What is the management for palpitations following a spider bite?

From the Guidelines

Management for palpitations following a spider bite should prioritize addressing both the underlying envenomation and the cardiac symptoms, with a focus on supportive care and monitoring, as outlined in the 2024 American Heart Association and American Red Cross guidelines for first aid 1. The approach to managing palpitations after a spider bite involves several key steps:

• Ensuring the patient is in a calm environment to reduce stress and potential exacerbation of symptoms.
• Monitoring vital signs, including heart rate, blood pressure, and oxygen saturation, to quickly identify any significant changes or concerns.
• For mild palpitations, reassurance and observation alone may be sufficient, as many cases are self-limiting and resolve within 24-48 hours.
• For symptomatic patients, administering antihistamines such as diphenhydramine (25-50 mg orally or IV) can help reduce allergic responses, and beta-blockers like metoprolol (25-50 mg orally) may be considered to control heart rate in cases of persistent tachycardia, although their use should be cautious due to potential interactions with venom effects 1.
• In severe cases, particularly those involving venomous spiders like black widows, antivenom may be indicated, and intravenous fluids should be administered if there are signs of hypotension or dehydration.
• Continuous cardiac monitoring is recommended for patients with persistent palpitations or other concerning symptoms, as the venom's neurotoxic effects can trigger catecholamine release or directly affect cardiac tissue, leading to dysrhythmias 1. It's crucial to note that while over-the-counter pain medications and topical treatments may be useful for local pain relief from scorpion stings, their application to spider bites is less clear, and evidence supporting their use in this context is indirect 1. Given the potential for severe manifestations, including compromised breathing, muscle injury, and kidney failure, especially in bites from certain spider species, emergency services should be called if systemic symptoms such as difficulty breathing, muscle rigidity, dizziness, or confusion develop, and medical care should be sought if pain is severe, not controlled by over-the-counter medications, or if an open wound develops 1.

From the Research

Management of Palpitations Following a Spider Bite

• The management of palpitations following a spider bite depends on the type of spider and the severity of the bite 2, 3.
• For black widow spider bites, which can cause palpitations, management may include:
  • Pain control with narcotics
  • Muscle relaxants such as methocarbamol and diazepam
  • Calcium gluconate
  • Antivenom in severe cases or in pregnancy 2, 3, 4
• In cases of myocarditis following a black widow spider bite, management may include:
  • Intravenous fluids
  • Analgesics
  • Spasmolytic drugs
  • Tetanus prophylaxis
  • Cardiac monitoring 5, 6
• Cardiac evaluation and monitoring are crucial in regions endemic with Latrodectus spiders, as myocarditis after a Latrodectus bite can be associated with serious complications 5, 6.
• A routine cardiac evaluation, serial ECG, serial cardiac markers, and echocardiography should be considered for any patient exposed to a black widow spider bite for detection of any potentially fatal cardiac abnormalities 6.