Influence of the right ventricular septum/free-wall boundary (hinge) on differentiation of the ventricular lead implantation site

BACKGROUND

The prognosis associated with right ventricular (RV) free-wall pacing is worse than that of septal pacing. Identification of the pacing site using a 12‑lead electrocardiogram (ECG) is controversial and may be influenced by ECG changes within the same septal or free-wall area. The relationship between the diagnostic capabilities of ECG and pacing sites has previously been qualitatively evaluated. However, in this study, this relationship was analyzed quantitatively, and accurate evaluation of the pacing site was determined using computed tomography (CT).

METHODS

Of 779 consecutive outpatients, 65 who underwent pacemaker implantation and thoracic CT were prospectively included and classified into the following groups according to the lead tip position: free-wall, septal, or septum/free-wall boundary (hinge) group. The hinge was used as an anatomical marker, and the distance from the hinge to the lead tip was measured. Under RV pacing, a 12‑lead ECG was obtained. ECG findings were evaluated using three criteria (including lead I, II, and aV_L and precordial leads V₅ and V₆) previously reported to be useful in differentiating pacing sites.

RESULTS

The lead tips were anchored at the free-wall in 10 patients, the septal wall in 19 patients, and the hinge in 32 patients. Paced QRS duration correlated with the distance from the hinge to the lead tip for the free-wall and septum (r = 0.47 and - 0.68, respectively). Estimation of the lead tip implantation site using the ECG algorithm was useful; however, the algorithm's accuracy decreased around the hinge.

CONCLUSIONS

ECG is useful in differentiating pacing sites but is less accurate around the hinge, which may be the reason that the identification of the RV pacing site using ECG remains controversial.

EHRA expert consensus statement and practical guide on optimal implantation technique for conventional pacemakers and implantable cardioverter-defibrillators: endorsed by the Heart Rhythm Society (HRS), the Asia Pacific Heart Rhythm Society (APHRS), and the Latin-American Heart Rhythm Society (LAHRS)

With the global increase in device implantations, there is a growing need to train physicians to implant pacemakers and implantable cardioverter-defibrillators. Although there are international recommendations for device indications and programming, there is no consensus to date regarding implantation technique. This document is founded on a systematic literature search and review, and on consensus from an international task force. It aims to fill the gap by setting standards for device implantation.