 sudden cardiac deaths each year in the United Kingdom, and survival rates are only 2%. The majority of these deaths are due to ventricular fibrillation secondary to myocardial infarction , or "heart attack". During ventricular fibrillation, cardiac output drops to zero, and, unless remedied promptly, death usually ensues within minutes. Lyman Brewer suggests that
9685-434: Is unclear if PCI or CABG in addition to the other treatments improves life expectancy or decreases heart attack risk. In 2015, CAD affected 110 million people and resulted in 8.9 million deaths. It makes up 15.6% of all deaths, making it the most common cause of death globally. The risk of death from CAD for a given age decreased between 1980 and 2010, especially in developed countries . The number of cases of CAD for
9834-457: 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 international consensus in 2012, also exists. This classifies myocardial infarctions into five types: There are many different biomarkers used to determine
9983-445: 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 saturated fat or increasing polyunsaturated fat intake affects heart attack risk. Dietary cholesterol does not appear to have
10132-532: The Brugada Syndrome may give clues to the underlying mechanism of ventricular arrhythmias. In the Brugada syndrome, changes may be found in the resting ECG with evidence of right bundle branch block (RBBB) and ST elevation in the chest leads V1-V3, with an underlying propensity to sudden cardiac death. The relevance of this is that theories of the underlying pathophysiology and electrophysiology must account for
10281-456: The University of Aberdeen , gave an accurate description of the arrhythmia in 1887. This definition still holds today, and is interesting in the fact that his studies and description predate the use of electrocardiography . His description is as follows: "The ventricular muscle is thrown into a state of irregular arrhythmic contraction, whilst there is a great fall in the arterial blood pressure,
10430-661: The elderly , in those with diabetes mellitus and after heart transplantation . In people with diabetes, differences in pain threshold , autonomic neuropathy , and psychological factors have been cited as possible explanations for the lack of symptoms. In heart transplantation, the donor heart is not fully innervated by the nervous system of the recipient. 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 ,
10579-480: The health impact assessment of regional and local plans and policies. 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. Statins , drugs that act to lower blood cholesterol, decrease
10728-994: The heart muscle . The most common symptom is retrosternal chest pain or discomfort that classically radiates to the left shoulder, arm, or jaw. The pain may occasionally feel like heartburn . This is the dangerous type of Acute coronary syndrome . Other symptoms may include shortness of breath , nausea , feeling faint , a cold sweat , feeling tired , and decreased level of consciousness . About 30% of people have atypical symptoms. Women more often present without chest pain and instead have neck pain, arm pain or feel tired. Among those over 75 years old, about 5% have had an MI with little or no history of symptoms. An MI may cause heart failure , an irregular heartbeat , cardiogenic shock or cardiac arrest . 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
10877-522: The single nucleotide polymorphisms that are implicated are within a non-coding region. The majority of these variants are in regions that have not been previously implicated in coronary artery disease. The following genes have an association with MI: PCSK9 , SORT1 , MIA3 , WDR12 , MRAS , PHACTR1 , LPA , TCF21 , MTHFDSL , ZC3HC1 , CDKN2A , 2B , ABO , PDGF0 , APOA5 , MNF1ASM283 , COL4A1 , HHIPC1 , SMAD3 , ADAMTS7 , RAS1 , SMG6 , SNF8 , LDLR , SLC5A3 , MRPS6 , KCNE2 . The risk of having
11026-481: 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 potentially reversible ischemia that progresses to become a full-thickness transmural infarct. The initial "wave" of infarction can take place over 3–4 hours. These changes are seen on gross pathology and cannot be predicted by the presence or absence of Q waves on an ECG. The position, size and extent of an infarct depends on
11175-551: The sympathetic nervous system , which occurs in response to pain and, where present, low blood pressure . Loss of consciousness can occur in myocardial infarctions due to inadequate blood flow to the brain and cardiogenic shock , and sudden death , frequently due to the development of ventricular fibrillation . When the brain was without oxygen for too long due to a myocardial infarction, coma and persistent vegetative state can occur. Cardiac arrest, and atypical symptoms such as palpitations , occur more frequently in females,
11324-471: The United States. In the developed world, the risk of death in those who have had a STEMI is about 10%. Rates of MI for a given age have decreased globally between 1990 and 2010. In 2011, an MI was one of the top five most expensive conditions during inpatient hospitalizations in the US, with a cost of about $ 11.5 billion for 612,000 hospital stays. Myocardial infarction (MI) refers to tissue death ( infarction ) of
