Faculty Bibliography

BACKGROUND:Earlier intervention for mitral valve (MV) regurgitation leads to smaller left ventricles (LV) and potentially increases the risk of post-operative systolic anterior motion (SAM). We performed left ventricular outflow tract (LVOT) modification in patients with an increased risk of SAM. METHODS:From January 2019 to May 2024, 800 consecutive totally endoscopic robotic MV repairs (TERMVR) were performed. Based on pre-bypass TEE, post-operative SAM risk was graded as low(n=610,76.2%), moderate(n=144, 18%), or high(n=46, 5.8%). Patients with moderate or high risk of SAM were categorized as "increased risk of SAM". To prevent post-operative SAM, LVOT modification consisted in ventricular septal bulge(VSB) myectomy and/or septal myocardial trabeculations(SMT) resection. Operative notes, echocardiograms, and STS dataset were analyzed. RESULTS:Mean patient age was 63.8 years (range= 22-90); 45(5.6%) had prior cardiac surgery. Thirty-day mortality was 5(0.6%). A total of 190(23.8%) patients had an increased risk of SAM. LVOT modification was performed in the majority with increased risk of SAM (139/190, 73.2%) and in a minority with low risk of SAM (42/610,6.9%). In those undergoing LVOT modification(n=181), isolated VSB myectomy was performed in 140(77.3%), isolated SMT resection in 32(17.7%), and both in 9(5.0%). The anterior leaflet was never detached. One patient experienced transient SAM while on inotropes. There was no need for intraoperative MV repair revision for SAM. CONCLUSIONS:Currently, a significant proportion of MV repairs are at elevated risk of post-operative SAM. In our TERMVR experience, LVOT modification was performed with minimal morbidity and prevented any subsequent MV repair revision for SAM.

OBJECTIVE:Hybrid coronary revascularization is a clinical strategy that uses a combination of surgical revascularization and percutaneous coronary intervention (PCI). Data on the hybrid approach for coronary artery disease involving the left main (LM) are scarce. We analyzed our cohort of hybrid coronary revascularizations with minimally invasive direct coronary artery bypass (MIDCAB) using robotic left internal mammary artery harvesting and PCI for multivessel disease with and without LM involvement. METHODS:= 40, 64.5%). RESULTS:= 0.699). CONCLUSIONS:Hybrid robotic MIDCAB for patients with and without LM disease can be performed with acceptable results in selected patients. However, it is not possible to draw definitive conclusions regarding safety and efficacy compared with conventional coronary artery bypass grafting.

OBJECTIVE/UNASSIGNED:Surgical management of mitral annular calcification remains challenging. Our institution pursued a strategy of total mitral annular calcification resection with pericardial patch reconstruction of the left ventricle when primary atrioventricular groove closure was not possible. We present the short-term outcomes derived after implementing this strategy. METHODS/UNASSIGNED:A single-institution retrospective analysis included patients with significant mitral annular calcification undergoing totally endoscopic robotic mitral valve surgery between October 2009 and August 2023. Mitral valve repair was performed in patients with sufficient posterior leaflet length. Patients requiring pericardial patch ventriculoplasty were compared with those in whom primary atrioventricular groove closure was possible (non-pericardial patch ventriculoplasty). RESULTS/UNASSIGNED: = .52). CONCLUSIONS/UNASSIGNED:Totally endoscopic robotic mitral valve repair is a safe and feasible technique for the management of mitral annular calcification with promising results at 3 years. Patients who required atrioventricular groove pericardial patch reconstruction had similar outcomes to those in whom primary closure was possible.

