OBJECTIVE To explore the relationship between fluid and electrolyte variables and the development of supraventricular tachycardia (SVT) after coronary artery bypass grafting (CABG) surgery. METHODS Retrospective chart review. Random selection from a list obtained from the medical records department and with use of the International Classification of Diseases code to identify patients undergoing their initial CABG. METHODS Medical records department of a southeastern 600-bed urban referral hospital with a large cardiovascular surgical program. METHODS Forty patients experiencing SVT and 40 patients not experiencing SVT during their stay in an intensive care unit after CABG. METHODS Fluid and electrolyte variables and the development of SVT in the intensive care unit after CABG. METHODS Data collected included preoperative demographic variables such as age and gender; previous history of SVT, congestive heart failure, cardiac arrest, previous surgery, diabetes, hypertension, valve disease, tobacco use, obesity; preoperative and postoperative medications; postoperative laboratory values of potassium, calcium, and magnesium; intravenous intake; hourly urine output; and chest tube drainage. RESULTS Demographic variables revealed that patients with SVT were older (p = 0.001) and had a higher incidence of preoperative SVT (p = 0.04). Although groups did not differ by numbers of patients with high or low potassium, calcium, or magnesium, patients receiving additional intravenous potassium by bolus after surgery had a higher incidence of SVT (p = 0.02). Patients who lost blood via the chest tube at a rate greater than 100 ml per hour for at least 1 hour after surgery had a higher incidence of SVT (p = 0.02). Patients with a urine output greater than 300 ml per hour for longer than 9 hours had an increased incidence of SVT (p = 0.02). In the patients experiencing SVT, 62% had it occur 24 to 48 hours after surgery. CONCLUSIONS These data suggest that shifts in fluid and electrolytes may be important characteristics of patients in whom SVT will develop, which could lead to better identification and nursing management of SVT and improve hemodynamic status, patient recovery, and cost after CABG.