11473-432: The acute diagnostic algorithm; however, it can confirm a clinical suspicion of Chronic Coronary Syndrome when the patient's history, physical examination (including cardiac examination ) ECG, and cardiac biomarkers suggest coronary artery disease. 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
11622-409: The affected artery, totality of the blockage, duration of the blockage, the presence of collateral blood vessels , oxygen demand, and success of interventional procedures. Tissue death and myocardial scarring alter the normal conduction pathways of the heart and weaken affected areas. The size and location put a person at risk of abnormal heart rhythms (arrhythmias) or heart block , aneurysm of
11771-544: The aim of depolarising enough of the myocardium for coordinated contractions to occur again. The use of this is often dictated around the world by Advanced Cardiac Life Support or Advanced Life Support algorithms, which is taught to medical practitioners including doctors, nurses and paramedics and also advocates the use of drugs, predominantly epinephrine , after every second unsuccessful attempt at defibrillation, as well as cardiopulmonary resuscitation (CPR) between defibrillation attempts. Though ALS/ACLS algorithms encourage
11920-524: The appearance of asystole on a defibrillator or cardiac monitor set to a low gain . Some clinicians may attempt to defibrillate fine V-fib in the hope that it can be reverted to a cardiac rhythm compatible with life, whereas others will deliver CPR and sometimes drugs as described in the advanced cardiac life support protocols in an attempt to increase its amplitude and the odds of successful defibrillation. Ventricular fibrillation has been described as "chaotic asynchronous fractionated activity of
12069-447: The appearance of "worm-like" movements of the heart in animals prior to death. The significance and clinical importance of these observations and descriptions possibly of ventricular fibrillation were not recognised until John Erichsen in 1842 described ventricular fibrillation following the ligation of a coronary artery (Erichsen JE 1842). Subsequent to this in 1850, fibrillation was described by Ludwig and Hoffa when they demonstrated
12218-612: The arrhythmia is detected is about 17% while in hospital it is about 46%. Ventricular fibrillation is a cause of cardiac arrest . The ventricular muscle twitches randomly rather than contracting in a coordinated fashion (from the apex of the heart to the outflow of the ventricles), and so the ventricles fail to pump blood around the body – because of this, it is classified as a cardiac arrest rhythm, and patients in V-fib should be treated with cardiopulmonary resuscitation (CPR) and prompt defibrillation . Left untreated, ventricular fibrillation
12367-413: The arterial walls when consumed in high amounts (and other positive measures towards physical health are not met). High levels of cholesterol in the bloodstream lead to atherosclerosis. With increased levels of LDL in the bloodstream, "LDL particles will form deposits and accumulate within the arterial walls, which will lead to the development of plaques, restricting blood flow". The resultant reduction in
12516-432: The atria out of the ray fish . Garrey cut out a similar ring from the turtle ventricle. They were both able to show that, if a ring of excitable tissue was stimulated at a single point, the subsequent waves of depolarisation would pass around the ring. The waves eventually meet and cancel each other out, but, if an area of transient block occurred with a refractory period that blocked one wavefront and subsequently allowed
12665-543: The blood (dyslipidemia), type 2 diabetes and being overweight or obese (having excess body fat)" due to lack of exercise and a poor diet. Some other risk factors include high blood pressure , smoking , diabetes , lack of exercise, obesity , high blood cholesterol , poor diet, depression , family history , psychological stress and excessive alcohol . About half of cases are linked to genetics. Smoking and obesity are associated with about 36% and 20% of cases, respectively. Smoking just one cigarette per day about doubles
12814-647: The blood thinner heparin , with the additional use of PCI in those at high risk. In people with blockages of multiple coronary arteries and diabetes, coronary artery bypass surgery (CABG) may be recommended rather than angioplasty . After an MI, lifestyle modifications, along with long-term treatment with aspirin, beta blockers and statins , are typically recommended. 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
12963-573: The bone morphogenic proteins are members of the TGF-beta superfamily, and likewise impact Treg differentiation. Several of the transcripts ( TMEM98 , NRCAM , SFRP5 , SHISA2 ) are elements of the Wnt signaling pathway, which is a major determinant of Treg differentiation. Limitation of blood flow to the heart causes ischemia (cell starvation secondary to a lack of oxygen) of the heart's muscle cells . The heart's muscle cells may die from lack of oxygen and this
