The Double Barrel Impella Exchange: A Reliable Method for Uninterrupted Mechanical Circulatory Support.

Classic Impella exchange interrupts flow when the old device is pulled into the aorta before advancing the new device across the aortic valve, threatening circulatory collapse and loss of left ventricular access. In "double barrel," uninterrupted Impella exchange, the new device is placed into the ventricle alongside the old, where flow is first transitioned completely. Of thirty-one consecutive patients undergoing this procedure, none experienced intraoperative cardiac arrest and 96.8% (30/31) had no new aortic insufficiency. One vascular complication ensued following known preoperative iliac injury. One patient suffered nonembolic stroke; another had subarachnoid hemorrhage. Fifty-five percent (17/31) of patients survived, with 22.6% (7/31) recovering, 25.8% (8/31) undergoing transplant, and 6.5% (2/31) transitioning to durable LVAD. Impella-only survival (83.3%, 10/12) was significantly higher than Impella-ECMO survival (36.8%, 7/19) (OR 14.46, 95% CI 1.74-119.93, p=0.01). We conclude "double barrel" technique is reliable in device-dependent cardiogenic shock patients, offering significant advantage and minimal risk.

Impella 5.5 Bridge to Heart Transplant: An Institutional Series and a Closer Look at Device Removal Technique.

Limited donor organ availability often necessitates mechanical circulatory support, and recently the Impella 5.5, as a bridge to heart transplant. Of 175 Impella 5.5-supported patients at our institution, 45 underwent transplantation in the largest series to date, for whom we analyzed outcomes. Two methods of complete device explant were evaluated: central Impella transection and removal via axillary graft. Median Impella days were 25 (16-41); median waitlist days were 21 (9-37). Eighty-nine percent (40/45) of patients had device placement via right axillary artery. Seventy-six percent (34/45) underwent central transection for device removal. Four patients (8.9%) required short-term venoarterial extracorporeal membranous oxygenation (VA ECMO) postoperatively for primary graft dysfunction (PGD). Two patients (4.4%) suffered postoperative stroke. Five patients (11.1%) required new RRT postoperatively. One patient (2.2%) returned to the operating room (OR) for axillary graft bleeding. A higher chance of procedural complications was found with the axillary removal technique (p = 0.014). Median intensive care unit (ICU) days, length of stay (LOS), and postoperative days to discharge were 46 (35-63), 59 (49-80), and 18 (15-24), respectively. Ninety-eight percent (44/45) survived to discharge. Thirty-day survival was 95.6% (43/45), with 1 year survival at 90.3% (28/31). Eighty-eight percent (37/42) remain without rejection. In our institutional experience, Impella 5.5 is a safe and reliable bridge to transplant.

Correlation between aortic valve protein levels and vector flow mapping of wall shear stress and oscillatory shear index in patients supported with continuous-flow left ventricular assist devices.

BACKGROUND: Continuous-flow left ventricular assist devices commonly lead to aortic regurgitation, which results in decreased pump efficiency and worsening heart failure. We hypothesized that non-physiological wall shear stress and oscillatory shear index alter the abundance of structural proteins in aortic valves of left ventricular assist device (LVAD) patients. METHODS: Doppler images of aortic valves of patients undergoing heart transplants were obtained. Eight patients had been supported with LVADs, whereas 10 were not. Aortic valve tissue was collected and protein levels were analyzed using mass spectrometry. Echocardiographic images were analyzed and wall shear stress and oscillatory shear index were calculated. The relationship between normalized levels of individual proteins and in vivo echocardiographic measurements was evaluated. RESULTS: Of the 57 proteins of interest, there was a strong negative correlation between levels of 15 proteins and the wall shear stress (R < -0.500, p ≤ 0.05), and a moderate negative correlation between 16 proteins and wall shear stress (R -0.500 to -0.300, p ≤ 0.05). Gene ontology analysis demonstrated clusters of proteins involved in cellular structure. Proteins negatively correlated with WSS included those with cytoskeletal, actin/myosin, cell-cell junction and extracellular functions. C: In aortic valve tissue, 31 proteins were identified involved in cellular structure and extracellular junctions with a negative correlation between their levels and wall shear stress. These findings suggest an association between the forces acting on the aortic valve (AV) and leaflet protein abundance, and may form a mechanical basis for the increased risk of aortic leaflet degeneration in LVAD patients.

A 52-Year-Old Man With Chest Pain and Dyspnea.

