Life-threatening postoperative pulmonary complications in patients with previous amiodarone pulmonary toxicity undergoing cardiothoracic operations

Abstract

Amiodarone therapy for cardiac arrhythmias is increasingly being recognized to be associated with pulmonary toxicity. In this report, we describe the case histories of four patients with previously diagnosed amiodarone pulmonary toxicity in whom the adult respiratory distress syndrome developed after cardiothoracic operations for malignant ventricular arrhythmias. Three patients underwent endocardial resection (two died), and a fourth patient had implantation of an automatic defibrillator unit. Radiographic changes and results of pulmonary function testing are evaluated during initial toxicity and preoperatively. These four patients (mean amiodarone dosage of 420 mg/day for 20 months) are compared to 13 other patients undergoing cardiothoracic operations with prior amiodarone treatment (one patient with preoperative pulmonary toxicity) in whom life-threatening postoperative pulmonary complications did not develop (mean dosage of 550 mg/day for 10 months). Mean preoperative serum amiodarone levels for the four patients were 1.5 micrograms/ml. In the two patients who died, desethylamiodarone levels were 510 and 4,400 micrograms/gm in pulmonary tissue. Histologic examination showed "honeycomb" appearance of the lung with prominent septae, alveolar foamy macrophages, and hyperplasia of alveolar lining cells, consistent with amiodarone pulmonary toxicity. Causes including pump-oxygenator time, oxygen toxicity, anesthetic agents, congestive heart failure, and pulmonary infection superimposed on amiodarone pulmonary toxicity are discussed with a review of the literature.