Cardiovascular Complications of Scorpion Stings and the Effects of Antivenom

The study was designed to evaluate (1) the frequency and types of cardiovascular complications caused by scorpion stings and (2) the effects of cardiovascular morbidity and mortality caused by changes in antivenom policy instituted in mid-1991 from an optimal treatment of none or 1 ampoule to the current mandatory dosage of five or more ampoules administered at point of first contact. From January 1992 to December 1995, prospective clinical and echocardiographic observations were made on 179 of968 cases of scorpion sting admissions who had cardiovascular complications. A retrospective analysis of deaths and of all cases of scorpion stings treated for pulmonary edema or cardiopulmonary arrest (among 162 admissions) in the two years preceding the policy change (January 1990 to December 1991) was also undertaken. Most patients in the preceding two years had received 0 to 1 ampoule of anti venom. In the prospective study, cardiovascular complications were observed in 179 (18.5%) cases. Electrocardiographic (ECG) abnormalities were most frequent (72%) and included sinus tachycardia (56%), tented T-waves (29%), non-Q infarct pattern (17%), Q-infarct pattern (3%); supraventricular tachycardia; atrial fibrillation; and second-degree AV block and nodal tachycardia in one patient each. Echocardiography obtained in 48 cases within 24 h of sting was normal in 23 (48%) but showed abnormal left ventricular systolic function in 25 (52%), including all 12 patients with pulmonary edema. Serial echoes in 14 abnormal cases showed significant improvements in ejection fraction from 36.7:t 14.6% to 58:t 11.4% (P = 0.00002) with corresponding significant changes in fractional shortening % (P = 0.00033) following therapy. Interventricular septal motion abnormality was most frequently seen, left ventricular posterior wall motion abnormality was less common, and global wall motion abnormality was seen only in the more severe cases. There was a reduction in the incidence of pulmonary edema from 11.1 % to 1.2% (P < 0.001), of cardiorespiratory arrest from 7.4% to 0.4% (P < 0.001), and cardiac-related deaths from 1.8% to 0% (P < 0.001), respectively, since the new serotherapy schedule. All cardiovascular changes including ECG and echocardiographic, congestive heart failure, and pulmonary edema were reversible in survivors.