Background: Veno-venous collaterals negatively affect the outcome after cavopulmonary connections (PCPC; TCPC) in univentricular heart (UVH) patients. However, there is no consensus on how and when to treat those abnormal vessels. We aimed to study the anatomical variations, hemodynamic effects, devices and techniques used for closure of veno-venous collaterals detected at various stages of UVH palliation.
Method: Retrospective descriptive study including all patients after PCPC and/or TCPC who suffered from arterial oxygen desaturation at the German Heart Center Munich from 2012 to 2022. Desaturation was defined as arterial oxygen saturation below 90% after TCPC and below 80% after PCPC.
Results: The study group consisted of 53 patients in whom 78 cardiac catheterizations were done: 46 after PCPC (median weight: 6.9 kg; range: 4.8–10.6 kg, mean PA pressure: 12.5 ± 2.6 mm Hg) and 32 after TCPC (median weight: 15 kg; range: 11.7–42 kg, mean PA pressure: 13.7 ± 3.6 mm Hg). A total of 134 veno-venous collaterals were detected; 49/134 (36%) originated from the innominate vein angle, 43/134 (32%) from the brachiocephalic veins, and the rest (42) had various origins. A total of 106 collaterals were successfully closed by using 86 coils and 20 devices. The morphology of the collaterals determined the type of the occlusion coils/device. Nester coils were the most commonly used coils (n = 42) followed by detachable or micro coils. Tortuous collaterals with distant target zones were closed by micro-coils, which can be deployed through a microcatheter as distal as possible. AVPII was the most commonly used device (n = 13). The median coil/collateral size ratio in our study was 1.33 (1.2–2) and the median device/ collateral size ratio was 1.2 (0.53–1.4). The mean increase in oxygen saturation was 14 ± 10% from the baseline readings (p ˂ 0.001). Small residual shunts were found in two patients. Embolization of coils with successful retrieval occurred in two patients.
Conclusion: Veno-venous collaterals are the most important cause of desaturation after surgical UVH palliation and may even be an emergency indication early after surgery. During routine pre-TCPC cardiac catheterization veno-venous collaterals with connection to the pulmonary venous system should be closed. Selection of the coil/device type and size depends mainly on the size of the venous collaterals regardless of the stage of UVH palliation. The risk of embolization was lower with hydrogel expandable coils due to the controlled release mechanism.
