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.

The Ranger drug-coated balloon: advances in drug-coated technology for treatment of femoropopliteal segment arterial disease.

Paclitaxel drug-coated balloons (DCBs) have been shown to improve patency and lower revascularization rates compared with plain old balloon angioplasty. DCBs continue to evolve by improving balloon-coating techniques that minimize the quantity of particles washed off into the bloodstream while maximizing drug retention and vascular-healing profile. Against this backdrop, it is clear that the future of antiproliferatives for the superficial femoral artery will focus on enhancements in device coating materials that will improve the efficiency of drug delivery. The Ranger DCB system recently gained US FDA approval for use. This review discusses the background of DCBs and how the Ranger DCB builds on these previous platforms based on experimental and clinical data.

Drug-coated balloons are medical devices used to open blocked arteries (a procedure called angioplasty) in patients who have atherosclerotic disease. The drug coating is provided to help keep the arteries open after treatment with the balloon. This is thought to occur through several mechanisms. In this review, we discuss recent advances in technology related to drug-coated balloons focusing on the recently introduced Ranger drug-coated Balloon.

Discovery of Discrete Stages in the Oxidation of exo-Tetrahydrodicyclopentadiene (C10H16) Droplets Doped with Titanium-Aluminum-Boron Reactive Mixed-Metal Nanopowder.

Titanium (Ti), aluminum (Al), and boron (B) reactive mixed-metal nanopowders (Ti-Al-B RMNPs) represent attractive additives to hydrocarbon fuels such as exo-tetrahydrodicyclopentadiene (C10H16; JP-10) enhancing the limited volumetric energy densities of traditional hydrocarbons, but fundamental mechanisms and combustion stages in the oxidation have been obscure. This understanding is of vital significance in the development of next-generation propulsion systems and energy-generation technologies. Here, we expose distinct oxidation stages of single droplets of JP-10 doped with Ti-Al-B-RMNP exploiting innovative ultrasonic levitator technology coupled with time-resolved spectroscopic (UV-vis) and imaging diagnostics (optical and infrared). Two spatially and temporally distinct stages of combustion define a glow flame stage in which JP-10 and nanoparticles combust via a homogeneous gas phase (Al) and heterogeneous gas-surface oxidation (Ti, B) and a slower diffusion flame stage associated with the oxidation of JP-10. These findings enable the development of next-generation RMNP fuel additives with superior payload delivery capabilities.

Combined Spectroscopic and Computational Investigation on the Oxidation of exo-Tetrahydrodicyclopentadiene (JP-10; C10H16) Doped with Titanium-Aluminum-Boron Reactive Metal Nanopowder.

We report the results on the combustion of single, levitated droplets of exo-tetrahydrodicyclopentadiene (JP-10) doped with titanium-aluminum-boron (Ti-Al-B) reactive metal nanopowders (RMNPs) in an oxygen (60%)-argon (40%) atmosphere by exploiting an ultrasonic levitator with droplets ignited by a carbon dioxide laser. Ultraviolet-visible (UV-vis) emission spectroscopy revealed the presence of gas-phase aluminum (Al) and titanium (Ti) atoms. These atoms can be oxidized in the gas phase by molecular oxygen to form spectroscopically detected aluminum monoxide (AlO) and titanium monoxide (TiO) transients. Analysis of the optical ignition videos supports that the nanoparticles are ignited before JP-10. The detection of boron monoxide (BO) further proposes an active surface chemistry through the oxidation of the RMNPs and the release of at least BO into the gas phase. The oxidation of gas-phase BO by molecular oxygen to boron dioxide (BO2) plus atomic oxygen might operate in the gas phase, although the involvement of surface oxidation processes of RMNPs to BO2 cannot be discounted. The UV-vis emission spectra also revealed the key reactive intermediates (OH, CH, C2, and HCO) of the oxidation of JP-10. Electronic structure calculations reveal that the presence of reactive radicals has a profound impact on the oxidation of JP-10. Although titanium monoxide (TiO) reacts to produce titanium dioxide (TiO2), it does not engage in an active JP-10 chemistry as all abstraction pathways are endoergic by more than 217 kJ mol-1. This is similar for atomic aluminum and titanium, whose hydrogen abstraction reactions from JP-10 were revealed to be endoergic by at least 77 kJ mol-1. Therefore, aluminum and titanium react preferentially with molecular oxygen to produce their monoxides. However, the formation of BO, AlO, and BO2 supplies a pool of highly reactive radicals, which can abstract hydrogen from JP-10 via transition states ranging from only 1 to 5 kJ mol-1 above the separated reactants, forming JP-10 radicals along with the hydrogen abstraction products (boron hydride oxide, aluminum monohydroxide, and metaboric acid) in the overall exoergic reactions. These abstraction barriers are well below the barriers of abstractions for ground-state atomic oxygen and molecular oxygen. In this sense, gas-phase BO, AlO, and BO2 catalyze the oxidation of gas-phase JP-10 via hydrogen abstraction, forming highly reactive JP-10 radicals. Overall, the addition of RMNPs to JP-10 not only provides a higher energy density fuel but is also expected to lead to shorter ignition delays compared to pure JP-10 due to the highly reactive pool of radicals (BO, AlO, and BO2) formed in the initial stage of the oxidation process.

