Physiology and Clinical Utility of HeartMate Pump Parameters.

The HeartMate 3 left ventricular assist device (LVAD) is now the only centrifugal pump intended for durable support being actively manufactured and implanted for adults in the United States. The changes in preload and afterload that accompany common clinical scenarios experienced by patients with an LVAD will cause specific changes to the LVAD pump parameters, namely, the pump power, pulsatility index, and flow. Appropriate care of this unique, and growing, population requires a full understanding of these variables as well as the underlying physiologic principles governing their derivation. The aim of this review is to focus on the updated functionality of the HeartMate 3, specifically in comparison to the HeartMate II, as well as the application of pump parameter interpretation to common clinical scenarios.

Postoperative tolvaptan use in left ventricular assist device patients: The TOLVAD randomized pilot study.

PURPOSE: Tolvaptan, a selective vasopressin type-2 antagonist, has been shown to increase serum sodium (Na) and urine output in hyponatremic left ventricular assist device (LVAD) patients in retrospective studies. In this prospective randomized pilot study, we aimed to assess the efficacy of tolvaptan in this population. METHODS: We conducted a prospective, randomized, non-blinded pilot study of LVAD recipients with post-operative hyponatremia (Na < 135 mEq/L) (NCT05408104). Eligible participants were randomized to receive tolvaptan 15 mg daily in addition to usual care versus usual care alone. The primary outcome was a change in Na level and estimated glomerular filtration rate (eGFR), from the first post-operative day of hyponatremia (the day of randomization) to discharge. RESULTS: A total of 33 participants were enrolled, and 28 underwent randomization (median age 55 [IQR 50-62]), 21% women, 54% Black, 32% ischemic cardiomyopathy, median baseline Na 135 (IQR 134-138). Fifteen participants were randomized to tolvaptan (TLV) and 13 were randomized to usual care alone (No-TLV). Mean change in Na from randomization to discharge in the TLV group was 2.7 mEq/L (95%CI 0.7-4.7, p = 0.013) and 1.8 (95%CI 0.5-4.0, p = 0.11) in the No-TLV group, though baseline and final Na levels were similar between groups. The mean change in eGFR was 2.6 ml/min/1.73 m2 (95%CI 10.1-15.3, p = 0.59) in TLV versus 7.5 ml/min/1.73 m2 (95%CI 5.2-20.2, p = 0.15) in No-TLV. TLV participants had significantly more urine output than No-TLV patients during their first 24 h after randomization (3294 vs 2155 ml, p = 0.043). CONCLUSION: TLV significantly increases urine output, with nominal improvement in Na level, in hyponatremic post-operative LVAD patients without adversely impacting renal function.

Postoperative extracorporeal membrane oxygenation can successfully support patients following upper airway reconstruction.

BACKGROUND: Patients requiring intensive upper airway reconstruction are anatomically restricted in terms of the respiratory support they can receive. While intraoperative extracorporeal membrane oxygenation (ECMO) has been effectively utilized, little has been shown regarding the utility of ECMO for long-term support in these patients. METHODS: We demonstrate how a patient with tongue and hypopharyngeal squamous cell carcinoma that necessitated upper airway reconstruction was supported with veno-venous (VV) ECMO due to postoperative respiratory failure and an inability to maintain a stable airway. RESULTS: By initiating VV ECMO, we were able to decrease positive pressure ventilation and FiO2 , thereby minimizing ventilator-associated trauma and irritation to facilitate wound healing. Over time, ventilatory support was increased in parallel with decreasing ECMO support, allowing discharge to rehabilitation after 74 days of ECMO. CONCLUSION: ECMO can effectively support patients with ongoing respiratory requirements following upper airway reconstruction when standard ventilatory techniques are inadequate or not feasible.

Home Inotropes in Patients Supported with Left Ventricular Assist Devices.

There is little data outlining the use of outpatient inotropic medications in patients with existing left ventricular assist devices (LVADs). This case series explores this patient population and seeks to define the indications, complications, and safety of dual support. A retrospective chart review was conducted for all patients on LVAD and then subsequently started on home inotropes post device implant. Eight patients met inclusion criteria. The indications for inotropes were right ventricular failure, aortic insufficiency with biventricular failure, LVAD thrombosis with contraindication to device exchange, and cannula malposition with elevated pulmonary vascular resistance. Mean duration of combined support was 273 ± 170 days. Cardiac index improved from 1.96 ± 0.24 to 2.31 ± 0.35 L/min/m(2) after inotropes (p = 0.02). There was no change in hospital admissions. The most common reason for readmission was heart failure symptoms, followed by bleeding. Five patients died during the study period, one underwent heart transplant, and two remain on inotropic support. Home inotropes may be indicated in selected continuous flow left ventricular assist device (CF-LVAD) patients with refractory right ventricular failure or impaired LVAD function. Inotropes can improve hemodynamics and provide palliation of symptoms. However, long-term inotrope use does not reduce hospital readmissions and is associated with multiple complications related to the need for an indwelling intravenous line.

Decoupling Between Diastolic Pulmonary Artery Pressure and Pulmonary Capillary Wedge Pressure as a Prognostic Factor After Continuous Flow Ventricular Assist Device Implantation.

BACKGROUND: A cohort of heart failure (HF) patients receiving left ventricular assist devices (LVADs) has decoupling of their diastolic pulmonary artery pressure and pulmonary capillary wedge pressure. However, the clinical implications of this decoupling remain unclear. METHODS AND RESULTS: In this prospective study, patients with LVADs underwent routine invasive hemodynamic ramp testing with right heart catheterization, during which LVAD speeds were adjusted. Inappropriate decoupling was defined as a >5 mm Hg difference between diastolic pulmonary artery pressure and pulmonary capillary wedge pressure. The primary outcomes of survival and heart failure readmission rates after ramp testing were assessed. Among 63 LVAD patients (60±12 years old and 25 female [40%]), 27 patients (43%) had inappropriate decoupling at their baseline speed. After adjustment of their rotation speed during ramp testing, 30 patients (48%) had inappropriate decoupling. Uni/multivariable Cox analyses demonstrated that decoupling was the only significant predictor for the composite end point of death and heart failure readmission during the 1 year following the ramp study (total of 18 events; hazards ratio, 1.09; 95% confidence interval, 1.04-1.24; P<0.05). Furthermore, normalization of decoupling (n=8) during ramp testing was significantly associated with higher 1-year heart failure readmission-free survival rate compared with the non-normalized group (n=19, 100% versus 53%; P=0.035). CONCLUSIONS: The presence of inappropriate decoupling was associated with worse outcomes in patients with LVADs. Prospective, large-scale multicenter studies to validate the result are warranted.