Acute Effects of Pacing at Different Ventricular Sites on Left Ventricular Rotational Mechanics in a Porcine Model

作者：Zhou Wei; Benharash Peyman; Chua Jason Han; Nakahara Shiro; Ho Jonathan K; Mahajan Aman^*

来源：Journal of Cardiothoracic and Vascular Anesthesia, 2015, 29(5): 1148-1154.

DOI：10.1053/j.jvca.2014.12.008

• ventricular tachycardia
• pacing site
• LV twist
• synchrony

Objective: The purpose of this study was to examine the acute effects of pacing at different ventricular sites on hemodynamics and left ventricular (LV) rotational mechanics using speckle-tracking echocardiography (STE) in a porcine model.
Design: A prospective laboratory investigation.
Setting: University research laboratory.
Participants: Yorkshire pigs.
Interventions: In 9 pigs, after midline sternotomy, epicardial pacing was performed from the right ventricular outflow tract (RVOT), right ventricular apex (RVA), and LV free wall.
Measurements and Main Results: Two-dimensional STE and conductance catheter-derived LV pressure-volume measurements were made to determine the impact of pacing from various sites on LV rotational parameters (twist/untwist) and hemodynamics. RVOT pacing caused the least decrease in end-systolic pressure from baseline (-9.5%), when compared with RVA (-19.1%) and LV (-23.4%). Systolic and diastolic parameters (Emax, Tau) also were different among RVOT (4.7 +/- 0.8 mmHg/mL, 32 +/- 4 ms), RVA (3.9 +/- 0.7 mmHg/mL, 37 +/- 6 ms), and LV sites (3.6 +/- 0.8 mmHg/mL, 42 +/- 7 ms). Similar to the effects of pacing on hemodynamics, RVOT pacing better preserved LV twist (11.1 +/- 1.8 v8.6 +/- 1.7, 5.9 +/- 0.7 degrees) and untwisting rate (64.6 +/- 8.5 v 56.2 +/- 5.3, 48.2 +/- 8.5 degrees/s) when compared with RV apical pacing and LV pacing. Furthermore, prolongation of conduction from LV lateral to anteroseptal at LV base (26.5 +/- 3.8 v 13.8 +/- 3.3 ms, p < 0.05) and LV midpapillary muscle level (35.6 +/- 5.6 v 14.1 +/- 2.4 ms, p < 0.05) was observed with LV pacing compared with RVOT pacing.
Conclusions: The present data showed that the LV twist/untwist and cardiac systolic and diastolic function were least affected by RVOT pacing. This finding may be explained by the proximity of this location to the native ventricular conduction system.

• 出版日期2015-10