Abstract
Aims: Right ventricular pacing results in a prolongation of the left ventricular activation time, which is attributed to delayed activation of the left ventricular lateral wall. Left ventricular activation time has only been indirectly recorded in human subjects. The objective of this study was to model to directly measure left ventricular activation time utilizing a novel left lateral accessory pathway model and assess its shortening with His-bundle pacing, a proposed physiological pacing modality. Materials and Methods: Consecutive adults with a pure retrograde conducting left lateral accessory pathway and both His-bundle as well as isolated myocardial capture were included. The interval from the pacing stimulus to the atrial activation in the left lateral region was measured as the left ventricular activation time, which was then compared during His-bundle versus myocardial pacing using paired t-test for means. Results: A total of 50 subjects were found eligible for inclusion (Males=27; mean age=39±14). His-bundle pacing resulted in a significant reduction of left ventricular activation time when compared to myocardial pacing (122±15 vs 152±17; p<0.001). Conclusion: Left ventricular activation time can be directly recorded in human subjects utilizing a pure-retrograde left lateral accessory pathway model and is significantly reduced with His-bundle pacing.
Highlights
Ventricular pacing should be as physiological as possible to prevent dyssynchrony and consequent ventricular dysfunction
Non-physiological pacing modalities, such as right ventricular pacing, have many negative hemodynamic effects that have been attributed to delayed activation of the left ventricular free wall [1] and the resultant increase in left ventricular activation time (LVAT)
Several methods have been used to measure LVAT in humans, including experimental techniques [5] as well as indirect measurements using three-dimensional electroanatomic mapping [6] and ventricular electrograms recorded from the coronary sinus [7]
Summary
Ventricular pacing should be as physiological as possible to prevent dyssynchrony and consequent ventricular dysfunction. Non-physiological pacing modalities, such as right ventricular pacing, have many negative hemodynamic effects that have been attributed to delayed activation of the left ventricular free wall [1] and the resultant increase in left ventricular activation time (LVAT). Direct His-bundle [2,3] and para-His [4] pacing with His bundle capture have been suggested as strategies to preserve the normal activation sequence and maintain synchrony by reducing LVAT. LVAT may be superior to surface ECG in the assessment of left ventricular synchrony and its accurate measurement may help predict response to physiological pacing modalities as well as cardiac resynchronization therapy. LVAT has not been directly recorded in human subjects. We utilized a novel left lateral accessory pathway (LLAP) model to directly measure LVAT in human subjects. Shortening of LVAT with His-bundle pacing as compared to direct myocardial pacing was assessed using this model
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