A housewife ingests a rodenticide white powder accidentally. She is brought to hospital where the examination shows generalized, flaccid paralysis and an irregular pulse. ECG shows multiple ventricular ectopics, generalized changes with ST. Serum potassium is 2.5 mE/l. The most likely ingested poison is -

Ingestion of ceain forms of barium (e.g., barium carbonate or barium fluoride) in toxic amounts can lead to gastrointestinal signs and symptoms (e.g., vomiting, abdominal pain, and watery diarrhea).Severe hypokalemia induced by barium toxicity can cause ventricular dysrhythmias Oral or inhalation administration of barium carbonate in rats resulted in adverse Other symptoms and signs are hypokalemia, cardiac arrhythmias, cardiac .ECG showed flat ST with U waves in 4 patients . Ref Harrison 20th edition pg 566