5-cardio

Question 1

what is the equation for cardiac work

Answer 1

stroke volume x arterial pressure

Question 2

what does increased cardiac work do to oxygen consumption

Answer 2

increases

Question 3

what two factors increase when LVEDP is increased

Answer 3

stroke volume (due to Frank-Starling) and cardiac work

Question 4

what happens with a venodilator to preload

Answer 4

it decreases

Question 5

what happens with a venodilator to stroke volume

Answer 5

decreases

Question 6

what happens with a venodilator to cardiac work

Answer 6

decreases

Question 7

what does arteriolar vasodilators do to afterload

Answer 7

decreases

Question 8

what does arteriolar vasodilators do to arterial pressure

Answer 8

decrease

Question 9

what does arteriolar vasodilators do to cardiac work

Answer 9

decrease

Question 10

how do the coronary vessels react when met with increased O2 demand

Answer 10

they dilate

Question 11

what causes angina

Answer 11

when oxygen demand is greater than supply, resulting in pain

Question 12

what 5 things can increase local coronary flow

Answer 12

• low o2 tension
• high co2 tension
• release of lactate (due to anaerobic metabolism)
• release of adenosine
• presence of prostacyclin (PGI2)

Question 13

what direction does coronary flow occur (where does it start and end)

Answer 13

from aorta to ventricles

Question 14

what is pressure difference in the heart during systole

Answer 14

pressure in ventricles greater than pressure in aorta

Question 15

what is the pressure difference in the heart during diastole

Answer 15

pressure in aorta greater than in ventricles

Question 16

does coronary flow happen during diastole or systole

Answer 16

diastole

Question 17

why does coronary flow occur during diastole

Answer 17

due to a reduction in mechanical pressure, and the pressure in the aorta being greater than the pressure in the ventricles

Question 18

what is the equation for coronary perfusion pressure

Answer 18

coronary artery diastolic pressure - left ventricular end diastolic pressure

Question 19

what happens to coronary vessels when there is angina/ischemia

Answer 19

maximally dilated (they want to get as much blood as possible)

Question 20

what happens when you use coronary dilators with angina

Answer 20

during angina, coronary vessels are already maximally dilated. it results in dilation of vessels in normal areas and less to ischemic areas - leads to coronary steal

Question 21

how do plaques affect coronary artery diastolic pressure

Answer 21

pressure will decrease distal to the plaque, leading to reduction of the pressure gradient and decreased coronary perfusion

Question 22

what happens to LVEDP when the ischemic heart starts to fail

Answer 22

it increases

Question 23

what are 3 different ways that anti-anginal drugs can work

Answer 23

• lower LVEDP (reduce preload)
• prolong diastolic time (reduce HR)
• reduce work load (reduce O2 demand)

Question 24

what is 1 thing all anti-anginal drugs do

Answer 24

reduce cardiac work load

Question 25

what class of drugs aim to lower LVEDP (preload)

Answer 25

venodilators

Question 26

what is an example of a venodilator

Answer 26

nitroglycerine (glyceryl trinitrate)

Question 27

does nitroglycerine dilate veins or arterioles more

Answer 27

dilates veins more than arterioles

Question 28

what does nitroglycerin do to venous capacitance?

Answer 28

increased, resulting in pooling

Question 29

what effect does nitroglycerin have on coronoary perfusion pressure? why?

Answer 29

increased coronary perfusion pressure (due to lowering of the LVEDP)

Question 30

what five factors does nitroglycerin decrease?

Answer 30

decrease venous return
decrease LVEDP
decrease stroke volume (shift Frank Starling back to normal range)
decrease arterial pressure
decrease workload (due to CW = SV x AP)

Question 31

what happens to stroke volume when you decrease LVEDP

Answer 31

decrease

Question 32

how does nitroglycerin produce coronary dilation without resulting in coronary steal?

Answer 32

by opening collateral vessels, increasing blood flow to ischemic areas

Question 33

how is nitroglycerine administered for acute attacks

Answer 33

sublingual

Question 34

how is nitroglycerine administered prophylactically

Answer 34

transdermal

Question 35

what are the untoward effects of nitroglycerine

Answer 35

headache and tolerance

Question 36

what class of drugs prolong diastole?

Answer 36

beta blockers (eg. propanolol)

Question 37

what are two effects of propanolol?

Answer 37

reducing HR during excersize, –> increased coronary perfusion time –> reducing O2 demand
reduce afterload by lowering BP, thus lowering cardiac work

Question 38

when is propranolol especially useful

Answer 38

after the first myocardial infarction to prevent re-infarction

Question 39

name 3 drugs that reduce cardiac work

Answer 39

verapamil, diltiazem, nifedipine

Question 40

how do verapamil and nifedipine work

Answer 40

block ca++ channels, reducing contractility, HR and afterload, thus reducing cardiac work

Question 41

how do dihydropyridines like nifedipine work?

Answer 41

target arterial smooth muscle channels, reducing contracility, HR and afterload, thus reducing cardiac work

Question 42

what are 3 ways to treat heart attack in emergency

Answer 42

aspirin (acetyl salicylic acid) , nitroglycerine (via IV), altepase (tissue plasminogen activator)

Question 43

what are 2 ways to prevent heart attack (drugs)

Answer 43

low dose aspirin (80mg/day) , antianginals (b blockers, ca channel blockers)

Question 44

how do nitrates relax coronary smooth muscle

Answer 44

they act like NO from endothelial cells

Question 45

what is the mechanism of action for nitrates on coronary smooth muscle

Answer 45

NO binds to heme moiety of guanylyl cyclase, activation of guanylyl cyclase, increased cGMP, cGMP relazed smooth muscle by dephosphorylating myosin-LC-PO4