B-po03-011 complete heart block. . .why now?

A 40 yo female with a history of hypertrophic obstructive cardiomyopathy (HOCM) s/p myectomy (age 17), LBBB, and VT s/p dual chamber ICD presented with lead abnormalities. RA lead showed chronically high impedance and threshold and RV lead showed noise. She was referred for extraction and re-implant of a subcutaneous ICD (S-ICD). S-ICD was chosen given < 1% historical RV pacing. N/A N/A In the OR, femoral venous access was obtained, and sheaths placed. A loop snare and deflectable EP catheter were advanced to the level of the IVC/RA junction and secured around the RV lead. The RA lead was fractured prohibiting placement of a stylet. A locking stylet was placed in the RV lead. A 14 Fr laser was used to begin to free the RV lead. At the first point of significant traction with the snare and the laser, which remained in the subclavian vein, the patient went in to CHB. Trans-cutaneous pacing was initiated, but unsuccessful, prompting chest compressions and placement of a pacing catheter in the RV. Compressions lasted approximately 2 minutes and were stopped after pacing capture was confirmed. The procedure was resumed and re-attempt at laser removal of the RV lead was made, however, the coil separated and the lead disintegrated. Further attempts were abandoned. Removal of the RA lead was difficult, as it appeared to wrap around the SVC coil. Ultimately, counter traction with a snare from below freed the lead, and it was removed from the groin. Post extraction, the patient remained in CHB. Given her history of rare pacing needs, it was felt her AV conduction would recover and therefore a single chamber ICD was implanted. Our HOCM patient presented with LBBB, no prior pacing needs, and a plan to proceed with S-ICD post extraction. It is unclear as to the exact mechanism of the patient's CHB, as this occurred with mere movement of the lead with a snare and modest traction, prior to any substantial manual traction being applied or removal of the RV lead from the endocardial tissue. The CHB was assumed to be temporary, and therefore a single chamber ICD was implanted with the expectation that her native conduction would recover. At her most recent follow up (8 months), conduction had not recovered, and she underwent upgrade of her single chamber ICD to a dual chamber.