Microvascular pulmonary arteriovenous malformations (pAVMs) can lead to profound hypoxemia. "Hepatic factor" is postulated to play a role in their development. Certain patients with congenital heart disease are at particular risk to develop pAVMs, including those with heterotaxy syndromes and complex Fontan palliation. Ideally, an underlying cause is identified and corrected, although pAVMs may persist despite those interventions. We report a patient with heterotaxy syndrome s/p Fontan who had pAVMs that persisted despite Fontan revision with equal hepatic flow to both lungs. We employed a novel method to produce a diabolo configuration of a large covered stent to restrict lung flow while maintaining the potential for future dilation.