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

Circulation ◽  
2000 ◽  
Vol 102 (suppl_3) ◽  
Author(s):  
Evgenij V. Potapov ◽  
Matthias Loebe ◽  
Boris A. Nasseri ◽  
Hendryk Sinawski ◽  
Andreas Koster ◽  
...  
Keyword(s):  
Ejection Fraction ◽  
Pulsatile Flow ◽  
Transcranial Doppler ◽  
Continuous Flow ◽  
Left Ventricular ◽  
Ventricular Assist Devices ◽  
Ventricular Assist ◽  
Doppler Signals ◽  
End Stage ◽  
Cranial Arteries

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 DeBakey VAD unloads the LV, which leads to a decrease in LV end-diastolic LV diameter and to the restoration of RV function. The unloaded LV and partially recovered RV provide a nearly physiological pulsatile flow despite the continuous flow of the VAD. Pulsatility is independent of peripheral vascular resistance. The first clinical experience with the DeBakey VAD was positive and has resulted in its continued use.

scholarly journals In Vitro Pulsatility Analysis of Axial-Flow and Centrifugal-Flow Left Ventricular Assist Devices

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
J. Ryan Stanfield ◽  
Craig H. Selzman
Keyword(s):  
Pulsatile Flow ◽  
Continuous Flow ◽  
Axial Flow ◽  
Left Ventricular ◽  
Ventricular Assist Devices ◽  
Left Ventricular Assist Devices ◽  
Centrifugal Pumps ◽  
Ventricular Assist ◽  
Assist Devices ◽  
Flow Devices

Recently, continuous-flow ventricular assist devices (CF-VADs) have supplanted older, pulsatile-flow pumps, for treating patients with advanced heart failure. Despite the excellent results of the newer generation devices, the effects of long-term loss of pulsatility remain unknown. The aim of this study is to compare the ability of both axial and centrifugal continuous-flow pumps to intrinsically modify pulsatility when placed under physiologically diverse conditions. Four VADs, two axial- and two centrifugal-flow, were evaluated on a mock circulatory flow system. Each VAD was operated at a constant impeller speed over three hypothetical cardiac conditions: normo-tensive, hypertensive, and hypotensive. Pulsatility index (PI) was compared for each device under each condition. Centrifugal-flow devices had a higher PI than that of axial-flow pumps. Under normo-tension, flow PI was 0.98 ± 0.03 and 1.50 ± 0.02 for the axial and centrifugal groups, respectively (p < 0.01). Under hypertension, flow PI was 1.90 ± 0.16 and 4.21 ± 0.29 for the axial and centrifugal pumps, respectively (p = 0.01). Under hypotension, PI was 0.73 ± 0.02 and 0.78 ± 0.02 for the axial and centrifugal groups, respectively (p = 0.13). All tested CF-VADs were capable of maintaining some pulsatile-flow when connected in parallel with our mock ventricle. We conclude that centrifugal-flow devices outperform the axial pumps from the basis of PI under tested conditions.

Restoring pulsatility and peakVO2 in the era of continuous flow, fixed pump speed, left ventricular assist devices: ‘A hypothesis of pump's or patient's speed?’

2019 ◽  
Vol 26 (17) ◽  
pp. 1806-1815 ◽  
Author(s):  
Ioannis D Laoutaris
Keyword(s):  
Pulsatile Flow ◽  
Continuous Flow ◽  
Left Ventricular ◽  
Ventricular Assist Devices ◽  
Peak Oxygen Consumption ◽  
Current Evidence ◽  
Left Ventricular Assist Devices ◽  
Ventricular Assist ◽  
Pump Speed ◽  
Left Ventricular Assist

Despite significant improvement in survival and functional capacity after continuous flow left ventricular assist device implantation, the patient's quality of life may remain limited by complications such as aortic valve insufficiency, thromboembolic episodes and gastrointestinal bleeding attributed to high shear stress continuous flow with attenuated or absence of pulsatile flow and by a reduced peak oxygen consumption (peakVO2) primarily associated with a fixed pump speed operation. Revision of current evidence suggests that high technology pump speed algorithms, a ‘hypothesis of decreasing pump's speed’ to promote pulsatile flow and a ‘hypothesis of increasing pump's speed’ to increase peakVO2, may only partially reverse these barriers. A ‘hypothesis of increasing patient's speed’ is introduced, suggesting that exercise training may further contribute to the patient's recovery, enhancing peakVO2 and pulsatile flow by improving skeletal muscle oxidative capacity and strength, peripheral vasodilatory and ventilatory responses, favour changes in preload/afterload and facilitate native flow, formulating the rationale for further studies in the field.

Abstract 5854: Serial Assessment of Pulsatile and Non-Pulsatile Left Ventricular Assist Devices on Left Ventricular Unloading

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Robert S George ◽  
Magdi H Yacoub ◽  
Carole Webb ◽  
Christopher Bowles ◽  
Robert Dean ◽  
...  
Keyword(s):  
Continuous Flow ◽  
Left Ventricular ◽  
Ventricular Assist Devices ◽  
Left Ventricular Assist Devices ◽  
Ventricular Assist ◽  
Pharmacological Agents ◽  
Left Ventricular Assist ◽  
Displacement Pump ◽  
End Stage ◽  
Lvad Support

Pulsatile and continuous flow left ventricular assist device (LVAD)s combined with pharmacological agents have been used to bridge patients with end-stage dilated cardiomyopathy (DCM) to recovery. The aim of this study was to compare the effects of pulsatile versus continuous flow LVADs on left ventricular (LV) unloading. Unloading was assessed by echocardiography at 1, 3 and 6 months in 50 non-ischaemic DCM patients with LVADs. 29 patients received a pulsatile volume displacement pump (HeartMate XVE (HM I group); Thoratec Corp.) and 21 patients received a continuous-flow rotary pump (HeartMate II (HM II group); Thoratec Corp.). Parameters measured included end-systolic and end-diastolic diameters (ESD and EDD) and ejection fraction (EF). There was no difference in pre-implantation data between the two groups. At 1 month post device implantation, HM I patients showed significantly greater LV unloading compared to HM II patients (ESD 30.6±10, EDD 44±9.7, EF 64.8±14.5 vs 41.5±10.7, 50.9±9.7, 45.5±15.9, respectively), but there was no difference in LV unloading at 3 or 6 months (table 1 ). In the patients recovered with HM I (n=16) there was a lower ESD and higher EF compared to those with HM II (n=7) at 1 month. No difference was seen at 3 or 6 months (table 2 ). HM I XVE provided a better degree of LV unloading compared to HM II at 1 month of LVAD support. At three and six months of LVAD support both devices provided an equivalent degree of LV unloading. Table 1. Comparison of LV unloading between HM I and HM II patients. Table 2. Comparison of LV unloading between HM I and HM II recovered patients

Sign in / Sign up

Export Citation Format

Share Document