Transcatheter Versus Surgical Aortic Valve Replacement in Patients With Prior Cardiac Surgery in the Randomized PARTNER 2A Trial.

OBJECTIVES: The aim of this study was to further evaluate clinical outcomes in patients with and without PCS. BACKGROUND: Prior cardiac surgery (PCS) is associated with increased surgical risk and post-operative complications following surgical aortic valve replacement (SAVR), but whether this risk is similar in transcatheter aortic valve replacement (TAVR) is unclear. METHODS: In the PARTNER 2A (Placement of Aortic Transcatheter Valve) trial, 2,032 patients with severe aortic stenosis at intermediate surgical risk were randomized to TAVR with the SAPIEN XT valve or SAVR. Adverse clinical outcomes at 30 days and 2 years were compared using Kaplan-Meier event rates and multivariate Cox proportional hazards regression models. The primary endpoint of the PARTNER 2 trial was all-cause death and disabling stroke. RESULTS: Five hundred nine patients (25.1%) had PCS, mostly (98.2%) coronary artery bypass grafting. There were no significant differences between TAVR and SAVR in patients with or without PCS in the rates of the primary endpoint at 30 days or 2 years. Nevertheless, an interaction was observed between PCS and treatment arm; whereas no-PCS patients treated with TAVR had higher rates of 30-day major vascular complications than patients treated with SAVR (adjusted hazard ratio: 2.66; 95% confidence interval: 1.68 to 4.22), the opposite was true for patients with PCS (adjusted hazard ratio: 0.27; 95% confidence interval: 0.11 to 0.66) (pinteraction <0.0001). A similar interaction was observed for life-threatening or disabling bleeding. CONCLUSIONS: In the PARTNER 2A trial of intermediate-risk patients with severe aortic stenosis undergoing SAVR versus TAVR, the relative risk for 2-year adverse clinical outcomes was similar between TAVR and SAVR in patients with or without PCS.

Longitudinal Hemodynamics of Transcatheter and Surgical Aortic Valves in the PARTNER Trial.

Importance: Use of transcatheter aortic valve replacement (TAVR) for severe aortic stenosis is growing rapidly. However, to our knowledge, the durability of these prostheses is incompletely defined. Objective: To determine the midterm hemodynamic performance of balloon-expandable transcatheter heart valves. Design, Setting, and Participants: In this study, we analyzed core laboratory-generated data from echocardiograms of all patients enrolled in the Placement of Aortic Transcatheter Valves (PARTNER) 1 Trial with successful TAVR or surgical AVR (SAVR) obtained preimplantation and at 7 days, 1 and 6 months, and 1, 2, 3, 4, and 5 years postimplantation. Patients from continued access observational studies were included for comparison. Interventions: Successful implantation after randomization to TAVR vs SAVR (PARTNER 1A; TAVR, n = 321; SAVR, n = 313), TAVR vs medical treatment (PARTNER 1B; TAVR, n = 165), and continued access (TAVR, n = 1996). Five-year echocardiogram data were available for 424 patients after TAVR and 49 after SAVR. Main Outcomes and Measures: Death or reintervention for aortic valve structural indications, measured using aortic valve mean gradient, effective orifice area, Doppler velocity index, and evidence of hemodynamic deterioration by reintervention, adverse hemodynamics, or transvalvular regurgitation. Results: Of 2795 included patients, the mean (SD) age was 84.5 (7.1) years, and 1313 (47.0%) were female. Population hemodynamic trends derived from nonlinear mixed-effects models showed small early favorable changes in the first few months post-TAVR, with a decrease of -2.9 mm Hg in aortic valve mean gradient, an increase of 0.028 in Doppler velocity index, and an increase of 0.09 cm2 in effective orifice area. There was relative stability at a median follow-up of 3.1 (maximum, 5) years. Moderate/severe transvalvular regurgitation was noted in 89 patients (3.7%) after TAVR and increased over time. Patients with SAVR showed no significant changes. In TAVR, death/reintervention was associated with lower ejection fraction, stroke volume index, and aortic valve mean gradient up to 3 years, with no association with Doppler velocity index or valve area. Reintervention occurred in 20 patients (0.8%) after TAVR and in 1 (0.3%) after SAVR and became less frequent over time. Reintervention was caused by structural deterioration of transcatheter heart valves in only 5 patients. Severely abnormal hemodynamics on echocardiograms were also infrequent and not associated with excess death or reintervention for either TAVR or SAVR. Conclusions and Relevance: This large, core laboratory-based study of transcatheter heart valves revealed excellent durability of the transcatheter heart valves and SAVR. Abnormal findings in individual patients, suggestive of valve thrombosis or structural deterioration, were rare in this protocol-driven database and require further investigation. Trial Registration: clinicaltrials.gov Identifier: NCT00530894.