13112-473: The channel of an artery, causing partial obstruction to blood flow. People with coronary artery disease might have just one or two plaques or might have dozens distributed throughout their coronary arteries . A more severe form is chronic total occlusion (CTO) when a coronary artery is completely obstructed for more than 3 months. Microvascular angina is a type of angina pectoris in which chest pain and chest discomfort occur without signs of blockages in
13261-510: The circulating immune system would be related to the immune synapse . One of the most differentially expressed genes, fibromodulin (FMOD), which is increased 2.8-fold in CAD, is found mainly in connective tissue and is a modulator of the TGF-beta signaling pathway. However, not all of the RNA changes may be related to the immune synapse. For example, Nebulette , the most down-regulated transcript (2.4-fold),
13410-405: 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 can't be ruled out or ruled in following initial ECG and Troponin testing. Myocardial perfusion imaging has no role in
13559-613: The diagnostic accuracy of troponin testing is improving over time. One high-sensitivity cardiac troponin can rule out a heart attack as long as the ECG is normal. 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 rapidly when used along with troponin. Electrocardiograms (ECGs) are
13708-409: The diameter of their blood vessels, leading to decreased progression of atherosclerosis. In contrast, females who had high levels of work-related stress experienced a decrease in the diameter of their blood vessels and significantly increased disease progression. Having a type A behavior pattern , a group of personality characteristics including time urgency, competitiveness, hostility, and impatience,
13857-533: The different variables above. A notable example is Framingham Score , used in the Framingham Heart Study . It is mainly based on age, gender, diabetes, total cholesterol, HDL cholesterol, tobacco smoking, and systolic blood pressure. When predicting risk in younger adults (18–39 years old), the Framingham Risk Score remains below 10–12% for all deciles of baseline-predicted risk. Polygenic score
14006-414: The elderly, those with diabetes, in people who have just had surgery, and in critically ill patients. "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
14155-421: The evidence for the effectiveness of physical activity to reduce chronic disease, morbidity, and mortality", only the effectiveness of counseling itself. The American Heart Association , based on a non-systematic review, recommends that doctors counsel patients on exercise. Psychological symptoms are common in people with CHD, and while many psychological treatments may be offered following cardiac events, there
14304-793: The evidence is weak. Specifically, its use does not change the risk of death in this group. In those who have had a stent, more than 12 months of clopidogrel plus aspirin does not affect the risk of death. Revascularization for acute coronary syndrome has a mortality benefit. Percutaneous revascularization for stable ischaemic heart disease does not appear to have benefits over medical therapy alone. In those with disease in more than one artery, coronary artery bypass grafts appear better than percutaneous coronary interventions . Newer "anaortic" or no-touch off-pump coronary artery revascularization techniques have shown reduced postoperative stroke rates comparable to percutaneous coronary intervention. Hybrid coronary revascularization has also been shown to be
14453-449: The first recorded account of ventricular fibrillation dates as far back as 1500 BC, and can be found in the Ebers papyrus of ancient Egypt . An extract, recorded 3500 years ago, states: "When the heart is diseased, its work is imperfectly performed: the vessels proceeding from the heart become inactive, so that you cannot feel them … if the heart trembles, has little power and sinks, the disease
14602-402: The future, and one in three healthy 40-year-old females. It is the most common reason for death of males and females over 20 years of age in the United States. Myocardial infarction A myocardial infarction ( MI ), commonly known as a heart attack , occurs when blood flow decreases or stops in one of the coronary arteries of the heart , causing infarction (tissue death) to
14751-465: The generation of arrhythmias. This work was also accompanied by Lewis, who performed further outstanding work into the concept of "circus movement". Later milestones include the work by W. J. Kerr and W. L. Bender in 1922, who produced an electrocardiogram showing ventricular tachycardia evolving into ventricular fibrillation. The re-entry mechanism was also advocated by DeBoer, who showed that ventricular fibrillation could be induced in late systole with
14900-630: The greatest support is the Mediterranean diet . Vitamins and mineral supplements are of no proven benefit, and neither are plant stanols or sterols . 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 activity. This may be part of regional cardiovascular disease prevention programs or through