In patients with severe acute respiratory distress syndrome caused by coronavirus 2019 (COVID-19), mortality remains high despite optimal medical management. Extracorporeal membrane oxygenation (ECMO) has been widely used to support such patients. ECMO is not a perfect solution; however, there are several limitations and serious complications associated with ECMO use. Moreover, the overall short-term mortality rate of patients with COVID-19 supported by ECMO is high (~30%). Some patients who survive severe acute respiratory distress syndrome have chronic lung failure requiring oxygen supplementation, long-term mechanical ventilation, or ECMO support. Although lung transplant remains the most effective treatment for patients with end-stage lung failure from COVID-19, optimal patient selection and transplant timing for patients with COVID-19-related lung failure are not clear. Access to an artificial lung (AL) that can be used for long-term support as a bridge to transplant, bridge to recovery, or even destination therapy will become increasingly important. In this review, we discuss why the COVID-19 pandemic may drive progress in AL technology, challenges to AL implementation, and how some of these challenges might be overcome.

Blood contact with high surface area medical devices, such as dialysis and extracorporeal life support (ECLS), induces rapid surface coagulation. Systemic anticoagulation, such as heparin, is thus necessary to slow clot formation, but some patients suffer from bleeding complications. Both problems might be reduced by 1) replacing heparin anticoagulation with artificial surface inhibition of the protein adsorption that initiates coagulation and 2) selective inhibition of the intrinsic branch of the coagulation cascade. This approach was evaluated by comparing clot formation and bleeding times during short-term ECLS using zwitterionic polycarboxybetaine (PCB) surface coatings combined with either a potent, selective, bicyclic peptide inhibitor of activated Factor XII (FXII900) or standard heparin anticoagulation. Rabbits underwent venovenous ECLS with small sham oxygenators for 60 min using three means of anticoagulation (n = 4 ea): (1) PCB coating + FXII900 infusion, (2) PCB coating + heparin infusion with an activated clotting time of 220-300s, and (3) heparin infusion alone. Sham oxygenator blood clot weights in the PCB + FXII900 and PCB + heparin groups were 4% and 25% of that in the heparin group (p < 10^-6 and p < 10^-5), respectively. At the same time, the bleeding time remained normal in the PCB + FXII900 group (2.4 ± 0.2 min) but increased to 4.8 ± 0.5 and 5.1 ± 0.7 min in the PCB + heparin and heparin alone groups (p < 10^-4 and 0.01). Sham oxygenator blood flow resistance was significantly lower in the PCB + FXII900 and PCB + heparin groups than in the heparin only group (p < 10^-6 and 10^-5). These results were confirmed by gross and scanning electron microscopy (SEM) images and fibrinopeptide A (FPA) concentrations. Thus, the combined use of PCB coating and FXII900 markedly reduced sham oxygenator coagulation and tissue bleeding times versus the clinical standard of heparin anticoagulation and is a promising anticoagulation method for clinical ECLS.

Under continuous-flow left ventricular assist device (CF-LVAD) support, the ventricular volume change and cardiac cycle between the left ventricle (LV) and right ventricle (RV) become dyssynchronous due to the shortening of the LV systole. The purpose of this study was to quantify interventricular dyssynchrony based on different CF-LVAD support conditions and assess its relationship with LV unloading. In this study, we evaluated seven goats (body weight 44.5 ± 6.5 kg) with normal hearts. A centrifugal LVAD was implanted under general anesthesia. We inserted the conductance catheters into the left ventricle (LV) and right ventricle (RV) to assess the volume signal simultaneously. We defined the interventricular dyssynchrony as a signal (increase or decrease) of LV volume (LVV) change opposite to that of RV volume (RVV) (i.e., (dLVV/dt) × (dRVV/dt) < 0). The duration of interventricular dyssynchrony (DYS) was reported as the percentage of time that a heart was in a dyssynchronous state within a cardiac cycle. The mean DYS of normal hearts, hearts with LVAD clamp and hearts supported by LVADs with a bypass rate of 50%, 75% and 100% were 5.6 ± 1.6%, 8.7 ± 2.4%, 8.6 ± 2.8%, 15.1 ± 5.1%, and 25.6 ± 8.0%, respectively. Furthermore, the DYS was found to be associated with the degree of LV stroke volume reduction caused by LV unloading. These findings may be useful for understanding interventricular interactions and physiology during CF-LVAD support. Influences on the right ventricular function and heart failure models warrant further study.

