Left ventricular assist device explantation using a new double-patch technique†.

OBJECTIVES: There are several surgical approaches for explanting a left ventricular assist device (LVAD) after recovery of cardiac function. Thus, remaining ventricular assist device components may bear significant risks of infection or thrombosis. We hereby report our technique and two-center experience with explantation of LVADs using a new double-patch technique. METHODS: From March 2019 to April 2021, five patients underwent LVAD explantation after myocardial recovery (HVAD, n = 2; HeartMate 3, n = 3). The mean patient age was 50.3 years (100% male); the mean time on the LVAD was 23.1 ± 20.8 months. The aetiology of the primary heart failure was dilated cardiomyopathy (n = 4) and myocarditis (n = 1).LVAD explantation was performed using a median sternotomy and cardiopulmonary bypass. The LVAD was stopped, and the outflow graft was clamped. The outflow graft was ligated and sutured close to the aortic anastomosis. The driveline was clipped and removed. Under induced fibrillation, the attachment of the LVAD was released from the apical cuff and the LVAD was removed. A round pericardial patch was fixed from the inner of the ventricle. This step sealed the apex of the heart. An additional Gore-Tex patch was continuously sutured epicardially over the suture ring. RESULTS: The 5 cases showed technically uncomplicated explantation of the LVADs. During the follow-up of a mean of 16.4 ± 16.9 months, we observed 100% survival. There were no bleeding complications or thromboembolic events during the follow-up period. CONCLUSIONS: LVAD explantation with the double-patch technique is feasible and safe. This technique allows discontinuation of anticoagulation. The 30-day survival was 100%. Further studies are needed to provide better evidence for LVAD explantation and long-term follow-up.

SARS-CoV-2 Vaccination-Induced Immunogenicity in Heart Transplant Recipients.

Among heart transplant (HT) recipients, a reduced immunological response to SARS-CoV-2 vaccination has been reported. We aimed to assess the humoral and T-cell response to SARS-CoV-2 vaccination in HT recipients to understand determinants of immunogenicity. HT recipients were prospectively enrolled from January 2021 until March 2022. Anti-SARS-CoV-2-Spike IgG levels were quantified after two and three doses of a SARS-CoV-2 vaccine (BNT162b2, mRNA1273, or AZD1222). Spike-specific T-cell responses were assessed using flow cytometry. Ninety-one patients were included in the study (69% male, median age 55 years, median time from HT to first vaccination 6.1 years). Seroconversion rates were 34% after two and 63% after three doses. Older patient age (p = 0.003) and shorter time since HT (p = 0.001) were associated with lower antibody concentrations after three vaccinations. There were no associations between vaccine types or immunosuppressive regimens and humoral response, except for prednisolone, which was predictive of a reduced response after two (p = 0.001), but not after three doses (p = 0.434). A T-cell response was observed in 50% after two and in 74% after three doses. Despite three vaccine doses, a large proportion of HT recipients exhibits a reduced immune response. Additional strategies are desirable to improve vaccine immunogenicity in this vulnerable group of patients.

Hyperammonemia by Ureaplasma urealyticum Pneumonia after Lung Transplantation.

Ureaplasma urealyticum is a commensal of the female genital tract and can be detected as a pathogen in urethritis and vaginitis. Its importance as a respiratory pathogen beyond the field of neonatology remains controversial. We report a case of Ureaplasma-pneumonia in a recently lung-transplanted patient, with hyperammonemic syndrome. The 51-year-old lung-transplanted female was admitted to the intensive care unit with new-onset reduction of her mental state due to hyperammonemia. A diagnostic bronchoscopy showed purulent bronchitis and multiple superficial ulcerations of the bronchial mucosa. The DNA-PCR from bronchoalveolar lavage confirmed the presence of Ureaplasma urealyticum in low concentration (about 5 * 104 copies/ml), which was interpreted as evidence of infection and treated with Doxycycline intravenously. Ureaplasma was also identified by DNA-PCR in the biopsy specimens of the inflammatory enlarged mediastinal lymph nodes. Bilateral pleural effusions were found to be transudative and culturally sterile. Ureaplasma-pneumonia can cause fatal hyperammonemia in lung-transplant patients and should be considered in the differential diagnosis of every unclear hyperammonemia with normal liver function. The early identification and treatment of the infection leads to clinical and biochemical resolution.

