3D Morphological Changes in LV and RV During LVAD Ramp Studies

Abstract

Objectives: The purpose of this study was to investigate the differential impact of the 2 most commonly available left ventricular assist device (LVAD) types on the right ventricle (RV) and left ventricle (LV) using 3-dimensional (3D) echocardiography-based analysis of ventricular morphology.

Background: LVADs have emerged as common therapy for advanced heart failure. Recent data suggest that the heart responds differently to speed settings in the 2 main devices available (HeartMate II [HMII], St Jude Medical, Pleasanton, California, and HVAD, HeartWare International, Framingham, Massachusetts). The authors hypothesized that 3D echocardiographic assessment of LV and RV volumes and shape would help describe the differential impact of the 2 LVAD types on the heart.

Methods: Simultaneous 3D echocardiography, ramp test, and right heart catheterization were performed in 31 patients with LVADs (19 with HMII and 12 with HVAD). Device speed was increased stepwise (8,000 to 12,000 for HMII and 2,300 to 3,200 revolutions per minute for HVAD). 3D echocardiographic full-volume LV and RV datasets were acquired, and endocardial surfaces were analyzed using custom software to calculate LV sphericity, conicity (perfect sphere/cone = 1) and RV septal and free-wall curvature (0 = flat; <0 = concave; >0 = convex).

Results: For both devices, cardiac output increased and wedge pressure decreased with increasing speed. In HMII, LV volumes progressively decreased (meanΔ = 127 ml) as the LV became less spherical and more conical, whereas the RV volume initially remained stable, but subsequently increased at higher speeds (meanΔ = 60 ml). Findings for the HVAD were similar, but less pronounced (LV:meanΔ = 51 ml, RV:meanΔ = 22 ml), and the LV remained significantly more spherical even at high speeds. On average, in HMII patients, the RV septum became more convex (bulging into the LV) at the highest speeds whereas in HVAD patients, there was no discernable change in the RV septum.

Conclusions: The heart responds differently to pump speed changes with the 2 types of LVAD, as reflected by the volume and shape changes of both the LV and RV. Our study suggests that adding RV assessment to the clinical echo-ramp study may better optimize LVAD speed. Further study is needed to determine whether this would have an impact on patient outcomes.

Keywords: 3-dimensional echocardiography; conicity; continuous-flow LVAD; curvature; ramp study; sphericity; ventricular shape.