Initial clinical experience with centrifugal pumps coated with the Carmeda process

From September 5 to November 4, 1991, four consecutive patients placed on centrifugal ventricular assist devices (VADs) for cardiac failure were supported with Biomedicus pumps coated with the Carmeda bioactive surface. The study included three men and one woman aged 52-65 years. Two patients were supported with a right VAD, one with a left VAD, and one with a biventricular VAD. Support ranged from 35.5 to 65.75 hr, and VAD flows ranged from 1.0-5.5 L/min. Three patients were weaned from the VADs, and two survived. At explant, all four systems had clots adherent to the surface of the tubing and connectors on the pump outflow side of the circuit. Two patients had clots in the pump. Some of the clots were firmly adherent, whereas others dislodged easily after being rinsed with saline. All patients received heparin for insertion, and in three patients, heparin was reversed with protamine. Two patients received no further anticoagulation, and two received continuous heparin within 24 hr of implant to maintain activated clotting times of 140-150 sec. All patients had bleeding complications before and after VAD placement, necessitating multiple blood product transfusions. One patient who was weaned and survived had multiple thromboembolic strokes. These data suggest that clots can form on surfaces coated with the Carmeda process, even if a low dosage of heparin is used.