15049-436: The harms most favorably in people at high risk for a cardiovascular event, where high risk is defined as at least a 3% chance over a five-year period, but others with lower risk may still find the potential benefits worth the associated risks. Clopidogrel plus aspirin (dual anti-platelet therapy) reduces cardiovascular events more than aspirin alone in those with a STEMI . In others at high risk but not having an acute event,
15198-450: The heart affected by atherosclerotic plaque. Stable coronary artery disease (SCAD) is also often called stable ischemic heart disease (SIHD). A 2015 monograph explains that "Regardless of the nomenclature, stable angina is the chief manifestation of SIHD or SCAD." There are U.S. and European clinical practice guidelines for SIHD/SCAD. In patients with non-severe asymptomatic aortic valve stenosis and no overt coronary artery disease,
15347-465: The heart is not contracting at all or so poorly that all vital organs cease to function, thus leading to death. It is also distinct from heart failure , in which the pumping action of the heart is impaired. However, an MI may lead to heart failure. 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. Chest pain
15496-410: The heart muscle ( myocardium ) caused by ischemia , 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 type of acute coronary syndrome, unstable angina , a myocardial infarction occurs when there is cell death , which can be estimated by measuring by
15645-466: The heart muscle). Diagnosis is clear-cut if ECGs show elevation of the " ST segment ", which in the context of severe typical chest pain is strongly indicative of an acute myocardial infarction (MI); this is termed a STEMI (ST-elevation MI) and is treated as an emergency with either urgent coronary angiography and percutaneous coronary intervention (angioplasty with or without stent insertion) or with thrombolysis ("clot buster" medication), whichever
15794-428: The heart muscle). If part of the heart seems to receive an insufficient blood supply, coronary angiography may be used to identify stenosis of the coronary arteries and suitability for angioplasty or bypass surgery . In minor to moderate cases, nitroglycerine may be used to alleviate acute symptoms of stable angina or may be used immediately before exertion to prevent the onset of angina. Sublingual nitroglycerine
15943-441: The heart ventricles , inflammation of the heart wall following infarction, and rupture of the heart wall that can have catastrophic consequences. 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
16092-467: The heart" (Moe et al. 1964). A more complete definition is that ventricular fibrillation is a "turbulent, disorganized electrical activity of the heart in such a way that the recorded electrocardiographic deflections continuously change in shape, magnitude and direction". Ventricular fibrillation most commonly occurs within diseased hearts, and, in the vast majority of cases, is a manifestation of underlying ischemic heart disease. Ventricular fibrillation
16241-783: The heart's blood supply due to atherosclerosis in coronary arteries "causes shortness of breath, angina pectoris (chest pains that are usually relieved by rest), and potentially fatal heart attacks (myocardial infarctions)". The heritability of coronary artery disease has been estimated between 40% and 60%. Genome-wide association studies have identified over 160 genetic susceptibility loci for coronary artery disease. Several RNA Transcripts associated with CAD - FoxP1 , ICOSLG , IKZF4/Eos , SMYD3 , TRIM28 , and TCF3/E2A are likely markers of regulatory T cells (Tregs), consistent with known reductions in Tregs in CAD. The RNA changes are mostly related to ciliary and endocytic transcripts, which in
16390-729: 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 death, gastroesophageal reflux disease ; pulmonary embolism , tumors of the lungs, pneumonia , rib fracture , costochondritis , heart failure and other musculoskeletal injuries. Rarer severe differential diagnoses include aortic dissection , esophageal rupture , tension pneumothorax , and pericardial effusion causing cardiac tamponade . The chest pain in an MI may mimic heartburn . Causes of sudden-onset breathlessness generally involve
16539-512: The immune synapse, there were numerous transcripts that related directly to T cell function and the control of differentiation. Butyrophilin is a co-regulator for T cell activation. Fibromodulin is a modulator of the TGF-beta signaling pathway, a primary determinant of Tre differentiation. Further impact on the TGF-beta pathway is reflected in concurrent changes in the BMP receptor 1B RNA (BMPR1B), because
16688-402: The incidence and mortality rates of myocardial infarctions. They are often recommended in those at an elevated risk of cardiovascular diseases. 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
16837-428: The increased troponin T (above 14 pg/mL) was found associated with an increased 5-year event rate of ischemic cardiac events ( myocardial infarction , percutaneous coronary intervention , or coronary artery bypass surgery ). Diagnosis of acute coronary syndrome generally takes place in the emergency department , where ECGs may be performed sequentially to identify "evolving changes" (indicating ongoing damage to