We developed a novel miniaturized extracorporeal centrifugal pump "BIOFLOAT NCVC (Nipro Corporation Osaka, Japan) as a ventricular assist device (VAD) and performed a preclinical study that is part of the process for its approval as a bridge to decision by the pharmaceutical and medical device agencies. The aim of this study was to assess the postoperative performance, hemocompatibility, and anticoagulative status during an extended period of its use. A VAD system, consisting of a hydrodynamically levitated pump, measuring 64 mm by 131 mm in size and weighing 635 g, was used. We installed this assist system in 9 adult calves (body weight, 90 ± 13 kg): as left ventricular assist device (LVAD) in 6 calves and right ventricular assist device (RVAD) in 3 calves, for over 30 days. Perioperative hemodynamic, hematologic, and blood chemistry measurements were obtained and end-organ effects on necropsy were investigated. All calves survived for over 30 days, with a good general condition. The blood pump was operated at a mean rotational speed and a mean pump flow of 3482 ± 192 rpm and 4.08 ± 0.15 L/min, respectively, for the LVAD and 3902 ± 210 rpm and 4.24 ± 0.3 L/min, respectively, for the RVAD. Major adverse events, including neurological or respiratory complications, bleeding events, and infection were not observed. This novel VAD enabled a long-term support with consistent and satisfactory hemodynamic performance and hemocompatibility in the calf model. The hemodynamic performance, hemocompatibility, and anticoagulative status of this VAD system were reviewed.

Current artificial lungs fail in 1-4 weeks due to surface-induced thrombosis. Biomaterial coatings may be applied to anticoagulate artificial surfaces, but none have shown marked long-term effectiveness. Poly-carboxybetaine (pCB) coatings have shown promising results in reducing protein and platelet-fouling in vitro. However, in vivo hemocompatibility remains to be investigated. Thus, three different pCB-grafting approaches to artificial lung surfaces were first investigated: 1) graft-to approach using 3,4-dihydroxyphenylalanine (DOPA) conjugated with pCB (DOPA-pCB); 2) graft-from approach using the Activators ReGenerated by Electron Transfer method of atom transfer radical polymerization (ARGET-ATRP); and 3) graft-to approach using pCB randomly copolymerized with hydrophobic moieties. One device coated with each of these methods and one uncoated device were attached in parallel within a veno-venous sheep extracorporeal circuit with no continuous anticoagulation (N = 5 circuits). The DOPA-pCB approach showed the least increase in blood flow resistance and the lowest incidence of device failure over 36-hours. Next, we further investigated the impact of tip-to-tip DOPA-pCB coating in a 4-hour rabbit study with veno-venous micro-artificial lung circuit at a higher activated clotting time of 220-300 s (N ≥ 5). Here, DOPA-pCB reduced fibrin formation (p = 0.06) and gross thrombus formation by 59% (p < 0.05). Therefore, DOPA-pCB is a promising material for improving the anticoagulation of artificial lungs. STATEMENT OF SIGNIFICANCE: Chronic lung diseases lead to 168,000 deaths each year in America, but only 2300 lung transplantations happen each year. Hollow fiber membrane oxygenators are clinically used as artificial lungs to provide respiratory support for patients, but their long-term viability is hindered by surface-induced clot formation that leads to premature device failure. Among different coatings investigated for blood-contacting applications, poly-carboxybetaine (pCB) coatings have shown remarkable reduction in protein adsorption in vitro. However, their efficacy in vivo remains unclear. This is the first work that investigates various pCB-coating methods on artificial lung surfaces and their biocompatibility in sheep and rabbit studies. This work highlights the promise of applying pCB coatings on artificial lungs to extend its durability and enable long-term respiratory support for lung disease patients.