Pathophysiology of Chronic Ischemic Heart Disease

Question 1

define unstable angina

Answer 1

sudden increase in tempo or severity of anginal episodes with less exertion or even at rest….typically from plaque rupture and thrombus formation…can lead to NSTEMI

Question 2

define stable angina

Answer 2

predictable chest pain with exertion or stress…due to a plaque blockage in one more coronary arteries…does not lead to infarction

Question 3

at rest what percent of oxygen is extracted from the blood in the heart?

Answer 3

almost 100%

Question 4

what two properties mediate the blood supply to the heart?

Answer 4

coronary blood flow and vascular resistance

Question 5

does most blood flow to the heart occur during systole or diastole? why?

Answer 5

diastole…because during systole the vessels get crunched within the contracting wall

Question 6

what is the coronary perfusion pressure typically equal to?

Answer 6

the diastolic pressure of the aorta

Question 7

what percent of blockage leads to the loss of dilatation by coronary arteries?

Answer 7

70%…they can no longer respond to the effects of NO

Question 8

how do vessels changes under acidosis?

Answer 8

vasodilate

Question 9

how do vessels changes under hypoxia?

Answer 9

vasodilate

Question 10

how do vessels changes under adenosine?

Answer 10

vasodilate

Question 11

what two ways does atherosclerosis limit blood flow in coronaries?

Answer 11

limit radius of vessel and make it dysfunctional and unable to respond to or release NO

Question 12

how does an adenosine stress test work?

Answer 12

it is a vasodilator for vessels that do not have plaques…so if there is a plque then after adenosine it will not show up, whereas the others will

Question 13

when is an exercise stress test positive?

Answer 13

if yields chest pain and ECG abnormality of ST segment depression of 1 mm

Question 14

if exercise stress test is positive…what can we add to see better?

Answer 14

radionuclide that will provide nuclear imaging and perfuse with vessels that are not blocked

Question 15

does the oxygen demand of the heart increase or decrease when catecholamines are present?

Answer 15

increases due to increasing heart rate and contractility

Question 16

how do catecholamines affect the coronary vessels?

Answer 16

cause more constriction that dilation…so decrease the supply of blood to the heart

Question 17

what is best class of drugs for the stable angina patient?

Answer 17

beta blockers

Question 18

what three beta blockers are best for ischemic heart disease and why?

Answer 18

atenolol, metoprolol and esmolol

because they are cardioselective…IE they target the B1 better than B2 receptor

Question 19

in what type of heart failure are beta blockers contraindicated?

Answer 19

acute…because heart is failing we dont want to slow it even more

Question 20

what two types of conduction issues are beta blockers contraindicated with?

Answer 20

AV block or severe bradycardia

Question 21

dihydropyridine calcium channel blockers target what? and have what effect?

Answer 21

smooth muscle cells…leads to vasodilation to help with coronary flow

Question 22

non dihydropyridines calcium channel blockers target what and have what effect?

Answer 22

the heart…leads to slower rate and increases time of diastole to decrease O2 demand of the heart

Question 23

when should you not give calcium channel blockers?

Answer 23

AV block or severe bradycardia

Question 24

nitroglycerin causes what vessel types to constrict or dilate?

Answer 24

arteries and veins…to dilate

Question 25

the venous dilation from nitoglycerine leads to what benefit for ischemic patients?

Answer 25

decreased LVEDV which leads to less O2 demand for heart

Question 26

the arterial dilation from nitroglycerine leads to what benefit for ischemic patients?

Answer 26

increased coronary supply to heart

Question 27

name the two side effects of nitroglycerin

Answer 27

headaches and hypotension

Question 28

in what scenarios should CABG be performed instead of PCI (3 scenarios)?

Answer 28

if LAD is over 50% blocked
if 3 vessels are blocked
if 2 vessels including LAD with low ejection fraction