Latex anaphylaxis causing heart block: role of ranitidine

Purpose: Treatment with H-2 receptor antagonists may cause the heart to be more susceptible to atrioventricular conduction delay when exposed to an ov erwhelming insult by histamine released during an anaphylactic reaction. We present the case of a woman, pretreated with ranitidine, who developed 3:1 heart block secondary to latex anaphylaxis. We propose that H-2 antagonist premedication alone in patients susceptible to anaphylaxis increases their risk of heart block. Clinical Features: A 38 yr old obese woman with cervical cancer presented f or a radical hysterectomy. Systems review yielded a history of sleep apnea, orthopnea, gastroesophageal reflux, and sciatica, Medications included pre operative ranitidine, 150 mg. There was no history of atopy or allergy, Fol lowing general anesthesia induction, at the onset of the surgical procedure the patient developed a severe anaphylactic reaction which was heralded by the onset of 3: 1 heart block, with decreases in SpO(2), PETCO2 and a decr ease in systolic blood pressure to 45 mmHg. This was diagnosed as a possibl e latex reaction and treated using epinephrine boluses and infusion, fluids , 50 mg diphenhydramine, 50 mg ranitidine and 100 mg hydrocortisone, Follow ing a 48 hr stay in the ICU the patient made an uneventful recovery. Allerg y testing with intradermal latex injection and increased plasma tryptase le vels confirmed a latex anaphylaxis, Conclusion: The use of H-2 antagonists alone as a prophylaxis for gastroeso phageal reflux may increase the risk of heart block in patients who develop anaphylaxis.