OBJECTIVES Right ventricular (RV) failure after left ventricular assist device (LVAD) implantation continues to be a morbid complication. In this study, we hypothesized that a less invasive approach to implantation would preserve RV function relative to a conventional sternotomy (CS) approach. METHODS All patients (2013–2017) who underwent LVAD implantation were reviewed. Patients were stratified by surgical approach: less invasive left thoracotomy with hemi-sternotomy (LTHS) and CS. The primary outcome was severe RV failure. RESULTS Eighty-three patients (LTHS: 37, CS: 46) were identified. The median Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) score was significantly worse in the LTHS compared to the CS cohort, and there was a trend towards higher RV failure scores and HeartMate II mortality scores. Preoperative RV dysfunction, in pulmonary artery pulsatility index and RV stroke work index were similar between the 2 groups. Though operative time did not significantly differ between the 2 groups, cardiopulmonary bypass time was significantly shorter in the LTHS group (61 vs 95 min, P < 0.001). The incidence of postoperative severe RV failure was significantly reduced in the LTHS group (16% vs 39%, P = 0.030), along with the need for temporary right ventricular assist device (3% vs 26%, P = 0.005). Improvement in RV function, along with a change in pulmonary artery pulsatility index, was significantly greater in the LTHS cohort. There was a trend towards improved Kaplan–Meier 1-year survival in the LTHS cohort (91% vs 56%, P = 0.056). CONCLUSIONS In this cohort, less invasive LVAD implantation appears to be associated with reduced postoperative RV failure, and equivalent or improved survival compared to conventional LVAD implantation.
A new solid-wall vascular graft which has a compliance approximating that of the natural artery has been prepared from a copolyether-urethane material. Six of nine of these compliant grafts implanted in dogs were patent on removal, the longest implant time being 77 days for a 4-mm I.D. femoral artery graft. This is in contrast to noncompliant grafts of the same copolyurethane in which failure usually occurred within 48 hr.
There are no evidence-based guidelines for antithrombotic therapy in left ventricular assist device patients. We evaluated the efficacy of a multi-agent, test-guided protocol, which remained consistent throughout our use of the Heartware HVAD. Thrombelastography and PFA-100 guide antiplatelet titration. Goals are normal kaolin thrombelastography maximum amplitude and prolonged PFA-100. We analyzed incidence and rates of nonprocedural bleeding, stroke, and pump thrombosis for all 81 primary Heartware left ventricular assist devices implanted since 2011. For each event, we examined whether each test was within goal range. We also compared medication burden and dosage between patients with and without events. Pump thrombosis and hemorrhagic stroke each occurred in two patients (2.7%; 0.03 events/patient-year [EPPY]), and ischemic stroke in six (7.4%; 0.10 EPPY). Nonprocedural bleeding occurred 75 times in 34 patients (42%; 1.24 EPPY), primarily gastrointestinal (28%; 0.66 EPPY). Subtherapeutic INR was the most common at thrombotic events; supratherapeutic partial thromboplastin time, INR, and PFA-ADP were common at bleeding events. Medication burden and dosage were lower in patients with events than in stable patients. Protocol-guided antithrombotic therapy resulted in low rates of pump thrombosis and hemorrhagic stroke. Ischemic stroke and gastrointestinal bleeding rates were higher than in a comparable HVAD population. Optimization of our protocol to decrease its complexity and to reduce bleeding is underway.
To address the challenge of unloading the left ventricle during pediatric mechanical circulatory support using next-generation rotary blood pumps, a novel inflow cannula was developed. This unique inflow cannula for pediatric, continuous-flow, left ventricular assist devices (VADs) with a parabolic-shaped inlet entrance was evaluated alongside a bevel-tip and fenestrated-tip cannula via an ex vivo, isolated-heart experimental setup. Performance was characterized using two clinical scenarios of over-pumping and hypovolemia, created by varying pump speed and filling preload pressure respectively, at ideal and off-axis cannula placement to assess ventricular unloading and positional sensitivity. Quantitative and qualitative assessments were performed on the resultant hemodynamics and intra-ventricular boroscopic images to classify conditions of non-suction, partial, gradual or severe entrainment, and ventricular collapse. The parabolic-tip cannula was found to be significantly less sensitive to placement position (p-values < 0.001) than the bevel-tip cannula under all conditions, while not statistically different from the fenestrated cannula. Visual analysis of the parabolic-tip cannula showed complete resistance to entrainment whereas the fenestrated-tip had partial entrainment in 90% and 87% of the over-pumping and hypovolemic studies, respectively. We conclude that future pediatric VAD designs may benefit from incorporating the parabolic-tip inflow cannula design in order to maximize unloading of the left ventricle in ideal and non-optimal conditions.
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