Experimental Study On Multifunctional Intracardiac Echocardiography Catheter Attentive Intima Drug Delivery

Objective: This study sought to develop a multifunctional intracardiac echocardiography catheter which integrated intracardiac echocardiography, ultrasound irradiation, electromapping and injection needle into a single catheter (10 F), and investigate the performance regarding handling, ultrasound irradiation transducer, 32-element ultrasound imaging transducer and the capability to guide transendocardial injection.Methods: Ultrasound phantom was employed to detect its resolution; cardiac structure was observed in vitro and in vivo; precision impedance analyzer and ultrasound powermeter were used to detect the frequency and power of ultrasound irradiation transducer, then multifunctional intracardiac echocardiography catheter was inserted into left ventricle of pig in vitro, transendocardial injection of microbubble within left ventricular wall and septum was performed to investigate the capability for real-time injection depth monitoring. Results: This multifunctional intracardiac echocardiography catheter (10 F) was one way steerable which integrated intracardiac echocardiography, transendocardial injection, ultrasound irradiation and electrophysiology mapping into a single catheter; the resolution in longitude and in lateral is 1 mm and 1 mm, respectively. Clear cardiac structure was observed in vitro and in vivo. In addition, this multifunctional intracardiac echocardiography catheter could achieve transendocardial injection depth monitoring and provide further information on the distribution of microbubble during injection. The frequency and power of ultrasound irradiation transducer were 7.2 MHz and 0.28 W, respectively, which can generate water column at work.Conclusions: This multifunctional intracardiac echocardiography catheter meets the interventional demand in size and the performance of functional units come up to the primary design, which may provide a safer and more effective strategy for transendocardial injection in future. Objectives: Percutaneous transluminal septal myocardial ablation was the major catheter-based strategy for the treatment of hypertrophic obstructive cardiomyopathy (HOCM), however some inherent deficiencies limited the therapeutic efficacy. This study sought to evaluate the feasibility and safety for target setpal ablation with transendocardial ethanol injection in canines with a novel multifunctional intracardiac echocardiography catheter.Methods: This new catheter (10 F), integrated with a nitinol needle (29 G) and a 6.5-10 MHz, 32-element, side-fire ultrasound imaging transducer, was delivered into right ventricle in 9 canines and left ventricle in 3 canines. 0.3 ml microbubble and 0.5 ml-1.5 ml absolute ethanol were sequentially injected into interventricular septum. ECG was recorded in the whole procedure. 3 h after this operation, the heart was harvested for gross and histological examination.Results: In all canines, this catheter contributed to provide anatomic structure and guide proper needle position within septum. Microbubble further confirmed needle location with focal echo-density enhancement. There was dose-related effect on myocardial ablation with different amounts of ethanol infusion. Macroscopic examination showed target myocardium changed into pale with distinct border between lesions and normal tissue. HE staining further confirmed necrosis within injection region. There was not complete heart block, malignant arrhythmia, mural thrombosis and remote myocardial necrosis in relation to this procedure.Conclusions: Transendocardial ethanol injection at interventricular septum resulted in controlled myocardial infarction. In addition, injection depth was visually followed by this new system which may provide a safer and more intuitive method for HOCM or other cardiomyopathy. Objectives: Transendocardial gene delivery may expose patients to the risk of pericardial perfusion due to excessive needle injection. This study investigated the feasibility and safety of percutaneous, catheter-based myocardial gene transfer with a new developed multifunctional intracardiac echocardiography catheter.Methods: This new system integrated intracardiac echocardiography, retractable 29 G needle and other accessories into a single catheter which allowed to be delivered into left ventricle via retrograde aortic approach. In 3 canines, the catheter was used to inject 0.2 ml of Evan's blue and 6 canines had myocardial injections of plasmid (100μg per site) containing the EGFP transgene. In addition, 2 canines received transendocardial injection of pAdTrace-bFGF (100μg per site). All canines with gene delivery were scarified after 3 days. The hearts were harvested for gross, histological examination and gene expression assessment.Results: Multifunctional intracardiac echocardiography catheter provided visual guidance of accurate needle tip position within target myocardium which was further confirmed by subsequent microbubble infusion. No animal had pericardial effusion or sustained ventricular arrhythmia. Tissue staining showed well-demarcated margin within target myocardium. In pEGFP-N1 injected animals, confocal microscope demonstrated successful gene expression. In pAdTrace-bFGF injected zones, immunohistochemistry also showed positive staining. In comparison to normal tissue (0.38±0.04), RT-PCR showed high levels of bFGF expression (0.63±0.02) in target area (P < 0.01).Conclusions: Transendocardial gene injection with multifunctional intracardiac echocardiography catheter is safe and feasible which may provide a new strategy for gene delivery in future.