Catheter-based interventions on extracardiac arterial and venous shunts

Abstract

Extracardiac shunts can result in deleterious alteration of effective pulmonary or systemic blood flow. The catheterization laboratory has become an environment in which both left-to-right and right-to-left shunts can be addressed with reasonable success in most cases. The development of transcatheter techniques and devices has increased markedly over the past two decades, and increasing experience is being obtained in palliative and curative procedures in these situations. The most common left-to-right shunt is the patent ductus arteriosus, in which transcatheter occlusion has become the standard of care in most infants and children. Various methods of closure have been widely described and employed. Systemic-to-pulmonary collaterals are ubiquitous in single-ventricle patients, and considerations for their closure (or potential benefits) are varied and important. Similarly, previously placed surgical shunts may no longer be necessary due to the development of native cardiac structures, and transcatheter occlusion is preferable over an open surgical approach in some patients. Closure of coronary artery fistulas, aortopulmonary windows, and sinus of Valsalva aneurysms has been successfully performed. Closure is not the only desired result with left-to-right shunts, however, and interventions to maintain surgical or native shunts may also be considered via stent placement. Right-to-left shunts, usually indicated by cyanosis, may also be addressed through transcatheter approach. Pulmonary arteriovenous malformations are the most widely described, and occlusion may be possible with various devices. Arteriovenous malformations may be of several morphologic types with differing etiologies, each of which requires unique considerations in evaluation and treatment. An unroofed coronary sinus to the left atrium provides a pathway for deoxygenated blood to enter the heart directly, and device placement may redirect flow away from the left atrium. Lastly, systemic vein-to-pulmonary vein collaterals and systemic venous collaterals in Glenn circulation may be amenable to intravascular occlusion, physiology permitting.