Effects of phenylephrine and noradrenaline on coronary artery motion in an open-chest porcine beating heart model.

Purpose: During off-pump coronary artery bypass (OPCAB), surgeons are required to perform a precise anastomosis on the beating heart. The hypotension caused by vertical displacement of the heart during OPCAB is usually treated with vasopressors, such as noradrenaline and phenylephrine. However, the effects of these agents on coronary artery motion are unknown. The present study analyzed the motion of the target coronary arteries during noradrenaline or phenylephrine infusion using three-dimensional motion capture and reconstruction technology.

Methods: The left anterior descending (LAD) artery, left circumflex (LCX) artery and right coronary artery (RCA) of 12 female landrace pigs (weight 50 ± 1 kg) were stabilized using a tissue stabilizer. The motions in the regions were captured before and during noradrenaline (n = 5) and phenylephrine (n = 7) infusion.

Results: Noradrenaline (0.15 μg/kg/min) and phenylephrine (1.1 μg/kg/min) significantly increased the blood pressure. Noradrenaline significantly increased the motion parameters, such as the distance moved, maximum velocity, acceleration and deceleration at the LAD (4.2 vs. 7.9 mm, P = 0.025; 95.7 vs. 215.5 mm/s, P = 0.0074; 35.3 vs. 83.6 m/s(2), P = 0.0096 and -35.6 vs. -83.6 m/s(2), P = 0.005, respectively). The values during phenylephrine infusion did not change except for the distance moved at the LAD (3.8 vs. 7.7 mm, P = 0.042). The motion parameters at the LCX and RCA during noradrenaline and phenylephrine infusion did not change significantly.

Conclusions: The effect of phenylephrine on the coronary artery motion was less dramatic than that of noradrenaline.