Transcranial detection of microembolic signals in patients with a novel nonpulsatile implantable LVAD

Abstract

Mechanical ventricular assist devices (VAD) have become an accepted therapy for the support of patients in severe heart failure. With the devices presently available, the incidence of thromboembolic complications is high. Since November 1998, we have used the DeBakey VAD (MicroMed, Inc., Woodlands, TX). To detect the effect of this VAD on the appearance of microthrombi or bubbles from cavitation, we measured Microembolic Signals (MES) with transcranial Doppler in patients after the implantation of the DeBakey VAD. Transcranial Doppler studies were performed with the MULTI-DOP X4 device with two 2 MHz probes (for the left and right middle cranial arteries [MCA]) in five patients preoperatively and during 10 weeks after VAD implantation. Both MCAs were monitored simultaneously for 60 minutes in 10 sessions in each patient. The detection and analysis of MES was performed in accordance with the technique and criteria described by the international consensus group. No MES were noted during the study period in four patients. In one patient with preoperatively noted MES the prevalence of MES postoperatively was 50%. The high speed rotating impeller of the DeBakey VAD did not produce any detectable microthrombi or bubbles from cavitation effects.