A modified intraventricular balloon method for functional assessment of hearts from donation after circulatory death.

Objective: Functional assessment of hearts during ex-vivo heart perfusion is not well-established. Conventional intraventricular balloon methods for large animals sacrifice the mitral valve. This study assessed the effectiveness of the modified intraventricular balloon method in comparison with other modalities used during working mode in juvenile pigs. Methods: Following asphyxia circulatory arrest, hearts were ischemic for 15 minutes and then reperfused on an ex-vivo device for 2 hours before switching to working mode. Left ventricular pressure was continuously measured during reperfusion by a saline-filled balloon fixated in the left atrium. Spearman Correlation Coefficients with linear regression lines with confidence intervals were analyzed. Results: Maximum dp/dt at 90 minutes of reperfusion and minimum dp/dt at 60 minutes of reperfusion showed a moderate positive correlation to that in working mode, respectively (Rs = 0.61, P = .04 and Rs = 0.60, P = .04). At 60 minutes of reperfusion, minimum dp/dt showed moderate positive correlation to tau (Rs = 0.52, P = .08). Myocardial oxygen consumption during reperfusion consistently decreased at least 30% compared to working mode (at 90 minutes as the highest during reperfusion, 3.3 ± 0.8; in working mode, 5.6 ± 1.4, mLO2/min/100 g, P < .001). Conclusions: Functional parameters of contractility and relaxation measured during reperfusion by the modified balloon method showed significant correlations to respective parameters in working mode. This mitral valve sparing technique can be used to predict viability and ventricular function in the early phase of ex-vivo heart perfusion without loading the heart during working mode.

Surgical Melody Mitral Valve: A Paradigm Shift for Infants with Unrepairable Mitral Valve Disease.

BACKGROUND: Melody valve (Melody) for mitral valve replacement (MVR)(MelodyMVR) has been an effective strategy to treat unrepairable mitral valve disease in small children. The purpose of this study is to analyze survival, durability, and complications of MelodyMVR strategy. METHODS: Patients who underwent MelodyMVR between 2014 and 2023 were included. Transplant-free survival was analyzed with Kaplan-Meier analysis. Fine and Gray sub-distribution method was applied to quantify the cumulative incidence. RESULTS: Twenty-five patients underwent MelodyMVR. Median age and weight were 6.3 (4.4-15.2) months and 6.36 (4.41-7.57) kg. 60% had congenital mitral valve disease and 52% had dominant mitral regurgitation. The median diameter of the implanted Melody was 16 (14-18) mm. Mortality at 6 months, 1 year, and 5 years was 8.3% (95% CI, 2.2%-29.4%), 12.5% (4.2%-33.9%), and 17.6% (7.0%-40.7%), respectively. Two (8%) hospital survivors required early Melody replacement. Competing risk analysis showed that approximately 50% of patients underwent mechanical MVR by 3.5 years after MelodyMVR. Freedom from bleeding and thrombosis at 4 years was 87.5% (95%CI, 74.2%-100%). Eleven patients underwent mechanical MVR with no mortality. One (9%) required pacemaker implantation after mechanical MVR. CONCLUSIONS: MelodyMVR provides reasonable early and medium-term survival in small children and a high rate of successful bridge to mechanical MVR. MelodyMVR is associated with minimal pacemaker requirement, bleeding, and thrombosis. Early Melody functional deterioration necessitates early re-MVR, which can be achieved with minimal mortality and morbidity.

Impact of Hemoglobin Level in Ex Vivo Heart Perfusion on Donation After Circulatory Death Hearts: A Juvenile Porcine Experimental Model.

BACKGROUND: Ex vivo heart perfusion (EVHP) of donation after circulatory death (DCD) hearts has become an effective strategy in adults; however, the small circulating volume in pediatrics poses the challenge of a low-hemoglobin (Hb) perfusate. We aimed to determine the impact of perfusate Hb levels during EVHP on DCD hearts using a juvenile porcine model. METHODS: Sixteen DCD piglet hearts (11-14 kg) were reperfused for 4 h in unloaded mode followed by working mode. Metabolism, cardiac function, and cell damage were compared between the low-Hb (Hb, 5.0-5.9 g/dL; n = 8) and control (Hb, 7.5-8.4 g/dL; n = 8) groups. Between-group differences were evaluated using 2-sample t-tests or Fisher's Exact tests. RESULTS: During unloaded mode, the low-Hb group showed lower myocardial oxygen consumption (P < 0.001), a higher arterial lactate level (P = 0.001), and worse systolic ventricular function (P < 0.001). During working mode, the low-Hb group had a lower cardiac output (mean, 71% versus 106% of normal cardiac output, P = 0.010) and a higher arterial lactate level (P = 0.031). Adjusted cardiac troponin-I (P = 0.112) did not differ between the groups. Morphological myocyte injury in the left ventricle was more severe in the low-Hb group (P = 0.028). CONCLUSIONS: Low-Hb perfusate with inadequate oxygen delivery induced anaerobic metabolism, resulting in suboptimal DCD heart recovery and declined cardiac function. Arranging an optimal perfusate is crucial to organ protection, and further endeavors to refine the priming volume of EVHP or the transfusion strategy are required.

