Physiology of Continuous‐Flow Left Ventricular Assist Device Therapy

Although continuous-flow left ventricular assist devices (CF-LVADs) provide an augmentation in systemic perfusion, there is a scarcity of in vivo data regarding systemic pulsatility on support. Patients supported on CF-LVAD therapy (n = 71) who underwent combined left/right catheterization ramp study were included. Aortic pulsatility was defined by the pulsatile power index (PPI), which was also calculated in a cohort of high-output heart failure (HOHF, n = 66) and standard HF cohort (n = 44). PPI was drastically lower in CF-LVAD–supported patients with median PPI of 0.006 (interquartile range [IQR], 0.002–0.012) compared with PPI in the HF population at 0.09 (IQR, 0.06–0.17) or HOHF population at 0.25 (IQR, 0.13–0.37; p < 0.0001 among groups). With speed augmentation during ramp, PPI values fell quickly in patients with higher PPI at baseline. PPI correlated poorly with left ventricular ejection fraction (LVEF) in all groups. In CF-LVAD patients, there was a stronger correlation with LV dP/dt (r = 0.41; p = 0.001) than LVEF (r = 0.21; p = 0.08; pint < 0.001). CF-LVAD support is associated with a dramatic reduction in arterial pulsatility as measured by PPI relative to HOHF and HF cohorts and decreases with speed. Further work is needed to determine the applicability to the next generation of device therapy.

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“…7,9 These data suggest that enhancing pulsatility is an important target for next-generation CF-LVADs. 22…”

Section: Discussionmentioning

confidence: 99%

Pulsatile Pressure Delivery of Continuous-Flow Left Ventricular Assist Devices Is Markedly Reduced Relative to Heart Failure Patients

et al. 2022

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“…The HM3 and HW incorporate a flow modulating algorithm using speed changes in order to reduce the burden of microthrombi 48 . For example, in the HeartMate 3 after implantation, a physician sets the rotor speed to a desired set point, generally in the 4800–6000 range.…”

Section: Third Generation Lvadsmentioning

confidence: 99%

“…The artificial pulse programs of the HM3 does little to increase the overall pulsatility of the combined output of the heart and pump. However, there is still an opportunity to explore increasing pulsatility to prevent the adverse effects of non‐pulsatile flow, as discussed above 48 . One method that has been studied is the synchronization of pump artificial pulse with the native heartbeat via electrocardiogram (ECG) or sensing inherent changes in intraventricular hemodynamics (pressure or power usage) 66 .…”

Section: Next Steps In Vad Engineeringmentioning

confidence: 99%

“…43 The HM3 and HW incorporate a flow modulating algorithm using speed changes in order to reduce the burden of microthrombi. 48 For example, in the HeartMate 3 after implantation, a physician sets the rotor speed to a desired set point, generally in the 4800-6000 range. In the HM3, during a given cycle, the "artificial pulse" program increases the pump speed by 2000 rpm for 0.20 s, decreases it to the set point for 1.65 s, decreases it further by 2000 rpm for 0.15 s, then repeats the cycle.…”

Section: = Du Dymentioning

confidence: 99%

“…However, there is still an opportunity to explore increasing pulsatility to prevent the adverse effects of non-pulsatile flow, as discussed above. 48 One method that has been studied is the synchronization of pump artificial pulse with the native heartbeat via electrocardiogram (ECG) or sensing inherent changes in intraventricular hemodynamics (pressure or power usage). 66 By synchronizing the "systolic" phase of the artificial pulse with specific phases of the native cardiac cycle, the pulsatile quality of the aortic pressure can be increased.…”

Section: Flow Modulationmentioning

confidence: 99%

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Left ventricular assist devices: A historical perspective at the intersection of medicine and engineering

2022

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Over the last half‐century, left ventricular assist device (LVAD) technology has progressed from conceptual therapy for failed cardiopulmonary bypass weaning to an accepted destination therapy for advanced heart failure. The history of LVAD engineering is defined by an initial development phase, which demonstrated the feasibility of such an approach, to the more recent three major generations of commercial devices. In this review, we explore the engineering challenges of LVADs, how they were addressed over time, and the clinical outcomes that resulted from each major technological development. The first generation of commercial LVADs were pulsatile devices, which lacked the appropriate durability due to their number of moving components and hemocompatibility. The second generation of LVADs was defined by replacement of complex, pulsatile pumps with primarily axial, continuous‐flow systems with an impeller in the blood passageway. These devices experienced significant commercial success, but the presence of excessive trauma to the blood and in‐situ bearing resulted in an unacceptable burden of adverse events. Third generation centrifugal‐flow pumps use magnetically suspended rotors within the pump chamber. Superior outcomes with this newest generation of devices have been observed, particularly with respect to hemocompatibility‐related adverse events including pump thrombosis, with fully magnetically levitated devices. The future of LVAD engineering includes wireless charging foregoing percutaneous drivelines and more advanced pump control mechanisms, including synchronization of the pump flow with the native cardiac cycle, and varying pump output based on degree of physical exertion using sensor or advanced device‐level data triggers.

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Role of Echocardiography in the Management of Patients with Advanced (Stage D) Heart Failure Related to Nonischemic Cardiomyopathy

Dandel¹

2022

Rev. Cardiovasc. Med.

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Echocardiography (ECHO) is indispensable for evaluation of patients with terminal chronic heart failure (HF) who require transplantation or mechanical circulatory support by a left- or biventricular assist device (LVAD or BiVAD, respectively). In LVAD candidates, ECHO represents the first-line investigation necessary for a timely discovery of heart-related risk factors for potentially life-threatening post-operative adverse events, including identification of patients who necessitate a biventricular support. ECHO is also required for intra-operative guiding of VAD implantation and finding of the most appropriate setting of the device for an optimal ventricular unloading, postoperative surveillance of the VAD support, and monitoring of the RV changes in LVAD recipients. Thanks to the ECHO, which has decisively contributed to the proof that prolonged VAD support can facilitate cardiac reverse remodeling and functional improvement to levels which allow successful weaning of carefully selected patients from LVAD or BiVAD, the previous opinion that chronic non-ischemic cardiomyopathy (NICMP) is irreversible could be refuted. In patients with normalized and stable right heart catheter-derived hemodynamic parameters obtained at short-term interruptions of VAD support, ECHO has proved able to predict post-weaning long-term freedom from HF recurrence in patients with pre-implant terminal chronic NICMP. The purpose of this article is to offer an actualized theoretical and practical support for clinicians engaged in this particularly challenging and topical issue especially due to the new practical aspects which have emerged in conjunction with the growing use of long-term ventricular assist devices as bridge-to-transplantation or as destination therapy, as well as the increasing evidence that, in some patients, such VAD can become a bridge-to-recovery, allowing the removal of the device after a longer support time.

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Physiology of Continuous‐Flow Left Ventricular Assist Device Therapy

Cited by 4 publications

References 394 publications

Pulsatile Pressure Delivery of Continuous-Flow Left Ventricular Assist Devices Is Markedly Reduced Relative to Heart Failure Patients

Pulsatile Pressure Delivery of Continuous-Flow Left Ventricular Assist Devices Is Markedly Reduced Relative to Heart Failure Patients

Left ventricular assist devices: A historical perspective at the intersection of medicine and engineering

Role of Echocardiography in the Management of Patients with Advanced (Stage D) Heart Failure Related to Nonischemic Cardiomyopathy

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