Discussion

Hypoplastic left heart accounts for a small proportion of CHDs and is classified into three morphological categories: mitral atresia/aortic atresia, mitral stenosis/aortic atresia, and mitral stenosis/aortic stenosis. ^{Reference Baffa, Chen, Guttenberg, Norwood and Weinberg2–Reference Nathan, Williamson, Mayer, Bacha and Juraszek4} Ventriculocoronary connections detectable by echocardiography have been described in about 15% of hypoplastic left heart cases and can lead to higher mortality and morbidity after stage I palliation. ^{Reference Vida, Bacha, Larrazabal and Gauvreau1,Reference Sathanandam, Cui and Nguyen5} When examined microscopically in post-mortem specimens, small connections are ubiquitous in cases with patent inflow and obstructed outflow. ^{Reference O’Connor, Cash, Cottrill, Johnson and Noonan6} Although ventriculocoronary connections form most frequently in mitral stenosis/aortic atresia phenotypes, they rarely develop in mitral stenosis/aortic stenosis phenotype, as seen in our case. We hypothesise that embryological sinusoids persisted in our patient to unload a left ventricle with suprasystemic pressure and an intact intraventricular septum. ^{Reference Baffa, Chen, Guttenberg, Norwood and Weinberg2} As demonstrated by angiographic studies, these connections demonstrate retrograde ventricle-to-right-coronarysystolic flow and antegrade diastolic flow into the left ventricle. ^{Reference Nathan, Williamson, Mayer, Bacha and Juraszek4,Reference Sathanandam, Cui and Nguyen5,Reference Hansen, Uebing, Scheewe, Kramer and Fischer7} While larger coronary fistulas carry the potential to deliver collateral myocardial perfusion during systole, they also cause diastolic run-off with consequent steal of coronary blood flow. ^{Reference Baffa, Chen, Guttenberg, Norwood and Weinberg2}

By this mechanism, ventriculocoronary connections can complicate staged palliation as they can hinder myocardial perfusion during bypass, resulting in right ventricular ischaemic injury and low cardiac output syndrome. ^{Reference Vida, Bacha, Larrazabal and Gauvreau1,Reference Stephens, Gupta, Bleiweis, Backer, Anderson and Spicer8} Procedures that avoid cardiopulmonary bypass, such as hybrid stage I or primary transplant, may benefit patients with large ventriculocoronary connections; however, benefits have not yet been proven. ^{Reference Sathanandam, Cui and Nguyen5} Continuous cold blood cardioplegia may also mitigate complications. ^{Reference Polimenakos, Sathanandam, Husayni, El Zein, Roberson and Ilbawi9} These alternative strategies were considered initially, but they did not provide any clear advantage over the Sano. Intervention on the fistula at the time of the stage I palliation was also considered but deemed too high risk given the similarly unproven benefits of this technique, increased bypass time, and concern for disruption of possible collateral myocardial perfusion during systole. ^{Reference Baffa, Chen, Guttenberg, Norwood and Weinberg2}

During the post-operative period, emergent surgical ligation and catheter-guided occlusion with coils were discussed as options to eliminate the ventriculocoronary connection but not pursued given the high risk of reoperation and the gradual stabilisation of the patient. ^{Reference Sathanandam, Cui and Nguyen5,Reference Baş and Alkara10} Ultimately, medical management, with the goal of balancing systemic and pulmonary flow, led to progressive right ventricular recovery. At the time of stage 2 palliation, despite surgeon preference for hemi-Fontan procedures, we elected for bidirectional Glenn procedure. Glenn afforded the benefit of avoiding cardiopulmonary bypass and compression of the left ventricular cavity.

Our case illustrates that medical management can result in good outcomes for hypoplastic left heart patients with large ventriculocoronary connections, even in cases with post-operative myocardial injury. Our research and case also both suggest that, if ventriculocoronary connections are to be intervened upon at any point, it should not be during a period of post-operative myocardial dysfunction . ^{Reference Sathanandam, Cui and Nguyen5,Reference Baş and Alkara10}