16986-404: The larger coronary arteries of their hearts when an angiogram (coronary angiogram) is being performed. The exact cause of microvascular angina is unknown. Explanations include microvascular dysfunction or epicardial atherosclerosis. For reasons that are not well understood, females are more likely than males to have it; however, hormones and other risk factors unique to females may play
17135-441: The likelihood of it successfully cardioverting a patient are small and this diminishes quickly in the first minute of onset. People who survive a "V-fib arrest" and who make a good recovery are often considered for an implantable cardioverter-defibrillator , which can quickly deliver this same life-saving defibrillation should another episode of ventricular fibrillation occur outside a hospital environment. Sudden cardiac arrest
17284-666: The lungs or heart – including pulmonary edema , pneumonia, allergic reactions and asthma , and pulmonary embolus, acute respiratory distress syndrome and metabolic acidosis . There are many different causes of fatigue, and myocardial infarction is not a common cause. 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 vaccine also appear to protect against myocardial infarction with
17433-424: The maximum diastolic potential is less negative and therefore exists closer to the threshold potential . Cellular depolarisation can be due to a raised external concentration of potassium ions K, a decreased intracellular concentration of sodium ions Na, increased permeability to Na, or a decreased permeability to K. The ionic basic automaticity is the net gain of an intracellular positive charge during diastole in
17582-633: The most common symptom reported by females of all races is shortness of breath. Other symptoms more commonly reported by females than males are extreme fatigue, sleep disturbances, indigestion, and anxiety. However, some females experience irregular heartbeat, dizziness, sweating, and nausea. Burning, pain, or pressure in the chest or upper abdomen that can travel to the arm or jaw can also be experienced in females, but females less commonly report it than males. Generally, females experience symptoms 10 years later than males. Females are less likely to recognize symptoms and seek treatment. Coronary artery disease
17731-610: The myocardial infarction are coronary spasm or coronary artery dissection . 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 in tissue being supplied by that artery. Atherosclerotic plaques are often present for decades before they result in symptoms. The gradual buildup of cholesterol and fibrous tissue in plaques in
17880-412: The myocardium. Stable angina is short-term chest pain during physical exertion caused by an imbalance between myocardial oxygen supply and metabolic oxygen demand. Various forms of cardiac stress tests may be used to induce both symptoms and detect changes by way of electrocardiography (using an ECG), echocardiography (using ultrasound of the heart) or scintigraphy (using uptake of radionuclide by
18029-484: The occurrence of fibrillation in the apparent "healthy" heart. It is evident that there are mechanisms at work that we do not fully appreciate and understand. Investigators are exploring new techniques of detecting and understanding the underlying mechanisms of sudden cardiac death in these patients without pathological evidence of underlying heart disease. Familial conditions that predispose individuals to developing ventricular fibrillation and sudden cardiac death are often
18178-403: The other to proceed retrogradely over the other path, then a self-sustaining circus movement phenomenon would result. For this to happen, however, it is necessary that there be some form of non-uniformity. In practice, this may be an area of ischemic or infarcted myocardium, or underlying scar tissue . It is possible to think of the advancing wave of depolarisation as a dipole with a head and
18327-547: The phenomenon of re-entry. Triggered activity can occur due to the presence of afterdepolarisations . These are depolarising oscillations in the membrane voltage induced by preceding action potentials. These can occur before or after full repolarisation of the fiber and as such are termed either early (EADs) or delayed afterdepolarisations (DADs). All afterdepolarisations may not reach threshold potential, but, if they do, they can trigger another afterdepolarisation, and thus self-perpetuate. The distribution of frequency and power of
18476-419: 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 ECG and who are able to exercise, for example, most likely do not merit routine imaging. There are many causes of chest pain , which can originate from
18625-471: The plaque and act to stabilize it. A stable plaque may have a thick fibrous cap with calcification . If there is ongoing inflammation, the cap may be thin or ulcerate. Exposed to the pressure associated with blood flow, plaques, especially those with a thin lining, may rupture and trigger the formation of a blood clot (thrombus). The cholesterol crystals have been associated with plaque rupture through mechanical injury and inflammation. Atherosclerotic disease
