Cardiac Power Output Index and Severe Primary Graft Dysfunction After Heart Transplantation.

OBJECTIVES: To evaluate the value of cardiac power output index (CPOi) in predicting severe primary graft dysfunction (PGD) after heart transplantation (defined as mechanical circulatory support [MCS] and/or mortality <30 days after transplant). DESIGN: Observational cohort study. SETTING: A heart transplant center in the United Kingdom. PARTICIPANTS: Consecutive patients who underwent heart transplantation from January 2014 to December 2019 (n = 160). Twenty patients were excluded, as MCS was instituted immediately after transplant. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Hemodynamic data on return to the intensive care unit (time 0, T0) and at 6 hours (T6) were collected to calculate CPOi at both points in 140 consecutive patients-22 patients developed severe PGD. The CPOi at T0 correlated with donor-recipient predicted heart mass and inversely with inotrope score. Patients who developed severe PGD had significantly lower CPOi at T0 and T6. The areas under the receiver operating characteristic curve for CPOi at T0 and T6 for the development of severe PGD were 0.90 and 0.92, respectively. Adjusting for vasoactive-inotrope score did not improve discrimination. The probability of severe PGD if CPOi at T0 <0.34 W/m2 and T6 <0.33 W/m2 was 79%, but was only 2% if both CPOi at T0 and T6 were >0.34 W/m2 and >0.33 W/m2, respectively. After adjusting for baseline differences, CPOi at T6 (odds ratio 0.78; 95% CI 0.67-0.91, p = .001) was significantly associated with severe PGD. CONCLUSION: Low CPOi at T0 is associated with severe PGD. Serial assessment of CPOi increases the diagnostic probability of severe PGD.

A national pilot of donation after circulatory death (DCD) heart transplantation within the United Kingdom.

BACKGROUND: The United Kingdom (UK) was one of the first countries to pioneer heart transplantation from donation after circulatory death (DCD) donors. To facilitate equity of access to DCD hearts by all UK heart transplant centers and expand the retrieval zone nationwide, a Joint Innovation Fund (JIF) pilot was provided by NHS Blood and Transplant (NHSBT) and NHS England (NHSE). The activity and outcomes of this national DCD heart pilot program are reported. METHODS: This is a national multi-center, retrospective cohort study examining early outcomes of DCD heart transplants performed across 7 heart transplant centers, adult and pediatric, throughout the UK. Hearts were retrieved using the direct procurement and perfusion (DPP) technique by 3 specialist retrieval teams trained in ex-situ normothermic machine perfusion. Outcomes were compared against DCD heart transplants before the national pilot era and against contemporaneous donation after brain death (DBD) heart transplants, and analyzed using Kaplan-Meier analysis, chi-square test, and Wilcoxon's rank-sum. RESULTS: From September 7, 2020 to February 28, 2022, 215 potential DCD hearts were offered of which 98 (46%) were accepted and attended. There were 77 potential donors (36%) which proceeded to death within 2 hours, with 57 (27%) donor hearts successfully retrieved and perfused ex situ and 50 (23%) DCD hearts going on to be transplanted. During this same period, 179 DBD hearts were transplanted. Overall, there was no difference in the 30-day survival rate between DCD and DBD (94% vs 93%) or 90 day survival (90% vs 90%) respectively. There was a higher rate of ECMO use post-DCD heart transplants compared to DBD (40% vs 16%, p = 0.0006), and DCD hearts in the pre pilot era, (17%, p = 0.002). There was no difference in length of ICU stay (9 DCD vs 8 days DBD, p = 0.13) nor hospital stay (28 DCD vs 27 DBD days, p = 0.46). CONCLUSION: During this pilot study, 3 specialist retrieval teams were able to retrieve DCD hearts nationally for all 7 UK heart transplant centers. DCD donors increased overall heart transplantation in the UK by 28% with equivalent early posttransplant survival compared with DBD donors.

Short-term intravenous sodium nitrite infusion improves cardiac and pulmonary hemodynamics in heart failure patients.

BACKGROUND: Nitrite exhibits hypoxia-dependent vasodilator properties, selectively dilating capacitance vessels in healthy subjects. Unlike organic nitrates, it seems not to be subject to the development of tolerance. Currently, therapeutic options for decompensated heart failure (HF) are limited. We hypothesized that by preferentially dilating systemic capacitance and pulmonary resistance vessels although only marginally dilating resistance vessels, sodium nitrite (NaNO2) infusion would increase cardiac output but reduce systemic arterial blood pressure only modestly. We therefore undertook a first-in-human HF proof of concept/safety study, evaluating the hemodynamic effects of short-term NaNO2 infusion. METHODS AND RESULTS: Twenty-five patients with severe chronic HF were recruited. Eight received short-term (5 minutes) intravenous NaNO2 at 10 µg/kg/min and 17 received 50 µg/kg/min with measurement of cardiac hemodynamics. During infusion of 50 µg/kg/min, left ventricular stroke volume increased (from 43.22±21.5 to 51.84±23.6 mL; P=0.003), with marked falls in pulmonary vascular resistance (by 29%; P=0.03) and right atrial pressure (by 40%; P=0.007), but with only modest falls in mean arterial blood pressure (by 4 mm Hg; P=0.004). The increase in stroke volume correlated with the increase in estimated trans-septal gradient (=pulmonary capillary wedge pressure-right atrial pressure; r=0.67; P=0.003), suggesting relief of diastolic ventricular interaction as a contributory mechanism. Directionally similar effects were observed for the above hemodynamic parameters with 10 µg/kg/min; this was significant only for stroke volume, not for other parameters. CONCLUSIONS: This first-in-human HF efficacy/safety study demonstrates an attractive profile during short-term systemic NaNO2 infusion that may be beneficial in decompensated HF and warrants further evaluation with longer infusion regimens.

Cardiac herniation and lung torsion following heart and lung transplantation.

A 45-year-old male heart-lung transplant recipient reported reduced exercise tolerance two months post-transplant. Spirometry, right heart pressures, bronchoscopy, trans-bronchial and endomyocardial biopsy were normal. Investigations demonstrated posterior and leftwards herniation of the heart through the posterior pericardial window created during the transplant operation with secondary 90 degrees forward twist of the left lung. This phenomenon generated mild functional narrowing of the left pulmonary artery demonstrable on magnetic resonance imaging. Cardiac herniation with lung torsion is a rare finding post heart-lung transplantation and usually manifests in the early postoperative period with haemodynamic compromise, requiring immediate correction. Our case demonstrates that heart graft herniation and secondary partial lung torsion can occur in the chronic phase without catastrophic consequences.

Acquired aorto-pulmonary artery fistula following proximal aortic surgery.

A 56-year-old man developed left heart failure secondary to left to right shunt due to acquired aorto-pulmonary artery (PA) fistula. He had previously undergone aortic root replacement for streptococcal aortic valve endocarditis. A modified strategy involving interventional radiology and surgical technique was employed to deal with this complex surgical challenge. A balloon catheter was placed in the right PA to enable fistula occlusion during cardiopulmonary bypass followed by repair using cardiopulmonary bypass and circulatory arrest.