This electrocardiogram in a 10-month-old infant demonstrates biatrial enlargement and biventricular hypertrophy.
The characteristic features of biatrial enlargement demonstrated here include broad P waves, indicating left atrial enlargement, with a tall initial component and slightly prolonged PR interval for age and heart rate, indicating right atrial enlargement.
The characteristic features of biventricular hypertrophy seen here include deep Q waves and tall R waves in left precordial leads, indicating left ventricular hypertrophy and tall R' waves in lead V1, indicating right ventricular hypertrophy.