Impact of Interventricular Interaction on Ventricular Function: Insights From Right Ventricular Pressure-Volume Analysis.

BACKGROUND: Interventricular interactions may be responsible for the decline in ventricular performance observed in various disease states that primarily affect the contralateral ventricle. OBJECTIVES: This study sought to quantify the impact of such interactions on right ventricular (RV) size and function using clinically stable individuals with left ventricular assist devices (LVADs) as a model for assessing RV hemodynamics while LV loading conditions were acutely manipulated by changing device speed during hemodynamic optimization studies (ie, ramp tests). METHODS: The investigators recorded RV pressure-volume loops with a conductance catheter at various speeds during ramp tests in 20 clinically stable HeartMate3 recipients. RESULTS: With faster LVAD speeds and greater LV unloading, indexed RV end-diastolic volume increased (72.28 ± 15.07 mL at low speed vs 75.95 ± 16.90 at high speed; P = 0.04) whereas indexed end-systolic volumes remained neutral. This resulted in larger RV stroke volumes and shallower end-diastolic pressure-volume relationships. Concurrently, RV end-systolic pressure decreased (31.58 ± 9.75 mL at low speed vs 29.58 ± 9.41 mL at high speed; P = 0.02), but contractility, as measured by end-systolic elastance, did not change significantly. The reduction in RV end-systolic pressure was associated with a reduction in effective arterial elastance from 0.65 ± 0.43 mm Hg/mL at low speed to 0.54 ± 0.33 mm Hg/mL at high speed (P = 0.02). CONCLUSIONS: Interventricular interactions resulted in improved RV compliance, diminished afterload, and did not reduce RV contractility. These data challenge the prevailing view that interventricular interactions compromise RV function, which has important implications for the understanding of RV-LV interactions in various disease states, including post-LVAD RV dysfunction.

Mitral Interventions in Heart Failure.

Patients with heart failure with reduced ejection fraction who have secondary mitral regurgitation (SMR) have poorer outcomes and quality of life than those without SMR. Guideline-directed medical therapy is the cornerstone of SMR treatment. Careful evaluation of landmark trials using mitral transcatheter edge-to-edge repair in SMR has led to an improved understanding of who will benefit from percutaneous interventions with emphasis on a multidisciplinary approach. The success with mitral transcatheter edge-to-edge repair in SMR has also spurred the evaluation of its role in populations that were not initially studied, such as end-stage heart failure and cardiogenic shock. A spectrum of transcatheter devices in development and clinical trials promise to further provide a growing array of management options for heart failure with reduced ejection fraction patients with symptomatic SMR.

Artificial Intelligence and Mechanical Circulatory Support.

Advances in machine learning algorithms and computing power have fueled a rapid increase in artificial intelligence research in health care, including mechanical circulatory support. In this review, we highlight the needs for artificial intelligence in the mechanical circulatory support field and summarize existing artificial intelligence applications in 3 areas: identifying patients appropriate for mechanical circulatory support therapy, predicting risks after mechanical circulatory support device implantation, and monitoring for adverse events. We address the challenges of incorporating artificial intelligence in daily clinical practice and recommend demonstration of artificial intelligence tools' clinical efficacy, reliability, transparency, and equity to drive implementation.

Wireless Hemodynamic Monitoring in Patients with Heart Failure.

PURPOSE OF REVIEW: Wireless hemodynamic monitoring in heart failure patients allows for volume assessment without the need for physical exam. Data obtained from these devices is used to assist patient management and avoid heart failure hospitalizations. In this review, we outline the various devices, mechanisms they utilize, and effects on heart failure patients. RECENT FINDINGS: New applications of these devices to specific populations may expand the pool of patients that may benefit. In the COVID-19 pandemic with a growing emphasis on virtual visits, remote monitoring can add vital ancillary data. Wireless hemodynamic monitoring with a pulmonary artery pressure sensor is a highly effective and safe method to assess for worsening intracardiac pressures that may predict heart failure events, giving lead time that is valuable to keep patients optimized. Implantation of this device has been found to improve outcomes in heart failure patients regardless of preserved or reduced ejection fraction.

Substantial Reduction in Driveline Infection Rates With the Modification of Driveline Dressing Protocol.

BACKGROUND: Driveline infection (DLI) is a cause of morbidity and mortality in patients with continuous-flow left ventricular assist devices (CF-LVADs). We hypothesized that an alternate dressing protocol would decrease the rate of DLIs. METHODS AND RESULTS: A retrospective review of CF-LVAD implants at a single institution from January 2010 to October 2015 was conducted. Patients were divided into implants before (group 1) and after (group 2) the introduction of the new protocol on September 1, 2012. Patients were followed until death, transplantation, change in dressing type, or 2 years. 153 patients were included: 61 in group 1 and 92 in group 2. Group 1 had fewer HVADs than group 2 (27.9% vs 71.7%; P < .001) and more destination therapy, although the latter was not statistically significant (50.8% vs 34.8%; P = .118). At 24 months, the freedom from DLI was 53% in group 1 and 89% in group 2 (P = .01). Group 1 had a significantly greater risk of DLI than group 2 (incident rate ratio 3.18, 95% confidence interval 1.23-8.18; P = .016). CONCLUSIONS: Dramatic improvement in freedom from DLI at 2 years was achieved with a new driveline dressing protocol. This demonstrates that DLI rates can be improved with alternate percutaneous site care techniques in CF-LVAD patients.

Activated alleles of the Schizosaccharomyces pombe gpa2+ Galpha gene identify residues involved in GDP-GTP exchange.

The Schizosaccharomyces pombe glucose/cyclic AMP (cAMP) signaling pathway includes the Gpa2-Git5-Git11 heterotrimeric G protein, whose Gpa2 Galpha subunit directly binds to and activates adenylate cyclase in response to signaling from the Git3 G protein-coupled receptor. To study intrinsic and extrinsic regulation of Gpa2, we developed a plasmid-based screen to identify mutationally activated gpa2 alleles that bypass the loss of the Git5-Git11 Gbetagamma dimer to repress transcription of the glucose-regulated fbp1(+) gene. Fifteen independently isolated mutations alter 11 different Gpa2 residues, with all but one conferring a receptor-independent activated phenotype upon integration into the gpa2(+) chromosomal locus. Biochemical characterization of three activated Gpa2 proteins demonstrated an increased GDP-GTP exchange rate that would explain the mechanism of activation. Interestingly, the amino acid altered in the Gpa2(V90A) exchange rate mutant protein is in a region of Gpa2 with no obvious role in Galpha function, thus extending our understanding of Galpha protein structure-function relationships.