Three-dimensional mapping of optimal left ventricular pacing site for cardiac resynchronization

Area of Science:

• Cardiology
• Biomedical Engineering
• Medical Imaging

Background:

• Cardiac resynchronization therapy (CRT) efficacy relies on precise left ventricular (LV) lead placement within the late-activated region.
• The exact 3D distribution and geographic extent of optimal LV CRT sites are not well understood.

Purpose of the Study:

• To determine the 3D distribution and geographic extent of LV sites that yield optimal CRT.
• To assess if optimal CRT sites differ between normal and failing hearts.

Main Methods:

• Utilized a canine model with normal or failing hearts, induced dyssynchrony via pacing or ablation.
• Employed an epicardial sock with 128 electrodes for biventricular CRT stimulation and recording.
• Assessed global cardiac function (conductance catheter) and mechanical synchrony (MRI tagging) at various LV sites.

Main Results:

• Optimal CRT was consistently achieved from LV lateral wall sites, slightly anterior and apical.
• LV sites providing ≥70% of maximal dP/dtmax increase spanned approximately 43% of the LV free wall.
• This optimal region was similar in normal and failing hearts and correlated with MRI-derived mechanical synchrony maps.

Conclusions:

• Optimized CRT is achievable over a broad area of the LV lateral wall in both nonfailing and failing hearts.
• Modest anterior or posterior deviations from the optimal lateral site can still yield effective CRT.
• Sites maximizing mechanical synchrony generally align with those improving global cardiac function, validating wall motion analysis for CRT optimization.