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Do coronary bypass graft flows differ between on-pump and off-pump operations?
Yves A G Louagie1, Jacques Jamart, André Gruslin
1Department of Cardiovascular and Thoracic Surgery, University Clinics of Mont Godinne, Université Catholique de Louvain, Yvoir, Belgium. louagie@chir.ucl.ac.be
The Annals of Thoracic Surgery
|May 28, 2005
Summary
Off-pump coronary bypass surgery shows lower graft flow velocity and higher resistance compared to on-pump surgery, primarily due to hematocrit changes from hemodilution.
Area of Science:
- Cardiovascular Surgery
- Hemodynamics
- Bypass Grafting
Background:
- Coronary artery bypass grafting (CABG) is a common procedure.
- On-pump CABG uses cardiopulmonary bypass, while off-pump CABG does not.
- Hemodynamic differences between these techniques require investigation.
Purpose of the Study:
- To compare hemodynamic parameters in coronary bypass grafts between on-pump and off-pump CABG.
- To identify factors influencing graft performance in both surgical approaches.
Main Methods:
- Two propensity score-matched cohorts of 89 patients each were analyzed.
- 408 dual beam Doppler flow measurements were obtained from patent, single terminolateral bypass grafts.
- Hemodynamic factors including flow, velocity, resistance, and pulsatility index were measured.
Main Results:
- Off-pump grafts exhibited lower flow velocity (20.5 cm/s vs 23.8 cm/s) and higher resistance (1.76 vs 1.50 mm Hg/(mL/min(-1))) compared to on-pump grafts (p<0.05).
- Hematocrit levels were significantly higher in the off-pump group (32.9% vs 23.5%, p<0.001).
- Hematocrit was the primary determinant of flow and velocity, with no significant differences in graft hemodynamics when hematocrit was matched.
Conclusions:
- Off-pump CABG is associated with reduced graft flow velocity and increased resistance, largely attributable to hemodilution-induced changes in hematocrit and viscosity.
- These findings highlight the impact of intraoperative fluid management on graft performance.
- Optimizing hematocrit may be crucial for improving off-pump graft outcomes.