An overview of mechanical circulatory support in single-ventricle patients

Abstract

The population of people with a single-ventricle is continually increasing due to improvements across the spectrum of medical care. Unfortunately, a proportion of these patients will develop heart failure.Often, for these patients, mechanical circulatory support (MCS) represents the only available treatment option. While single-ventricle patients currently represent a small proportion of the total number of patients who receive MCS, as the single-ventricle patient population increases, this number will increase as well.Outcomes for these complex single-ventricle patients who require MCS has begun to be evaluated. When considering the entire population, survival to hospital discharge is 30-50%, though this must be considered with the significant heterogeneity of the single-ventricle patient population. Patients with a single-ventricle have unique anatomy, mechanisms of failure, indications for MCS and the type of support utilized. This has made the interpretation and the generalizability of the limited available data difficult. It is likely that some subsets will have a significantly worse prognosis and others a better one. Unfortunately, with these limited data, indications of a favorable or poor outcome have not yet been elucidated. Though currently, a database has been constructed to address this issue. While the outcomes for these complex patients is unclear, at least in some situations, they are poor. However, significant advances may provide improvements going forward, including new devices, computer simulations and 3D printed models. The most important factor, however, will be the increased experience gained by the heart failure team to improve patient selection, timing, device and configuration selection and operative approach.

Pediatric ventricular assist devices: Bridge to a new era of perioperative care

“…It is not clear how VAD support can help the late failing Fontan with preserved ventricular function (PVF) but systemic VAD support may help those with IVF, symptom progression, and elevated central venous pressure (CVP). A decrease in CVP after commencing inotropes may demonstrate the potential benefit of a VAD . CF devices may be better than pulsatile devices in providing the high cardiac index that is often required to overcome the baseline elevated pressure of the Fontan circulation and to accommodate increased flow from collaterals.…”

“…The devices used include TAH, Berlin Heart Excor, and HVAD with the inflow cannula in the ventricular apex or the common atrium. Atrial cannulation avoids the extensive dissection and trabecular resection which may be required with ventricular cannulation but there is a risk of suck down events because of the thin atrial wall . Cavo‐pulmonary assist devices where blood is “sucked” across the pulmonary vascular bed have also been described, with or without a systemic VAD.…”

“…4,7,23 In particular, postcardiotomy salvage VADS involving postcardiotomy ECMO to durable VADS after congenital heart surgery have very poor outcomes. 23 However, due to an increasing population of patients with SV palliation 24 and the chronic shortage of donor heart organs, there is a growing need for a successful mechanical circulatory support strategy for these patients when their SV circulation fails. VAD therapy for the failing SV is challenging due to the unique physiological support required for the three different stages of SV palliation.…”

“…28 may be required with ventricular cannulation but there is a risk of suck down events because of the thin atrial wall. 24 Cavo-pulmonary assist devices where blood is "sucked" across the pulmonary vascular bed have also been described, 29 with or without a systemic VAD. Although there is no consensus on the optimal strategy, VAD support for the failing Fontan appears to have more successful outcomes than for the other stages of SV palliation.…”

Energetics of blood flow in Fontan circulation under VAD support

“…When cardiac failure develops in the Fontan patients it is necessary to provide them a mechanical circulatory support (MCS); however, the outcome of single‐ventricle patients who require MCS still remains unclear . In order to increase the positive outcome for these patients, new devices are currently being under development.…”