Pulmonary Valve Opening With Two Rotary Left Ventricular Assist Devices for Biventricular Support

Abstract

Right ventricular failure is a common complication associated with rotary left ventricular assist device (LVAD) support. Currently, there is no clinically approved long-term rotary right ventricular assist device (RVAD). Instead, clinicians have implanted a second rotary LVAD as RVAD in biventricular support. To prevent pulmonary hypertension, the RVAD must be operated by either reducing pump speed or banding the outflow graft. These modes differ in hydraulic performance, which may affect the pulmonary valve opening (PVO) and subsequently cause fusion, valvular insufficiency, and thrombus formation. This study aimed to compare PVO with the RVAD operated at reduced speed or with a banded outflow graft. Baseline conditions of systemic normal, hypo, and hypertension with severe biventricular failure were simulated in a mock circulation loop. Biventricular support was provided with two rotary VentrAssist LVADs with cardiac output restored to 5 L/min in banded outflow and reduced speed conditions, and systemic and pulmonary vascular resistances (PVR) were manipulated to determine the range of conditions that allowed PVO without causing left ventricular suction. Finally, RVAD sine wave speed modulation (±550 rpm) strategies (co- and counter-pulsation) were implemented to observe the effect on PVO. For each condition, outflow banding had higher PVR (97 ± 20 dyne/s/cm higher) for when the pulmonary valve closed compared to reduced speed. In addition, counter-pulsation demonstrated greater PVO than co-pulsation and constant speed. For the purpose of reducing the risks of pulmonary valve insufficiency, fusion, and thrombotic event, this study recommends a RVAD with a steeper H-Q gradient by banding and further exploration of RVAD speed modulation.

Artificial Organs 2018: A Year in Review

“…Eric L. Wu et al of The Prince Charles Hospital, Brisbane, Australia, reported on pulmonary valve opening (PVO) with two rotary left ventricular assist devices (LVAD) for biventricular support by comparing PVO with the right VAD operated at reduced speed or with a banded outflow graft. Baseline conditions were simulated in a mock circulation loop.…”

Diamond‐like carbon films prepared by a low temperature periodic process for application in ventricular assist devices

“…1 With the development of technologies, VADs have evolved from pulsatile volume displacement pumps (first generation) to rotary pumps (second and third generation). 2 To minimize mechanical wear, the third generation VADs are operated with hydrodynamic or magnetic levitation system to suspend the impellers in the pump housings. 2 However, impeller touchdown can happen in such systems due to pump start up, pump stoppage, ventricular suction, unbalanced force caused by change in patient and/or device state, and so forth.…”

“…2 To minimize mechanical wear, the third generation VADs are operated with hydrodynamic or magnetic levitation system to suspend the impellers in the pump housings. 2 However, impeller touchdown can happen in such systems due to pump start up, pump stoppage, ventricular suction, unbalanced force caused by change in patient and/or device state, and so forth. Due to the poor anti-wear properties of titanium (Ti) and its alloy Ti6Al4V (commonly used for VADs manufacturing), such contact can cause damage to the surface of the housing wall and impeller.…”

Surface Coatings for Rotary Ventricular Assist Devices: A Systematic Review

“…These rotary VADs use either mechanical bearings (in second-generation pumps) or hydrodynamic/magnetic levitation systems (in third-generation pumps) to suspend impellers within their pump housings. 3 As the key components of rotary VADs, impellers and housings have stringent requirements on wear resistance and hemocompatibility of their construction materials and surfaces. The interaction between blood and the blood-contacting surfaces of pumps like impellers and housing walls can cause complications like thrombosis and hemolysis.…”

“…However, these devices were large and not fully implantable and had many moving parts that were prone to wear and other forms of mechanical damage that caused device failure. 3 The second and third generations of devices are developed as small (some are fully implantable) rotary pumps which generate continuous flow. These rotary VADs use either mechanical bearings (in second-generation pumps) or hydrodynamic/magnetic levitation systems (in third-generation pumps) to suspend impellers within their pump housings.…”