UW cardio q Id: 244[621802]

[MudPhud20XX]

Could we discuss this q?

A 72 yr old man with long-standing dyspnea was seen by his primary care physician after experiencing an episode of syncope. Physical exam showed weak and slowly rising arterial pulses. Cardiac auscultation showed weak and slowly rising arterial pulses. Cardiac auscultation showed a harsh midsystolic murmur best heard at the second right intercostal space with decreased intensity of the second heart sound. EKG and echocardiogram confirmed the diagnosis of severe aortic stenosis. Two months later, the pt comes to the emergency dept with palpitations and increased shortness of breath. His bp is 90/60 mm Hg and his heart rate is 130/min with an irregularly irregular rhythm. EKG shows new onset atrial fibrillation w/o significant ST segment or T wave changes. Chest x-ray shows bilateral pulmonary edema. Which of the following hemodynamic changes most likely caused this pt's acute pulmonary findings?

A. sudden dec in Lt. ventricular contractility
B. sudden dec in Lt ventricular preload
C. sudden inc in Lt. ventricular afterload

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[dfib slim]

He is in Afib now so his atria are unable to pump blood into his ventricles. Blood backs up into the lungs leading to pulm edema. Since the blood is backing up it leads to a decrease in preload.

 

[MudPhud20XX]

but how does that explain the cause of the pulmonary edema? I went for inc Lt. ventricular afterload which I thought explains the cause of the pulmonary edema. What am I missing here? Isn't it the inc afterload that causes the back up of bloods into the lung???

 

[dfib slim]

Afterload is what the heart has to push against. A sudden increase in afterload would be something like an infusion of Levophed raising the systemic BP. The decrease in preload causes the pulm edema because where else is that blood going to go? If it all can't go forward because the atria is in fibrillation some goes backwards.

 

[MudPhud20XX]

yeah you're right man. now it makes sense. it has to be the increased preload to explain the pulmonary edema. Thanks man!