Cardiology USMLE step 1
, Cardiology USMLE step 1
right coronary a perfuses - Answer: SA, AV node
posterior descending branch--> inferior LV
(Right dominant, if left dominant, PD is
derived from the circumflex artery)
marginal a. --> right ventricle
left coronary perfuses - Answer: LAD --> anterior LV
MOST COMMON SITE OF OCCLUSION
circumflex a. --> posterior LV
coronary arteries fill during - Answer: diastole
most posterior part of the heart - Answer: LA
enlargement --> dysphagia, hoarseness
CO - Answer: = SVxHR
= rate O2 consumed/(PaO2-PvO2)
= EDV - ESV
, Cardiology USMLE step 1
MAP - Answer: COxTPR
exercise - Answer: initially, incr in CO via incr HR
later, incr SV and incr contractility play a big role
incr symp stim:
incr venous return
contracts arterioles EXCEPT in working muscle and dumps volume into the muscle
--> local mediators in muscle:
adenosine, K, ATP, CO2, lactate
this DECREASE in SYSTEMIC VASCULAR RESISTANCE by dilating muscle vessels
allows for BP to be relatively stable during exercise despite incr CO
CO variables - Answer: SV - affected by contractility, afterload, +
preload
SV incr with:
anxiety, exercise, pregnancy
Contractility/SV incr with:
catecholamines (incr Ca pump in SR)
incr intracellular Ca
decr extracellular Na (decr Ca/Na
exchange)
, Cardiology USMLE step 1
Digitalis - incr intracellular Na-->incr Ca
Contractility/SV decr with:
beta block (decr cAMP)
systolic heart fail
acidosis
hypoxia/hypercapnea
non-dihydropyridine Ca channel blockers
these incr myocardial O2 demands - Answer: incr afterload/arterial pressure
incr contractility
incr HR
incr heart size
incr wall tension
preload/afterload - Answer: preload = ventricular EDV
afterload = MAP ~ PR
venodilators decr preload (nitro)
vasodilators decr afterload (hydralazine)
incr preload with exercise, blood volume, sympathetic/excitement
starling curve (CO) + venous return graphs - Answer: basically CO (SV) incr with
preload - from fiber stretch
, Cardiology USMLE step 1
right coronary a perfuses - Answer: SA, AV node
posterior descending branch--> inferior LV
(Right dominant, if left dominant, PD is
derived from the circumflex artery)
marginal a. --> right ventricle
left coronary perfuses - Answer: LAD --> anterior LV
MOST COMMON SITE OF OCCLUSION
circumflex a. --> posterior LV
coronary arteries fill during - Answer: diastole
most posterior part of the heart - Answer: LA
enlargement --> dysphagia, hoarseness
CO - Answer: = SVxHR
= rate O2 consumed/(PaO2-PvO2)
= EDV - ESV
, Cardiology USMLE step 1
MAP - Answer: COxTPR
exercise - Answer: initially, incr in CO via incr HR
later, incr SV and incr contractility play a big role
incr symp stim:
incr venous return
contracts arterioles EXCEPT in working muscle and dumps volume into the muscle
--> local mediators in muscle:
adenosine, K, ATP, CO2, lactate
this DECREASE in SYSTEMIC VASCULAR RESISTANCE by dilating muscle vessels
allows for BP to be relatively stable during exercise despite incr CO
CO variables - Answer: SV - affected by contractility, afterload, +
preload
SV incr with:
anxiety, exercise, pregnancy
Contractility/SV incr with:
catecholamines (incr Ca pump in SR)
incr intracellular Ca
decr extracellular Na (decr Ca/Na
exchange)
, Cardiology USMLE step 1
Digitalis - incr intracellular Na-->incr Ca
Contractility/SV decr with:
beta block (decr cAMP)
systolic heart fail
acidosis
hypoxia/hypercapnea
non-dihydropyridine Ca channel blockers
these incr myocardial O2 demands - Answer: incr afterload/arterial pressure
incr contractility
incr HR
incr heart size
incr wall tension
preload/afterload - Answer: preload = ventricular EDV
afterload = MAP ~ PR
venodilators decr preload (nitro)
vasodilators decr afterload (hydralazine)
incr preload with exercise, blood volume, sympathetic/excitement
starling curve (CO) + venous return graphs - Answer: basically CO (SV) incr with
preload - from fiber stretch
