A 40-year-old male was admitted with acute watery diarrhea for 3 days and a history of recurrent diarrhea over the past 4 months. Laboratory tests found HIV positivity and hypokalemia. An ECG showed changes consistent with hypokalemia including ST depression and flattened T waves. After potassium supplementation, a repeat ECG showed normalization of potassium levels and resolution of the hypokalemia-related ECG changes.

1. DR. PRIYA KUBENDIRAN M-1 UNIT PROF DR.RUCKMANI’S UNIT

2. BRIEF HISTORY A 40 year old male was admitted on 10.08.09 with c/o acute watery diarrhoea – 3 days No H/O vomiting/fever No H/O any chest discomfort H/O recurrent episodes of diarrhoea over the past 4 months. Not a k/c of DM/SHT/PT/BA/IHD

3. O/E : conscious, oriented afebrile pallor + mild dehydration + PR – 110/min BP – 96/70 mm Hg RS – NVBS +, no added sounds CVS – S1 S2 +, no murmur P/A – soft, no organomegaly CNS- NFND

5. ECG TAKEN ON 10.08.09 HR – 100/min Normal sinus rhythm Axis – 70˚ PR interval – 0.16 s QRS interval – 0.08 s QU – 0.48 s

6. Lab investigations : B.urea - 36 mg/dl S.creatinine – 0.7 mg/dl S.electrolytes Na – 138 meq/l Cl - 90 meq/l Hco3 – 20 meq/l K - 2.2 meq/l ELISA for HIV1 - positive

8. Cardiac evaluation Echocardiogram: No RWMA Normal Echo study

9. After adequate hydration, i.v antibiotics and corrective measures for hypokalemia oral KCl 15 ml tds i.v - 20 mEq/day 3 days later repeat s.potassium – 4.2 mEq/L A repeat ecg was taken

11. REPEAT ECG ON 14.08.09 HR – 43/min Normal sinus rhythm QRS axis - 60˚ PR interval – 0.16 s QRS interval – 0.08 s QT interval – 0.48 QTc – 0.41 s

12. ECG CHANGES IN HYPOKALEMIA The ecg changes are due to DELAYED VENTRICULAR REPOLARIZATION Diagnosis is therefore based on ST segment, T wave & U wave abnormalities

13. T wave -progressive dimunition in amplitude, may eventually disappear - a remnant of T maybe visible as a slight irregularity (minimal upward bump) on ST segment U wave progressive increase in amplitude & maintains its rounded appearance may get superimposed on T -TU complex ST segment ST depression is seen in all leads which may be horizontal or concave upwards

14. Prominent U waves combined with ST segment depression & flattened T waves – ROLLER COASTER EFFECT

15. QT interval U wave may be mistaken for a T wave leading to an incorrect diagnosis of prolonged QT interval QT interval is usually unchanged P wave increase in amplitude/ duration PR interval 1 st degree AV block is common Prolongation may lead to superimposition of P on TU – TUP complex 2 nd degree AV block of Wenkebach type may be seen

16. QRS complex decreased voltage & increased duration Arrythmias Atrial & ventricular ectopics Atrial tachycardia with block with AV dissociation Ventricular tachycardia Ventricular fibrillation Torsades de pointes

17. ST depression ≥ 0.5 mm U wave amplitude > 1 mm U wave amplitude > T wave amplitude in same lead Typical ecg : 3 features in 2 leads Compatible ecg : 2 features- U wave related characteristics is present