Omecamtiv mecarbil is a cardiac-selective myosin activator and potential heart failure treatment, but its electrophysiological profile remains incompletely characterized. We investigated omecamtiv mecarbil in a Langendorff-perfused rabbit heart model. Forty-eight rabbit hearts were retrogradely perfused; twenty-four in a ventricular and twenty-four in an atrial setup. In the ventricular setup, action potential duration at 90% repolarization (APD90), QT interval, and dispersion of repolarization were assessed during pacing at seven cycle lengths. After baseline recordings, Group 1 (n = 12) received 1, 5 and 10 µM omecamtiv mecarbil sequentially, while Group 2 (n = 12) received 100 µM sotalol followed by 5 µM omecamtiv mecarbil. In the atrial setup, Group 3 (n = 12) received 5 and 10 µM omecamtiv mecarbil, and Group 4 (n = 12) received isoproterenol/acetylcholine (IsoACh) to increase atrial fibrillation (AF) susceptibility, followed by 5 µM omecamtiv mecarbil. Omecamtiv mecarbil alone shortened ventricular APD90 and QT interval, increased dispersion of repolarization, and raised ventricular arrhythmia incidence. Sotalol prolonged APD90, QT interval, and dispersion, with a marked rise in VT episodes; additional omecamtiv mecarbil did not further prolong repolarization but increased arrhythmia susceptibility further. In the atrial setup, omecamtiv mecarbil alone prolonged conduction time and increased AF inducibility. Under IsoACh, which shortened atrial APD and refractoriness and increased AF episodes, additional omecamtiv mecarbil slowed atrial conduction and markedly suppressed AF. In summary, omecamtiv mecarbil was proarrhythmic at the ventricular level, particularly under reduced repolarization reserve, but showed antiarrhythmic effects in an IsoACh-induced AF model and proarrhythmic properties in the healthy atrium, indicating a substrate-dependent electrophysiological profile.

Comprehensive knowledge of feline vascular anatomy is essential for accurate diagnostic imaging interpretation and safe thoracic cardiovascular surgery. This study aimed to characterize the branching patterns, quantitative morphometry, and precise topographical positions of the aortic arch branches and subclavian arteries in domestic cats (Felis catus). Twenty adult cat cadavers from Northwestern Iran were examined. Coloured latex was injected into the aortic arch, followed by fixation in 10% neutral buffered formalin and subsequent meticulous gross dissection. Topographical positions relative to thoracic skeletal landmarks and morphometric distances were recorded. Non-parametric Mann-Whitney U tests were used for statistical comparisons between identified patterns. Two branching configurations of the brachiocephalic trunk were identified: a bifurcated pattern (85%, n = 17) and a trifurcated pattern (15%, n = 3). The aortic arch was predominantly located at the fourth intercostal space (90%). For the left subclavian artery, three branching patterns were identified, with sequential origin (VT-IT-CCT-SC) being predominant (55%). The right subclavian artery exhibited three distinct arrangements, dominated by sequential (45%) and opposite [IT≡VT] origins (45%). Significant side-dependent variations were observed in the branching order and topography. Morphometric distances (BC + RS, BC-LS, and LCC-RCC) showed no statistically significant differences between bifurcated and trifurcated patterns (p > 0.05). Feline aortic arch branches exhibit substantial topographical variation despite overall metric consistency across branching types. The observed bilateral asymmetry and internal thoracic artery positional mobility likely reflect distinct embryological origin pathways. These findings provide critical baseline anatomical data for improving the accuracy and safety of feline surgical interventions and diagnostic imaging interpretation.

Venous thromboembolism (VTE), including deep-vein thrombosis and pulmonary embolism, is the third most common cause of vascular death worldwide and a major contributor to costly and debilitating non-fatal complications. Despite the changing landscape of risk factors, preventive and diagnostic strategies, risk stratification and therapies, no contemporary global summary of the burden of VTE is available. In a collaborative, multinational effort, we provide a global overview of the incidence and outcomes of VTE. Reliable data were available for only a limited number of countries (predominantly in Northern America, Western Europe and Oceania), with notable regional differences. During 2012-2016, the global annual incidence of deep-vein thrombosis ranged from 25.1 to 131.5 per 100,000 of the population. The incidence of pulmonary embolism rose from 2012-2016 to 2017-2022 in Northern America and Asia but remained stable in Oceania. Among patients with pulmonary embolism, 30-day all-cause mortality ranged globally from 1.0% to 9.0%, and the 1-year cumulative incidence of recurrent VTE ranged from 2.9% to 8.1%. These findings reveal the substantial global burden of VTE, sources of heterogeneity and stark regional gaps in the data, demanding coordinated surveillance, standardized reporting and research into local and global drivers to curb worldwide morbidity and mortality.