Conduction system pacing in difficult cardiac anatomies: Systematic approach with the 3D electroanatomic mapping guide

Abstract

Introduction: Restoring physiological cardiac electrical activity in patients with conduction disease can be crucial for the survival and quality of life. Conduction system pacing (CSP) is a valuable option, although it is limited by technical challenges in difficult anatomies. 3D electroanatomical mapping (3D-EAM) can support CSP ensuring high electro-anatomical precision and low fluoroscopy.

Objectives: We evaluated the feasibility and effectiveness of a systematic 3D-EAM use to guide CSP in difficult anatomical scenarios (highly dilated atria, congenital cardiomyopathies, failed biventricular implants (BiV) and pacing-induced cardiomyopathy (PICM)).

Methods: Forty-three consecutive patients (27 males, 75 ± 10 years old) with standard pacing indications and difficult anatomical scenarios were included. The right atrium, His cloud, and atrio-ventricular septum were reconstructed by 3D-EAM. The His bundle (HB) was the initial target, while left bundle branch area pacing (LBBAP) was aimed at in case of unsatisfactory parameters, sub-optimally paced QRS, or impossibility of reaching the HB.

Results: CSP was successful in 37 (86%) patients (15 HBP; 22 LBBAP). Mean mapping, fluoroscopy, and procedural times were 18 ± 7 min, 7 ± 5 min, 98 ± 47 min, respectively. The mean pacing threshold, R wave sensing, and pacing impedance of CSP lead were 1.2 ± 0.5V@0.5ms, 11.4 ± 6.2 mV, 736 ± 306 Ω, respectively. Baseline and paced QRS were 139 ± 38 ms and 114 ± 23 ms, respectively. No procedural complications were observed.

Conclusions: 3D-EAM allowed the accurate definition of the His cloud and high ventricular septum and effectively guided CSP. It facilitated CSP in complex anatomies, with a procedural success rate of 86%. The results were satisfactory and reproducible, with acceptable fluoroscopy and procedural times.

Fig. 1

3D-EAM implant procedure step-by-step. Panel A shows the left anterior oblique view and Panel B shows the right anterior oblique view of the right atrium reconstructed by the mapping catheter. The mapping catheter is connected to both the mapping system and the EP recording system. Red traces in Panels A and B show the electrical signals visualized on the 3D-EAM. "His cloud" is the map of the entire HB potentials recorded. Panels C, D, E: 12-lead ECG together with the electrical signals recorder from the decapolar mapping catheter as visualized in the EP recording system. Based on the A:V ratio and the HV interval, the proximal, medium, and distal parts of the His Bundle were distinguished and different colors in the His cloud were assigned correspondingly. Panel F: 12-lead ECG and “ENDO” signals, which is the unipolar signals recorded from the tip of the pacing lead positioned on the His cloud. The lead is also visualized in Panels A and B as the green tip and the terminal part of the catheter. Panel G: the pacing maneuvers at implant. Starting from high voltage (5V@0.5ms), the output is decreased until the loss of capture (1.1V@0.5 ms) is reached. At 1.3V@0.5 ms corresponds to QRS-paced morphology change, which identify non-selective His Bundle capture. Baseline QRS duration is 108 ms, paced QRS during non-selective HBP is 110 ms. CS: coronary sinus; SVC: superior vena cava; IVC: inferior vena cava; TV: tricuspid annulus. A: atrial signal; H: His signal; V: ventricular signal.

Fig. 2

The His cloud is represented by multiple tags in different colors to distinguish His proximal, His medium, and His distal based on the HV duration and the A:V ratio of the recorded electrical signals. Panel A is the left anterior oblique view, and panel B is the right anterior oblique view of the anatomical reconstruction of the right atrium. The yellow tags correspond to His proximal, where the HV interval is measured at 101 ms. Green tags correspond to His distal, where HV interval is measured at 64 ms.