Page 188 - Clinical Pearls in Cardiology

176 Clinical Pearls in Cardiology

• Wolff-Parkinson-White syndrome
• Posterior wall myocardial infarction
• Hypertrophic cardiomyopathy
• Muscular dystrophy
• Dextrocardia
• Normal variant.
Isolated posterior wall myocardial infarction is
uncommon, and can cause ST segment depression and
upright T waves in leads V1 to V3, in addition to tall R
wave in V1. These are exactly ‘reverse’ changes of acute
anteroseptal myocardial infarction. These ‘reverse’
changes can be confirmed by turning over the ECG and
holding it against bright light. Then the tall R wave will
appear as the pathological Q wave, and ST segment
depression and upright T wave would appear as ST
segment elevation and T inversion, respectively. This
is the positive ‘mirror test’ and is a simple method to
diagnose posterior wall MI.
28. What do you know about long QT syndromes?
The long QT syndrome is a disorder of myocardial
repolarization (congenital or acquired) characterized
by a prolonged QT interval on the electrocardiogram
and an increased risk of sudden cardiac death. The
primary symptoms in patients with this syndrome
include palpitations, syncope, seizures and cardiac
arrest. This syndrome is associated with an increased
risk of a characteristic type of life-threatening cardiac
arrhythmia, known as torsades de pointes or “twisting
of the points” (Fig. 12).