Pulsatile Flow in Patients With a Novel Nonpulsatile Implantable Ventricular Assist Device

Abstract

Background-Ventricular assist devices (VADs) are an accepted therapy for patients with end-stage heart failure. The implantable devices that are available produce a pulsatile flow and are very large. In 6 patients, beginning in November 1998, we started to use the continuous-flow implantable DeBakey VAD device, which weighs 93 g. To detect the flow in peripheral vessels, we measured transcranial Doppler signals in patients after implantation. Methods and Results-Transcranial Doppler studies were performed with the MULTI-DOP X4 device with two 2-MHz probes (for the middle cranial arteries) in 4 patients for up to 12 weeks twice weekly after implantation. The blood velocity was measured, and the pulsation index (PI) calculated. The measured pump flow and rotations per minute were registered. The preoperative echocardiographic assessment values were compared with those acquired 6 weeks after implantation. The PI increased continually in all patients after VAD implantation, left ventricular (LV) ejection fraction did not improve, but right ventricular (RV) ejection fraction after implantation improved compared with preoperative values. The LV end-diastolic diameter after implantation decreased between 11% and 46% intraindividually. There was no correlation between PI and blood pressure or, except in 1 patient, between PI and blood flow through the VAD. Conclusions-The

Ventricular Assist Device – How to Obtain Optimal Benefits?

“…There has been much debate over the need for pulsatility. Animal data suggest that non-pulsatile flow might not deliver as much perfusion to the distal vasculature and might lead to weakening of the muscle in the walls of major arteries (Yada et al, 1999;Potapov et al, 2000). The pulsatile devices are bulky as they have to at least be the size of the bladder displacement (usually 60 to 80 cc) and hence have to be placed in the pre-or intraperitoneal space.…”

Cost–effectiveness of left ventricular-assist devices in end-stage heart failure

“…81,85,86 The other studies of first-generation LVADs were a cohort analytic study comparing the short-and long-term use of the Novacor LVAD, 87 a case series of the Toyobo LVAD, 88 and two case reports of the Thoratec device. 89,90 Of the five studies of second-generation LVADs, three were before and after cohort studies of the MicroMed DeBakey LVAD [91][92][93] and the other two were case series of the Jarvik 2000 LVAD, one of which was a multicentre case series, with individual centres reporting their patient data at different periods of follow-up for different subgroups.…”

“…The methodological quality of the three before and after cohort studies evaluating the MicroMed DeBakey device [91][92][93] was judged to be weak (Appendix 17). These studies are subsets of a multicentre study and are therefore likely to include some repeat observations in their publications.…”

“…Although the authors of these studies were contacted to establish the possible overlap, they were unable to clarify the position. There was a moderate 92 to high 91,93 risk of selection bias in the studies as they provided limited information on the selection of patients. None of the studies discuss the blinding of outcome assessment or the validity and reliability of data collection tools and are considered to be methodologically weak.…”

“…Withdrawals and drop-outs were discussed and patients are analysed on an intention-to-treat basis in two studies, limiting the effects of attrition bias. 92,93 In the other study, limited information is provided on withdrawals and whether the patients were assessed as intention-to-treat. 91 The criteria judging confounding were not assessed as they were thought not to be relevant to before and after cohort studies.…”