VOM ethanol infusion
VOM ethanol infusion was performed prior to transseptal puncture and systemic heparinization in the first several cases but following left atrial mapping in the subsequent ones. From a femoral approach, the CS was cannulated with an SL-2 sheath over a deflectable decapolar catheter. A floppy tip straight 0.35” guidewire (MagicTorque, Boston Scientific or Wholey wire, Medtronic) was advanced passed Vieussens valve into the great cardiac vein to retain access and a venogram was performed through the sheath in the right anterior oblique projection to highlight the VOM. Often the VOM was not identifiable on venography but was subsequently found either proximal to the sheath tip or just proximal to Vieussens valve. An IMA guide catheter was carefully advanced over another 0.35” guidewire into the CS. The guidewire was then exchanged for an 0.14” angioplasty wire preloaded with an over the wire balloon to occlude the proximal VOM (1.5mm-2.5mm range though typically 2mm, Emerge Dilation catheter, Boston Scientific). An 0.14” PT Graphix wire (Straight tip, 300cm, Boston Scientific) was used for the initial cases but all subsequent ones were performed with the low tip weight Suoh wire (0.3 gf, Asahi) to virtually eliminate the risk of wire perforation. After VOM ethanol infusion, CS ablation was systematically performed through the SL-2 sheath. A rare subset of cases were performed from a superior approach, including the initial case in the series as well as subsequent ones wherein the VOM could not be stably cannulated from a femoral approach. After proximal VOM occlusion, a selective venogram was performed and up to 4 injections of anhydrous ethanol were performed of 1-3 cc, each over 30-60 seconds. Echogenicity was usually noted on ICE and a low voltage zone of varying size and confluency was demonstrated on electroanatomical mapping. VOM venograms were not systemically performed between ethanol injections, fearing additive risk of dissection of the VOM from viscous iodinated contrast unless there was suspicion of poor occlusion, balloon movement, or dissection, particularly in the absence of a significant ethanol response. Due to a series of dissections noted on initial venography and the delayed pericardial effusions noted in this study, for the final twenty one cases in the series, systematic use of the initial VOM venogram was abandoned unless prompted by concern of poor ethanol delivery on imaging or mapping due to the perceived dissection risks from brisk injections of contrast.