Transmural temporospatial left ventricular activation during pacing from different sites: potential implications for...

Area of Science:

• Cardiology
• Electrophysiology
• Cardiac Pacing

Background:

• Right ventricular (RV) endocardial pacing may negatively impact left ventricular (LV) function, even in patients with normal baseline LV function.
• The underlying mechanisms of RV endocardial pacing-induced LV dysfunction remain unclear.
• Understanding LV activation patterns during different pacing strategies is crucial for optimizing cardiac pacing.

Purpose of the Study:

• To compare left ventricular (LV) transmyocardial activation profiles during normal sinus rhythm versus various cardiac pacing sites.
• To investigate the impact of RV endocardial pacing on LV activation patterns.
• To evaluate alternative pacing sites, including LV septal pacing, for achieving more physiological activation.

Main Methods:

• Mongrel dogs were instrumented with transmural electrodes to record LV activation sequences at five sites.
• Pacing and recording catheters were placed in the RV apex, RV/LV septum, and on the LV epicardium.
• Electrograms were analyzed during sinus rhythm and pacing from RV endocardium, LV septum, LV epicardium, and during biventricular pacing.

Main Results:

• RV endocardial pacing significantly prolonged LV transmural activation compared to normal sinus rhythm (23.0 +/- 2.6 ms vs. 6.1 +/- 1 ms).
• RV endocardial pacing disrupted the ordered temporospatial activation pattern, leading to increased dispersion.
• LV epicardial and biventricular pacing failed to normalize these abnormal activation patterns.
• LV septal pacing demonstrated transmural and transseptal activation sequences similar to normal sinus rhythm.

Conclusions:

• Current cardiac pacing methods, including biventricular pacing, result in abnormal transmyocardial activation patterns.
• LV septal pacing effectively replicates the physiological transmyocardial activation observed during sinus rhythm.
• LV septal pacing may represent a more optimal strategy for preserving LV function during cardiac pacing.