Tricuspid regurgitation worsening after transcatheter or surgical aortic valve replacement

Background

Tricuspid regurgitation (TR) often occurs concomitantly with severe aortic stenosis. Post-operative worsening of tricuspid regurgitation has been observed after surgical and transcatheter aortic valve replacement (SAVR, TAVR) [1,2].

Purpose

Pre-procedural severe tricuspid regurgitation has been shown to be a predictor of all-cause mortality in patients undergoing transcatheter aortic valve replacement (TAVR) [3,4]. However, little is known about the incidence of worsening tricuspid regurgitation after SAVR and TAVR and the impact on post-procedural outcomes. This study aims to evaluate, characterize and compare the incidence of worsening TR after TAVR and SAVR.

Methods

Retrospective single-center study of patients undergoing Transcatheter and Surgical Aortic Valve Replacement for severe aortic stenosis between 2014 and 2020. Incidence of tricuspid regurgitation was noted on echocardiogram at baseline and 1 year after TAVR or SAVR. This study enrolled 430 patients in the TAVR group and 237 patients in the SAVR group. The SAVR group only included patients who underwent isolated SAVR without any other valve intervention. Patients with severe TR at baseline were excluded from the study. Progression of TR severity was defined as deterioration by at least 1 grade of severity compared to baseline on echocardiography. Multivariable logistic regression analysis was performed to identify associations with worsening TR.

Results

Mean age of TAVR patients was higher than the SAVR patients (79±9 vs 68±12 years, p<0.0001). TAVR patients also had a significantly higher EuroSCORE than the SAVR patients (8.0±7 vs 3.5±4, p<0.0001). TAVR group was more likely to have atrial fibrillation than the SAVR group (34% vs 24%, p=0.006). Baseline right ventricular dysfunction and right ventricular enlargement were significantly higher in the TAVR group compared to the SAVR group [9% vs 4%, (p=0.009) and 10% vs 6%, (p=0.04), respectively]. Progression of TR severity occurred in 21.8% (94/430) of TAVR patients and 31.2% (74/237) of SAVR patients. Majority of these patients progressed from absent TR to mild TR [13.2% (57) in TAVR group vs 19.8% (47) in SAVR group (p=0.02)]. 6.3% (27) of patients in the TAVR group and 8.8% (21) of patients in the SAVR group had mild to moderate worsening of TR (p=0.22). 1.63% (7) in the TAVR group and 2.1% (5) in the SAVR group had progression from moderate to severe TR (p=0.65). On multivariable analysis, SAVR (Odds ratio, 2.46 [CI, 1.6–3.7]) and age (Odds ratio, 1.03 [CI, 1.03–1.05]) were associated with worsening TR severity.

Conclusions

In this retrospective observational study, SAVR and age were found to be associated with worsening tricuspid regurgitation. Majority of these patients progressed from absent TR to mild TR after SAVR. Further studies are necessary to determine long term outcomes of worsening tricuspid regurgitation after TAVR and SAVR.

Funding Acknowledgement

Type of funding sources: None.

Prolonged total circulatory support using direct mechanical ventricular actuation

Direct mechanical ventricular actuation (DMVA) is a unique, non blood contacting method for biventricular cardiac assist. Although DMVA has successfully provided cardiac assist for more than 7 days in humans, with long-term survival, its potential for long-term circulatory support has not been adequately investigated. DMVA has not been studied in the large ruminants commonly used to evaluate support devices. To develop a large animal experimental model of prolonged total circulatory support using DMVA, Suffolk sheep (n = 10) underwent sterile instrumentation for hemodynamic and chemistry monitoring. After baseline values were obtained, a left lateral thoracotomy and pericardotomy were performed. Upon electrical ventricular fibrillation (VF), DMVA was begun and the thoracotomy closed. Total circulatory support was continued until mean arterial pressure (MAP) persisted below 50% of the baseline value for more than 1 hr, with a goal of 7 days' support. Mean duration (plus or minus the standard deviation [SD]) of circulatory support was 65.9 +/- 56.8 hr (range, 10-168 hr). Pressors were not used during DMVA support. The subject supported for the maximal time (7 days) was defibrillated into sinus rhythm. No CK-MB fraction was greater than 1%, suggesting that DMVA, even with prolonged application during VF, does not result in myocardial injury. Blood urea nitrogen and creatinine levels indicate renal function was preserved. The model described represents the longest period any animal has been supported in VF using DMVA. This new model will be useful in determining what limitations, if any, exist to the prolonged use of DMVA for circulatory support.

