The technique of fetal endoscopic tracheal occlusion FETO was developed to totally occlude the fetal trachea using an intratracheal balloon in the treatment of congenital diaphragmatic hernia with lung hypoplasia. To improve this approach, we developed a method for non-contact, rapid destruction of the balloon using high intensity focused ultrasound HIFU , a speci c balloon injection uid, and euthanized rabbits 1 kg. In an initial experiment 5 rabbits , we in ated an intratracheal balloon by injecting in 1.0 ml of uid and demonstrated that HIFU could successfully burst the balloon in all cases, although the tracheal membranous portion and the skin overlying the trachea were injured in 4 and 2 cases, respectively. In our second experiment 6 animals , we in ated the balloon using only 0.5-0.6 ml of fluid. In all cases, HIFU either burst 1 animal or deflated 5 animals the balloon and there was substantially decreased injury of the tracheal membranous portion 2 cases or overlying skin 2 cases. The total HIFU energy output revealed no signi cant difference between the rst and second experimental groups. In conclusion, the intratracheal balloon placed by FETO can be removed using HIFU alone.
In recent years, several fetal cardiac malformations such as hypoplastic left heart syndrome have been increasingly treated before birth with gradually improved outcome, although the technique is still invasive. We newly developed an automatic delivery system of high-intensity focused ultrasound (HIFU) with real-time 2D-ultrasound imaging analysis to correct cardiac morphologic abnormalities less invasively. The system could be controlled by a computer-based analysis of 2D-ultrasound left ventricular images for optimal HIFU deliveries. Using beating heart of four anesthetized adult rabbits, the system successfully achieved a non-touch gross ablation of the atrial septum in three animals, and in the other HIFU delivery was slightly mistargeted on the posterior wall of the left atrium with a resultant small transmural opening. We believe that the system will be introduced with pinpoint accuracy to minimally invasive fetal cardiac interventions that have intact or highly restrictive atrial septum.
Key WordsHypoplastic left heart syndrome, Analysis of 2D-ultrasound left ventricular image, Pinpoint ablation of the atrial septum.
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