jean robert
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A 72 y.o caucasian male who was diagnosed with severe Aortic Stenosis six months ago presents to the ER with acute pulmonary edema. His BP 90/60 and his HR 130 bpm with a rythm that s irregularly irregular.ECG shows AF without significant ST segment or T wave changes.
Which of the following hemodynamic changes most likely contributed to the patient condition?
a) Sudden increase of the left ventricular afterload
b) Sudden increase in left ventricular filling
c) Sudden decrease of left ventricular preload
d) Sudden decrease in left ventricular contractility
e) Insidious right ventricular hypertrophy
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| jole
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C?
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| ssrpk
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yes.. its C
in patients with restrictive pattern of heart failure because of ventricular hypertrophy whihch in this case is due to pulmoinary edema, atrial kick has a significant contribution in ventricular filling, which will decrease left ventricular preload while elevating left atrial pressure and thus pulmonary edema
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| SILVER
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a) Sudden increase of the left ventricular afterload
if the aortic valve is stenosed then less blood is being pumped in to the aorta therefore LVEDV is increasing and ultimately preload will also increase (which is why i think it can't be C) so this backup of blood will transmit to the lt. atrium and eventually the lungs--->pul. edema
when blood isn't completely being pumped in to the aorta then it has to accumalate in the lt. vent and the afterload will increase, and as more blood enters the lt. vent. from lt. atrium that will add and increase the preload.
Edited by silver on 06/02/07 - 02:39 PM
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| new_n_lost
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a) Sudden increase of the left ventricular afterload
Diastolic dysfunction is due to inc afterload in AS. Both impaired LV relaxation and decreased LV compliance that is caused by increased afterload
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| Luckyall
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i am totally into A ) !!!
to my knowledge option C) is more of an conseq. of A. Fib., thas wht you should expect once A. Fib.
Further more, our pt dont have significant ST segment or T wave changes ( LHF) wich tells me there it has to be somethg ACUTE that created this sudden PE & A. Fib.
To me is unequivocally A)
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| Luckyall
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Silver, C) is a tricky option, it would happen eventually... i would expect it once A. Fib, however the Qs asks "Which of the following hemodynamic changes most likely CONTRIBUTED to the patient condition? "
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| ssrpk
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there is no indication of sudden increase in left ventricular afterload in this patient, he has been having severe aortic stenosis diagnosed 6 months ago and now he is presenting with acute decompensation which has resulted in pulmonary edema and systemic hypotension....
now there can be two causes for tht in such a aptient, either patient develops acute MI with cardiogenic shock, but then there would have been ST and T wave changes, but here there is no eveidence of even ischemia signified by normal T waves...thus sudden onset systlic dysfunction is very unlikely here.
if it were due to sudden increase in afterload blood pressure won't be low, or if it is low then there has to be some degree of ischemia causing it, as there is none, therefore afterload increase is not the reason.
it is true that increasae in afterload will eventually cause backing up of blood into the lungs, but that would be a slow insidiuos process which progresses gradually not acutely!
Here in this instance the most likely explanation of acute hemodynamic decompensation is Atrial fibbrilation,
Management of acute pulmonary edema with systemic hypotension, ecg should be done first to rule any arryhtmia that may have caused decreased ventricular filling and it can happen with AS,MS or even restrictive heart diseases.
Also pulmonary vasculature is a very compliant system thus gradually increasing atrial pressure will cause pulmonary HTN while acutely will result in pulmonary edema.
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| ssrpk
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Furthermore, arrhythmias causing rapid heart rate and hemodynamic collapse should be treated with immediate defibrillation.
This patient also requires a valve replacement.
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| ssrpk
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for the same reason patients with diastolic dysfunction do poorly with rapid heart rate and inotropics because they decrease diastolic interval and subsequently diminishes ventricular filling.
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| SILVER
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Luckyall wrote:
Silver, C) is a tricky option, it would happen eventually... i would expect it once A. Fib, however the Qs asks "Which of the following hemodynamic changes most likely CONTRIBUTED to the patient condition? "
????
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| new_n_lost
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in this pt we have lost the LV function and the cause of Atrial Fib is due to the volume overloading of LV & Lt Atrium making the Lt Atrium hypertrophy n have conduction problems. the Atrial Fib will cause the Sudden decrease in the Preload but Atrial Fib is caused by Lt Atrium hypertrophy which is due to persistent increase in Afterload.
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| new_n_lost
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Interesting Discussion Wud Definitely like to see the Whole Explanation provided by the Source.
Edited by new_n_lost on 06/02/07 - 05:56 PM
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| epica
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Jean,
Pl post the ans
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| jean robert
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C is the correct answer. It was really a trichy Question. Only 23% of people answer correctly. Here is the explanation provided by UW:
Acute Atrial Fibrillation most likely precipitated sudden onset of heart failure in this patient. AF occurs in up to 10% of patients with severe Aortic Stenosis. Patients with severe AS may already have a reduced Cardiac Output.
The sudden loss of the contribution of normal atrial contraction to ventricular filling ( loss of the atrial systolic Kick) decreases left ventricular preload ( end diastolic volume), which can further reduce Cardiac output and produce severe hypotension.
Additionally, many patients with chronic AS have concentric LV hypertrophy and therefore reduced LV compliance. Loss of the atrial kick in these patients may mean that a significant increase in Mean Pulmonary Venous Pressure is required to maintain the new steady state LV preload.
The result may be Acute Pulmonary Edema in addition to hypotension as occurred in this patient. Because of these dangers, CARDIOVERSION is indicated for acute atrial fibrillation in patients with severe AS.
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| inkspot
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great question and good explanation by ssrpk!
these questions require more thinking than just abrupt ans.
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