Thermodynamic Evaluation of 4 Open-Irrigated Catheters. Introduction: New generation open-irrigated catheters aim to improve irrigation efficiency. This may change lesion patterns, challenging operators. Indeed, safety issues have recently arisen. We aimed to experimentally assess 4 open-irrigated catheters, comparing lesion size, safety, and heat transfer. Methods: The thigh lesion model was employed in 6 anesthetized pigs to assess the morphology of perpendicular and tangential lesions (n = 140) created by the newer catheters ThermoCool R SF, CoolFlex TM , and Blazer TM Open-Irrigated, and the standard ThermoCool R , at a constant power of 30 W (60 seconds). To evaluate the propensity for deep-tissue overheating, a set of 120 applications were performed at 50 W (180 seconds) comparing pop rates. Thermal assessment of the lesion generation process (20 W, 60 seconds, n = 32) was performed with an infrared camera on bovine ventricular tissue.Results: At 30 W, the newer catheters showed lower temperature readings compared with the ThermoCool R . No major efficacy or safety differences were found at tangential applications; however, at perpendicular applications: (1) the SF at 17 mL/min better preserved the superficial layers and focused its maximum thermal effect deeper, but at recommended flow rates (8 mL/min) it generated the largest superficial lesions; (2) CoolFlex TM created smaller lesions than SF and readily induced steam pops at 50 W without temperature control; and (3) no major differences were found comparing Blazer TM Open-Irrigated and ThermoCool R .Conclusions: The lower temperature readings in the newer catheters make them more prone to deliver the maximum programmed power. Under experimental conditions, the SF catheter focuses its maximum effect deeper and the CoolFlex TM can be more prone to induce steam pops at high power settings.

Microcirculatory alterations displayed by patients with heart failure (HF) induce structural and functional intestinal changes that may affect normal gut microbial community. At the same time, gut microbiota can influence pathological mechanisms implicated in HF progression. However, it is unknown whether gut microbiota dysbiosis can precede the development of cardiac alterations in HF or it is only a mere consequence. Our aim was to investigate the potential relationship between gut microbiota composition and HF development by comparing spontaneously hypertensive heart failure and spontaneously hypertensive rat models. Gut microbiota from spontaneously hypertensive heart failure, spontaneously hypertensive rat, and normotensive Wistar Kyoto rats at 9 and 19 months of age was analyzed by sequencing the 16S ribosomal RNA gene, and KEGG metabolic pathways associated to 16S profiles were predicted. Beta diversity, Firmicutes / Bacteroidetes ratio, taxonomic abundances, and potential metabolic functions of gut microbiota were significantly different in spontaneously hypertensive heart failure with respect to spontaneously hypertensive rat before (9 months) and after (19 months) cardiac differences were presented. Nine-month-old spontaneously hypertensive heart failure showed a significant increase in the genera Paraprevotella, Oscillospira, Prevotella 9, Faecalitalea, Faecalibacterium, Ruminiclostridium 6, Phascolarctobacterium, Butyrivibrio, Parasutterella, and Parabacteroides compared with both Wistar Kyoto and spontaneously hypertensive rat, while Ruminiclostridium 9 , Oscillibacter , Ruminiclostridium , Mucispirillum, Intestinimonas, and Akkermansia were diminished. Of them, Akkermansia, Prevotella 9 , Paraprevotella, and Phascolarctobaterium were associated to changes in cardiac structure and function. Our results demonstrate an association between specific changes in gut microbiota and the development of HF in a hypertensive model of HF and further support the intervention to restore gut microbiota as an innovative therapeutic strategy for preventing HF.

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