Effects of Continuous-Flow Versus Pulsatile-Flow Left Ventricular Assist Devices on Myocardial Unloading and Remodeling

Abstract

Background Continuous-flow left ventricular assist devices (LVAD) are increasingly used for patients with end-stage heart failure (HF). We analyzed the effects of ventricular decompression by continuous- versus pulsatile-flow LVADs on myocardial structure and function in this population. Methods and Results Sixty-one patients who underwent LVAD implantation as bridge-to-transplant were analyzed (pulsatile-flow LVAD: Group P, n=31; continuous-flow LVAD: Group C, n=30). Serial echocardiograms, serum levels of brain natriuretic peptide (BNP) and extracellular matrix biomarkers (ECM) were compared between the groups. Myocardial BNP and ECM gene expression were evaluated in a subset of 18 patients. Postoperative left ventricular (LV) ejection fraction was greater (33.2±12.6 vs. 17.6±8.8%, p<0.0001) and the mitral E/E′ was lower (9.9±2.6 vs. 13.2±3.8, p=0.0002) in Group P versus Group C. Postoperative serum levels of BNP, metalloproteinases (MMP)-9 and tissue inhibitor of MMP (TIMP)-4 were significantly lower in Group P compared to Group C (BNP: 552.6±340.6 vs. 965.4±805.7 pg/mL, p<0.01; MMP9: 309.0±220.2 vs. 475.2±336.9 ng/dL, p<0.05; TIMP4: 1490.9±622.4 vs. 2014.3±452.4 ng/dL, p<0.001). Myocardial gene expression of ECM markers and BNP decreased in both groups; however, expression of TIMP-4 decreased only in Group P (p=0.024). Conclusions Mechanical unloading of the failing myocardium using pulsatile devices is more effective as indicated by echocardiographic parameters of systolic and diastolic LV function as well as dynamics of BNP and ECM markers. Therefore, specific effects of pulsatile mechanical unloading on the failing myocardium may have important implications for device selection especially for the purpose of bridge-to-recovery in patients with advanced HF.

Slope of the Anterior Mitral Valve Leaflet: A New Measurement of Left Ventricular Unloading for Left Ventricular Assist Devices and Systolic Dysfunction

“…22 Similar to SLAM, dP/dt has been shown to improve by increasing upon CF-LVAD implanta- tion. 8 Regardless of the cause of cardiomyopathy, a high LVEDP and weak contractile function culminate in ineffective unloading, which is consistent with the delayed-closure physiology of the mitral valve observed in M-mode echocardiography, and which in this study was quantified as the SLAM.…”

“…Even in circumstances in which accurate Doppler evaluation is possible, some studies in CF-LVAD patients have revealed that, although E/e′ ratio decreases after LVAD implantation, it correlates poorly with invasive measurements of pulmonary capillary wedge pressure (PCWP). 7,8 Other guidelines are therefore needed to supplement current knowledge toward evaluating LV unloading and clinical status in CF-LVAD-supported patients.…”

“…20 In addition, our patient population showed a reduction in BNP similar to that in other institutional populations after LVAD surgery, from an average of 1,715 to 305 pg/mL (P <0.0001). 8 Concomitant…”

“…Even in circumstances in which accurate Doppler evaluation is possible, some studies in CF-LVAD patients have revealed that, although E/e′ ratio decreases after LVAD implantation, it correlates poorly with invasive measurements of pulmonary capillary wedge pressure (PCWP). 7,8 Other guidelines are therefore needed to supplement current knowledge toward evaluating LV unloading and clinical status in CF-LVAD-supported patients.The mitral valve is a fast-moving structure, the motion of which is best detected with the superior temporal resolution of M-mode echocardiography in the parasternal views. 9 In the presence of elevated filling pressures, the anterior mitral leaflet tracing in M-mode displays gradual closure after the peak of the A-wave in cardiac diastole, as compared with brisk closure in patients with normal filling pressures.…”

Magnitude and Time Course of Changes Induced by Continuous-Flow Left Ventricular Assist Device Unloading in Chronic Heart Failure: Insights into Cardiac Recovery

“…Compared with pulsatile LVADs, these newer devices produce a qualitatively different type of unloading (10,(12)(13)(14)(15). Large-scale trials that evaluated the clinical effectiveness of chronic continuous-flow LVAD unloading as a bridge to transplantation or destination therapy were primarily focused on morbidity, mortality and changes in end-organ function, and did not include evaluation of serial myocardial functional or structural data (1,2,(16)(17)(18).…”