History of Present Illness: A 75-year-old male with a history of paroxysmal atrial fibrillation, on apixaban and digoxin, type 2 diabetes, on dapagliflozin, congestive heart failure (CHF), nonischemic cardiomyopathy with an ejection fraction of 25%, automatic implantable cardiac defibrillator (AICD), and cirrhosis was brought in by ambulance from home to a community emergency department (ED) for one day history of nausea, vomiting, and fatigue. The patient later admitted to intentionally overdosing on his apixaban, digoxin, and dapagliflozin over 24 hours prior to his presentation. Pertinent Physical Exam: Afebrile. Blood pressure 103/59 mmHg, heart rate 107, respiratory rate of 12 and oxygen saturation of 98% on room air. The patient was elderly and frail appearing. He was awake but confused and a poor historian. Pupils 4 millimeters, equal, round, and reactive to light. Mucosa moist. Sclera were icteric. Heart was tachycardic and regular rhythm without murmurs, rubs or gallops. Lungs were clear to auscultation. Abdomen was soft and non-tender. No ascites. Skin was jaundiced and legs were edematous with chronic wounds. Neurological exam revealed generalized weakness but was non-focal. No clonus.
Pertinent Laboratory Data: Labs were significant for a sodium of 128 mmol/L (normal range 136-145 mmol/L), potassium of 3.3 mEq/L (normal range 3.7-5.2 mEq/L), and chloride of 79 mEq/L (normal range 96-106 mEq/L). Creatinine was normal at 0.87 mg/dL. Glucose was normal at 77 mg/dL. Total bilirubin 11 mg/dL (normal range 0.1-1.2 mg/dL). Digoxin level was 7.2 ng/ml (therapeutic range 0.8-2.0 ng/mL). INR was elevated at 4.9. Salicylate and acetaminophen levels and urine toxicologic screen were normal.
Case
Discussion: An electrocardiogram (EKG) was obtained which demonstrated a rare example of bidirectional ventricular tachycardia (BiVT) which was first described by Carl Schwensen in 1922 (1). It is most commonly seen with digoxin toxicity, but has also been described to be caused by Catecholamine Polymorphic VT (a genetic dysrhythmia induced by exercise, physical, or emotional stress), acute myocardial ischemia, ischemic cardiomyopathy, myocarditis, and cardiac sarcoidosis (2).
Our community hospital does not have point of care laboratory testing, so the patient was treated with calcium chloride for possible hyperkalemia while awaiting lab results. He received one liter of normal saline. His cardiac monitor revealed wide fluctuations in his rate and rhythm. Digoxin toxicity was strongly suspected. Since digoxin immune fab was not available in our ED, toxicology was consulted and the patient was transferred to a tertiary care hospital where he was treated with two doses of digoxin immune fab with improvement in his symptoms.
Pearls: • Digoxin is derived from the foxglove plant. Its positive inotropic effects are used to improve systolic function in patients with CHF, and its atrioventricular nodal blocking effect is used to control atrial tachydysrhythmias (3). • Digoxin has a narrow therapeutic window and is renally excreted. • Signs and symptoms of digoxin toxicity include confusion, decreased appetite, nausea, vomiting, diarrhea, and visual changes (rare). • Bidirectional ventricular tachycardia is a rare finding, but highly suggestive of digoxin toxicity. • Administration of calcium in hyperkalemic patients with digoxin toxicity had once been thought to put patients at risk for “stone heart” (irreversible global myocardial contraction), but this has been debunked (3). References and Acknowledgements (Optional) 1. Schwensen, C. (1922). Ventricular tachycardia as the result of the administration of digitalis. Heart, 9(April), 199. 2. Almarzuqi A, Kimber S, Quadros K, Senaratne J. Bidirectional Ventricular Tachycardia: Challenges and Solutions. Vasc Health Risk Manag. 2022 Jun 7;18:397-406. doi: 10.2147/VHRM.S274857. PMID: 35698640; PMCID: PMC9188370. 3. Cummings ED, Swoboda HD. Digoxin Toxicity. [Updated 2023 Mar 4]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK470568/
