RF wire recanalization has been successfully used to treat pulmonary atresia, to create atrial septal perforation, to recanalize completely occluded thoracic aorta and to recanalize chronic or malignant central venous obstructions after failure of conventional endovascular techniques (Guimaraes et al., 2012; Auyang et al., 2018). In these studies, RF wire successfully recanalized upto 10 cm long chronic occlusions within SV, BV and SVC (Guimaraes et al., 2012). However use of RF wire to cross long IVC occlusions has not been reported. Anticipated obstacles for RF wire recanalization were long course of IVC, tough organized scar tissue within these chronic occlusions, risk of damaging critical neighboring structures due to high penetrability and flexibility of RF wire tip, and constant destabilization of RF wire tip due to motion of the heart.
In order to safeguard neighboring critical structures, we used following techniques. We placed indicator VCF-1 catheter in the aorta and constantly monitored Power wire tip to avoid deviation towards periaortic area. Unpredictable movement of the RF wire tip was a major concern while crossing long occlusive segment in caudal to cranial direction, especially when the flexible tip moves away from the power generator towards the beating heart. Use of steerable sheath allowed us to have better control of RF wire tip. Also by placing a 25 mm snare tip at the IVC-atrial junction, Power wire trajectory was given a precise target.
Due to easy penetrability of heated tip of RF wire, prior studies used techniques such as short duration of RF energy delivery and very small advancements of RF wire tip (Guimaraes et al., 2012). We used 300 milliseconds duration RF delivery pulse and traversed only 2 mm during each pulse. After 2 mm cranial advancement, multiple real time anteroposterior (AP) & oblique views were obtained to confirm the intraluminal location of RF wire. Use of cone beam CT could be an additional safe alternative to monitor the RF wire trajectory (Auyang et al., 2018).
Multiple cranial and/or femoral access approaches have been reported in the literature to treat chronic complex central venous occlusions (Massmann et al., 2016). We chose combined femoral and transhepatic approach due to simultaneous presence of SVC obstruction. Transhepatically placed snare not only helped us to direct the trajectory of RF wire but also to ensnare tip of the RF wire. As the wire crossed the intrahepatic IVC obstruction, we snared the tip of the wire and then advanced the IMA catheter containing goose neck snare into the right atrium. This maneuver allowed the safe and predictable passage of snared Power wire from intrahepatic IVC to right atrium, in the vicinity of beating heart. Thus with the use of appropriate techniques; Power wire recanalization of long occlusive segment of IVC has shown to be safe and effective.