Presented by Hong Kong College of Emergency Medicine
Chairperson: Dr Yiu-cheung Chan
FHKCEM, FHKAM
Associate Consultant
Hong Kong Poison Information Centre
Discussant: Dr Michael Chio-ho Chan
FHKCP, FHKAM
Resident Specialist, Prince of Wales Hospital Poison Treatment
Centre
Discussant: Dr Wing-tat Poon
MRCP(UK), FHKAM(Pathology)
Associate Consultant
Hospital Authority Toxicology Reference Laboratory
Discussant: Dr Man-li Tse
FHKCEM, FHKAM
Senior Medical Officier
Hong Kong Poison Information Centre
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Synopsis
A 65 year old lady with rectal cancer presented with chronic diarrhoea and syncope.
On arrival to an emergency department, she was alert and was found to be bradycardic (52 beats per minute) with a normal blood pressure (138/55). Physical examination revealed a normal hydrated lady with no focal neurology and unremarkable cardiovascular system.
Serum electrolytes showed mild hypokalemia (2.8mmol/l), normal serum calcium and magnesium. Electrocardiogram showed sinus bradycardia and normal machine calculated QRS interval (0.096 seconds) and corrected QT interval
(0.422 seconds)

She was treated with intravenous fluid and potassium replacement and was admitted to general medical ward for management. During observation, she developed repeated episodes of polymorphic ventricular tachycardia (Torsades de
Pointes) with transient loss of consciousness. Electrocardiogram showed a corrected QT interval of 0.616 seconds. She was then treated with intravenous magnesium.
Drug history revealed that she was on methyldopa, dologesic and lomotil on PRN basis from general outpatient clinic. Besides, she had been taking naturopathic medicine to treat her cancer for months…………………..
A diagnostic serum test was done to confirm the diagnosis and she was treated with an antidote…………………