Non-contact left ventricular endocardial mapping in cardiac resynchronisation therapy

Area of Science:

• Cardiology
• Electrophysiology
• Medical Devices

Background:

• Up to 30% of heart failure patients do not respond to cardiac resynchronisation therapy (CRT).
• Suboptimal response may be due to coronary sinus lead placement in slow conduction regions, despite current positioning criteria.
• Identifying these slow conduction areas is crucial for improving CRT efficacy.

Purpose of the Study:

• To characterize left ventricular activation using non-contact mapping during CRT.
• To investigate electrophysiological factors influencing optimal left ventricular lead placement.
• To correlate lead position with conduction velocity and hemodynamic outcomes.

Main Methods:

• Non-contact mapping was used in 10 patients with biventricular pacemakers.
• Conduction velocity was measured in regions with and without the coronary sinus lead.
• Hemodynamic parameters (cardiac output, dP/dt(max)) were assessed under different pacing strategies.

Main Results:

• Six patients had leads in slow conduction regions (0.4 m/s vs. 1.8 m/s in normal regions).
• Pacing outside slow conduction areas significantly reduced left ventricular activation time.
• Optimized biventricular pacing improved mean velocity time integral and fusion of depolarization wavefronts.

Conclusions:

• Non-contact mapping effectively identifies slow conduction zones for CRT lead placement.
• Pacing outside identified slow conduction areas leads to significant hemodynamic improvements.
• Failure to achieve CRT benefits may be overcome by repositioning leads away from slow conduction areas.