Myocardial tolerance to mechanical actuation is affected by biomaterial characteristics

Direct mechanical ventricular actuation (DMVA) uses a pressure regulated heart cup, fabricated from silicone rubber (SR) for mechanical massage of the heart. Because DMVA has demonstrated potential for long-term circulatory support, investigations are currently exploring the use of more durable materials for fabricating DMVA heart cups. This study assessed the acute effects of heart cups fabricated from SR versus polyurethane (PU) on the myocardium. Dogs (n - 18) received DMVA for 4 hr of ventricular fibrillation (VF) using either SR (n = 10) or PU (n = 8) cups. Microspheres were used to determine perfusion during sinus rhythm (control) and at 2 and 4 hr of support. After support, myocardial biopsies were assayed for high energy phosphate content. Results demonstrated that PU cups required relatively frequent adjustments in drive line parameters that were likely due to material softening during PU cup support. Both PU and SR cups achieved similar hemodynamics during 4 hr of support. Myocardial perfusion, however, demonstrated a marked hyperemia at 4 hr of PU versus SR cup support. Regional high energy phosphate content was significantly decreased in hearts supported by PU versus SR cups. These results suggest that the relatively compliant characteristics of SR materials are important for achieving effective DMVA support without injuring the myocardium.

Regulation of glucose utilization during the inhibition of fatty acid oxidation in rat myocytes

The study of the regulation of glucose utilization by inhibition of fatty acid oxidation is greatly enhanced by the availability of specific inhibitors of fatty acid oxidation. This study examines the regulation of cardiac glucose utilization by inhibition of fatty acid oxidation at different sites. The effects of Etomoxir and 4-bromocrotonic acid (4-BCA) on the oxidation of [1-14C]palmitate, [1-14C]-octanoate and [U-14C]glucose were studied in isolated rat myocytes. Fifty percent inhibition of palmitate oxidation was achieved at 8 microM Etomoxir and 40 microM 4-BCA. Octanoate oxidation was inhibited only by 4-BCA. In contrast to their effect on palmitate oxidation, these inhibitors significantly stimulated the oxidation of glucose in a concentration-dependent manner. Moreover, the oxidation of [2-14C]pyruvate was increased two-fold by these compounds. The rate of utilization of [U-14C]-2-deoxyglucose was also stimulated 2-3 times by these inhibitors. These studies suggest that the stimulation of glucose utilization via the inhibition of fatty acid oxidation may be mediated through the stimulation of both glucose transport and the oxidation of pyruvate by the pyruvate dehydrogenase complex.

Pulsatile versus nonpulsatile reperfusion improves cerebral blood flow after cardiac arrest

Cardiopulmonary bypass using nonpulsatile flow (NF) is currently advocated for treating refractory cardiac arrest. Although the heart can be revived using cardiopulmonary bypass support, the brain must recover if such therapy is to be considered successful. Previous studies have demonstrated that pulsatile flow (PF) reperfusion can improve neurologic outcome compared with NF reperfusion after cardiac arrest. The purpose of this study was to assess cerebral perfusion and oxygen consumption during either PF or NF reperfusion after cardiac arrest. Dogs (n = 22) underwent a 15-minute cardiac arrest followed by 1 hour of either PF or NF reperfusion. Microsphere techniques were used to assess cerebral perfusion and oxygen consumption at 3, 15, and 60 minutes of reperfusion. Mean arteriovenous gradients and total brain flows were similar in both groups. However, cerebral oxygen consumption was significantly improved at 3 minutes of reperfusion with PF versus NF (1.8 +/- 0.3 versus 0.9 +/- 0.3 mL O2.dL-1.min-1, respectively; p < 0.05). These results were coincident with improved gray-to-white flow ratios at 3 minutes of PF versus NF reperfusion (5.2 +/- 1.0 versus 2.0 +/- 0.3, respectively; p < 0.05). There were no statistically significant differences in brain perfusion variables by 15 minutes of reperfusion. However, a relative hyperemia was exhibited at 15 minutes of NF versus PF reperfusion, which suggests nutrient flow was insufficient during early NF versus PF reperfusion. In conclusion, PF reperfusion can better restore cerebral blood flow and oxygen consumption than can NF reperfusion.(ABSTRACT TRUNCATED AT 250 WORDS)