ECG findings

'Saw-tooth' pattern with normal complexes

• Atrial flutter

Absent 'p' wave

• Atrial fibrillation
• Sinoatrial block

Bifid 'p' wave

• Left atrial hypertrophy, e.g. mitral stenosis

Peaked 'p' wave

• Right atrial hypertrophy, e.g. pulmonary hypertension, tricuspid stenosis

ST depression

• Myocardial ischaemia (MI)

ST elevation

• Acute myocardial infarction (MI)
• Left ventricular aneurysm

'Saddle'-shaped ST elevation

• Acute constrictive pericarditis

Pulmonary embolus

• SI,QIII,TIII pattern (Deep S waves in I, Q waves in III, inverted T waves in III)

Tall tented 't' waves, wide QRS complex (sine wave)

• Hyperkalaemia

Flattened 't' waves, prominent 'U' waves (muscle weakness, cramps, tetany)

• Hypokalaemia

Long 'Q-T' interval, tetany, perioral paraesthesia, carpopedal spasm

• Hypocalcaemia