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.

Prior to enrollment, the patient would have received Biotronik pacemaker with His bundle lead placement for at least 30 days and CLS will be programmed ON for at least 7 days as part of routine care.

Exercise testing will be scheduled on the same day as the enrollment visit and within 30 days after post-implant visit. The standard protocol will be typically set at an initial workload of 15Watts and go up by increments of 10 Watts every 3 minutes, as follows: Stage 1 - 15 W Stage 2 - 25 W Stage 3 - 35 W Stage 4 - 45 W

CLS rate response will be analyzed individually for each subject by comparing the CLS response, which is collected by the CLS Action Log, to heart rate information.

Inclusion Criteria: Documented sinus node dysfunction Biotronik pacemaker implanted with His bundle lead placement for standard indications Implanted at least 30 days CLS has been enabled for at least 7 days or will be programmed ON for at least 7 days prior to exercise test Leads and device are functioning appropriately Exclusion Criteria: Inability to complete treadmill/bicycle exercise test Planned surgical revision or replacement of the device and/or leads Patients who are unwilling or unable to provide informed consent