Left Pulmonary Artery Ligation and Chronic Pulmonary Artery Banding Model for Inducing Right Ventricular-Pulmonary Hypertension in Sheep.

Pulmonary hypertension (PH) is a progressive disease that leads to cardiopulmonary dysfunction and right heart failure from pressure and volume overloading of the right ventricle (RV). Mechanical cardiopulmonary support has theoretical promise as a bridge to organ transplant or destination therapy for these patients. Solving the challenges of mechanical cardiopulmonary support for PH and RV failure requires its testing in a physiologically relevant animal model. Previous PH models in large animals have used pulmonary bead embolization, which elicits unpredictable inflammatory responses and has a high mortality rate. We describe a step-by-step guide for inducing pulmonary hypertension and right ventricular hypertrophy (PH-RVH) in sheep by left pulmonary artery (LPA) ligation combined with progressive main pulmonary artery (MPA) banding. This approach provides a controlled method to regulate RV afterload as tolerated by the animal to achieve PH-RVH, while reducing acute mortality. This animal model can facilitate evaluation of mechanical support devices for PH and RV failure.

Impact of implantation time on early function of cardiac transplant.

BACKGROUND: Data on out-of-ice implantation ischemia in heart transplant are scarce. We examined implantation time's impact on allograft dysfunction. METHODS: We conducted a single-site retrospective review of all primary adult heart transplants from June 2012 to August 2019 for implantation warm ischemic time (WIT), defined as first atrial stitch to aortic crossclamp removal. Univariate regression was used to assess the relationship of perioperative variables to primary graft dysfunction (PGD) and to pulmonary artery pulsatility index (PAPi) at postoperative hour 24. A threshold of p < .10 was set for the inclusion of covariates in multivariate regression. Secondary analyses evaluated for consistency among alternative criteria for allograft dysfunction. A post hoc subgroup analysis examined WIT effect in prolonged total ischemia of 240 min or longer. RESULTS: Complete data were available for 201 patients. Baseline characteristics were similar between patients who did and did not have WIT documented. In univariate analysis, female gender, longer total ischemic time (TIT), longer bypass time, greater blood transfusions, and pretransplant intensive care unit (ICU) care were associated with PGD, whereas longer bypass time was associated with worse PAPi and pretransplant ICU care was associated with better PAPi. In multivariate analysis, longer bypass time predicted PGD, and worse PAPi and preoperative ICU admission predicted PGD and better PAPi. Results did not differ in secondary or subgroup analyses. CONCLUSIONS: This study is one of few examining the functional impact of cardiac implantation ischemia. Results suggest allograft implantation time alone may not impact postoperative graft function, which was driven by intraoperative bypass duration and by preoperative ICU care, instead.

Predictors of Stroke After Minimally Invasive Mitral Valve Surgery Without the Cross-Clamp.

Minimally invasive mitral valve surgery (mini-MVS) with hypothermic fibrillatory arrest has been associated with an increased risk of stroke. We aim to investigate the incidence, predictors, and outcomes of stroke in a large cohort of patient who underwent clampless mini-MVS. Between January 2008 and June 2017, we performed 1247 mini-MVSs. The clinical, operative, and postoperative outcomes were analyzed. Univariable and multivariable regression analyses were used to identify predictors of postoperative stroke. The median follow-up was 5.2 years (interquartile range 2.6-7.5). The etiology of mitral valve (MV) disease was degenerative (60.4%, n = 753), functional (12.8%, n = 160), rheumatic (8.7%, n = 109), endocarditis (3.1%, n = 39), and reoperative MV surgery (14.9%, n = 186). The overall incidence of postoperative neurologic event was 2.5% (n = 31/1247). Univariable predictors of stroke were a higher Society of Thoracic Surgeons mortality risk (6.0 ± 11.8% vs 3.3 ± 5.2%, P < 0.001), advanced age, (69.6 ± 12.1 years vs 63.0 ± 13.6 years, P = 0.002), female gender (71.0% vs 46.3%, P = 0.007), and a history of a cerebrovascular accident (22.6% vs 8.7%, P = 0.008). Stroke patients had a higher 30-day mortality (22.6% vs 1.6%, P < 0.001) and a higher risk for long-term mortality (hazard ratio = 5.56, 95% confidence interval [CI] 3.2-9.6, P < 0.001). Advanced age (odds ratio [OR] 2.1; 95% CI 1.1-4.0; P = 0.02), female gender (OR 2.3; 95% CI 0.9-5.2; P = 0.05), and history of cerebrovascular accident (OR 3.1; 95% CI 0.98-10.1; P = 0.05) remained as independent predictors of stroke in the multivariable analysis. Our decade-long experience indicates that clampless mini-MVS is associated with a low incidence of postoperative stroke, and that the predictors of stroke are not specific to this approach.

A Dual-Lumen Bicaval Cannula for Venovenous Extracorporeal Membrane Oxygenation.

BACKGROUND: Single-site, dual-lumen venovenous extracorporeal membrane oxygenation ECMO) facilitates mobilization, reduces recirculation, and mitigates insertion and infectious risks of an additional access site. This study reports the experience with a bicaval dual-lumen cannula that comprises a robust physical design allowing for easy and safe cannulation, precise positioning and monitoring, and appropriate physiologic support for patients with acute respiratory failure. METHODS: Statistical analysis was performed from data gathered retrospectively from the electronic medical records of 20 adult patients who were cannulated for ECMO with this bicaval dual-lumen cannula from August 2018 through May 2019. RESULTS: Gas exchange and blood flow were optimized in all patients after cannulation (median pH, 7.42 [interquartile range {IQR}, 7.39, 7.44], ratio of arterial partial pressure of oxygen to fraction of inspired oxygen, 186.5 [Pao2:Fio2, 116.5, 247.0]; pump flow, 3.9 L/min [IQR, 3.1, 4.3]). Eleven patients (55%) were able to be freed from mechanical ventilation after cannulation, 9 (45%) patients underwent a tracheostomy procedure while undergoing ECMO, and no patients required reintubation. No morbidity or mortality was related to the cannulation strategy or the catheter. Two patients required cannula repositioning. Survival to decannulation was 90%, and survival to hospital discharge was 80%. CONCLUSIONS: The bicaval dual-lumen cannula maintains the advantages of upper body single-site configuration to provide the adjunctive respiratory support necessary to facilitate awakening and rehabilitation while minimizing the use of invasive mechanical ventilation. This cannula introduces design qualities that may offer advantages for acute respiratory failure requiring venovenous ECMO.