In Vitro Hemodynamic Evaluation of Ventricular Suction Conditions of the EVAHEART Ventricular Assist Pump

Abstract

Purpose: Mismatches between pump output and venous return in a continuous-flow ventricular assist device may elicit episodes of ventricular suction. This research describes a series of in vitro experiments to characterize the operating conditions under which the EVAHEART centrifugal blood pump (Sun Medical Technology Research Corp., Nagano, Japan) can be operated with minimal concern regarding left ventricular (LV) suction. Methods: The pump was interposed into a pneumatically driven pulsatile mock circulatory system (MCS) in the ventricular apex to aorta configuration. Under varying conditions of preload, afterload, and systolic pressure, the speed of the pump was increased step-wise until suction was observed. Identification of suction was based on pump inlet pressure. Results: In the case of reduced LV systolic pressure, reduced preload (≤10 mmHg), and afterload (≤60 mmHg), suction was observed for speeds ≥2,200 rpm. However, suction did not occur at any speed (up to a maximum speed of 2,400 rpm) when preload was kept within 10–14 mmHg and afterload ≥80 mmHg. Although in vitro experiments cannot replace in vivo models, the results indicated that ventricular suction can be avoided if sufficient preload and afterload are maintained. Conclusion: Conditions of hypovolemia and/or hypotension may increase the risk of suction at the highest speeds, irrespective of the native ventricular systolic pressure. However, in vitro guidelines are not directly transferrable to the clinical situation; therefore, patient-specific evaluation is recommended, which can be aided by ultrasonography at various points in the course of support.

Use of 3D anatomical models in mock circulatory loops for cardiac medical device testing

“…11,25,36,38,45,54,63,64,[67][68][69][70]73 In these cases, ventricular blood flow was simulated either as a generic sinusoidal waveform or using pulsatile pumps that could change the stroke volume, heart rate and systolediastole ratio. More sophisticated MCLs considered either part 12,[16][17][18][19]22,23,[30][31][32][33][34][35]46,48,52,60,61,65,66,74 or all the cardiovascular system 13,14,29,39,40,49,50,53,75 by including compliance chambers and variable resistances or, in few cases, by simulating it computationally.…”

“…To simulate the latter event, named suction, a dedicated repfresentation of the ventricular anatomy, or of part of it, using a compliant material is needed. A few MCLs included a collapsible element representing only the ventricular apex 29–31 . In Figure 2 a scheme of the set up used by Rocchi et al 29 is shown.…”

“…A few MCLs included a collapsible element representing only the ventricular apex. [29][30][31] In Figure 2 a scheme of the set up used by Rocchi et al 29 is shown. In their study a hybrid simulator is used.…”

“…Moreover, the collapse of the compliant model is actively generated by squeezing the compliant element rather than spontaneously elicited by the emptying of the ventricular chamber. Ferreira et al 30 developed a MCL with a full silicone ventricle to study suction events with an EVAHEART Centrifugal VAD (Evaheart, Inc., Houston…”

“…Moreover, the collapse of the compliant model is actively generated by squeezing the compliant element rather than spontaneously elicited by the emptying of the ventricular chamber. Ferreira et al 30 developed a MCL with a full silicone ventricle to study suction events with an EVAHEART Centrifugal VAD (Evaheart, Inc., Houston TX). The silicone ventricle was placed in a rigid chamber where pressurized air was delivered cyclically with a sine wave to mimic the ventricular systolic contraction.…”