Effectiveness of Closed Loop Stimulation (CLS) With His Bundle Lead Placement

This study is a prospective, non-randomized pilot study looking to evaluate the effectiveness of Closed Loop Stimulation (CLS) in sinus node dysfunction patients with HIS bundle placement. Patients with sinus node dysfunction who have previously received a Biotronik pacemaker with His bundle lead placement as part of routine care will be recruited for the study. A hand-grip exercise will be performed at the conclusion of bicycle exercise testing in order to assess the performance of CLS during isometric exercise. After the study exercise testing is completed, data will be collected from the pacemaker.