Coil Embolization of Patent Ductus Arteriosus (PDA)
Coil embolization of Patent Ductus Arteriosus (PDA) is one of the options for non-surgical closure of ductus. The other non-surgical option is device closure with Amplatzer PDA occluder. Coil embolisation can be done using single or multiple coils, depending on the size of the ductus and ampulla. Single coils can be directly delivered using an introducer sheath. Single coils can also be delivered using a bioptome. Bioptome assisted delivery gives better control. Once the coil is kept in position, a descending aortic angiogram is taken to confirm ductal closure. After confirmation of ductal closure, the coil can be released from the bioptome. Bioptome is also useful while delivering two or more coils intertwined together.
This method of delivering the coil is by the transvenous approach. Initially a Cournand catheter is passed from the right femoral vein through inferior vena cava into right atrium. Then it is passed through right ventricle into the pulmonary artery and into the descending aorta through the ductus. A guide wire is passed into the descending aorta through the catheter and the catheter withdrawn with the wire left in situ. A long sheath is threaded over the guide wire into the descending aorta. Then the coil held at the tip of the bioptome is introduced into the sheath using a loader. Coil is allowed to loop in the descending aorta after introduction through the sheath. Then the whole assembly is pulled back so that all except the proximal half loop of the coil is nicely packed in the ampulla of the ductus. The coil is released after angiographic confirmation of ductal closure as mentioned above. Rarely the coil may embolize into the pulmonary artery branches or descending aortic branches. Embolised coils can be retrieved using wire loop snares, if needed. Sometimes a coil which has embolized into a distal pulmonary artery can be safely left alone. If there is residual ductal flow after coil embolisation, a close follow up is needed to look for hemolysis, which manifests by hemoglobinuria and anemia. If this occurs, the residual duct has to be closed either by additional coil delivery or using a device, which is often difficult. Surgical closure of a residual duct after coil closure is difficult and may need division and suture under cardiopulmonary bypass. Sometimes a small residual shunt seen immediately after coil closure disappears on follow up as clot formation over the coil progresses.