|Year : 2002 | Volume
| Issue : 1 | Page : 5
Transient atrial fibrillation induced by black ant sting
Amar Mohammad Salam1, MS El-Tawil2, Hassan Abuzaid2
1 Department of Cardiology and Cardiovascular Surgery, Hamad General Hospital, Doha, Qatar
2 Accident and Emergency Department, Hamad General Hospital, Doha, Qatar
|Date of Web Publication||22-Jun-2010|
Amar Mohammad Salam
Department of Cardiology and Cardiovascular Surgery, Hamad Medical Corporation, P.O.Box 3050, Doha
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Salam AM, El-Tawil M S, Abuzaid H. Transient atrial fibrillation induced by black ant sting. Heart Views 2002;3:5
| Case presentation|| |
A 47-year-old gentleman presented to the emergency department with dizziness, palpitations and shortness of breath shortly following black ant sting on the right foot two and a half hour prior to presentation. He gave a past history of black ant sting allergy; observed twice in accident and emergency 2 and 7 years ago.
He was on no medications. On physical examination he looked ill and sweaty. His pulse rate was 140/minute and was irregularly irregular, BP was 90/50 mmHg, T 370C, RR 20/minute. Examination of the skin revealed a maculopapular, erythematous patch at the site of the sting on the right leg.
Chest auscultation revealed harsh vesicular breath sounds. Heart examination revealed variable first heart sound, normal second sound and no murmurs. Electrocardiogram (ECG) showed atrial fibrillation with a fast ventricular response of 140 beats/minutes [Figure 1]. The patient was treated with 100% oxygen by facemask and given intravenous antihistamine (Avil) and hydrocortisone.
He also received fast drip of normal saline. Digoxin 0.25 mg intravenously was also given to control the ventricular response.
Very shortly after that the patient reverted spontaneously to normal sinus rhythm. He was admitted to the cardiology ward for observation. A repeat ECG showed that he was in normal sinus rhythm [Figure 2]. Chest X-ray revealed normal cardiac size and clear lung fields. Laboratory tests such as CBC, platelets, urea and electrolytes, cardiac enzymes, and thyroid function tests were normal.
A review of his past medical records showed an ECG, which was normal sinus rhythm [Figure 3] four years prior to this presentation.
He did well after that with normal blood pressure and was discharged home in good general condition.
| Discussion|| |
Insect stings can cause local or systemic reactions that range from mild to fatal .
They are one of the most common causes of anaphylaxis .
Estimates of the incidence in the general population of anaphylaxis caused by insect stings range from 0.3 to 3 percent , . In addition, venom anaphylaxis remains an often unrecognized cause of sudden death. Allergy to the sting of black ants from the species Acanthonyps (lasius) nigar constitutes a considerable clinical problem in Qatar  . Allergic reactions vary from a localized skin allergic reaction to severe systemic anaphylaxis. The usual reaction to an insect sting is localized pain, swelling, and erythema at the site of the sting. This reaction usually subsides within several hours.
Little treatment is needed, other than analgesics and cold compresses.
The clinical features of anaphylaxis from an insect sting are the same as those of anaphylaxis from any other cause.
The most common symptoms are dermal:
generalized urticaria, flushing, and angioedema.
Symptoms usually start within 10 to 20 minutes after the sting; on occasion, reactions have occurred as long as 72 hours later ,,,, . There have been rare reports of abnormalities such as vasculitis, nephritis, neuritis, encephalitis, and serum sickness occurring in a temporal relation to insect stings , . Life-threatening symptoms include edema of the upper airways, circulatory collapse with shock and hypotension, and bronchospasm. Cardiovascular collapse results from hypovolemia (due to increased vascular permeability and loss of up to 50 percent of blood volume), alterations in peripheral vascular resistance, and myocardial depression ,,. The cardiac output is initially elevated but may become depressed.
The pulmonary and systemic vascular resistances are usually low, but may be elevated in some patients due to maximal vasoconstriction in response to the loss of intravascular volume. These latter patients may be unresponsive to pressor agents alone because they are already maximally vasoconstricted , . EKG monitoring may demonstrate tachycardia, relative bradycardia, arrhythmias, or ST-T wave changes ,.
Multifocal premature ventricular contractions are the most commonly reported arrhythmia. Atrial fibrillation due to insect sting has not been reported in the literature.
Our case demonstrates an unusual clinical presentation of black ant sting allergy in the form of transient atrial fibrillation in a man with a normal healthy heart.
Whether this episode was provoked by the cardiotoxic effects of the ant venom or by the release of humoral factors involved in the allergic reaction is still not known.
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[Figure 1], [Figure 2], [Figure 3]