Related Experiment Videos
Sequential deformation and physiological considerations in unipolar right or left ventricular pacing
Oliver J Liakopoulos1, Hideyuki Tomioka, Gerald D Buckberg
1Department of Surgery, Division of Cardiothoracic Surgery, David Geffen School of Medicine at University of California Los Angeles, 10833 Le Conte Avenue, 62-258 CHS, Los Angeles, CA 90095-1741, USA.
Summary
Ventricular pacing disrupts the heart's natural contraction sequence, impairing left ventricular (LV) function. This study shows pacing alters myocardial band shortening and reduces overall cardiac efficiency.
Area of Science:
- Cardiology
- Cardiac Electrophysiology
- Biomedical Engineering
Background:
- The helical ventricular myocardial band is crucial for coordinated left ventricular (LV) contraction.
- Understanding how artificial pacing affects this natural sequence is vital for cardiac health.
Purpose of the Study:
- To investigate the impact of ventricular pacing on the helical ventricular myocardial band's contraction sequence.
- To assess the subsequent effects on overall left ventricular (LV) function.
Main Methods:
- Sonomicrometry was used to measure percent segmental shortening (%SS) in pigs along the LV myocardial band.
- Unipolar pacing electrodes were placed in the right atrium, right ventricular apex (RVA), right ventricular outflow tract (RVOT), or LV posterior wall.
- Systemic hemodynamics, cardiac index (CI), and pressure-dimension (P-D) loops were analyzed.
Main Results:
- Ventricular pacing, unlike atrial pacing, significantly prolonged the QRS-interval and decreased mean arterial pressure, CI, and systolic LV pressure.
- Ventricular pacing reduced %SS in all measured LV segments and disrupted the normal sequence of shortening.
- A loss of the characteristic LV twisting pattern and desynchronized P-D loops were observed.
Conclusions:
- Ventricular pacing significantly disrupts the coordinated shortening sequence of the myocardial band.
- This induced dyssynchrony leads to impaired left ventricular (LV) function and reduced cardiac efficiency.