I read with interest the article by Landoni and colleagues  regarding acute renal failure and mitral valve surgery. Acute renal failure is one of the most serious complications of cardiac surgery, with high morbidity and mortality, although the subject is still not completely understood. Most of the research related to valve surgery and cardiopulmonary bypass (CPB) is from the 1960s and 1970s [2,3]. The current practice of valve surgery, recent development in CPB and new postoperative strategies offers us a different situation.
Early work in valvular surgery patients stated that CPB was the main cause of renal dysfunction and acute renal failure. There are a number of papers, showing that, contrary to this belief, CPB is not the main cause of this morbidity. However, most of this work has been performed in patients undergoing coronary artery surgery [4,5].
A recent study by our group (unpublished results)  shows that in valvular surgery patients (mitral and aortic valve), the pattern of renal function during CPB, studied with inulin infusion for glomerular filtration rate (GFR) and I131 Hipuran for effective renal plasma flow (ERPF) is well preserved and no differences were found when compared with our own earlier studies in coronary patients [4,5] (Fig. 1). To our knowledge, that was the first such study in valvular surgery patients. GFR and ERPF were well preserved throughout, but ERPF was reduced before surgery. Similar results have been found in others types of surgery .
We agree with Landoni and colleagues that the risk for renal dysfunction and acute renal failure depends on many other factors: fasting, hypovolaemia, low cardiac output, emergencies, bleeding and preoperative renal dysfunction. Perioperative factors other than CPB should be considered the main reasons for acute renal failure in patients undergoing coronary and valvular surgery.
1. Landoni G, Roberti A, Boroli F et al
. Mitral valve surgery and acute failure. Eur J Anesthesiol
2. Porter GA, Kloster FE, Herr RJ et al
. Renal complications associated with valve replacement surgery. J Thorac Cardiovasc Surg
3. Porter GA, Kloster FE, Herr RJ et al
. Relationship between alterations in renal hemodynamics during cardiopulmonary bypass and postoperative renal function. Circulation
4. Lema G, Meneses G, Urzua J et al
. Effects of extracorporeal circulation on renal function in coronary surgical patients. Anesth Analg
5. Lema G, Urzúa J, Jalil R et al
. Renal protection in patients undergoing cardiopulmonary bypass with preoperative abnormal renal function. Anesth Analg
6. Lema G, Canessa R, Carvajal C et al
. Renal function in valvular and coronary patients undergoing surgery with extracorporeal circulation. Abstract. 29th Annual Meeting & Workshops, Society of Cardiovascular Anesthesiologist, Montreal, Canada, 2007.
7. Colson P, Ribstein J, Seguin JR et al
. Mechanisms of renal hemodynamic impairment during infrarenal aortic cross-clamping. Anesth Analg