Cardiac Drugs: CHF and Anti-Anginals

Question 1

determinants of oxygen supply

Answer 1

Question 2

oxygen use it proportional to work performed. the more heart beats the more work, and the more wall tension, the more work. Explain wall tension

Answer 2

wall tension: area in pressure volume-loop = work.

pressure andd volume are determinants of myocardial demand.

Larger radius and larger volume = larger wall tension.

Wall tension = pressure x radius

Question 3

4 mechanisms of how nitroglycerine can be beneficial in a cardiac event

Answer 3

1. arterial dilation results in lower O2 demand because lower BP = less tension = less work
2. coronary dilation: diameter will increase and will allow for increased coronary blood flow and = increased O2 supply
3. systemic venous dilation = causes venous pooling in UE and LE and abodmen = less blood in heart = lower ventricular volume = lower ventricular radius = lower tension = less work = lower demand.
4. coronary venous dilation = increased venous capacitance = reduced venous return = lower preload = lower ventricular diastolic pressure= CORONARY PERFUSION PRESSURE = CORONARY BLOOD FLOW = INCREASED O3 SUPPLY
   - if LV pressure is lower, the graident between aorta and LV increases, therefore the CPP increases and thus coronary blood flow increases

Question 4

what is coronary perfusion pressure

Answer 4

the pressure difference between the AORTA AND THE MYOCARDIUM. Myocardial pressure is bout the same as the pressure INSIDE THE VENTRICLE. (10)

Question 5

explain how perfusion (of LV) happens in diastole rather than in systole

Answer 5

in systole, the left ventricle and the myocardium pressure difference is about 0. there is no perfusion.

During diasole though, the left ventricle pressure is a lot lower, and the aorta pressure is high (because the aortic calce is closed and all the pressure is held in the aorta). The myocardium pressure is about the same as the left ventirclar pressure, and thus the myocardium also has a lower pressure. Therefore, the pressure difference between aorta and myocardium (coronary perfusion pressure) is larger, allowing for perfusion.

Question 6

Question 7

Overall, BPP = ___ aortia pressure minus LV_pressure

Answer 7

diastolic aortic pressure minue LVEDP

• remembe, myocardial perfusion occurs in diastole

Question 9

How does BP affect nitroglycerine use and CPP

Answer 9

low blood pressure will DECREASE CPP. Nitro also decreases BP indirectly by promoting vessel dilation. therefore you will pass out lol. Always check to BP before giving NTG

Question 10

3 mechanisms of action behind beta blockers

Answer 10

1. slower heart rate = fewer heartbeats = decreased O2 dmand
2. slower heart rate = longer diastolic time = increased O2 supply
3. lower contactility = lower pressure = lower tenson = decreased O2 demand

Question 11

how do beta blockers afftect CPP

Answer 11

Question 12

why should you not abruptly discontinue beta blockers

Answer 12

they should not be abruptly discontinued: a “rebound” hypertension and tachycardia can result

Question 13

in congestive heart failure, ventricle contraction is weak causing reduced ejection fraction. the body tries to compensate by increasing preload through water retention so that more can get ejected with the lower EF. This causes decompensation though. How can we reduce preload?

Answer 13

1. nitro to provoke venous dilation. more blood pooling in extremities and reduces venous retturn = lower preload
2. diuretic = pee more = volume loss = lower preload

Question 14

side effects of loop diuretics

Answer 14

common side effects;

- if you give too much. = dehydration and its consequences

- lower K+

- high H high bicarb = metabolic alkalosis.

• rarely can cause hearing loss.

Question 15

how does preload, contractility and afterload affect stroke volume?

Answer 15

CO = SV x HR

• HIGHER PRELOAD = LARGER SV
• contractility = higher produces larger SV
• afterload = LOWER SV

Question 17

method of afterload reduction

Answer 17

recall; afterload is the resistance pressure that the ventricular contractile pressure has to overcome to pump the blood out.

ACEinhibitors causes vasodilation and less sodium adn water retension

2. Afterload reduction can be accomplished aslo with ARBS. instead of blocking conversion through ACE, you can block the receptor and promote vasodilation plus less sodium adn water retension.
3. aldosterone blocker: K sparing diuertic. Spironolactone

Question 18

which class of vasodilation medicaation can lead to chronic cough

Answer 18

ace inhibitors