Ann Thorac Surg 2006;82:2186
© 2006 The Society of Thoracic Surgeons
Original Articles: Cardiovascular
Invited commentary
Y. John Gu, MD, PhD
University Medical Center Groningen, University of Groningen, Hanzeplein 1, Groningen, 9700 RB the Netherlands
(Email: y.j.gu{at}med.rug.nl).
Systemic stress hormone response to cardiopulmonary bypass has been acknowledged for decades since the initial phase of open-heart surgery. Classically this response is reflected by an increase in plasma levels of cortisol, vasopressin, epinephrine, or norepinephrine. In addition, changes in the hypothalamic-pituitary-adrenal axis and the renin-angiotensin-aldosterone system have also been investigated and documented during and after cardiopulmonary bypass. In the present study, Hoda and coworkers [1] introduced leptin, a relatively newly defined molecule known to be released primarily by adipocytes and involved actively in the acute stress response, regulation of the hypothalamic-pituitary-adrenal axis, glucose and insulin metabolism, immune response, cardiovascular response, and angiogenesis. During the study, the authors took a series of venous blood samples from 1 day before operation to postoperative day 3 to search for the temporal changes of plasma leptin levels in three groups of patients (ie, a group with coronary bypass grafting, a group with valve replacement, and another group with off-pump coronary bypass surgery without cardiopulmonary bypass). They found a drop of leptin in all patient groups at 2 hours after operation, which was most likely due to a combined effect of starvation, anesthesia, and intraoperative hemodilution. This drop was followed by a rebound within 24 hours and then returned to baseline within 72 hours. A strange finding of this study was an extremely low baseline level of leptin in the off-pump patients, which did not seem to be associated with the preoperative patients’ body mass index and any sampling error, because baseline levels of the other biochemical measurements in the off-pump patients, including the baseline concentration of cortisol, were comparable with those in the on-pump patients.
Although this is a well-performed descriptive clinical study exploring the kinetic change of the newly defined stress hormone leptin in either on-pump or off-pump patients, the finding does not seem to be in agreement with another recently published study [2] claiming a similar systemic stress hormone response found in both the on-pump and off-pump patients. Therefore, for the time being, we still do not know which factor (ie, cardiopulmonary bypass or the surgical trauma) plays a predominant role in the initiation of systemic stress hormone response in cardiac surgical patients.
At the moment it is uncertain whether a transit increase of plasma leptin level in patients undergoing cardiopulmonary bypass has any clinical implications within a short term. However, from the long term it is interesting to follow the patients to see whether changes in leptin during and after the operation would be linked to patients’ body fat mass and adipocyte metabolism. Furthermore it is of interest to study the relationship between leptin release and postoperative glucose metabolism and insulin resistance or any involvement of leptin in post-injury vascular inflammation and regeneration. Probably, the biological effect of leptin disturbance during and after the operation is of more importance than it merely serves as a biomarker of systemic stress hormone response in cardiac surgical patients with and without cardiopulmonary bypass.
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References
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- Hoda MR, El-Achkar H, Schmitz E, Scheffold T, Vetter HO, De Simone R. Systemic stress hormone response in patients undergoing open heart surgery with or without cardiopulmonary bypass Ann Thorac Surg 2006;82:2179-2186.[Abstract/Free Full Text]
- Velissaris T, Tang AT, Murray M, et al. A prospective randomized study to evaluate stress response during beating-heart and conventional coronary revascularization Ann Thorac Surg 2004;78:506-512.[Abstract/Free Full Text]
Related Article
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Systemic Stress Hormone Response in Patients Undergoing Open Heart Surgery With or Without Cardiopulmonary Bypass
- M. Raschid Hoda, Habib El-Achkar, Edgar Schmitz, Thomas Scheffold, Herbert O. Vetter, and Raffaele De Simone
Ann. Thorac. Surg. 2006 82: 2179-2186.
[Abstract]
[Full Text]
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