Transthoracic Three-dimensional Echocardiographic Phenotyping of Pacemaker Lead Position: Defining “Danger Zones” for Tricuspid Regurgitation and Right Ventricular Remodeling

Background: Transvenous permanent pacemaker (PPM) leads are an important, potentially modifiable cause of tricuspid regurgitation (TR), but conventional two-dimensional (2D) echocardiography often cannot define the mechanism of valve–lead interaction. Transthoracic three-dimensional (3D) echocardiography can provide an en face view of the tricuspid valve and lead trajectory in routine practice. Objectives: To use transthoracic 3D echocardiography to classify pacemaker lead position at the tricuspid valve, evaluate its association with TR severity, and quantify its impact on right-sided pressures and remodeling. Methods: In a single-center cross-sectional study, 31 consecutive patients with transvenous PPMs underwent standard echocardiography with an additional apical full-volume 3D acquisition. Datasets were cropped to a right-atrial “surgeon’s view”, and lead position was categorized as Central, Commissural, or Impinging. TR was graded using American Society of Echocardiography-recommended 2D criteria. Right ventricular systolic pressure (RVSP), right atrial (RA) and right ventricular (RV) dilatation, and Tricuspid annular plane systolic excursion were recorded. Results: Valid 3D lead localization was achieved in 30/31 patients: Central 11 (36.7%), commissural 11 (36.7%), impinging 8 (26.7%). All central leads had only trace–mild TR, whereas all Impinging leads had moderate–severe TR; Commissural leads showed an intermediate distribution (45.5% moderate–severe; P < 0.001). Mean RVSP increased stepwise from Central (30.0 ± 3.1 mmHg) to Commissural (44.2 ± 12.7 mmHg) to Impinging (51.6 ± 12.7 mmHg; P < 0.001). RA and RV dilatation were much more frequent with Impinging than with Central leads (75% vs. 0% and 50% vs. 0%, respectively). Conclusions: A simple transthoracic 3D protocol identifies central “safety” and impingement “danger” zones with clear gradients in TR and right-heart load.