USMLE STEP 1 CARDIOLOGY EXAM UPDATED QUESTIONS
AND ANSWERS
right coronary a perfuses - CORRECT ANSWER✅✅✅SA, AV node
posterior descening branch--> inferior LV
(right dominant, if left dominant, PD is
derived from the circumflex artery)
marginal a. --> right ventricle
left coronary perfuses - CORRECT ANSWER✅✅✅LAD --> anterior LV
MOST COMMON SITE OF OCCLUSION
circumflex a. --> posterior LV
coronary arteries fill during - CORRECT ANSWER✅✅✅diastole
most posterior part of the heart - CORRECT ANSWER✅✅✅LA
enlargement --> dysphagia, hoarseness
CO - CORRECT ANSWER✅✅✅= SVxHR
= rate O2 consumed/(PaO2-PvO2)
= EDV - ESV
MAP - CORRECT ANSWER✅✅✅COxTPR
,exercise - CORRECT 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 - CORRECT 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)
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 - CORRECT ANSWER✅✅✅incr afterload/arterial
pressure
incr contractility
incr HR
incr heart size
incr wall tension
preload/afterload - CORRECT 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 - CORRECT ANSWER✅✅✅basically CO (SV)
incr with preload - from fiber stretch
force of contraction ~ initial length of cardiac muscle fiber ~ preload
ejection fraction - CORRECT ANSWER✅✅✅= SV/EDV
= (EDV - ESV)/ EDV
, EF is an index of VENTRICULAR CONTRACTILITY
NORMAL ≥ 55%
DECR EF WITH HEART FAILURE
resistance, pressure, flow - CORRECT ANSWER✅✅✅P = QxR
R ~ (viscosity x length)/radius^4
ARTERIOLES account for most of the TPR, regulate capillary flow
resistance of vessels in series= R1 + R2
1/total resistance in parallel=1/R1 + 1/R2
...remember that if youre adding 1/Rn then you have to flip sum to get Rtotal
viscosity ~ hematocrit
incr viscosity in POLYCYTHEMIA, HYPERPROTEIN
(MM), HEREDITARY SPHEROCYTOSIS
cardiac cycle - CORRECT ANSWER✅✅✅
PV loop - CORRECT ANSWER✅✅✅bounded by systolic volume curve (ESPVR) on top,
and diastolic volume (EDPVR) curve on bottom
PV loop changes - CORRECT ANSWER✅✅✅
pacemaker and myocyte membrane changes - CORRECT ANSWER✅✅✅
AND ANSWERS
right coronary a perfuses - CORRECT ANSWER✅✅✅SA, AV node
posterior descening branch--> inferior LV
(right dominant, if left dominant, PD is
derived from the circumflex artery)
marginal a. --> right ventricle
left coronary perfuses - CORRECT ANSWER✅✅✅LAD --> anterior LV
MOST COMMON SITE OF OCCLUSION
circumflex a. --> posterior LV
coronary arteries fill during - CORRECT ANSWER✅✅✅diastole
most posterior part of the heart - CORRECT ANSWER✅✅✅LA
enlargement --> dysphagia, hoarseness
CO - CORRECT ANSWER✅✅✅= SVxHR
= rate O2 consumed/(PaO2-PvO2)
= EDV - ESV
MAP - CORRECT ANSWER✅✅✅COxTPR
,exercise - CORRECT 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 - CORRECT 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)
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 - CORRECT ANSWER✅✅✅incr afterload/arterial
pressure
incr contractility
incr HR
incr heart size
incr wall tension
preload/afterload - CORRECT 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 - CORRECT ANSWER✅✅✅basically CO (SV)
incr with preload - from fiber stretch
force of contraction ~ initial length of cardiac muscle fiber ~ preload
ejection fraction - CORRECT ANSWER✅✅✅= SV/EDV
= (EDV - ESV)/ EDV
, EF is an index of VENTRICULAR CONTRACTILITY
NORMAL ≥ 55%
DECR EF WITH HEART FAILURE
resistance, pressure, flow - CORRECT ANSWER✅✅✅P = QxR
R ~ (viscosity x length)/radius^4
ARTERIOLES account for most of the TPR, regulate capillary flow
resistance of vessels in series= R1 + R2
1/total resistance in parallel=1/R1 + 1/R2
...remember that if youre adding 1/Rn then you have to flip sum to get Rtotal
viscosity ~ hematocrit
incr viscosity in POLYCYTHEMIA, HYPERPROTEIN
(MM), HEREDITARY SPHEROCYTOSIS
cardiac cycle - CORRECT ANSWER✅✅✅
PV loop - CORRECT ANSWER✅✅✅bounded by systolic volume curve (ESPVR) on top,
and diastolic volume (EDPVR) curve on bottom
PV loop changes - CORRECT ANSWER✅✅✅
pacemaker and myocyte membrane changes - CORRECT ANSWER✅✅✅
