Flashcards in CV math stuff Deck (16):
equations for cardiac output
CO = SV X HR
Fick principle: CO = total body oxygen consumption rate/ (arterial O2-venous O2 content)
mean arterial pressure equations
MAP = CO X total peripheral resistance
MAP = (2/3 diastolic) + (1/3 systolic)
What is the pulse pressure? relationships with other measures?
systolic-diastolic pressure. it is directly proportional to stroke volume and inversely proportional to arterial compliance
What are the equations for stroke volume?
SV = end diastolic volume - end systolic volume
may also be calculated from cardiac output (CO = SV X HR)
How does cardiac output change during exercise?
early stages, CO maintained by incr. HR and incr. SV. later, though, CO is maintained only by HR becasue SV plateaus
What conditions cause changes to pulse pressure?
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
What are conditions where stroke volume may increase?
exercise, anxiety, pregancy
wall tension = (pressure X radius)/ (2 X wall thickness). LV compensates for incr. afterload by thickening its wall. this decreases wall tension.
What drugs decrease preload?
venodilators, like nitroglycerins
What factors (preload/afterload) are affected by ACE-I and ARBs?
both preload and afterload decr.
What drugs decrease afterload?
vasodilators (arterial). ex: hydralazine
Ejection fraction equation. What is normal?
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).
resistance, pressure, flow equation
dela P = Flow X resistance
What conditions caused increased viscosity? Decreased viscocity?
polycythemia, hyperproteinimic states like multiple myeloma, and ahereditary spherocytosis. decreased viscosity seen in anemia
Mathematical relationships with resistance (ie. what is it proportional to)
directly proportional to viscosity and vessel length. inversely proportional to radius to the 4th power.