CV math stuff

Question 1

equations for cardiac output

Answer 1

CO = SV X HR

Fick principle: CO = total body oxygen consumption rate/ (arterial O2-venous O2 content)

Question 2

mean arterial pressure equations

Answer 2

MAP = CO X total peripheral resistance
MAP = (2/3 diastolic) + (1/3 systolic)

Question 3

What is the pulse pressure? relationships with other measures?

Answer 3

systolic-diastolic pressure. it is directly proportional to stroke volume and inversely proportional to arterial compliance

Question 4

What are the equations for stroke volume?

Answer 4

SV = end diastolic volume - end systolic volume

may also be calculated from cardiac output (CO = SV X HR)

Question 5

How does cardiac output change during exercise?

Answer 5

early stages, CO maintained by incr. HR and incr. SV. later, though, CO is maintained only by HR becasue SV plateaus

Question 6

What conditions cause changes to pulse pressure?

Answer 6

pulse pressure increases in hyperthyroidism, aortic regurg, arteriosclerosis, obstructive sleep apnea (from incr. sympathetic tone), exercise (transient)
pulse pressure decr. in aortic stenosis, cardiogenic shock, cardiac tamponade, and advanced heart failure

Question 7

What are conditions where stroke volume may increase?

Answer 7

exercise, anxiety, pregancy

Question 8

LaPlace’s Law

Answer 8

wall tension = (pressure X radius)/ (2 X wall thickness). LV compensates for incr. afterload by thickening its wall. this decreases wall tension.

Question 9

What drugs decrease preload?

Answer 9

venodilators, like nitroglycerins

Question 10

What factors (preload/afterload) are affected by ACE-I and ARBs?

Answer 10

both preload and afterload decr.

Question 11

What drugs decrease afterload?

Answer 11

vasodilators (arterial). ex: hydralazine

Question 12

Ejection fraction equation. What is normal?

Answer 12

EF = SV/EDV = (EDV-ESV)/EDV. normal EF > 55%. EF is decreased in systolic heart failure and increased in diastolic heart failure (aka high output heart failure).

Question 13

resistance, pressure, flow equation

Answer 13

dela P = Flow X resistance

Question 14

What conditions caused increased viscosity? Decreased viscocity?

Answer 14

polycythemia, hyperproteinimic states like multiple myeloma, and ahereditary spherocytosis. decreased viscosity seen in anemia

Question 15

Mathematical relationships with resistance (ie. what is it proportional to)

Answer 15

directly proportional to viscosity and vessel length. inversely proportional to radius to the 4th power.

Question 16

What vessels account for most of the total peripheral resistance?

Answer 16

arterioles