18774-524: The presence of a voltage-dependent channel activated by potentials negative to –50 to –60 mV. Myocardial cells are exposed to different environments. Normal cells may be exposed to hyperkalaemia; abnormal cells may be perfused by normal environment. For example, with a healed myocardial infarction, abnormal cells can be exposed to an abnormal environment such as with a myocardial infarction with myocardial ischaemia. In conditions such as myocardial ischaemia, possible mechanism of arrhythmia generation include
18923-487: 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 occurs within 2–3 hours of injury to the heart muscle, and peaks within 1–2 days. The level of the troponin, as well as a change over time, are useful in measuring and diagnosing or excluding myocardial infarctions, and
19072-503: The primary cause of myocardial infarction, with other risk factors including male sex, low levels of physical activity, a past family history , obesity , and alcohol use . Risk factors for myocardial disease are often included in risk factor stratification scores, such as the Framingham Risk Score . At any given age, men are more at risk than women for the development of cardiovascular disease. High levels of blood cholesterol
19221-589: The propensity of a fiber to initiate an impulse spontaneously. The product of a hypoxic myocardium can be hyperirritable myocardial cells. These may then act as pacemakers. The ventricles are then being stimulated by more than one pacemaker . Scar and dying tissue is inexcitable, but around these areas usually lies a penumbra of hypoxic tissue that is excitable. Ventricular excitability may generate re-entry ventricular arrhythmia . Most myocardial cells with an associated increased propensity to arrhythmia development have an associated loss of membrane potential . That is,
19370-416: The proteasomal regulator SIAH3 , and the ubiquitin ligase MARCHF10 . On the ciliary aspect of the immune synapse, several of the modulated transcripts are related to ciliary length and function. Stereocilin is a partner to mesothelin , a related super-helical protein, whose transcript is also modulated in CAD. DCDC2 , a double-cortin protein, is a modulator of ciliary length. In the signaling pathways of
19519-404: The provocation of ventricular fibrillation in an animal by applying a " Faradic " (electrical) current to the heart. In 1874, Edmé Félix Alfred Vulpian coined the term mouvement fibrillaire , a term that he seems to have used to describe both atrial and ventricular fibrillation. John A. MacWilliam, a physiologist who had trained under Ludwig and who subsequently became Professor of Physiology at
19668-466: The rare coronary artery disease that is more common in females, as mentioned, is a diagnosis of exclusion. Therefore, usually, the same tests are used as in any person suspected of having coronary artery disease: Stable angina is the most common manifestation of ischemic heart disease, and is associated with reduced quality of life and increased mortality. It is caused by epicardial coronary stenosis which results in reduced blood flow and oxygen supply to
19817-460: The result of gene mutations that affect cellular transmembrane ion channels. For example, in Brugada Syndrome, sodium channels are affected. In certain forms of long QT syndrome, the potassium inward rectifier channel is affected. In 1899, it was also found that ventricular fibrillation was, typically, the ultimate cause of death when the electric chair was used. Automaticity is a measure of
19966-439: The resulting decreased internal K concentration, the increased external K concentration, norepinephrine release and acidosis. When myocardial cell are exposed to hyperkalemia, the maximum diastolic potential is depolarized as a result of the alteration of Ik1 potassium current, whose intensity and direction is strictly dependent on intracellular and extracellular potassium concentrations. With Ik1 suppressed, an hyperpolarizing effect
20115-460: The risk of CAD. Lack of exercise has been linked to 7–12% of cases. Exposure to the herbicide Agent Orange may increase risk. Rheumatologic diseases such as rheumatoid arthritis , systemic lupus erythematosus , psoriasis , and psoriatic arthritis are independent risk factors as well. Job stress appears to play a minor role accounting for about 3% of cases. In one study, females who were free of stress from work life saw an increase in
20264-431: The risk of cardiovascular disease and death. Vegetarians have a lower risk of heart disease, possibly due to their greater consumption of fruits and vegetables. Evidence also suggests that the Mediterranean diet and a high fiber diet lower the risk. The consumption of trans fat (commonly found in hydrogenated products such as margarine ) has been shown to cause a precursor to atherosclerosis and increase