CASE PRESENTATION: A 52-year-old man came to the cardiac surgery clinic for pulmonary thromboendarterectomy (PTE) evaluation. He had initially appeared at an outside hospital 1 year earlier, with chest pain and shortness of breath. He had no known chronic conditions. A CT pulmonary angiogram (CTPA) at that time showed a filling defect at the bifurcation of the main pulmonary artery. A transthoracic echocardiogram revealed mild mitral valve regurgitation, but otherwise the results were normal. As he was hemodynamically stable and not hypoxemic, he was treated solely by anticoagulation. Despite adhering to prescribed apixaban, he developed progressive dyspnea and reduced exercise tolerance over the subsequent year. A repeat CTPA performed 12 months after the initial presentation showed a persistent filling defect at the level of the pulmonary artery bifurcation, with a new extension now completely occluding the right main pulmonary artery. A pulmonary angiogram confirmed this complete occlusion, and right heart catheterization revealed precapillary pulmonary hypertension, with a mean pulmonary artery pressure of 50 mm Hg. His anticoagulation was transitioned to enoxaparin for presumed apixaban treatment failure, and an investigation for hypercoagulable conditions was initiated. His lupus anticoagulant test result was positive, but he did not meet the criteria for antiphospholipid syndrome because he was negative for anticardiolipin and ß2-glycoprotein antibodies. Assays for antithrombin III, protein C, prothrombin gene, and factor V Leiden mutations produced normal results.

The rapid transformation of cardiac surgery practice in the coronavirus disease 2019 (COVID-19) pandemic: Insights and clinical strategies from a center at the epicenter.

BACKGROUND: The onset of the coronavirus disease 2019 (COVID-19) pandemic has forced our cardiac surgery program and hospital to enact drastic measures that has forced us to change how we care for cardiac surgery patients, assist with COVID-19 care, and enable support for the hospital in terms of physical resources, providers, and resident training. METHODS: In this review, we review the cardiovascular manifestations of COVID-19 and describe our system-wide adaptations to the pandemic, including the use of telemedicine, how a severe reduction in operative volume affected our program, the process of redeployment of staff, repurposing of residents into specific task teams, the creation of operation room intensive care units, and the challenges that we faced in this process. RESULTS: We offer a revised set of definitions of surgical priority during this pandemic and how this was applied to our system, followed by specific considerations in coronary/valve, aortic, heart failure and transplant surgery. Finally, we outline a path forward for cardiac surgery for the near future. CONCLUSIONS: We recognize that individual programs around the world will eventually face COVID-19 with varying levels of infection burden and different resources, and we hope this document can assist programs to plan for the future.

The rapid transformation of cardiac surgery practice in the coronavirus disease 2019 (COVID-19) pandemic: insights and clinical strategies from a centre at the epicentre.

OBJECTIVES: The onset of the coronavirus disease 2019 (COVID-19) pandemic has forced our cardiac surgery programme and hospital to enact drastic measures that has forced us to change how we care for cardiac surgery patients, assist with COVID-19 care and enable support for the hospital in terms of physical resources, providers and resident training. METHODS: In this review, we review the cardiovascular manifestations of COVID-19 and describe our system-wide adaptations to the pandemic, including the use of telemedicine, how a severe reduction in operative volume affected our programme, the process of redeployment of staff, repurposing of residents into specific task teams, the creation of operation room intensive care units, and the challenges that we faced in this process. RESULTS: We offer a revised set of definitions of surgical priority during this pandemic and how this was applied to our system, followed by specific considerations in coronary/valve, aortic, heart failure and transplant surgery. Finally, we outline a path forward for cardiac surgery for the near future. CONCLUSIONS: We recognize that individual programmes around the world will eventually face COVID-19 with varying levels of infection burden and different resources, and we hope this document can assist programmes to plan for the future.

The Rapid Transformation of Cardiac Surgery Practice in the Coronavirus Disease 2019 (COVID-19) Pandemic: Insights and Clinical Strategies From a Center at the Epicenter.

BACKGROUND: The onset of the coronavirus disease 2019 (COVID-19) pandemic has forced our cardiac surgery program and hospital to enact drastic measures that has forced us to change how we care for cardiac surgery patients, assist with COVID-19 care, and enable support for the hospital in terms of physical resources, providers, and resident training. METHODS: In this review, we review the cardiovascular manifestations of COVID-19 and describe our system-wide adaptations to the pandemic, including the use of telemedicine, how a severe reduction in operative volume affected our program, the process of redeployment of staff, repurposing of residents into specific task teams, the creation of operation room intensive care units, and the challenges that we faced in this process. RESULTS: We offer a revised set of definitions of surgical priority during this pandemic and how this was applied to our system, followed by specific considerations in coronary/valve, aortic, heart failure and transplant surgery. Finally, we outline a path forward for cardiac surgery for the near future. CONCLUSIONS: We recognize that individual programs around the world will eventually face COVID-19 with varying levels of infection burden and different resources, and we hope this document can assist programs to plan for the future.

