In high-grade tricuspid insufficiency, percutaneous implantation of valved stents in the central venous position reduces venous regurgitation and improves haemodynamics in the animal experiment. Implantation of one or two valves in central venous position is technically feasible. Functional replacement of the insufficient tricuspid valve leads to an increase in CO. This technique expands the potential therapeutic options for patients with relevant tricuspid valve regurgitation having a high risk for open heart surgery.
Background: To investigate the feasibility and safety of transthoracic HIFU ablation for blocking cardiac electrical conduction in a canine model. Methods: Degreasing, degassing and establishment of artificial pleural effusion were induced in 21 canines. We used HIFU to target the right side of the central fibrous body guided by echocardiography. 10 canines received ablation only, 8 canines received ablation and cardiac pacing for 2h, while 3 canines received ablation and cardiac pacing for 3 months. At each endpoint, the targeted tissues were retrieved for gross, histological and immunohistochemical evaluation. Results: Complete atrioventricular block (AVB) was achieved in all 21 canines using 400Wϫ22.5Ϯ8.8s HIFU energy after acoustic coupling was improved. Recovery of AV conduction was observed neither in the 8 canines with cardiac pacing for 2h, nor in the 3 canines which were maintained with cardiac pacing for 3 months. The ablation lesion had a clear margin at the top part of interventricular septum with a necrosis of the conduction fiber in all analyzed animals whereas small fibrosis of the target regions within intact endothelium was found in the animals maintained for 3 months. No other complications were observed except that mild hemorrhagic injury in the inferior lobe of left lung was found in one animal. Conclusions: Our findings indicate that the transthoracic HIFU for blocking cardiac conduction is specific, safe and efficient, lending itself as a potentially novel approach for arrhythmia therapy.
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