Anatomical factors influencing fixation of endocardial pacing leads in the right ventricle.

The anatomical factors influencing fixation of endocardial pacing leads were studied in 50 hearts. Many variations were found in the anterior, posterior and septal papillary muscles, interpapillary connections, and the moderator band. Those variations conducive to lead fixation are illustrated. Vertical bands of muscle that could influence lead fixation were seen inside the right ventricle. Variations in the conus papillary muscle and right ventricular outflow tract that facilitate lead fixation are also illustrated. In a few hearts, attention is drawn to slender support of the anterior cusp of the tricuspid valve.