Left Bundle Area Versus Selective His Bundle Pacing

This is a voluntary research study to find out which location in the heart a pacemaker wire is the most efficient for a patient's heart and for battery life. Patients who volunteer and are eligible for the study will be randomized to receive one of two positions for the wire to be screwed into, in addition to studying multiple positions in the heart during the pacemaker insertion. Enrolled patients will be in the study for 1 year. They will also have an Ultrasound of their heart performed to assess how the pacemaker wire is affecting their heart. Pacemakers are connected to the heart by wires that are screwed into the heart. The wires can be connected to the heart in different places, which can affect how well the heart beats over time. The typical position is at the tip of the heart. This position may cause the heart to beat inefficiently. Over time, this could lead to weakened heart muscle, irregular heart rhythm, and more hospitalizations. The heart has special muscle cells and fibers that carry electrical signals through and around the heart. An alternative spot to place the pacemaker wire is in an area where these special cells are grouped together (called the HIS bundle). The pacemaker wire can be connected to the heart at a location which may allow the heart to beat more efficiently when compared to putting the wire at traditional spots in the heart (called HIS bundle pacing). However, sometimes connecting the wire into the HIS bundle may cause the pacemaker battery to wear out faster. Physicians can also connect the pacemaker wired near the HIS bundle (called Left left Bundle bundle area pacing). The study physicians hope this will allow the heart to beat more efficiently without causing the battery to wear out faster. The study physicians would like to study how different wire positions change heart beat efficiency and how long the pacemaker battery lasts when the wires are placed in different locations. This study will connect the pacemaker wire at either the HIS Bundle or the left bundle area pacing, to see how effectively the heart pumps and how much battery is being used.

This is a single center, open label, prospective randomized pilot study to evaluate the capture threshold of His Bundle versus left bundle area pacing. Secondary analysis will focus on changes in left ventricular performance and mechanical synchrony. Symptomatic bradyarrhythmias are effectively treated with cardiac pacemakers.The amount of pacing by the lead positioned in the bottom chamber of the heart at traditional sites such as the right ventricular apex have been associated with increased rates of atrial fibrillation, heart failure, and mortality. Traditional pacing sites result in cardiac electromechanical dyssynchrony, for which alternate pacing sites to minimize these untoward effects have been sought. HIS bundle pacing, which utilizes a patient's native conduction, has demonstrated improved electrical synchrony and left ventricular function when compared to traditional pacing at the tip of the bottom chamber. Barriers to wide spread application to this technique include the His bundle anatomic location and its attendant difficulties associated with implant, as well as higher capture thresholds leading to decreased battery duration of the pacemaker. An alternative to HIS bundle pacing is placing the lead just past the HIS bundle area, which is further in the heart, and to actively fixate the lead into the interventricular septum. This is referred to as Left Bundle Pacing, as it may electrically capture the left bundle, which would simulate a patient's native conduction. The researchers will evaluate the two different pacing sites (HIS bundle and Left Bundle area sites) to determine how effectively the heart pumps with each pacing site.

Patients requiring pacemaker implant will be screened for study eligibility and approached for informed consent. Baseline assessments including echocardiogram and ECG will be obtained. A standard of care echo done within 3 months of the procedure will be used as the baseline echo. Once enrolled, the researchers will randomize patients to one of two arms. One arm will fixate the ventricular pacemaker lead to the HIS bundle area while the other arm will have the leads fixed into the left bundle area. The pacemaker wires will be connected in accordance with randomization group. The day after the procedure, a chest x-ray, EKG and pacemaker evaluation will be performed. An echocardiogram will be obtained at 3 months post procedure. At 6 and 12 months post procedure, EKG rhythm strips will be obtained from patients' standard of care remote pacemaker monitoring systems.

Eligibility Criteria:
Inclusion Criteria:

1. Over 18 years old.
2. With signed consent.
3. Pacemaker indication according to 2018 American College of Cardiology/American Heart Association/Heart Rhythm Society Guideline on the Evaluation and Management of Patients with Bradycardia and Cardiac Conduction Delay. With one or both of the following:

   1. Symptomatic sinus node dysfunction.
   2. Symptomatic Atrioventricular (AV) block or high degree AV block.
   3. Tachy-Brady syndrome

Exclusion Criteria:

1. Previously implanted cardiac pacing devices except transvenous temporary pacemaker.
2. Patients who are eligible for appropriate cardiac resynchronization therapy(CRT) or implantable cardiovert defibrillator (ICD) implantation
3. Patients with prior septal myectomy
4. Patients with prior surgical or transcatheter aortic valve replacement
5. Anatomy precluding implant evaluated during the screening or identified during the procedure.
6. Those without ability to achieve selective His bundle pacing evaluated during the screening or identified during the procedure
7. Pregnant women