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guillo12
What does "fixed cardiac output" signify?
+1
usmleuser007
"fixed cardiac output" might mean that with the stenosis (ie. narrowed aortic valve) there is a limited or rather reduced cardiac output. Exercise would not increase cardiac output because the stenosis is caused by a mechanical (physical) rather than a biochemical process. Therefore, At any given moment the heart can not increase its output no matter how forcefully it contracts.
+11
sunshinesweetheart
@fallot4logy LVH does not lead to coronary artery compression. only reallyyyy rarely will pulmonary artery dilation cause coronary artery compression. plus that would cause angina but probably wouldnt decrease cerebral bloodflow to syncope. her murmur + LVH point us toward aortic stenosis which does cause those --> fixed CO
+2
drpatinoire
@fallot4logy LVH can cause coronary artery compression, but typically leading to coronary ischemia after exercise (i.e. stable angina in this patient). The question is asking what leads to her syncope. Syncope actually means her brain is lacking blood supply abruptly.
+5
rainlad
how do we rule out mitral valve prolapse in this case?
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spow
@rainlad murmurs at the right upper sternal border are aortic in nature. Mitral murmurs are heard at left 5th intercostal at the midaxillary line.
+1
jj375
Also, nobody mentioned the "prominent left ventricular impulse". I kinda get thrown off by these. Anyone have thoughts? Google was telling me it is from a hypertrophied ventricle so I'm thinking her aortic stenosis causes the LV hypertrophy and an impulse. Is this the correct line of thinking?
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cbreland
Great, same thought process, murmur made me think of aortic stenosis, supported by the LV hypertrophy in stem. Then you have syncope during exercise because the heart is not able to keep up with the demands of the body
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submitted by โneonem(630)
this patient has symptomatic aortic stenosis. This can be identified by the ventricular hypertrophy (to compensate for increased functional afterload from non-compliant aortic valve), midsystolic murmur and the location at the normal aortic area.
Per UpToDate on Clinical manifestations of Aortic Stenosis:
"Dizziness and syncope โ Syncope occurs as a presenting symptom in approximately 10 percent of patients with symptomatic severe AS (or approximately 3 percent of all patients with severe AS) [3]. There are several proposed explanations for exertional dizziness (presyncope) or syncope in patients with AS, both of which reflect decreased cerebral perfusion. Exercise-induced vasodilation in the presence of an obstruction with fixed cardiac output can result in hypotension."