Implementing the Sano Modification in an Experimental Model of First-stage Palliation of Hypoplastic Left Heart Syndrome

Abstract

This study describes the implementation of an experimental model of the "Sano" variant (right-ventricle to pulmonary-artery shunt) of the Norwood operation used to treat hypoplastic left-heart syndrome (HLHS). The Sano operation is an alternative to the modified Blalock-Taussig shunt (innominate to pulmonary artery shunt). In the experimental setup, the single ventricle is simulated using a Berlin Heart Excor ventricular assist device and the Sano shunt is constructed by attaching a Tygon tube (6 mm internal diameter, 40 mm long) to the perforated de-airing valve of the Berlin Heart at one end, and to a pulmonary compliance chamber at the other end. The feasibility of the setup was verified by testing two rapid-prototyped patient-specific anatomical models (one without and one with aortic coarctation) under pulsatile flow conditions typical of Norwood patients. Results showed physiological and repeatable pressure and flow signals, as well as physiological values for pulmonary and aortic flow. Shunt flow was regulated by shunt size, and diastolic runoff through the shunt was also observed, both being features of Sano physiology. This system allows for comparing variations of first stage palliation of HLHS in vitro, and it also represents a source of data for validation of computational models.