Ischemic Heart Disease

Question 1

Definition of ischemic heart disease

Answer 1

Condition in which imbalance between myocardial oxygen supply and demand results in myocardial hypoxia and accumulation of waste metabolites. Most often caused by atherosclerotic disease or the coronary arteries.

Question 2

2 determinants of myocardial oxygen supply.

Answer 2

1 O2 content

2 coronary blood flow

a) external compression
b) internal regulation

Question 3

Three determinants of myocardial oxygen demand

Answer 3

1) Wall stress (P x r/2h)
2) heart rate
3) contractility

Question 4

3 factors that regulate coronary vascular resistance

Answer 4

1) metabolic factors
- Accumulation of metabolites when tissue is in hypoxic state can cause vasodilation. Specifically adenosine from accumulates atp.

2) Endothelial factors
- NO, prostacyclin, endothelin 1

3) Neural factors.
- sympathetic and parasympathetic.
- alpha = vasoconstriction
- beta2 = vasodilation

Question 5

What is ventricular wall stress and was determined it.

Answer 5

The tangential force acting on the myocardial fibers, pulling them apart.

Thus it is directly proportional to systolic ventricular pressure.

It is also related to the radius of the ventricle and wall thickness.