Cardioprotective Actions of a Glucagon-like Peptide-1 Receptor Agonist on Hearts Donated After Circulatory Death.

Background Heart transplantation with a donation after circulatory death (DCD) heart is complicated by substantial organ ischemia and ischemia-reperfusion injury. Exenatide, a glucagon-like peptide-1 receptor agonist, manifests protection against cardiac ischemia-reperfusion injury in other settings. Here we evaluate the effects of exenatide on DCD hearts in juvenile pigs. Methods and Results DCD hearts with 15-minutes of global warm ischemia after circulatory arrest were reperfused ex vivo and switched to working mode. Treatment with concentration 5-nmol exenatide was given during reperfusion. DCD hearts treated with exenatide showed higher myocardial oxygen consumption (exenatide [n=7] versus controls [n=7], over 60-120 minutes of reperfusion, P<0.001) and lower cardiac troponin-I release (27.94±11.17 versus 42.25±11.80 mmol/L, P=0.04) during reperfusion compared with controls. In working mode, exenatide-treated hearts showed better diastolic function (dp/dt min: -3644±620 versus -2193±610 mm Hg/s, P<0.001; Tau: 15.62±1.78 versus 24.59±7.35 milliseconds, P=0.02; lateral e' velocity: 11.27 ± 1.46 versus 7.19±2.96, P=0.01), as well as lower venous lactate levels (3.17±0.75 versus 5.17±1.44 mmol/L, P=0.01) compared with controls. Higher levels of activated endothelial nitric oxide synthase (phosphorylated to total endothelial nitric oxide synthase levels: 2.71±1.16 versus 1.37±0.35, P=0.02) with less histological evidence of endothelial damage (von Willebrand factor expression: 0.024±0.007 versus 0.331±0.302, pixel/µm, P=0.04) was also observed with exenatide treatment versus controls. Conclusions Acute treatment of DCD hearts with exenatide limits myocardial and endothelial injury and improves donor cardiac function.

Modified Warden Procedure for Partial Anomalous Pulmonary Venous Drainage to Promote Growth.

Extreme forms of partially anomalous pulmonary venous drainage with high entrance of the pulmonary veins into the superior caval vein can be challenging to correct without obstructing both systemic and pulmonary venous pathways. We report an unusual morphologic subform of this malformation and a surgical technique to address its specific anatomic peculiarities while maintaining growth potential of the venous pathways. We highlight that even such complex reconstructions can be performed minimally invasively.

Impact of pulmonary artery coarctation on pulmonary artery growth and definitive repair following modified Blalock-Taussig shunt.

OBJECTIVE: Pulmonary artery coarctation may pose a risk for pulmonary stenosis and subsequent failure to achieve definitive repair. We sought to assess the impact of pulmonary artery coarctation on pulmonary artery growth. METHODS: A retrospective chart review was performed in 130 patients, including 37 single ventricles with a modified Blalock-Taussig shunt as first palliation. Pulmonary artery coarctation was defined as discrete stenosis of the pulmonary artery, with a diameter of less than 3 mm and with the ductus arteriosus connected. Preoperative echocardiography showed pulmonary artery coarctation in 29 patients (22%). Concomitant pulmonary artery plasty was performed in 14 patients with discrete stenosis having a diameter of less than 2 mm. RESULTS: Pre-modified Blalock-Taussig shunt left pulmonary artery z-scores were lower in patients with pulmonary artery coarctation than in those without (-4.0 [-5.8, -2.1] vs -1.7 [-2.6, -0.8], P < .001), and this remained the same even after modified Blalock-Taussig shunt (-2.5 [-5.1, -0.5] vs -0.5 [-2.4, 0.8], P = .010). Concomitant pulmonary artery plasty did not result in catch-up growth of the left pulmonary artery (post-modified Blalock-Taussig shunt left pulmonary artery z-score in patients with pulmonary artery plasty: -3.0 (-6.5, -2.0) versus those without: -1.8 (-3.3, -0.3), P = .279). Definitive repair/Fontan completion was achieved in 111 patients (85%), and this was not affected by the presence of pulmonary artery coarctation. CONCLUSIONS: Pulmonary artery coarctation affected disproportionate pulmonary artery growth throughout the staged repair, but did not result in failure of definitive repair/Fontan completion. Pulmonary artery plasty during the neonatal period did not contribute to catch-up growth of the left pulmonary artery; therefore, surgical indications and timing should be carefully considered.

