Journal of Postgraduate Medicine Medknow Publications and Staff Society of Seth GS Medical College and KEM Hospital, Mumbai, India ISSN: 0022-3859 EISSN: 0972-2823 Vol. 49, Num. 3, 2003, pp. 254-255

Journal of Postgraduate Medicine, Vol. 49, No. 3, July-Sept, 2003, pp. 254-255

Case Report

Atrial Flutter following a Wasp Sting

Fisher BA, Antonios TF

Blood Pressure Unit, Department of Cardiovascular Sciences, St George’s Hospital Medical School, Cranmer Terrace, London SW17 0RE
Correspondence Address: Blood Pressure Unit, St. George’s Hospital Medical School,Cranmer Terrace, London SW17 0RE t.antonios@sghms.ac.uk

Code Number: jp03069

ABSTRACT

Wasp stings have been associated with a wide variety of local and systemic reactions including, rarely, tachyarrhythmias. We discuss a case of atrial flutter occurring in a 64-year-old man following a single sting in the absence of anaphylaxis. The pathogenesis is discussed and the literature reviewed.

Wasp stings have been associated with a wide variety of local and systemic reactions including tachyarrhythmias. We report a case of atrial flutter occurring after a single wasp sting in the absence of anaphylaxis in an apparently healthy individual. The occurrence of sustained atrial tachyarrhythmia after insect stings suggests the presence of atrial disease that should be further evaluated.

Keywords: Insect sting, Wasp sting, Arrhythmia, Artial flutter

CASE HISTORY

A 64-year-old previously healthy man was stung on the left leg by a wasp. Ten minutes later he suddenly developed palpitations, shortness of breath, dizziness, and headache. He called the emergency services and was brought to our hospital by ambulance. He had no history of ischaemic or rheumatic heart disease, hypertension, diabetes, angina, palpitations or allergy. He was on no regular medications. On examination, he was afebrile, his pulse was 110 beats per min and irregular, and his blood pressure was 132/70 mm Hg. There were no signs of hyperthyroidism or chronic obstructive pulmonary disease. His chest was clear and the rest of the clinical examination was unremarkable apart from a small erythematous area on his left calf with no barb or venom sac. In particular there was no evidence of a skin rash or swelling of soft tissues of the mouth or larynx. A 12-lead electrocardiogram revealed atrial flutter with variable block [Figure-1]. Routine plasma biochemistry, including urea, electrolytes, creatinine, liver and thyroid function tests were normal and there was no elevation of creatinine kinase or cardiac troponin T levels. His chest radiograph was unremarkable. He was anticoagulated with low-molecular weight heparin and an initial attempt at chemical cardioversion with intravenous flecainide was unsuccessful. Sinus rhythm was then restored with a single 50-joule synchronized transthoracic cardioversion. A repeat electrocardiogram showed regular sinus rhythm with biphasic P waves in Lead V1 and borderline prolonged PR interval (209 m.sec) [Figure-2]. Two days after cardioversion he remained in sinus rhythm and was discharged. Transthoracic echocardiography subsequently showed a dilated left atrium with an aneurysm of the atrial septum. The mitral and aortic valves were normal with no evidence of stenosis or regurgitation. Left ventricular ejection fraction was 60% with no left ventricular hypertrophy. Three months after discharge the patient remained asymptomatic in sinus rhythm and required no additional therapy.

DISCUSSION

Wasps, bees, and ants are stinging insects that belong to the order Hymenoptera. Wasp stings have long been known to be associated with a variety of local and systemic reactions in humans. These reactions range from mild erythema and oedema at the envenomation site to a number of potentially severe systemic effects including fatal anaphylaxis.[1] Reported cardiovascular complications have included acute myocardial infarction in patients with normal and abnormal coronary arteries.[2],[3] To our knowledge there is only 1 previous report of atrial flutter occurring after a single wasp sting in the absence of anaphylaxis. [Table-1] summarizes previous case reports in the literature about insect sting-induced tachyarrhythmias. Atrial fibrillation after stings has been described in patients with anaphylactic shock before receiving adrenaline, and following venom and pollen immunotherapy.[4],[5] Atrial flutter is a commonly occurring arrhythmia in individuals with preexisting heart disease. It is particularly associated with left atrial enlargement, left ventricular or biventricular failure. Patients who are restored to sinus rhythm often show evidence of atrial disease as shown by abnormal P waves or demonstration of intra-atrial conduction delays or left atrial enlargement.[6] In our patient left atrial enlargement was documented by transthoracic echocardiography, however, the significance of this finding is not entirely clear as there was no evidence of mitral stenosis or regurgitation and the transmitral Doppler was normal. The arrhythmogenic mechanism of wasp or bee venom is unknown. Many pharmacologically active constituents of wasp venom have been isolated, including histamine, serotonin, dopamine and noradrenaline, mellitin, hyaluronidase, apamin and phospholipase A.[7] More recently a new neurotoxin, a­pompilidotoxin (a-PMTX), has been isolated from the venom of a solitary wasp and has been shown to slow or block the inactivation of the voltage-sensitive Na+ channels.[8] In the presence of anaphylaxis other possible mechanisms include a direct antigen-antibody myocardial reaction, a pharmacological effect of mediators released during anaphylaxis, the effects of agents such as adrenaline used for treatment, hypoxia, hypotension, preexisting heart disease or a combination of several factors.

REFERENCES

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