CORONARY ARTERY DISEASE & ISCHEMIA
A patient reports chest pressure only when climbing stairs that resolves with rest and nitroglycerin. What pathophysiologic process is occurring?
Fixed coronary artery narrowing causing decreased myocardial oxygen supply during increased demand (stable angina)
Which biomarker is most specific for myocardial injury and why?
✅ Answer: Troponin — it is released when myocardial cells undergo necrosis
What is the primary hemodynamic problem in left-sided heart failure?
✅ Answer: Inability of the left ventricle to pump blood effectively forward
Which cardiomyopathy is characterized by dilated chambers and reduced systolic function?
✅ Answer: Dilated cardiomyopathy
Chest pain that improves when leaning forward is most characteristic of what condition?
✅ Answer: Pericarditis
Why does stable angina NOT usually cause elevated troponin levels?
✅ Answer: Ischemia occurs without permanent myocardial cell death
Why may troponin levels be normal early after the onset of chest pain?
✅ Answer: It takes several hours for troponin to be released into the bloodstream after cell injury
Why does left-sided heart failure cause pulmonary edema?
✅ Answer: Blood backs up into the pulmonary circulation, increasing capillary hydrostatic pressure and fluid leakage
What is the main functional impairment in restrictive cardiomyopathy?
✅ Answer: Impaired ventricular filling during diastole
What causes the pericardial friction rub heard in pericarditis?
✅ Answer: Inflamed pericardial layers rubbing against each other
A plaque ruptures in a coronary artery. What immediate cascade increases the risk of MI?
✅ Answer: Platelet aggregation → thrombus formation → acute reduction in coronary blood flow
A STEMI causes ST elevation on ECG. What does this reflect at the cellular level?
✅ Answer: Full-thickness (transmural) myocardial injury causing changes in electrical conduction
A patient with heart failure has an elevated BNP. What does this indicate physiologically?
✅ Answer: Ventricular stretch due to increased volume and pressure
Why is hypertrophic cardiomyopathy especially dangerous during exertion?
✅ Answer: Thickened myocardium obstructs outflow and predisposes to fatal arrhythmias
Why does myocarditis commonly follow a viral illness?
✅ Answer: Viral infection triggers inflammation and damage to myocardial cells
A patient has chest pain at rest with no ST elevation but elevated troponin. Explain what is happening at the myocardial level.
✅ Answer: Partial coronary occlusion causing subendocardial ischemia and myocardial necrosis (NSTEMI)
Why are ventricular arrhythmias a common complication after MI?
✅ Answer: Ischemic myocardium disrupts electrical conduction pathways, increasing automaticity and irritability
Explain why right-sided heart failure causes hepatomegaly and ascites.
✅ Answer: Venous congestion increases pressure in systemic circulation, causing fluid accumulation
A patient has preserved ejection fraction but symptoms of heart failure. Which cardiomyopathy best explains this?
✅ Answer: Restrictive cardiomyopathy (diastolic dysfunction)
Which organism is most associated with infective endocarditis in IV drug users and why?
✅ Answer: Staphylococcus aureus due to direct bloodstream inoculation
Why does the subendocardial layer of the myocardium become ischemic before the epicardial layer?
✅ Answer: It is farthest from coronary blood supply and experiences the highest wall stress during systole
Explain why an anterior wall MI (LAD involvement) carries a worse prognosis than an inferior wall MI.
✅ Answer: The LAD supplies a large portion of the left ventricle, so damage significantly reduces cardiac output
Why can long-standing left-sided heart failure eventually lead to right-sided heart failure?
✅ Answer: Increased pulmonary pressure raises right ventricular workload, leading to right ventricular failure
Explain why hypertrophic cardiomyopathy can cause sudden cardiac death in young athletes.
✅ Answer: Stress triggers ventricular arrhythmias due to abnormal myocardial architecture and conduction
Explain how infective endocarditis can cause stroke or organ infarction.
✅ Answer: Septic emboli break off vegetations and lodge in systemic circulation