MRCP2-1287

MRCP2-1287

A 70-year-old Japanese male presents to the emergency department with sudden onset shortness of breath associated with palpitations. He has previously experienced similar palpitations 8 months ago but did not seek medical attention. He was last completely well and described by his son to be at baseline 24 hours ago when they had lunch together. The patient denies any chest pain, nausea, vomiting or sweating. On examination, the patient is pyrexic at 38.5 degrees and tachycardic, with a regular pulse at 130-140 beats per minute. Heart sounds demonstrate a gallop rhythm; auscultation of his chest reveals bibasal inspiratory coarse crackles and no wheeze. He has bilateral mild lower limb pitting oedema to low ankles. Examination of the abdominal and neurological systems is unremarkable. A chest radiograph demonstrates bibasal alveolar shadowing with mild bilateral pleural effusions. An ECG demonstrated sinus tachycardia at 130 beats per minute. Blood tests are as follows:

Hb 120 g/l
Platelets 280 * 109/l
WBC 8.5 * 109/l

Na+ 140 mmol/l
K+ 4.0 mmol/l
Urea 6.8 mmol/l
Creatinine 95 µmol/l

TSH < 0.01 mU/l
Free T4 135 pmol/l
Free T3 38 pmol/l

Nursing staff have kindly taken blood cultures and taken measures to cool the patient. What is the next most appropriate immediate treatment?