Permanent in-series cardiac assistance with the dynamic aortic patch: Blood-prosthesis interaction in long-term canine experiments.

The blood-prosthesis interaction of the dynamic aortic patch (DAP), an in-series assist device for permanent circulatory support which is implanted in the descending thoracic aorta, was studied in 65 long-term experiments. Periods of postoperative observation with the device inactive or activated ranged from 2 weeks to 22 months. The intravascular surface of the DAP, fabricated of Dacron velour backed by bioelectric polyurethane, displayed various degrees of organization, ranging from a thin fibrin layer to a well organized pseudointima. Activation of the system did not prevent the development of an organized pseudointima. Changes in free-plasma hemoglobin were minimal; platelet count per square millimeter and state of reactivity remained within normal limits. Evidence of renal embolization, attributable to activation of the device, was found in five animals. Frequent lethal complications were aortic rupture and infections of the thoracic cavity originating at the implantation site. Further improvement of the DAP and the techniques of implantation is indicated to insure its efficacy during long-term implantation and activation.