Mod 4

Question 1

What 3 factors does the hearts oxygen demand depend on?

Answer 1

Heart rate
Myocardial contractility
Wall tensions

Question 2

The delivery of blood to the heart is dependant on:

Answer 2

The capacity of blood to carry oxygen
Coronary perfusion pressure
Coronary vascular resistance

Question 3

Variant angina (Prinzmetal’s)

Answer 3

Most common in premenopausal women. Random episodes of angina even at rest cause by an arterial spasm.

Question 4

Unstable Angina

Answer 4

Arriving suddenly in an otherwise asymptomatic patient. Many cases is follow by MI in the next few hours or days after.
Possible origins
Sub intima lol hemorrhage in artherosclerotic plaque
Rupture and embolization of plaque lipids
Coronary artery spasm
Formation of platelet plug or thrombus over plaque

Question 5

Treatment of angina

Answer 5

nitrates - potent vasodilators (increase coronary flow, reduce peripheral resistance, reduce venous return back to the heart)
Beta adrenergic blocking agents- catecholamine antagoniast that slow heart and reduce workload
Calcium antagonists- some slow myocardial cell depolarization (prevent tachy) others are coronary and peripheral vasodilators

Question 6

Acute MI causes

Answer 6

Thrombosis superimposed on an atherosclerotic lesion in one of the coronary arteries or branches (85% of cases)

• embolization of atherosclerotic plaque material
• thromboemboli
• Coronary artery rupture or spasm
• sudden increase in myocardial oxygen demand.

Question 7

Creatine kinase

Answer 7

Second of the muscle enzymes that appear in blood, detectable 6 hours post MI, levels peak 18/24

Question 8

Other enzymes that appear post MI

Answer 8

#1- troponin
#2- CK
#3-Glutatmic-oxaloacetic transaminase rises later peaks at 24-36 hrs.  Return to normal on 4/5th day
-Lactic dehydrogenase (LDH) release slowly, peaks 48-72hrs declines 1-3 weeks later

Question 9

Inflammatory response provoke by necrosis Clinical observations

Answer 9

• Erythrocytes sedimentation rate (ESR) rises
• Fever, rarely exceeds 38 degrees 24hrs-1week. RXN from pyrogens released from necrotic cells and accumulation of leukocyte
• WBC count elevated for a week, neutrophils accumulate. During this phas MI can be located using radionuclide scanning