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THE JOURNAL OF CARDIOVASCULAR SURGERY
Rivista di Chirurgia Cardiaca, Vascolare e Toracica
Indexed/Abstracted in: BIOSIS Previews, Current Contents/Clinical Medicine, EMBASE, PubMed/MEDLINE, Science Citation Index Expanded (SciSearch), Scopus
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ORIGINAL ARTICLES CARDIAC SECTION
The Journal of Cardiovascular Surgery 2006 June;47(3):305-13
Myocardial metabolism before and after valve replacement for aortic stenosis
Vánky F. B. 1, Håkanson E. 2, Szabó Z. 2, Jorfeldt L. 3, Svedjeholm R. 1
1 Department of Cardiothoracic Surgery Linköping Heart Center University Hospital, Linköping, Sweden
2 Department of Cardiothoracic Anesthesia Linköping Heart Center University Hospital, Linköping, Sweden
3 Department of Molecular Medicine and Surgery Division of Clinical Physiology Karolinska Institute, Stockholm, Sweden
Aim. Post ischemic disturbances of myocardial metabolism that may contribute to postoperative heart failure and are accessible to metabolic treatment have been identified early after coronary surgery. Knowledge derived from these studies may not be applicable to other patient groups. Therefore we studied myocardial energy metabolism in patients operated for isolated aortic stenosis.
Methods. Twenty patients undergoing isolated aortic valve replacement (AVR) because of aortic stenosis without significant regurgitation were studied before and immediately after surgery. Myocardial uptake of oxygen and energy substrates was assessed with coronary sinus catheter technique.
Results. Free fatty acids (FFA) were the main source of myocardial energy before and after AVR. A significant uptake of lactate was only recorded preoperatively. A significant uptake of glutamate of the same magnitude as previously described in coronary patients was found pre- and postoperatively. Postoperatively a relative decrease of myocardial oxygen extraction ratio (P<0.001) and oxygen consumption (P=0.14) by approximately 20% was observed.
Conclusion. Preoperative and postoperative metabolic adaptation with substantial uptake of glutamate, previously claimed to be due to chronic or repetitive ischemia, was demonstrated. The results indicate that oxidative metabolism had not fully recovered when the procedure was completed. However, the potentially unfavorable postoperative metabolic state with predominant reliance on FFA as energy source was outbalanced by the unloading effect of AVR with a reduction in myocardial oxygen extraction.