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What is the timeframe for the appearance of macrophages in a fully formed recent infarct?
What is the primary cause of death in the first few hours following an infarction?
Which laboratory marker peaks at 24 hours following myocardial infarction?
What type of pericarditis may be associated with myocardial infarction?
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When does complete healing of an infarct typically occur?
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What complication can arise from rupture of a papillary muscle following myocardial infarction?
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Which enzyme persists for the longest period after myocardial infarction?
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What is the effect of neutrophilic liquefactive enzymes following myocardial infarction?
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What percentage of individuals develop a myocardial infarct and die from it?
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What type of ischemic heart disease affects the whole thickness of the heart wall?
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Which coronary artery is primarily responsible for the anterior descending infarctions?
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What is the primary cellular change observed in coagulative necrosis?
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Which area of the heart is mainly affected by ischemic heart disease?
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After how many hours does coagulative necrosis become apparent following an ischemic event?
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In which scenario is hypo perfusion rather than actual coronary artery occlusion responsible?
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What is the probable color change of the infarcted area 24-72 hours after an ischemic event?
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What defines ischemic heart disease?
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Which type of angina is characterized by severe pain precipitated by less effort?
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What typically precipitates angina pectoris?
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Which of the following conditions is NOT a cause of ischemic heart disease?
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Which is a characteristic of Prinzmetal (vasospastic) angina?
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What is one possible unusual cause of coronary arterial blockage?
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What results from acute ischemia of the myocardium?
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Which statement reflects a risk factor contributing to ischemic heart disease?
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What is the role of macrophages in the early stages of a myocardial infarct?
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Which laboratory diagnostic marker first shows a positive result 6 hours after myocardial infarction?
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What complication can arise from hemorrhage into the pericardial space after infarction?
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What is the likely outcome of interventricular septum rupture following myocardial infarction?
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What is a defining characteristic of stable angina?
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In the context of healing, what characterizes the granulation tissue in a myocardial infarct?
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Which of the following is NOT a known precipitating factor for angina pectoris?
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What defines the time frame for the peak levels of LDH after a myocardial infarction?
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What is the primary concern with arrhythmias shortly after an infarction?
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What type of angina is described as being relieved by nitroglycerine therapy?
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Which change in the myocardium corresponds to the first few days after an infarction?
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Which risk factor is specifically related to complicated atheroma of coronary vessels?
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What is the most immediate consequence of acute ischemia in the myocardium?
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What factor may increase the load on the heart, potentially leading to ischemic heart disease?
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Which of the following types of ischemic heart disease is characterized by gradual incomplete occlusion?
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What can result from a sudden stoppage of arterial blood flow in coronary arteries?
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What type of myocardial infarction involves the entire thickness of the heart wall?
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Which coronary artery typically contributes to infarctions in the posterior wall of the left ventricle?
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What is the initial appearance of myocardial tissue affected by ischemic heart disease before the 6-hour mark?
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In which scenario is hypoperfusion rather than actual coronary artery occlusion primarily responsible for the condition?
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What cellular changes indicate the transition to coagulative necrosis in affected myocardial tissue?
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What is a common histological feature seen in myocardial infarction within 24 to 72 hours?
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What percentage of individuals may live with either myocardial infarct or silent occlusion?
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Which area of the heart is least commonly affected by circumferential subendocardial ischemia?
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Study Notes
Ischemic Heart Disease
- Group of diseases due to insufficient arterial blood flow to myocardium.
- Acute ischemia can result in myocardial infarction.
- Chronic Ischemia can result in angina pectoris.
Acute Ischemia
- Sudden stoppage of arterial blood flow in coronary arteries or one of the major branches
- Causes:
- Complicated atheroma of coronary vessel
- Thrombosis
- Rupture of the plaque or hemorrhage into the plaque
- Unusual causes
- Embolism due to vegetations of bacterial endocarditis of aortic valve
- Polyarteritis nodosa
- Occlusion of coronary ostia in dissecting aneurysms and syphilis
- Coronary spasm
- Complicated atheroma of coronary vessel
Chronic Ischemia
- Caused by gradual incomplete occlusion and manifested as angina pectoris.
- Types:
- Stable angina: evoked by exercise and relieved by rest.
- Unstable angina: severe pain precipitated by less and less effort (pre-infarction angina).
- Prinzmetal (vasospastic) angina: occurs at rest, due to coronary spasm, relieved by vasodilator (nitroglycerine) therapy.
Myocardial Infarction
- Massive area of coagulative necrosis of myocardium due to complete cut of arterial blood supply.
- Causes:
- Sudden complete coronary occlusion
- Thrombosis, embolism, spasm
- It may be:
- Transmural: involving the whole thickness of the heart wall in certain anatomical area supplied by certain coronary artery.
- Circumferential subendocardial: involving subendocardium of left and less commonly right ventricles.
- Sudden complete coronary occlusion
Myocardial Infarction: Pathological Changes
- The left ventricle is mainly affected.
- In order of frequency:
- Anterior descending of left coronary (40%)
- The infarct is in anterior wall of left ventricle, anterior wall of right ventricle and anterior part of interventricular septum and apex.
