Implementing the Sano Modification in an Experimental Model of the Norwood Circulation

Surgical palliation of hypoplastic left heart syndrome (HLHS) is performed in three stages, the first of which is known as the Norwood procedure [1]. Traditionally, this operation involves securing an unobstructed outlet for the systemic circulation in infants for whom the single right ventricle is the only pump in the system, with pulmonary flow sourced via a modified Blalock-Taussig (BT) shunt. In 2003, Sano et al. have proposed a radical variation of this operation, known as the Sano modification [2]. In this case, the pulmonary circulation is supplied directly from the systemic right ventricle via an unvalved ventriculo-pulmonary Goretex conduit, or Sano shunt. Characteristically, flow in the Sano shunt continues throughout diastole (diastolic runoff). Differences between surgical approaches for stage 1 palliation have been addressed in the literature [3]. A computational model of Norwood procedure and Sano modification has also been proposed [4]. However, an experimental model of this complex physiology is currently lacking. Having recently presented an in vitro model of stage 1 physiology with a BT shunt arrangement [5], we propose here a compact mock circulatory system suitable for simulating the Sano physiology in patient-specific anatomical models.