In ex vivo and in vivo models, decreased osmolarity and charge density increased RF energy delivery to tissue, resulting in larger lesions for both open and closed irrigated ablations. A perpendicular catheter position created larger lesions across all irrigants for both open and closed irrigation ablation. The incidence of steam pops was observed more frequently with high power open irrigated using D5W, especially if the catheter was in a perpendicular position. Further research is required to evaluate any clinical role for using different irrigants with an externally irrigated catheter.

SummaryPoloxamer 188 (P188) is a nonionic triblock copolymer believed to prevent cellular injury after ischemia and reperfusion. This study compared intracoronary (IC) infusion of P188 immediately after reperfusion with delayed infusion through a peripheral intravenous catheter in a porcine model of ST-segment elevation myocardial infarction (STEMI). STEMI was induced in 55 pigs using 45 min of endovascular coronary artery occlusion. Pigs were then randomized to 4 groups: control, immediate IC P188, delayed peripheral P188, and polyethylene glycol infusion. Heart tissue was collected after 4 h of reperfusion. Assessment of mitochondrial function or infarct size was performed. Mitochondrial yield improved significantly with IC P188 treatment compared with control animals (0.25% vs. 0.13%), suggesting improved mitochondrial morphology and survival. Mitochondrial respiration and calcium retention were also significantly improved with immediate IC P188 compared with control animals (complex I respiratory control index: 7.4 vs. 3.7; calcium retention: 1,152 nmol vs. 386 nmol). This benefit was only observed with activation of complex I of the mitochondrial respiratory chain, suggesting a specific effect from ischemia and reperfusion on this complex. Infarct size and serum troponin I were significantly reduced by immediate IC P188 infusion (infarct size: 13.9% vs. 41.1%; troponin I: 19.2 μg/l vs. 77.4 μg/l). Delayed P188 and polyethylene glycol infusion did not provide a significant benefit. These results demonstrate that intracoronary infusion of P188 immediately upon reperfusion significantly reduces cellular and mitochondrial injury after ischemia and reperfusion in this clinically relevant porcine model of STEMI. The timing and route of delivery were critical to achieve the benefit.

The presence of fQRS or BBB pattern in patients with pulmonary sarcoidosis is associated with cardiac involvement and therefore should prompt further evaluation.

Background Patients with pulmonary hypertension caused by chronic lung disease (Group 3 PH ) have disproportionate right ventricle ( RV ) dysfunction, but the correlates and clinical implications of RV dysfunction in Group 3 PH are not well defined. Methods and Results We performed a cohort study of 147 Group 3 PH patients evaluated at the University of Minnesota. RV systolic function was quantified using right ventricular fractional area change ( RVFAC ) and + dP /dt max /instantaneous pressure. Tau and RV diastolic stiffness characterized RV diastolic function. Multivariate linear regression was used to define correlates of RVFAC . Kaplan‐Meier and Cox proportional hazards analyses were used to examine freedom from heart failure hospitalization and death. Positive correlates of RVFAC on univariate analysis were pulmonary arterial compliance, cardiac index, and left ventricular diastolic dimension. Conversely, male sex, N‐terminal pro‐brain natriuretic peptide, heart rate, right atrial enlargement, mean pulmonary arterial pressure, and pulmonary vascular resistance were negative correlates. Male sex was the strongest predictor of lower RVFAC , after adjusting for pulmonary vascular resistance and pulmonary arterial compliance. When comparing sexes, males had lower RVFAC (26% versus 31%, P =0.03) both overall and for any given mean pulmonary arterial pressure and pulmonary vascular resistance value. Males exhibited a reduction in + dP /dt max /instantaneous pressure as pulmonary vascular resistance increased, whereas females did not. There were no sex differences in RV diastolic function. RV dysfunction ( RVFAC <28%) was associated with increased risk of heart failure hospitalization or death (hazard ratio: 1.84, 95% CI : 1.04–3.10, P =0.035). Conclusions Male sex is associated with RV dysfunction in Group 3 PH , even after adjusting for RV afterload. RV dysfunction ( RVFAC <28%) identifies Group 3 PH patients at risk for poor outcomes.

In our ex vivo model, externally irrigated radiofrequency catheters produced drag lesion volumes equal to or larger than those created by a point-by-point method.We also found decreased lesion size due to intermittent contact can be overcome by increasing duration of ablation time.