A 64-year-old male patient with a known history of coronary artery disease had undergone a CRTD implant in November 2015 for IVCD with wide QRS (159 ms), QLV was 102 ms (Fig. 1) and NYHA class III-IV with LVEF 15%. The post-CRT paced ECG showed positive V1 and negative lead I with QRS duration of 160 ms (Fig. 2a). The patient remained symptomatic despite being on optimal medical therapy qualifying as a non-responder. Since the device had reached recommended replacement time (RRT) and patient continued to be symptomatic for HF in NYHA class III with an EF of 15% and pulmonary artery systolic pressure (PASP) 60 mm of Hg, an alternative technique to physiologically pace via the His bundle pacing (HBP)/left bundle branch pacing (LBBP) with appropriately timed pacing of left ventricle (LV) for a narrower fusion complex was considered.
A left axillary/subclavian venogram was taken from peripheral access vein to confirm patency. A significant narrowing at left brachiocephalic and superior vena cava (SVC) junction was seen (Fig. 3 a). A fluoroscopy-guided left subclavian access was obtained using Seldinger technique. A slippery Terumo wire was passed through the venous narrowing and access secured. The previous device was removed and the old leads parameters checked and secured. A fixed-curve sheath (C315 His, Medtronic Inc., Minneapolis, MN) was advanced over long Teflon wire into the right ventricle (RV). The Select Secure lumen less 4.1-F sized, 69-cm length 3830 SelectSecureTM active pacing lead (Medtronic Inc., Minneapolis, MN) was taken into the sheath. The lead was connected to Workmate Claris EP system for intracardiac electrogram (EGM). C315 catheter was pulled back into right atrium (RA) and turned anticlockwise to align it along the upper tricuspid annulus/RA junction. Local EGM showed His bundle potential in unipolar configuration. Pacing was done 5V @ 1 ms, resulting in nonselective HBP pacing. The threshold was 2.5/1 ms. Distal His position was tried but the threshold remained high (Fig. 4). Therefore LBBP was considered alternative and was attempted. The C315 sheath was advanced over the Teflon wire into the apex of right ventricle (RV) in right anterior oblique (RAO) projection along an imaginary line between the His bundle (HB) and RV apex using a road map of initial position of HB. The C315 sheath was positioned along the interventricular septum, 1–1.5 cm below the HB position but the lead could not be screwed into the left bundle as there was reverse transfer of the torque. Keeping in view the possibility of basal septal scar, posterior fascicle pacing was attempted by targeting the mid and posterior septum. Up to four sites including a distal part of septum were tried but lead did not advance beyond the initial one or two turns. In view of the possibility of tissue in helix of lead, it was cleaned of tissue bites after every attempt. Challenge was predominantly reaching mid-myocardial. Some maneuvers were done to let lead jump across the mid-myocardial scar and fall into LBB area like giving rapid turns with some force on the sheath but were not successful. After the failure to achieve LBBP, we returned to mapping the HB region, in search of a better pacing threshold. With some effort, we could find a spot with good local HB potential below the tricuspid valve with a pacing threshold of 1.7 @ 1 ms. R wave obtained at this position was 9 mV. The lead was given a 5–6 clockwise turn to fix at HB (Fig. 3c, d).
The HB lead was attached in RV pacing port (DF1 RV lead), coronary sinus (CS) lead in LV port, and RA lead in atrial port in the new pulse generator. Previous RV pace-sense lead terminal was buried deep in the pocket. The pre-pectoral device pocket was closed in three layers; DFT (defibrillation threshold test) was not done as per protocol.
The strategy of fused complex was employed whereby LV pacing timing was delayed, relative to HBP output (Fig. 5). A narrow (106 ms) complex QRS was achieved with an AV delay of 80 ms and HBP-LV delay of 40 ms (Fig. 2b). QRS resulting from HBP + LV pacing (106 ms) and only LV pacing (138 ms) is shown in Fig. 5. At 6 months follow-up, patient showed improvement to functional NYHA class I-II and 2D echo showed LVEF 30% with PASP of 25 mm of Hg.
