Cardiology-Ischemic Heart Disease

Question 0

Stable Angina

Key facts

Answer 0

atherosclerosis of coronary arteries with >70% occlusion/stenosis
reversible injury to myocytes
chest pain <20 minutes (irreversible after this)
ST segment depression with EKG

Question 1

Hallmark of cell death

Discussed with coagulative necrosis

Answer 1

Removal of nucleus (pyknosis, karrhyorexis, karrhyolysis)

Question 2

Hallmark of reversible injury

Answer 2

Cellular swelling

Question 3

Hallmark of Subendocardial Ischemia

Answer 3

ST segment depression

examples: stable and unstable angina

Question 4

Nitroglycerin

Answer 4

Vasodilates arteries and veins (veins > arteries, decreases preload of heart)

Question 5

Unstable Angina

Answer 5

Incomplete occlusion of coronary artery
Reversible injury to myocytes
ST segment depression

Question 6

Prinzmetal angina

Answer 6

Vasospasm of coronary artery
–> complete occlusion of coronary artery for short period of time cuts off blood supply to entire wall
Episodic chest pain
ST segment elevation (transmural ischemia)

Question 7

Hallmark of Transmural Ischemia

Answer 7

ST segment elevation

examples: Prinzmetal’s angina, myocardial infarction

Question 8

Myocardial Infarction Overview (Pathology)

Answer 8

necrosis of cardiac myocytes (>20 minutes)
complete occlusion of coronary artery (rupture of atherosclerotic plaque with thrombosis)

ST segment elevation
symptoms NOT relieved by nitroglycerin

dyspnea: heart not pumping as well –> pulmonary congestion and edema

other causes: coronary artery vasospasm, emboli, vasculitis (kawasaki disease)

Question 9

Myocardial Infarction

Susceptible Arteries

Answer 9

• Right Ventricle and Atria generally spared*
• -> affects Left Ventricle

Arteries: LAD (anterior wall of LV, ant portion interventricular septum) > R coronary (posterior wall of LV and post portion interventricular septum) > L circumflex (lateral wall of LV)

Question 10

Myocardial Infarction: Labs

Answer 10

Enzymes in cardiac myocytes leak out into blood

Troponin I: most sensitive and specific (rises 2-4 hours after infarction, peaks at 24 hours, returns to normal by 7-10 days)
CK-MB: useful for detecting reinfarction days after MI (returns to normal by 72 hours)

Question 11

Reperfusion Consequences

Answer 11

1. Contraction band necrosis: return calcium back to dead tissue, enters cell, causes contraction
2. Reperfusion injury: return oxygen which generates free radicals which can further injure myocardium
   (cardiac enzymes continue to rise due to this injury post-reperfusion)

Question 12

Complications of MI <4 hours

Answer 12

cardiogenic shock (massive infarction)= lack of bloodflow to vital organs, inability to maintain systemic blood pressure
congestive heart failure= blood backed up not pumped forward well (hallmark = decreased ejection fraction)
arrhythmia

Question 13

Complications of MI 4-24 hours

Answer 13

Arrhythmia (damage conducting system in heart, will present early)

Question 14

Complications of MI 1-3 days

Answer 14

fibrinous pericarditis= inflammatory exudate from transmural infarct goes out into pericardium
–> (presents with chest pain and friction rub)

Would not see this with subendocardial infarction!!!

Question 15

Complications of MI 4-7 days

Answer 15

Rupture!
macrophages come in to eat up dead and necrotic debris –> wall is weakest
1. rupture of ventricular free wall could –> cardiac tamponade (wall ruptures, blood goes into pericardium, compresses heart
2. rupture of interventricular septum –> shunt (opening created bw RV and LV, shunting of blood from RV to LV)
3. rupture of papillary muscle (chordae attach to papillary muscle, which helps close mitral valve) –> cannot close valve completely –> mitral insufficiency (blood goes backwards during systole)
Papillary muscle fed by RCA so occlusion of RCA has risk of papillary muscle rupture

Question 16

Complications of MI (months)

Answer 16

Aneurysm = (balloonlike dilatation of ventricular wall); scar not as strong as myocardium
Mural Thrombus = stasis of blood (aneurysm and scar both risk for this); thrombus forming along wall of scar
Dressler syndrome (rare)= inflammation of pericardium could expose pericardial antigens to immune system --> antibodies against pericardium --> autoimmune pericarditis

Question 17

Sudden cardiac death

Answer 17

unexpected death due to cardiac disease
occurs without symptoms or <1 hour after symptoms
usually due to fatal ventricular arrythmia

causes: Most common etiology = acute ischemia
90% patients have preexisting severe atherosclerosis
other: mitral valve prolapse, cardiomyopathy, cocaine abuse (with vasospasm related to cocaine)