Long-term heart transplant outcomes after lowering fixed pulmonary hypertension using left ventricular assist devices.

OBJECTIVES: Fixed pulmonary hypertension (fPH) is a contraindication for heart transplantation (HTX). Left ventricular assist device (LVAD) implantation as a bridge to candidacy can reverse fPH in patients with terminal heart failure by chronic left ventricular unloading. We report our institutional experience with terminal heart failure patients and fPH that were successfully bridged to candidacy and underwent subsequent HTX. METHODS: We retrospectively reviewed the data of 79 patients with terminal heart failure and fPH who were successfully bridged to candidacy for HTX with 6 different LVAD devices at our centre from October 1998 to September 2016 (Novacor n = 4, MicroMed DeBakey n = 29, DuraHeart n = 2, HeartMate II n = 14, HVAD n = 29 and MVAD n = 1). Median duration of LVAD support was 288 days (range 45-2279 days). Within the same timeframe, a control group of 48 patients underwent HTX after bridge-to-transplant LVAD therapy for reasons other than PH. Study end points were (i) development of fPH after LVAD implantation, (ii) post-transplant outcomes and (iii) incidence of severe adverse events. RESULTS: Pulmonary vascular resistance, assessed by vasodynamic catheterization, was 4.3 ± 1.8 WU before LVAD implantation. After a median support period of 89 days (interquartile range 4-156 days), pulmonary vascular resistance decreased to 2.0 ± 0.9 WU (P ≤ 0.001), and patients were listed for HTX. Median duration of LVAD support in the study group was 288 days (45-2279 days). We observed 2 patients (2.5%) with acute right heart failure who required extracorporeal mechanical support after HTX in the study group. Long-term post-transplant survival between the study group (3 years: 83.5%, 5 years: 81.0%) and the control group (3 years: 87.5%, 5 years: 85.4%) was comparable (log-rank: P = 0.585). CONCLUSIONS: LVAD implantation as a bridge to candidacy reverses fPH in patients with terminal heart failure. Post-HTX survival is excellent and comparable to results obtained in patients without fPH at the time of HTX listing.

Extracorporeal membrane oxygenation support for right ventricular failure after left ventricular assist device implantation.

OBJECTIVES: Right ventricular (RV) failure complicating left ventricular assist device implantation is associated with increased mortality. Despite a lack of supporting evidence, venoarterial extracorporeal membrane oxygenation (ECMO) support is increasingly being used as an alternative to traditional temporary RV support. We report our institutional experience with ECMO-facilitated RV support after left ventricular assist device implantation. METHODS: We retrospectively reviewed the concept of temporary ECMO support for perioperative RV failure in 32 consecutive left ventricular assist device (mean age 52 ± 14 years; male 84.4%; ischaemic cardiomyopathy 40.6%; INTERMACS Level I 71.8%; INTERMACS Level II 6.3%; INTERMACS Level III 12.5%; INTERMACS Level IV-VII 9.4%; HeartWare ventricular assist device 75%; HeartMate II: 25%) from May 2009 to April 2014. The study end points were RV recovery during ECMO support, mortality and causes of death. RESULTS: Twenty-nine (90.6%) patients were successfully weaned from ECMO support after RV recovery. Three (9.4%) patients expired during ECMO support. ECMO support improved RV function and haemodynamic parameters (central venous pressure 13 mmHg vs 10 mmHg, P < 0.01; mean pulmonary artery pressure 28 mmHg vs 21 mmHg, P < 0.01; cardiac output 5.1 l/min vs 5.9 l/min, P = 0.09) over a median period of 3 (range 1-15) days. Thirty-day and in-hospital mortality were 18.8% and 25%, respectively. One-year survival was 75%, causes of death were multiorgan dysfunction syndrome (50%), sepsis (25%), haemorrhagic stroke (12.5%) and ischaemic stroke (12.5%). Causes of death during ECMO support were ischaemic stroke, sepsis and multiorgan dysfunction syndrome. CONCLUSIONS: Temporary ECMO-facilitated RV support is associated with good long-term outcomes and high rates of RV recovery.

Continuous Monitoring of Aortic Valve Opening in Rotary Blood Pump Patients.

GOAL: Rotary blood pumps (RBPs) typically support the left ventricle by pumping blood from the ventricle to the aorta, partially bypassing the aortic valve (AV). Monitoring the AV opening during RBP support would provide important information about cardiac-pump interaction. However, currently this information is not continuously available. In this study, an algorithm to determine AV opening using available pump signals was evaluated in humans. METHODS: Pump speed changes were performed in 15 RBP patients to elicit opening of the AV. Simultaneously to pump data recordings, the AV was continuously monitored using echocardiography. The algorithm, which classifies the AV state utilizing three features (skewness, kurtosis, and crest factor) calculated from the pump flow waveform, was compared to echocardiography by using cross-validation analysis. Additionally, numerical simulation was used to evaluate effects of different pump characteristics and cannula length, as well as mitral valve insufficiency on the AV opening detection method. RESULTS: More than 7000 heart beats were analyzed. The correct classification rate using the developed algorithm was 91.1% (sensitivity 91.0%, specificity 91.2%). Numerical simulations showed that the flow waveform shape used for AV opening detection is preserved under the different conditions studied. CONCLUSION: This study demonstrates that the AV opening can be reliably detected in RBP patients using available pump data. SIGNIFICANCE: Once implemented in RBP controllers, this method will provide a novel tool to improve the management of RBP patients, particularly for adjustments of the pump speed and flow and for the evaluation of the assisted cardiac function.