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Implication of myocardial lactate metabolism during coronary artery bypass grafting
1Cardiovascular Surgery, Cardiac Center, Iizuka Hospital, Yoshio-Machi, Japan.
Insights
Patients with left main coronary artery disease experience significant myocardial ischemia during cardiac surgery's empty beating phase. This can be dangerous if prolonged, despite short-term functional recovery.
Area of Science:
- Cardiology
- Cardiac Surgery
- Cardiovascular Physiology
Background:
- Coronary artery disease (CAD) affects myocardial function during cardiac surgery.
- Left main coronary artery disease (LMCAD) presents unique challenges during surgical procedures.
Purpose of the Study:
- To analyze myocardial lactate extraction in patients with and without LMCAD during cardiac surgery.
- To assess the impact of the empty beating state on myocardial ischemia in LMCAD patients.
Main Methods:
- Analysis of 66 consecutive CAD patients, with 16 having LMCAD.
- Measurement of myocardial lactate extraction during the empty beating phase and reperfusion.
- Comparison of hemodynamic parameters including hemoglobin levels and left ventricular stroke work index.
Main Results:
- Patients with LMCAD showed significantly negative myocardial lactate extraction (-29.8%) during the empty beating state, unlike those without LMCAD (12.0%).
- No significant differences in lactate extraction were observed during reperfusion.
- Hemoglobin levels dropped significantly during cardiopulmonary bypass in both groups.
Conclusions:
- The empty beating state prior to aortic clamping can induce significant myocardial ischemia in LMCAD patients.
- While short ischemic periods may not impair functional recovery, prolonged ischemia in LMCAD is potentially dangerous.
Abstract:
Sixty-six consecutive patients with coronary artery disease were analysed in terms of myocardial lactate extraction during cardiac surgery. Sixteen patients had left main coronary heart disease and 50 were without such disease. Mean (s.d.) lactate extraction during empty beating in patients with and without left main coronary tract disease was -29.8(67)% and 12.0(15.3)%, respectively (P<0.001). No significant differences in lactate extraction were recognized during 15 min of reperfusion. Mean (s.d.) preoperative values of haemoglobin were 11.2(1.0) g/dl and these fell to 6.5(0.9) g/dl in an empty beating state during cardiopulmonary bypass (P<0.001). There was no significant difference between the two groups in preoperative and postoperative left ventricular stroke work index. An empty beating state before aortic clamping could induce unexpected ischaemia in the heart with left main coronary tract disease. A short duration of this ischaemic state does not influence functional recovery; however, exposing the left main coronary artery diseased heart to such a condition for long periods would be dangerous.