Serial Changes in Right Ventricular Systolic Function Among Rejection-Free Children and Young Adults After Heart Transplantation.

BACKGROUND: Evolution of right ventricular (RV) systolic function after pediatric heart transplantation (HT) has not been well described. METHODS: We analyzed echocardiograms performed over the first year after HT among children and young adults who remained rejection-free. Ninety-six patients (median age 7.1 [0.1-24.4] years at HT) were included: 22 infants (≤1 year) and 74 noninfants (>1 year). Two-dimensional tricuspid annular plane systolic excursion (TAPSE), tissue Doppler-derived tricuspid annular systolic velocity (S'), fractional area change (FAC), myocardial performance index (MPI), and two-dimensional speckle-tracking-derived RV global longitudinal (GLS) and free wall strain (FWS) were assessed. RESULTS: All measures of RV function were impaired immediately after HT and significantly improved over the first year: TAPSE z-score (-8.15 ± 1.88 to -3.94 ± 1.65, P < .0001), S' z-score (-4.30 ± 1.36 to -2.28 ± 1.33, P < .0001), FAC (24.37% ± 7.71% to 42.02% ± 7.09%, P < .0001), MPI (0.96 ± 0.47 to 0.41 ± 0.22, P < .0001), GLS (-10.37% ± 3.86% to -21.05% ± 3.41%, P < .0001), and FWS (-11.2% ± 4.08% to -23.66% ± 4.13%, P < .0001). By 1 year post-HT, TAPSE, S', GLS, and FWS, remained abnormal, whereas FAC and MPI nearly normalized. Patients transplanted during infancy demonstrated better recovery of RV systolic function. CONCLUSIONS: Although RV systolic function improved over the first year after HT in children and young adults without rejection, measures that assess longitudinal contractility remained abnormal at 1 year post-HT. These findings contribute to our understanding of RV myocardial contractility after HT in children and young adults and improve our ability to assess function quantitatively in this population.

Two-Dimensional Speckle Tracking Echocardiography-Derived Strain Measurements in Survivors of Childhood Cancer on Angiotensin Converting Enzyme Inhibition or Receptor Blockade.

Speckle tracking echocardiography (STE)-derived strain indices are believed to detect early cardiac dysfunction in survivors of childhood cancer and have potential to identify patients who may benefit from early heart failure treatment. However, effects of heart failure treatment on STE-derived strain measurements in this population are unknown. The aim of this study was to assess STE-derived strain measurements in survivors of childhood cancer treated with angiotensin converting enzyme inhibition or receptor blockade (ACEi/ARB). Two-dimensional speckle tracking analysis was retrospectively performed on echocardiograms from childhood cancer survivors before and during therapy with ACEi/ARB. Global left ventricular longitudinal and circumferential strain (GLS and GCS) and strain rates (LSR and CSR) were assessed and correlated with conventional echocardiographic measures of function. In 22 childhood cancer survivors (median age: 14.8, range 6.4-21.6 years), mean GLS (- 13.83 ± 0.74% to - 15.94 ± 0.74%, p = 0.002), GCS (- 18.79 ± 1.21% to - 20.74 ± 0.84%, p = 0.027), LSR (- 0.78 ± 0.04 to - 0.88 ± 0.04 s-1, p = 0.022), and CSR (- 1.08 ± 0.07 to - 1.21 ± 0.06 s-1, p = 0.027) improved on therapy. Improvement in GLS was maintained for greater than 1 year on ACEi/ARB (p = 0.02). Measures of strain and strain rate correlated with standard echocardiographic measures of function and were reproducible. These findings support the use of ACEi/ARB to treat post-chemotherapy-related cardiovascular changes in childhood cancer survivors, provide proof-of-concept that STE-derived strain and strain rate may be used to reliably monitor cardiac function during therapy, and support continued investigation into the clinical benefit of strain measurements in this population.

Longitudinal Analysis of Echocardiographic Abnormalities in Children With Sickle Cell Disease.