Renal protection strategies after heart transplantation.

Renal dysfunction caused by calcineurin inhibitor (CNI) nephrotoxicity occurs often and contributes significantly to late mortality after heart transplantation (HTx). Over the last decades, this has prompted many clinical studies in an effort to develop kidney-protecting immunosuppressive strategies including delayed CNI start, minimization, withdrawal, or even de novo CNI avoidance. In the past, these strategies often failed due to the lack of efficacy. Since 2009, novel CNI-reducing strategies have been under investigation. These strategies minimize renal damage using induction agents such as antithymocyte globulin and alternative immunosuppressive agents such as the mechanistic target of rapamycin inhibitors (sirolimus or everolimus) or mycophenolate. This review outlines the recent results of using these renal protection strategies including their drawbacks. We also discuss alternative approaches to optimize individual immunosuppressive therapies after HTx.

Miniaturization of left ventricular assist devices: the ongoing trend.

The shortage of appropriate donor hearts and the expanding pool of patients waiting for a heart transplantation have led to growing interest in alternative strategies, particularly in mechanical circulatory support. With expanding clinical experience and continued technical advances, continuous-flow pumps are evolving from bridge to transplantation to destination therapy for advanced heart failure. This review describes the clinical use and outcome of currently available miniaturized left ventricular assist devices (LVADs). It provides an outlook of the ongoing process of the miniaturization of LVADs, new concepts of partial support and, furthermore, it commentates on the current challenges with LVADs and the 5-year perspective.

Modeling of temperature mapping for quantitative dynamic infrared coronary angiography for intraoperative graft patency control.

OBJECTIVES: Intraoperative application of thermal coronary angiography based on dynamic infrared imaging leads to useful qualitative information concerning coronary artery bypass graft flow and anatomy. Additional quantitative flow estimation is desirable to detect graft failures. The aim of this study was to develop a heat-transfer model for quantitative flow estimation in an experimental setup. The first clinical results in coronary artery bypass grafting are reported. METHODS: Dynamic infrared imaging was applied in pig hearts to collect video data of the rewarming process of the left anterior descending artery supplied by antegrade perfusion. For mathematic description, we used the dynamic enthalpy balance for open systems, and a Laplace transformation was carried out. Therefore the time constant tau was calculated by performing a nonlinear fit procedure on the averaged dynamic temperature curves recorded over a left anterior descending artery segment. Subsequently, left internal thoracic artery-left anterior descending artery bypass graft flow was assessed intraoperatively. Effective left anterior descending artery flow was determined by using a transit-time flowmeter. RESULTS: Tau is a system constant and changes depending on the flow and the system capacity. Assuming system capacity to be constant, tau only depends on the flow. It follows from the differential equation that there is a potential relation between tau and the flow. An excellent comparison (R2 = 0.968, P <.005) was demonstrated. By using the algorithms, quantitative flow estimation in pig hearts was possible. For clinical application, the formulas were applied to intraoperatively derived dynamic temperature curves with a good comparison to the actual left internal thoracic artery-left anterior descending artery flow. CONCLUSION: The developed heat-transfer model allows for precise measurement of graft flow by using dynamic infrared imaging and can be applied for noninvasive graft flow estimation in beating-heart surgery.

Novel apoptosis assay to analyze immunosuppression.

BACKGROUND: We developed a novel whole blood assay to assess the effects of immunosuppressants on lymphocyte apoptosis. METHODS: Peripheral blood for six experiments for each drug was treated either with cyclosporin A (CsA), mycophenolate acid (MPA), tacrolimus (TRL) or rapamycin (RAPA). Whole blood was stimulated with different concentrations of staurosporine (0-5 microM) for 24 h. Using FACS, apoptosis were measured by Annexin V expression (%cells +/- SEM). RESULTS: MPA, RAPA, TRL, but not CsA, increased (P < 0.05) apoptotic cells (MPA:20.9 +/- 3.7; RAPA:17.5 +/- 3.3; TRL:16.4 +/- 2.9 vs. control:15.2 +/- 2.8). CONCLUSION: This new whole blood assay exhibited that MPA has a stronger effect on apoptosis than RAPA and TRL, whereas CsA had no effect.