Complications and Side Effects
Because the devices generally result in blood flowing over a non-biologic surface, predisposing the blood to clotting, there is need for anticoagulation measures. One device, the HeartMate XVE, is designed with a biologic surface derived from fibrin and does not require long term anticoagulation (except aspirin); unfortunately, this biologic surface may also predispose the patient to infection through selective reduction of certain types of leukocytes.
New VAD designs which are now approved for use in the European Community and are undergoing trials for FDA approval have all but eliminated mechanical failure.
VAD-related infection can be caused by a large number of different organisms:
- Gram positive bacteria (Staphylococci especially Staph. aureus, Enterococci)
- Gram negative bacteria (Pseudomonas aeruginosa, Enterobacter species, Klebsiella species)
- Fungi especially Candida sp.
Treatment of VAD-related infection is exceedingly difficult and many patients die of infection despite optimal treatment. Initial treatment should be with broad spectrum antibiotics, but every effort must be made to obtain appropriate samples for culture. A final decision regarding antibiotic therapy must be based on the results of microbiogical cultures.
Other problems include immunosuppression, clotting with resultant stroke, and bleeding secondary to anticoagulation. Some of the polyurethane components used in the devices cause the deletion of a subset of immune cells when blood comes in contact with them. This predisposes the patient to fungal and some viral infections necessitating appropriate prophylactic therapy.
As of July 2007, 69-year old Peter Houghton was the longest surviving recipient of a VAD for permanent use. He received an experimental Jarvik 2000 LVAD in June 2000. Since then, he completed a 91-mile charity walk, published two books, lectured widely, hiked in the Swiss Alps and the American West, flew in an ultra-light aircraft, and traveled extensively around the world. He died of acute renal failure in 2007.
VADs extend the quantity of life. People who have had VADs implanted have had lower rates of depression than those people suffering from cardiac disease that have not undergone implantation surgery.
In a small number of cases left ventricular assist devices, combined with drug therapy, have enabled the heart to recover sufficiently for the device to be able to be removed (explanted).
The majority of VADs on the market today are somewhat bulky. The smallest device approved by the FDA, the HeartMate II, weighs about 1 pound (0.45 kg) and measures 3 inches (7.6 cm). This has proven particularly important for women and children, for whom alternatives would have been too large
One device gained CE Mark approval for use in the EU and began clinical trials in the US (VentrAssist). As of June 2007 these pumps had been implanted in over 100 patients. In 2009, Ventracor was placed into the hands of Administrators due to financial problems and was later that year liquidated. No other companies purchased the technology, so as a result the VentrAssist device was essentially defunct. Around 30–50 patients worldwide remain supported on VentrAssist devices as of January 2010.
The Heartware HVAD works similarly to the VentrAssist – albeit much smaller and not requiring an abdominal pocket to be implanted into. The device has obtained CE Mark in Europe and is currently in clinical trials in the USA. Recently, it was shown that the Heartware HVAD can be implanted through limited access without sternotomy.
Read more about this topic: Ventricular Assist Device
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