Mechanical Circulatory Support for Advanced Heart Failure: Are We about to Witness a New “Gold Standard”?

Abstract

The impact of left ventricular assist devices (LVADs) for the treatment of advanced heart failure has played a significant role as a bridge to transplant and more recently as a long-term solution for non-eligible candidates. Continuous flow left ventricular assist devices (CF-LVADs), based on axial and centrifugal design, are currently the most popular devices in view of their smaller size, increased reliability and higher durability compared to pulsatile flow left ventricular assist devices (PF-LVADs). The trend towards their use is increasing. Therefore, it has become mandatory to understand the physics and the mathematics behind their mode of operation for appropriate device selection and simulation set up. For this purpose, this review covers some of these aspects. Although very successful and technologically advanced, they have been associated with complications such as pump thrombosis, haemolysis, aortic regurgitation, gastro-intestinal bleeding and arterio-venous malformations. There is perception that the reduced arterial pulsatility may be responsible for these complications. A flow modulation control approach is currently being investigated in order to generate pulsatility in rotary blood pumps. Thrombus formation remains the most feared complication that can affect clinical outcome. The development of a preoperative strategy aimed at the reduction of complications and patient-device suitability may be appropriate. Patient-specific modelling based on 3D reconstruction from CT-scan combined with computational fluid dynamic studies is an attractive solution in order to identify potential areas of stagnation or challenging anatomy that could be addressed to achieve the desired outcome. The HeartMate II (axial) and the HeartWare HVAD (centrifugal) rotary blood pumps have been now used worldwide with proven outcome. The HeartMate III (centrifugal) is now emerging as the new promising device with encouraging preliminary results. There are now enough pumps on the market: it is time to focus on the complications in order to achieve the full potential and selling-point of this type of technology for the treatment of the increasing heart failure patient population.

Two year adverse outcomes of the magnetic levitated centrifugal continuous flow circulatory pump versus the axial continuous-flow pump for advanced heart failure

“…Nevertheless, thrombus formation has been a major concern for patients who were implanted with those left ventricular assisted devices. Even if the HeartMate II (axial) and the HeartWare HVAD (centrifugal) are being continually used in patients with advanced heart failure, [ 9 ] it is high-time to focus more on the potential complications [ 10 ] in other to further expand this technology for the treatment of such patients. The impact of anticoagulation on the reduction of stent thrombosis in these patients should also be considered.…”

Physiology of the Assisted Circulation in Cardiogenic Shock: A State-of-the-Art Perspective

“…PF-devices are known to be more efficient for LV volume unloading than CF-devices, whereas CF-LVADs need positive pressure in the left ventricle for optimal pump flow. 19,20 Recent experimental studies have shown that axial CF-pumps are associated with higher LV unloading than contemporary centrifugal pumps, suggesting a lower risk of LV suction with CF centrifugal technology. 21…”

Aortic Valve Ejection Fraction for Monitoring Heart Contractility in Patients Supported with a Continuous Flow Left Ventricular Assist Device

“…In this section, we establish a one-to-one relationship between change in AVEF and E max , and examine the corresponding Frank-Starling curve using components of AVEF as defined in (2). The Frank-Starling curve establishes a relationship between SV and end diastolic volume [8,31].…”

“…Recent studies have identified LVAD parameters to assess contractility of the heart [2,17]. The measurement of cardiac performance as an assessment of heart contractility has also been studied extensively [6,15,16,18].…”