**3. VOM-ETHO procedure**

The technique was pioneered by Valderrabano and coworkers in 2009 [11]. The protocol was studied in 17 dogs. VOM was visualized in 13. The electroanatomical map of left atrium repeated after ethanol infusion demonstrated a new crescentshaped scar extending from mitral annulus in the posterior wall toward left pulmonary veins. To test the feasibility of VOM-ETHO in humans, 6 patients undergoing pulmonary veins antral isolation, had successful VOM cannulation and ethanol infusion with the confirmation of a new scar formation involving the inferoposterior left atrial wall extending toward the left pulmonary veins.

A right jugular approach [11–14] and femoral vein approach [15] have been described for VOM cannulation and alcohol delivery. There are reports of success rate of 74% (23 out 31 patients) for VOM venogram using the right jugular approach and 89% (17 out 19 patients) using the femoral approach. Valderrabano et al. reported that 86% (188 of 218) of the VOM was accessible using a right jugular approach with a LIMA angiographic catheter [16].

The technique for VOM cannulation and ethanol infusion was subsequently well reported by the Bordeaux group [17] demonstrating a high success rate of VOM cannulation of 92.6% (50 of 54) with a femoral approach using the LIMA (left internal mammary artery) catheter (**Figure 2**).
