Circulation 112:1580–1586Īranda JM, Conti JB, Johnson JW et al (2004) Cardiac resynchronization therapy in patients with heart failure and conduction abnormalities other than left bundle-branch block: analysis of the multicenter InSync randomized clinical evaluation (MIRACLE). Yu CM, Bleeker GB, Fung JW-H et al (2005) Left ventricular reverse remodeling but not clinical improvement predicts long-term survival after cardiac resynchronization therapy. This experience highlights the importance of assessing the interventricular septum (IVS) anatomy by echocardiography, fluoroscopy, or may be cardiac MRI before proceeding with the case. In our case, it was extensive calcification, due to which the clockwise torque on the lead instead of being transmitted forward for penetration was coming back causing the lead to make multiple turns and get entangled (Fig. This challenge can happen with interstitial fibrosis or scar or thickness or unusual orientation in dilated heart or calcification of septum. It is important to orient the sheath perpendicular to the septum and maintain the counter clockwise torque on the sheath during lead placement (hub must point towards 3’O clock position). The reasons for failure are inadequate sheath support, improper sheath-septum orientation, failure to penetrate the lead deep into the septum, tissue lodged in the helix, septal scar, or entanglement of septal tricuspid leaflet. The reported success rate of LBBP in various reports is between 80.5 and 93%. We failed to penetrate the mid-myocardial septum to reach the LV side of the septum to selectively pace the LBB. In this case interestingly, we encountered a very rare but not yet reported limitation of the current hardware for LBBP. With this premise, we attempted physiological pacing using HOT-CRT strategy. However, a recent demonstration of significant narrowing of QRS duration and improvement in LVEF in patients with RBBB by HBP has paved the way for such technique in these groups of patients as well.
In addition, the evidence for CRT in patients with non-specific IVCD with wide QRS and RBBB is sparse with conflicting results. 3c, d).Ībout 30–50% of patients with HF who meet the criteria do not benefit by CRT. The lead was given a 5–6 clockwise turn to fix at HB (Fig. R wave obtained at this position was 9 mV. 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. After the failure to achieve LBBP, we returned to mapping the HB region, in search of a better pacing threshold. 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. Challenge was predominantly reaching mid-myocardial. In view of the possibility of tissue in helix of lead, it was cleaned of tissue bites after every attempt. Up to four sites including a distal part of septum were tried but lead did not advance beyond the initial one or two turns. Keeping in view the possibility of basal septal scar, posterior fascicle pacing was attempted by targeting the mid and posterior septum. 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. 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. Therefore LBBP was considered alternative and was attempted. Distal His position was tried but the threshold remained high (Fig. Pacing was done 5V 1 ms, resulting in nonselective HBP pacing. Local EGM showed His bundle potential in unipolar configuration. C315 catheter was pulled back into right atrium (RA) and turned anticlockwise to align it along the upper tricuspid annulus/RA junction. The lead was connected to Workmate Claris EP system for intracardiac electrogram (EGM). 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. A fixed-curve sheath (C315 His, Medtronic Inc., Minneapolis, MN) was advanced over long Teflon wire into the right ventricle (RV). The previous device was removed and the old leads parameters checked and secured. A slippery Terumo wire was passed through the venous narrowing and access secured. A fluoroscopy-guided left subclavian access was obtained using Seldinger technique. A significant narrowing at left brachiocephalic and superior vena cava (SVC) junction was seen (Fig. A left axillary/subclavian venogram was taken from peripheral access vein to confirm patency.
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