BACKGROUND: Cardiac abnormalities have been described in echocardiograms of children with sickle cell disease (SCD). However, longitudinal studies investigating progression of echocardiographic abnormalities across the pediatric age spectrum in SCD are lacking. METHODS: A retrospective longitudinal analysis of 829 echocardiograms from pediatric patients with SCD at steady-state was performed. Left heart parameters included left ventricular end-systolic, end-diastolic diameters, fractional shortening, and mass. Right ventricular pressure was estimated by tricuspid regurgitation gradient. Tricuspid regurgitation gradient ≥25 mm Hg, a z-score ≥2 for LV parameters and ≤-2 for left ventricular fractional shortening were considered abnormal. RESULTS: Kaplan-Meier analysis revealed that echocardiographic abnormalities were detected by 5 years of age, and the cumulative incidence progressively increased throughout childhood. Age, male gender, HbSS and Sß thalassemia genotype, white blood cell count, platelet count, total bilirubin, admissions for pain crises and acute chest syndrome were positively, whereas hemoglobin was negatively associated with cardiac abnormalities. CONCLUSION: Cardiac abnormalities began early in childhood and progressively increased with age. Our study highlights the high cumulative incidence of cardiac abnormalities in children with SCD, which could represent a marker of disease severity.

An electrospun scaffold integrating nucleic acid delivery for treatment of full-thickness wounds.

We developed a multi-functional construct capable of controlled delivery of bioactive substances that can improve wound repair by supporting the intrinsic ability of the skin to heal. We synthesized electrospun scaffolds-composed of a blend of the degradable polymers poly(l-lactide) (PLA) or polycaprolactone (PCL)-that produce highly efficient non-viral in vivo gene delivery to cells in the wound bed, provide a protective barrier during early wound healing, and support cell migration and growth. This multi-functional material was tested for its influence on wound healing: scaffolds were loaded with plasmids encoding keratinocyte growth factor (KGF) and applied to full-thickness wounds in mice. Compared to scaffolds with control plasmids, animals receiving the KGF plasmid-loaded scaffold produced significant enhancements in wound healing, which was quantified by improvements in the rate of wound re-epithelialization, keratinocyte proliferation, and granulation response. Further, we quantified the expression level of endogenous and plasmid-derived KGF in wound samples: qRT-PCR on wound sections revealed a correlation between the levels of plasmid-derived protein expression and histological analysis of wound healing, revealing an inverse relationship between the expression level of exogenous KGF and the size of the unhealed epithelial layer in wounds. Our findings suggest that engineered nanofiber PLA/PCL scaffolds are capable of highly efficient controlled DNA delivery and are promising materials for treatment of cutaneous wounds.

Determining the fate of seeded cells in venous tissue-engineered vascular grafts using serial MRI.

A major limitation of tissue engineering research is the lack of noninvasive monitoring techniques for observations of dynamic changes in single tissue-engineered constructs. We use cellular magnetic resonance imaging (MRI) to track the fate of cells seeded onto functional tissue-engineered vascular grafts (TEVGs) through serial imaging. After in vitro optimization, murine macrophages were labeled with ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles and seeded onto scaffolds that were surgically implanted as inferior vena cava interposition grafts in SCID/bg mice. Serial MRI showed the transverse relaxation times (T(2)) were significantly lower immediately following implantation of USPIO-labeled scaffolds (T(2) = 44 ± 6.8 vs. 71 ± 10.2 ms) but increased rapidly at 2 h to values identical to control implants seeded with unlabeled macrophages (T(2) = 63 ± 12 vs. 63 ± 14 ms). This strongly indicates the rapid loss of seeded cells from the scaffolds, a finding verified using Prussian blue staining for iron containing macrophages on explanted TEVGs. Our results support a novel paradigm where seeded cells are rapidly lost from implanted scaffolds instead of developing into cells of the neovessel, as traditionally thought. Our findings confirm and validate this paradigm shift while demonstrating the first successful application of noninvasive MRI for serial study of cellular-level processes in tissue engineering.

Bioengineering approaches to controlled protein delivery.

Proteins are of crucial importance in all biologic organisms, in terms of both structure and function. Their deficits play central roles in many pathologic states, and their potential as powerful therapeutic agents has been widely recognized. Many issues, however, exist in delivery of biologically active proteins to target tissues and organs. Recent advances in biomedical engineering have lead to development of advanced techniques for controlled delivery of peptides and proteins, paving the way for their efficient use in treating human injury and disease. With a particular emphasis on most recent advances, this review discusses currently available techniques for controlled delivery of proteins and considers future research directions.