- Right coronary artery (40%):
- Posterior wall of Left.ventricle, posterior wall of Right Ventricle and posterior part of interventricular septum.
- Circumflex branch of left coronary: Lateral wall of Left ventricle.
- Left coronary
- Anterior descending of left coronary (40%)
- Pathological changes
- 6-8 hours: affected area is pale, opaque and dry, becomes more acidophilic, striations lost, nuclei disappear
- Next day: color changes from gray to yellow.
- 24-72 hours: infarct is soft yellow center and well circumscribed.
- 3-10 days: fully formed infarct which is swollen yellow, soft and friable surrounded by zone of hyperemia, macrophages appear with polymorphs to remove the necrotic tissue and granulation tissue is seen at the periphery.
- 4-6 weeks: removal of necrotic tissue and organization with scar formation, granulation tissue invades the infarct and starting formation of fibrous tissue which is usually completed by the end of 6 weeks.
Myocardial Infarction: Effects
- Most common cause of death in the first few hours following infarction.
- Arrhythmia can lead to congestive heart failure and/or cardiogenic shock.
- Ventricular rupture can happen 4-7 days after infarction (due to neutrophilic liquifactive enzymes).
- Ventricular rupture can lead to:
- Cardiac tamponade and compression of heart by hemorrhage into pericardial space.
- Papillary muscle → mitral incompetence
- Interventricular septum → acute heart failure
- With thrombosis inside.
- 25% of people develop infarct and die from it
- 25% live either with myocardial infarct, or with silent occlusion (adequate collaterals)
Myocardial Infarction: Diagnosis
- ECG and echocardiography.
- Laboratory diagnosis :
- CK-MB, TROPONIN, LDH
- Peak levels
- CK-MB, TROPONIN: 24 hours
- LDH: 3-4 days
Myocardial Infarction
- A massive area of coagulative necrosis of myocardium caused by obstruction to the supplying coronary artery by a thrombus, embolism, or spasm
- Left ventricle is most commonly affected by myocardial infarction
- The order of frequency of coronary artery involvement in myocardial infarction is: Left Anterior Descending, Right Coronary Artery, Circumflex Branch of Left Coronary, and Left Coronary Artery
- Myocardial infarction can be transmural (involving the whole thickness of the heart wall) or circumferential subendocardial (involving the subendocardium of left and right ventricles)
Myocardial Infarction: Features within 3-10 days
- Infarct will be swollen, yellow, soft and friable
- Surrounded by a zone of hyperemia
- Usually involves the whole thickness of the myocardium
Myocardial Infarction: Features within 4-6 weeks
- Macrophages appear with polymorphs to clean up necrotic tissue
- Granulation tissue invades the infarct and fibrous tissue begins to form at the periphery
- Complete healing takes different times, depending on the size of the infarct
- Pericarditis and mural thrombus may be seen
Ischemic Heart Disease
- A group of diseases that stem from insufficient arterial blood flow to the myocardium
- Can be categorized as acute ischemia or chronic ischemia
Acute Ischemia
- Results in myocardial infarction
- Can be precipitated by physical effort, emotional excitement, heavy meals, and cold
- Usually the result of sudden complete coronary occlusion
Chronic Ischemia
- Results in Angina Pectoris: characterized by temporary relative acute ischemia on top of chronic ischemia
- May manifest clinically as attacks of severe retrosternal pain
Stable Angina
- Evoked by exercise and relieved by rest
- Results from chronic coronary occlusion
- Characterized as a gradual incomplete blockage
Unstable Angina
- A severe pain precipitated by less effort (pre-infarction angina)
- Indicates a more significant or unstable (plaque rupture) coronary occlusion and higher risk of MI
Prinzmetal (Vasospastic) Angina
- Occurs at rest, due to coronary spasm
- Relieved by vasodilator therapy (nitroglycerine)
Causes for Angina Pectoris
- Atheroma and anemia
- Factors increasing load on the heart, like hypertension, valvular disorders (aortic), cardiomyopathy, and hyperthyroidism
- Ventricular hypertrophy due to any cause
- Coronary vasospasm
Clinical Manifestations of Myocardial Infarction
- Arrhythmia: Most common cause of death in the first few hours following infarction
- Myocardial Pump Failure: Results in congestive heart failure and cardiogenic shock
- Myocardial Rupture: Most likely to happen 4-7 days after infarction
- Cardiac Tamponade: Compression of the heart from hemorrhage into the pericardial space
- Mitral Incompetence: Rupture of the papillary muscle
- Acute Heart Failure: Rupture of the interventricular septum
- Myocardial Infarction Effects: 25% of patients die from infarction. Another 25% develop an infarct but survive with a silent occlusion (adequate collaterals)
Laboratory Diagnosis of Myocardial Infarction
- CK-MB: Elevated 6 hours after infarction, peaks at 12-16 hours, persists for 2 days
- Troponin: Elevated within 6 hours after infarction, peaks at 12-16 hours, persists for 4-7 days
- LDH: Elevated 2 days after infarction, peaks on the third day, and persists for 4-7 days.
Electrocardiography (ECG) and Echocardiography
- Used for diagnosis of Myocardial Infarction
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