Short-Term Atrioventricular Sequential Pacing Does Not Adversely Affect Collateral Blood Flow: A Study During Angioplasty

Altered sequence of ventricular activation sequence results in marked derangements in mechanical events. In the present study, we investigated the comparative effects of atrial and AV sequential pacing on collateral blood flow during angioplasty. Twenty-eight patients with stable angina and left anterior descending artery disease undergoing balloon angioplasty were studied. Collateral flow was determined during balloon inflation from the distal flow velocity of the ipsilateral artery (17 patients) or from the increase of the maximal diastolic blood flow velocity (Vc) of the contralateral artery (11 patients). Flow measurements were made using the Doppler flow guidewire. The relative resistance in the collateral vascular bed (RRj also was estimated in the latter group of patients. After the first balloon inflation, two similar consecutive balloon inflations were done under atrial and AV sequential pacing, at a rate of 15 beats/min higher than the sinus rate, in the absence ofvasoactive medication. One minute after the initiation of pacing, the second and third balloon inflations were begun and the pacing continued until the balloon inflations were completed. In the ipsilateral group, average peak velocity was 84.6 t 24.2 mm/s during atrial pacing and 82.7 ± 29.7 mm/s during AV sequential pacing (P = NS). In the contralateral group. Vc was l8%± 12% during atrial pacing and 17%± 14% during AV sequential pacing, and the RR was 4.5 ± 4.7 and 4.9 ± 6.4, respectively (both P = NS). The coronary wedge/mean blood pressure was similar during the two tested balloon inflations. Short-term AV sequential pacing at rest does not adversely affect collateral blood flow and resistance in patients with left anterior descending artery disease.