A Possible Role for Pacing the Left Ventricular Septum in Cardiac Resynchronization Therapy

Area of Science:

• Cardiology
• Electrophysiology
• Medical Devices

Background:

• Cardiac resynchronization therapy (CRT) typically uses biventricular pacing from the right ventricle (RV) and the left ventricular lateral wall (LVlat).
• Left bundle branch block (LBBB) involves significant electrical delay across the ventricular septum, impacting cardiac function.

Purpose of the Study:

• To evaluate left ventricular septal (LVs) pacing as an alternative CRT strategy.
• To assess if LVs pacing avoids coronary sinus and phrenic nerve stimulation.
• To determine if LVs pacing creates a more physiological activation sequence.

Main Methods:

• Animal studies in dogs with LBBB (with and without myocardial infarction) using pacing leads in RA, RV, LVs, and LVlat.
• Hemodynamic and electrical activation synchrony measurements using conductance catheter and epicardial mapping.
• Clinical study in 12 CRT patients comparing RV+LVs pacing with conventional RV+LVlat pacing.

Main Results:

• LVs and RV+LVs pacing demonstrated electrical and hemodynamic benefits comparable to conventional biventricular pacing in canines.
• LVs stimulation reduced repolarization dispersion, unlike LVlat pacing.
• Hemodynamic benefits in patients were similar across RV+LVs, RV+LVlat, and RV+LVlat endocardial pacing.

Conclusions:

• Left ventricular septal pacing is a viable alternative for CRT, offering comparable synchronization and hemodynamic improvements.
• LVs pacing may offer an advantage over epicardial pacing by reducing repolarization dispersion.
• This approach provides an alternative to coronary sinus and phrenic nerve stimulation.