Vascular Hemodynamics Flashcards
primary determinant of myocardial oxygen supply
coronary blood flow, as determined by vascular resistance
Tx for stable angina
first line is medical: reduce myocardial demand w/ beta blockers (lower HR and contractility) and nitrates (reduce preload), also use aspirin and statins to prevent athero and ACS
can move to PCI, improves life but NOT mortality
part of system that regulates MAP
arterioles
compliance
distensibility of a vessel, determines capacitance
2 components of vascular compliance
passive: extracellular matrix like collagen and elastin)
active: smooth muscle tone
venous compliance
greater than arteries, will have less pressure for the same volume
regulation of venous compliance
a1 adrenergic receptors when activated increase venous tone and decrease venous compliance, increasing venous return to heart (preload)
ateriosclerosis and compliance
reduction of vessel compliance in aging, diabetes, chronic HTN, etc by decreasing ECM elasticity
and also from atherosclerosis
functional hyperemia
vasodilation in response to increase in metabolic demand, mediated by metabolites such as adenosine, Pi, CO2, H+
main regulator of coronary vascular resistance
metabolic control, mainly adenosine, CO2, and H+
describe adenosine nuclear stress test
give adenosine which acts as a metabolite vasodilator, healthy vessels will show relatively more perfusion than atherosclerotic ones
how to determine wall tension in vessels
Laplace equation, T=Pr/h
in Laplace terms, how do vessels adapt to higher pressures
medial hypertrophy, increasing the h variable to lower the tension (chronically this hyaline hypertrophy w/ extracellular matrix, acute is more SMC)
arteries naturally have thicker walls given the higher P and r values as opposed to capillaries
when to Tx AAA?
larger than 5.5 cm or growing more than .5 cm a year or symptomatic
rupture is emergent repair
ventricular response to higher blood pressure
concentric hypertrophy increases h and reduces r, therefore counteracting the rise in P to avoid super high tension