20413-541: The risk of coronary artery disease by about 25%. Life's Essential 8 are the key measures for improving and maintaining cardiovascular health, as defined by the American Heart Association. AHA added sleep as a factor influencing heart health in 2022. Most guidelines recommend combining these preventive strategies. A 2015 Cochrane Review found some evidence that counseling and education to bring about behavioral change might help in high-risk groups. However, there
20562-410: The risk of coronary artery disease. Evidence does not support a beneficial role for omega-3 fatty acid supplementation in preventing cardiovascular disease (including myocardial infarction and sudden cardiac death ). There is tentative evidence that intake of menaquinone ( Vitamin K 2 ), but not phylloquinone ( Vitamin K 1 ), may reduce the risk of CAD mortality . Secondary prevention
20711-486: 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 starch, reducing sugar intake (particularly of refined sugar), consuming five portions of fruit and vegetables daily, consuming two or more portions of fish per week, and consuming 4–5 portions of unsalted nuts , seeds , or legumes per week. The dietary pattern with
20860-492: The risk profile. Noninvasive imaging options include; Computed tomography angiography (CTA) (anatomical imaging, best test in patients with low-risk profile to "rule out" the disease), positron emission tomography (PET), single-photon emission computed tomography (SPECT)/nuclear stress test/myocardial scintigraphy and stress echocardiography (the three latter can be summarized as functional noninvasive methods and are typically better to "rule in"). Exercise ECG or stress test
21009-414: The smooth, elastic lining inside a coronary artery (the arteries that supply blood to the heart muscle) develops atherosclerosis . With atherosclerosis, the artery's lining becomes hardened, stiffened, and accumulates deposits of calcium, fatty lipids, and abnormal inflammatory cells – to form a plaque . Calcium phosphate (hydroxyapatite) deposits in the muscular layer of the blood vessels appear to play
21158-399: The start of daylight saving time . 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. Endometriosis in women under the age of 40 is an identified risk factor. Air pollution
21307-400: The studies showing these differences had high variability. Females are less likely to report chest pain during a heart attack and more likely to report nausea, jaw pain, neck pain, cough, and fatigue, although these findings are inconsistent across studies. Females with heart attacks also had more indigestion, dizziness , loss of appetite , and loss of consciousness. Shortness of breath is
21456-406: The use of antibiotics is not currently supported for preventing secondary coronary heart disease. A thorough systematic review found that indeed there is a link between a CHD condition and brain dysfunction in females. Consequently, since research is showing that cardiovascular diseases, like CHD, can play a role as a precursor for dementia, like Alzheimer's disease, individuals with CHD should have
21605-425: The use of drugs, they state first and foremost that defibrillation should not be delayed for any other intervention and that adequate cardiopulmonary resuscitation be delivered with minimal interruption. The precordial thump is a manoeuver promoted as a mechanical alternative to defibrillation. Some advanced life support algorithms advocate its use once and only in the case of witnessed and monitored V-fib arrests as
21754-475: The ventricles become dilated with blood as the rapid quivering movement of their walls is insufficient to expel their contents; the muscular action partakes of the nature of a rapid incoordinate twitching of the muscular tissue … The cardiac pump is thrown out of gear, and the last of its vital energy is dissipated in the violent and the prolonged turmoil of fruitless activity in the ventricular walls." MacWilliam spent many years working on ventricular fibrillation and
21903-529: 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 affected arterial walls. Over time, they become laden with cholesterol products, particularly LDL , and become foam cells . A cholesterol core forms as foam cells die. In response to growth factors secreted by macrophages, smooth muscle and other cells move into
22052-492: Was insufficient evidence to show an effect on mortality or actual cardiovascular events. In diabetes mellitus , there is little evidence that very tight blood sugar control improves cardiac risk although improved sugar control appears to decrease other problems such as kidney failure and blindness . A 2024 study published in The Lancet Diabetes & Endocrinology found that the oral glucose tolerance test (OGTT)
22201-445: Was one of the first to show that ventricular fibrillation could be terminated by a series of induction shocks through the heart. The first electrocardiogram recording of ventricular fibrillation was by August Hoffman in a paper published in 1912. At this time, two other researchers, George Ralph Mines and Garrey, working separately, produced work demonstrating the phenomenon of circus movement and re-entry as possible substrates for
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