PV Loops With CNT in Multiple Pacing Sites

Inclusion Criteria: * Subject is ≥ 18 years of age. * Subject is indicated for an implant or a replacement with a planned upgrade of a device capable of pacing (pacemaker, ICD, CRT-P, CRT-D). * Subject is willing and able to comply with the study procedures. Exclusion Criteria: * Subject is dependent on 100% ventricular pacing. * Subject has symptoms of heart failure, NYHA Class III or greater * Subject has an ejection fraction of 25% or less * Subject's systolic blood pressure is less than 100 mmHg on the day of implant * Subject has decompensated heart failure * Subject has significant (\>2+) valvular regurgitation or any valvular stenosis. * Subject has permanent atrial fibrillation * Subject has atrial fibrillation on the day of the study. * Subject has hypertrophic cardiomyopathy, restrictive cardiomyopathy, or interventricular septal thickness ≥15 mm * Subject is on dialysis * Subject has a history of prior neurological events (stroke or TIA) within the past year or a neurological event (stroke) at any prior time that has resulted in residual neurologic deficit. * Subject has a history of autonomic dysfunction * Patient cannot receive heparin for any reason (such as a history of Heparin induced thrombocytopenia (HIT)) * Women who are pregnant or breast-feeding * Subject cannot or is unwilling to provide informed consent.