Coronary Circulation Flashcards
What effect does Nitric oxide and adenosine have on coronary arteries?
Both nitric oxide and adenosine are potent vasodilators.
At what % reduction in coronary artery diameter from stenosis is resting coronary flow reduced?
Resting coronary flow is reduced starting when a coronary artery stenosis results in ~70-90% reduction in vessel diameter.
What is the primary regulator of coronary vascular resistance?
Does autoregulation occur with coronary blood flow?
The coronary artery endothelium is a primary regulator of coronary vascular resistance (changing diameter).
Coronary blood flow is autoregulated.
On which ventricular myocardium does systolic compression have more of an effect on blood flow?
Systolic compression has much less effect on flow through the right ventricular myocardium than the left.
Unlike other body tissues, how much oxygen does the myocardium extract from coronary blood flow?
The myocardium extracts nearly all of the oxygen delivered to it from coronary blood flow.
Blood flow occurs more during which stage (diastole/systole) in the left coronary artery?
In the right?
In the left coronary artery, more flow occurs during diastole than during systole.
In the right coronary artery, flow is fairly even during systole and diastole.
The coronary arterioles downstream of the stenotic regions during the anginal episodes are most likely dilated fully. What is the primary cause of this vasodilation?
adenosine.
Norepinephrine has what effect on vessels?
norepinephrine constricts blood vessels.
The shear stress caused by high velocity flow can cause vasodilation via _______
nitric oxide release
The major (biochemical) controller of coronary blood flow is what?
Infusion of adenosine or local release of adenosine normally increases the coronary blood flow.
Bradykinin, prostaglandins, carbon dioxide, and potassium ions serve as __________ for the coronary artery system.
vasodilators
The contraction of the cardiac muscle around the vasculature, particularly in the subendocardial vessels, causes what effect on blood flow?
A decrease in blood flow.
The normal resting coronary blood flow is approximately how many ml/min?
225 ml/min.
During systole, the percentage decrease in _________ flow is greater than the percentage decrease in ________ flow
Therefore, during the systolic phase of the cardiac cycle, the subendocardial flow clearly decreases, and the decrease in epicardial flow is relatively minor.
Which of the following is the most frequent cause of decreased coronary blood flow in patients with ischemic heart disease?
Atherosclerosis
Several factors contribute to decreased coronary flow in patients with ischemic heart disease. Some patients have spasm of the coronary arteries, which acutely decreased coronary flow. However, the major cause of decreased coronary flow is an atherosclerotic narrowing of the lumen of the coronary arteries.
