Partial aortic valve fusion induced by left ventricular assist device

Background. Left ventricular assist devices (LVADs) may be used (1) as a br idging device to cardiac transplantation, (2) for permanent replacement of left ventricular function, and (3) as a bridge to recovery of ventricular f unction, for example, in recoverable myocardial disease. In this third grou p of patients, it is important that the LVAD does not produce changes in th e heart that will have a deleterious effect on cardiac function once the de vice is removed. Furthermore, if the LVAD fails, survival depends on optima l function of the diseased heart. Methods. All hearts with LVADs encountered as surgical specimens following heart transplantation or at autopsy at the Fairview-University of Minnesota Medical Center during the 5-month period August 1998 to January 1999 were examined for native valvular heart disease. The nature and extent of commis sural fusion was noted and measured. Light microscopy was performed on any valve lesions. Results. Four of 6 patients with HeartMate (Thermo Cardiosystems, Inc, Wobu rn, MA) LVADs showed evidence of commissural fusion (acquired aortic stenos is). In 1 patient, this condition was caused by an organizing thrombus unit ing a 14-mm length of the commissural region of the right coronary and nonc oronary cusps of the aortic valve. Fibrous commissural fusion due to totall y organized thrombus in the other 3 patients affected one aortic commissure (2 patients, 2 mm and 4 mm, respectively) and two commissures (1 patient, 2 mm and 5 mm). Partial cuspal fusion in each case was due to permanent clo sure of the native aortic valve induced by the LVAD's operating in its auto matic setting. Mean length of commissural fusion was 5.4 mm (range, 2 to 14 mm; standard deviation [SD] = +/-5.0 mm). Mean duration of implantation of the six LVADs was 180.3 days (range, 26 to 689 days; SD = +/-253.8 days). The LVADs of the 3 patients with fibrous fusion of the commissures had been implanted for an average of 252.3 days (range, 26 to 689 days; SD = +/-378 .2 days). Conclusions. Normal function of the LVAD produces permanent closure of the native aortic valve. Stasis on the ventricular aspect of the aortic valve, combined with a low level of anticoagulation, favors thrombosis at this sit e. Thrombus organization leads to aortic stenosis of variable severity. Thi s previously unsuspected complication was not detected clinically in any of our patients. Aortic stenosis may hold serious implications for patients i n whom the LVAD acts as a bridge to recovery or in those in whom the LVAD f ails. Prevention may be achieved by intermittently reducing LVAD pumping ac tion. A built-in venting cycle would be of value in long-term implants. Thr ombi on the aortic valve may also predispose patients to infective endocard itis, because bloodstream infection is common in patients with LVADs. (C) 2 000 by The Society of Thoracic Surgeons.