The significance of
hyperamylasemia and its relationship to
pancreatitis after cardiac surgery is controversial. Three hundred consecutive patients undergoing
cardiopulmonary bypass were prospectively studied to determine the incidence and significance of postoperative
hyperamylasemia. Ninety-six of three hundred patients (32%) developed
hyperamylasemia. Fifty-six patients (19%) were classified as having isolated
hyperamylasemia because they were asymptomatic and had normal serum
lipase. Thirty-two patients (10.7%) had subclinical
pancreatitis defined as elevation of serum
amylase and
lipase or pancreatic
isoamylase. Many of these patients had mild gastrointestinal symptoms that were self-limited. Eight patients (2.7%) had overt
pancreatitis documented by clinical findings, biochemical abnormalities, and computed tomography (CT) scan or autopsy.
Isoamylase analysis demonstrated that isolated
hyperamylasemia usually originated from nonpancreatic sources. However,
hyperamylasemia occurring in conjunction with abdominal signs and symptoms or elevated serum
lipase was almost always pancreatic in origin. Patients with
hyperamylasemia had a significantly higher mortality rate (seven of 96 patients, 7.5%) than those with normal serum
amylase (two of 204 patients, 0.9%) (p less than 0.01) even when the
amylase was nonpancreatic in origin (five of 56 patients, 9%). The reason that nonpancreatic
hyperamylasemia is associated with increased postoperative mortality is not established but may represent a variety of metabolic aberrations or tissue
injuries. It is concluded that 1)
hyperamylasemia after
cardiopulmonary bypass is a marker of potential clinical importance, and 2)
pancreatitis in this setting is more common than previously recognized and is a potentially lethal complications. Successful treatment depends on early diagnosis and aggressive treatment.