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Published on: December 11, 2017
Effect of myocardial revascularization and vein graft blood flow on pacing function
S E McNulty1, S Goldman, J L Seltzer
1Jefferson Medical College, Thomas Jeffer- son University, Philadelphia, PA 19107, USA.
Insights
Myocardial revascularization impacts pacing function. Changes in vein graft blood flow significantly alter pacing resistance and threshold, offering insights into heart muscle condition.
Area of Science:
- Cardiovascular Surgery
- Electrophysiology
Background:
- Myocardial revascularization aims to restore blood flow to the heart muscle.
- Assessing myocardial condition during cardiac surgery is crucial for patient outcomes.
Purpose of the Study:
- To investigate the effect of aortocoronary bypass vein graft blood flow on cardiac pacing function.
- To determine if pacing variables can indicate myocardial status during cardiopulmonary bypass.
Main Methods:
- Nine patients undergoing aortocoronary bypass were studied.
- Pacing variables (threshold, current, resistance) were measured using a pacing system analyzer.
- Measurements were taken before, during, and after temporary occlusion of vein grafts.
Main Results:
- Significant decreases in resistance (P < 0.003) and threshold (P < 0.03) were observed after establishing vein graft blood flow.
- Temporary interruption of vein graft blood flow led to a significant increase in resistance (P < 0.03).
- All pacing variables returned to baseline upon restoration of blood flow.
Conclusions:
- Pacing function measurements are sensitive to alterations in vein graft blood flow.
- These measurements may offer valuable, real-time information on myocardial condition, particularly before weaning from cardiopulmonary bypass.
Abstract:
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.
