Ischemic Heart Disease Flashcards
Define ischemic heart disease.
Imbalance between myocardial oxygen demand and supply
During what phase of the cardiac cycle is there the lease resistance to coronary artery blood flow?
Diastole
What is the most common site for coronary artery thrombosis?
LAD
What regions does the LAD perfuse?
Anterior LV, anterior 2/3 IVS, apex
What is the second most common site of coronary artery thrombosis?
RCA
What regions does the RCA perfuse?
Posterior LV, posterior 1/3 IVS, RV, posteriormedial papillary muscle, SA/AV nodes
What is the most common manifestation of IHD?
Angina pectoris
What are the causes of stable angina?
Atherosclerotic CAD (most common), AV stenosis or HTN w/ concentric LVH, hypertrophic cardiomyopathy, cocaine induced coronary artery vasoconstriction
What is the pathogenesis of stable angina pectoris?
Subendocardial ischemia; decreased coronary artery blood flow or concentric hypertrophy
What are the clinical findings in stable angina?
Exertion induced substernal chest pain, often accompanied by SOB, diaphoresis
What is the treatment for an acute episode of stable angina?
Nitroglycerin (0.3-0.6 mg SL q5min)
What is the mechanism of action for nitroglycerin?
Decreases oxygen demand (dec. preload due to venoldilation)
Increased oxygen supply (inc. coronary perfusion and decrease vasospasm)
In a patient with stable angina, what would be seen on ECG?
ST-segment depressions (>1mm)
Prinzmetal (variable) angina is characterized by intermittent coronary artery vasospasm at rest or w/o superimposed CAD. What would a stress test show?
ST-segment elevations
Define unstable angina.
Increased frequency and duration of angina episodes produced by less exertion or at rest; high frequency of progression of MI if untreated
What diagnostic tests are helpful in diagnosis IHD?
Resting ECG, stress test, coronary angiography
What drugs are used to treat IHD; how do they work; when would you use them?
Nitrates
Beta-blockers (decreas oxygen demand by decreasing HR and contractility) initial tx for all patients with stable angina)
Ca channel blockers (decrease preload, wall stress, contractility, HR, coronary vasospasm and increase coronary perfusion; variant angina)
Aspirin for all, clopidogrel if pt allergic to aspirin
Heparin+aspirin (unstable angina)
Ranolazine (decresaes late inward Na current; stable angina for pts refractory to other drugs)
Statins (inhibit HMG-CoA which decreases LDL and increases HDL, also anti-inflammatory; pts w/ dyslipidemia)
What are the side effects of nitrates?
Headaches, hypotension, reflex tachycardia
What are the side effects of beta blockers?
Excessive bradycardia, decreased LV contractile function (worsening of HF), bronchoconstriction, fatigue, impotence
What are the side effects of Ca channel blockers?
Headache/flushing, decreased LV contraction, marked bradycardia, edema, constipation
What are the adverse effects of Ranolazine?
Dizziness, headache, constipation, nausea
What drug is used to prevent thrombosis in revascularization procedures?
Abciximab
When is CABG indicated?
Left main coronary artery disease or symptomatic 3 vessel disease
What graft is the best for CABG?
Internal mammary artery>saphenous vein
What is the pathogenesis of a MI?
Plaque rupture, thrombosis, infarct
What role does TxA2 play in formation of an MI?
Aids in platelet aggregation and acts as vasoconstrictor
What are the types of of MI?
STEMI and NSTEMI
What are the two therapeutic methods of reperfusion in MI?
PCI, fibrinolytic therapy
Why is early reperfusion important in MI?
Increases early and long term survival
When do contraction bands appear?
Reperfusion of irreversibly damaged cells that leads to the entry of Ca in to cytosol causing hypercontraction
When does coagulation necrosis appear following an MI?
24 hours
When do macrophages break down the necrotic tissue and what danger exists during this period?
3-7 days; danger of rupture
What are the clinical findings of MI?
Sudden onset of severe retrosternal pain, usually longer than 30 min, not relieved by nitroglycerin, usually radiates, associated with sweating/anxiety/hypotension
What is the most common cause of death in STEMI?
V-fib
What are the complications of STEMI?
Cardiogenic shock, arrhythmias (ventricular most common), CHF, rupture, mural thrombus, pericarditis, ventricular aneurysm
Detail the temporal sequence of CK-MB.
Appears in 4-8 hours, peaks at 24 hours, disappears in 3 days
Detail the temporal sequence of cardiac troponins.
Appear 3-12 hours, peak at 24 hours, disappear in 10 days
What serum biomarker can be used to diagnose reinfarction?
CK-MB
What serum biomarker is the gold standard for diagnosis of MI?
Cardiac troponins
