Monday, May 11, 2015

Advanced Circulatory Support I

This may be an unfair case as it's quite complicated, but I figure I've spent some of the last week taking care of these patients and its good to review mechanical circulatory support devices.

A patient with end stage nonischemic cardiomyopathy undergoes placement of a permanent left ventricular assist device as a bridge to cardiac transplantation. It is a continuous flow device. His surgery is uncomplicated, he is started on coumadin, and then discharged to home. Several weeks later, he calls your office because over the last few days, his device has been reporting changing numbers. The pump speed, revolutions per minute, is the same as it was when he was discharged. The cardiac output is similar to his discharge value at 3.5 L/min. However, the pump power, has been markedly rising. It is now five times what it was at discharge (2W versus 10W). The patient has been doing his usual activities, does not feel thirsty or dehydrated, and feels otherwise well.

Challenge: What is your main concern?

Image shown under Creative Commons Attribution Share-Alike License, from Wikipedia.


RaH said...

Seems like there must be an increase in peripheral resistance...if the output stays the same but the Workload increased, the resistance somewhere must have increased! the viscosoty shouldnt be changing this hard. the length of the vessels should stay constant, so there could be a change in diameter of an artery, due to spasm, sclerosis or stenosis

Craig Chen said...

great reasoning! it is an increase in resistance to the pump - and if you talk to any VAD specialist, they will worry it is a pump clot
Advanced Circulatory Support I

Increases in pump power without changes in pump speed, volume status, or afterload reduction may indicate device malfunction from thrombus formation. The patient needs to be admitted for systemic anticoagulation, echocardiography, and consideration for pump exchange.

Source: UpToDate.