A 56-year-old man with New York Heart Association class II heart failure and moderate mitral regurgitation underwent balloon cryoablation for atrial fibrillation. Unsatisfactory nadir temperatures were obtained in the left veins (left superior pulmonary vein: −29, −36, and −37°C, left inferior pulmonary vein: −39 and −33°C) despite optimal venous occlusion. In contrast, much colder nadir temperatures obtained in the right veins (right superior pulmonary vein: −53 and −51°C; right inferior pulmonary vein: −54 and −52°C). Assessment of pulmonary vein conduction using a circular mapping catheter demonstrated persisting electrical connections of the left veins and electrical isolation of the right veins. Radiofrequency ablation was required to complete isolation of the left veins.
Transoesophageal echocardiography during cryoablation demonstrated functional mitral regurgitation with a large regurgitant directed towards the left-sided veins and away from the right-sided veins (Figure). We theorize that failure to achieve adequate balloon and tissue temperatures in the left-sided veins was caused by the warming effect of the left-directed mitral regurgitant jet.
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