Assessment of the right ventricle in donation after circulatory death hearts.

In donation after circulatory death heart transplantation, the donor heart is exposed to circulatory load. The right ventricle, due to its structure, has high compliance for volume load but is particularly vulnerable to increased pressure load. This study used a porcine model to conduct a functional assessment of the hemodynamics of the heart, with a focus on the right ventricle. Six pigs weighing 24.6 ± 1.4 kg were used. Circulatory death was induced by asphyxiation after median sternotomy. After 30 minutes in the state of global warm ischemia, the ascending aorta was clamped, followed by a 20-minute reperfusion of the heart with a 20°C blood cardioplegia solution. Systemic circulation was established by cardiopulmonary bypass after aortic cross-clamping. After initial reperfusion, the blood cardioplegia solution was replaced with blood. The blood was then rewarmed while the heart was still in a non-working state. Cardiac function was assessed twice in situ, first by the thermodilution method, and then, by the pressure-volume measurement both at preischemia and at three hours after initiation of reperfusion. The recovery rate of cardiac output was 75%. End-systolic elastance (P = .02) and pulmonary arterial elastance significantly increased (P = .03), but the ratio of arterial elastance to end-systolic elastance was preserved (P = .91) in the right ventricle. Despite a decrease in cardiac output after reperfusion from warm ischemia, the right ventricle had a potential to respond the elevated afterload. It is important that donations after circulatory death heart transplantation should be performed with attention to avoiding right ventricular distension.

Ex vivo evaluation of the biventricular cardiac function for donation after circulatory death model: An experimental study.

Few reports on a biventricular working heart model with ex vivo perfusion exist owing to the complexity of establishing a circuit. Hence, we investigated it for donation after circulatory death. The heart in six juvenile pigs (~20 kg) was arrested by asphyxiation. After 30 minutes of global ischemia, the heart was harvested, reperfused with normoxemic blood cardioplegia for 20 minutes, and subsequently perfused with hyperxemic blood. After 70 minutes of controlled reperfusion, the system was switched to the biventricular working mode. Cardiac function was assessed before anoxia and during the biventricular mode. Left and right ventricular functions worsened during the biventricular mode, as compared to those before anoxia (dP/dtmax , 673 ± 120 vs. 283 ± 95 and 251 ± 35 vs. 141 ± 21 mm Hg/s, respectively; P < .001). Systemic (resistance/100 g net heart weight) and pulmonary vascular resistance indexes during the biventricular mode were similar to those before anoxia (829 ± 262 vs. 759 ± 359, P = .707, and 167 ± 57 vs. 158 ± 83 dynes·sec·cm-5 - l-100-g net heart weight, P = .859, respectively). The biventricular working heart model with ex vivo perfusion was feasible, exhibited stable hemodynamics, and has the potential to be a powerful tool for direct cardiac function assessment.

The impact of pulmonary artery banding and cardiac resynchronization therapy for the adult patient with congenitally corrected transposition of the great arteries.

It has been controversial how to manage severe dysfunction of the systemic right ventricle and severe tricuspid regurgitation for adult patients with congenitally corrected transposition of the great arteries. We reported a 43-year-old man with these disorders, who received pulmonary artery banding and cardiac resynchronization therapy without cardiopulmonary bypass. The degree of the tricuspid regurgitation was improved to mild-moderate and systemic right ventricular ejection fraction was improved from 28 to 45% after surgery. Cardiopulmonary exercise testing showed that the predictive value of anaerobic threshold and peak oxygen uptake improved from 65 to 99% and 59 to 92%, respectively. In conclusion, pulmonary artery banding and cardiac resynchronization therapy can be the first choice of surgery for severe tricuspid regurgitation with severely impaired systemic right ventricular function. After improving systemic right ventricular dysfunction tricuspid surgery could be the next choice as a surgical intervention in the future.