Saturday, February 24, 2007

A New LVAD Device Begins Early Testing

Testing of a new left ventricular assist device (LVAD) developed by an Australian company, Sunshine Heart, is in its very early stages of testing that has the advantage of not contacting the blood pool. In its early design shown here, an inflatable bladder encases the ascending aorta and uses the patient's own EKG to time the inflation and deflation of the bladder surrounding the aorta - it deflates when the heart contracts (systole) and inflates when the heart is relaxed (diastole). It function is analogous to intraaortic balloon pumps used in catheterization laboratories that use counterpulsation to decrease the work of the heart and improve coronary blood flow, but its mechanism resides outside the aorta, rather than within it, limiting the need for blood thinners with the device. An animation of the device is also demonstrated at the company's website.

At first glance, I was surprised that the device was placed on the ascending aorta (probably to facilitate access by the implanting surgeon), but the potential for migration of the device toward the coronary arteries and aorta (causing compromized coronary blood or changes to closure of the aortic valve) and its potential to disturb existing plaque in the ascending aorta and shower it to the brain suggests its use, in its present design, will be limited to younger patients or those without aortic disease. Whether such problems with this new device will manifest remains to be seen.

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