Cardiac cannulation, sodium and water balance, and ANF plasma levels

Abstract

Atrial natriuretic factor (ANF) is released in response to atrial distention and has been suggested to play an important role in the regulation of sodium and water homeostasis.1Genest J Cantin M Atrial natriuretic factor.Circulation. 1987; 75: I118-I124Google Scholar In an interestingstudy, Omari, Nelson and Robertson2Omari BO Nelson RJ Robertson JM Effect of right atrial appendectomy on the release of atrial natriuretic hormone.J Thorac Cardiovasc Surg. 1991; 102: 272-279Google Scholar reported reduced sodium and water excretion in patients after coronary bypass grafting in whom an atrial appendectomy was performed. The reduction of sodium and water excretion was accompanied by reduced plasma levels of atrial natriuretic peptide (ANF) after volume challenge with 5% human albumin infusion (12.5 ml/kg intravenously). This study is of great potential clinical relevance, because an alternative approach to venous cannulation, like cannulation of the lateral atrial wall, could be applied to limit damage to the right atrial appendage. As an extension to this study, we have investigated sodium and water excretion, as well as plasma ANF levels (studied with a radioimmunoassay), after coronary artery bypass grafting in two groups of patients. One group (n = 10) was operated on with cannulation of the right atrium and removal of a small piece of appendage tissue; in the second group of patients (n = 10), venous cannulation was performed through the right lateral atrial wall with careful avoidance of mechanical irritation of the atrium. In the postoperative phase, patients were given optimal medical treatment without experimental interventions like volume loading. Only patients with normal left ventricular function were enrolled to avoid interferences from extraatrially formed ANF.3Michel J-B Arnal J-F Corvol P Atrial natriuretic factor as a marker in congestive heart failure.Horm Res. 1990; 34: 166-168Crossref Scopus (9) Google Scholar Fig. 1 summarizes the data. No significant difference was noted between the two groups concerning renal sodium excretion before, during, and 3 hours after bypass. Similar results were obtained with urinary output. In addition, no difference was found in plasma ANF concentrations, although pieces of atrial myocardium of 323.8 ± 104.4 mg (range 100 to 1230 mg) containing ANF concentrations of 0.97 ± 0.23 pmol/mg (range 0.55 to 2.58 pmol/mg) had to be removed during atrial cannulation. Taken together, these data suggest that partial removal of atrial myocardium from the right appendage for venous cannulation during coronary artery bypass grafting does not lead to postoperative disturbances in water and sodium excretion or decreases in plasma ANF levels. Thus cannulation of the right atrial appendage does not lead to serious complications when extreme situations like volume overload or total atrial appendectomy are avoided. Studies addressing such clinically important questions should be performed under appropriate conditions that reflect the clinical conditions of optimal patient care.