Russell, Stuart D.

AbstractBackgroundAs heart transplant guidelines evolve, the clinical indication for 73% of durable left ventricular assist device (LVAD) implants is now destination therapy. Although completely magnetically levitated LVAD devices have demonstrated improved durability relative to previous models, LVAD replacement procedures are still required for a variety of indications. Thus, the population of patients with a replaced LVAD is growing. There is a paucity of data regarding the outcomes and risk factors for those patients receiving first‐time LVAD replacements.MethodsThe study cohort consisted of all consecutive patients between 2006 and 2020 that received a first‐time LVAD replacement at a single institution. Preoperative clinical and laboratory variables were collected retrospectively. The primary endpoint was death or need for an additional LVAD replacement. Data were subjected to Kaplan–Meier, univariate, and multivariate Cox hazard ratio analyses.ResultsIn total, 152 patients were included in the study, of which 101 experienced the primary endpoint. On multivariate analysis, patients receiving HeartMate 3 (HM3) LVADs as the replacement device showed superior outcomes (HR 0.15, 95% CI 0.065–0.35, p < 0.0001). Independent risk factors for death or need for additional replacement included preoperative extracorporeal membrane oxygenation (ECMO) (HR 4.44, 95% CI 1.87–14.45, and p = 0.00042), increased number of sternotomies (HR 5.20, 95% CI 1.87–14.45, and p = 0.0016), and preoperative mechanical ventilation (HR 1.98, 95% CI 1.01–3.86, and p = 0.045).ConclusionsReplacement with HM3 showed superior outcomes compared to all other pump types when controlling for both initial pump type and other independent predictors of death or LVAD replacement. Preoperative ECMO, mechanical ventilation, and multiple sternotomies also increased the odds for death or the need for subsequent replacement.

Background— Right ventricular failure from increased pulmonary vascular loading is a major cause of morbidity and mortality, yet its modulation by disease remains poorly understood. We tested the hypotheses that, unlike the systemic circulation, pulmonary vascular resistance (R PA ) and compliance (C PA ) are consistently and inversely related regardless of age, pulmonary hypertension, or interstitial fibrosis and that this relation may be changed by elevated pulmonary capillary wedge pressure, augmenting right ventricular pulsatile load. Methods and Results— Several large clinical databases with right heart/pulmonary catheterization data were analyzed to determine the R PA -C PA relationship with pulmonary hypertension, pulmonary fibrosis, patient age, and varying pulmonary capillary wedge pressure. Patients with suspected or documented pulmonary hypertension (n=1009) and normal pulmonary capillary wedge pressure displayed a consistent R PA -C PA hyperbolic (inverse) dependence, C PA =0.564/(0.047+R PA ), with a near-constant resistance-compliance product (0.48±0.17 seconds). In the same patients, the systemic resistance-compliance product was highly variable. Severe pulmonary fibrosis (n=89) did not change the R PA -C PA relation. Increasing patient age led to a very small but statistically significant change in the relation. However, elevation of the pulmonary capillary wedge pressure (n=8142) had a larger impact, significantly lowering C PA for any R PA and negatively correlating with the resistance-compliance product ( P <0.0001). Conclusions— Pulmonary hypertension and pulmonary fibrosis do not significantly change the hyperbolic dependence between R PA and C PA , and patient age has only minimal effects. This fixed relationship helps explain the difficulty of reducing total right ventricular afterload by therapies that have a modest impact on mean R PA . Higher pulmonary capillary wedge pressure appears to enhance net right ventricular afterload by elevating pulsatile, relative to resistive, load and may contribute to right ventricular dysfunction.

Background— Nearly half of patients with heart failure have a preserved ejection fraction (HFpEF). Symptoms of exercise intolerance and dyspnea are most often attributed to diastolic dysfunction; however, impaired systolic and/or arterial vasodilator reserve under stress could also play an important role. Methods and Results— Patients with HFpEF (n=17) and control subjects without heart failure (n=19) generally matched for age, gender, hypertension, diabetes mellitus, obesity, and the presence of left ventricular hypertrophy underwent maximal-effort upright cycle ergometry with radionuclide ventriculography to determine rest and exercise cardiovascular function. Resting cardiovascular function was similar between the 2 groups. Both had limited exercise capacity, but this was more profoundly reduced in HFpEF patients (exercise duration 180±71 versus 455±184 seconds; peak oxygen consumption 9.0±3.4 versus 14.4±3.4 mL · kg −1 · min −1 ; both P <0.001). At matched low-level workload, HFpEF subjects displayed ≈40% less of an increase in heart rate and cardiac output and less systemic vasodilation (all P <0.05) despite a similar rise in end-diastolic volume, stroke volume, and contractility. Heart rate recovery after exercise was also significantly delayed in HFpEF patients. Exercise capacity correlated with the change in cardiac output, heart rate, and vascular resistance but not end-diastolic volume or stroke volume. Lung blood volume and plasma norepinephrine levels rose similarly with exercise in both groups. Conclusions— HFpEF patients have reduced chronotropic, vasodilator, and cardiac output reserve during exercise compared with matched subjects with hypertensive cardiac hypertrophy. These limitations cannot be ascribed to diastolic abnormalities per se and may provide novel therapeutic targets for interventions to improve exercise capacity in this disorder.