Effect of myocardial revascularization and vein graft blood flow on pacing function.
The effect of myocardial revascularization and vein graft blood flow on pacing function was determined in nine patients undergoing aortocoronary bypass. Pacing variables including threshold, current, and resistance were measured with a pacing system analyzer during intermittent pacing with a transluminal bipolar ventricular pacing probe. Pacing function was analyzed immediately before cardiopulmonary bypass (CPB) and compared with measurements taken eight minutes after full flow through the vein grafts had been established. Comparison of these two times showed a significant decrease in resistance, P < 0.003, and threshold, P < 0.03. After the second measurement, left anterior descending (n = 8), or right coronary (n = 1) vein graft blood flow was interrupted. Pacing variables were analyzed at one minute, two minutes, and four minutes following vein graft clamping; and a final set of measurements was obtained one minute following release of the vein graft clamp. Threshold increased but did not reach statistical significance. Resistance increased significantly: P < 0.03. All values returned to baseline following release of the vein graft clamp and full return of blood flow. The results of this study suggest that pacing function measurements are sensitive to changes in vein graft blood flow and may provide useful information about the condition of the myocardium, especially immediately prior to weaning from CPB.
McNulty
S E
SE
Jefferson Medical College, Thomas Jeffer- son University, Philadelphia, PA 19107, USA.
Goldman
S
S
Seltzer
J L
JL
D002304:Cardiac Pacing, Artificial; D002315:Cardiopulmonary Bypass; D001026:Coronary Artery Bypass; D003326:Coronary Circulation; D004562:Electrocardiography; D006801:Humans