The electrocardiographic recognition of left atrial enlargement in childhood

Abstract

The P wave of the scalar electrocardiogram has been evaluated in a group of normal infants and children, and in a group of children with left atrial volume overload due either to ventricular septal defect or mitral regurgitation. In the normal group the P wave in Lead V 1 was frequently diphasic, with the terminal negative deflection smaller than the initial positive component, however. With left atrial overload, the negative P-V 1 deflection becomes more prominent, and the P wave in Lead V 2 may also become diphasic. Amplitude and duration of the terminal negative P-V 1 have been measured, and their product, the “terminal P-V 1 index”, obtained. In the absence of left atrial overload, the terminal P-V 1 index is ordinarily not greater than 0.015 mm. sec., the 90th percentile, or one half of a small square on ECG paper. Patients with left atrial overload have a significantly greater terminal P-V 1 index and can thus be identified. Abnormal negativity of the P-V 1 deflection, as expressed in the terminal P-V 1 index, does not occur with mild left atrial overload, but is consistently present with more significant degrees of overload. In a group of patients with prominent left atrial overload, the terminal P-V 1 index was abnormal in 92 per cent. The terminal P-V 1 index is compared with other electrocardiographic measures of left atrial abnormality. Prolonged P duration is more sensitive an indicator than terminal P-V 1 index, but is frequently not present in patients with prominent overload. Abnormal P morphology is confined to patients with more severe left atrial overload, but identifies less than half the number of these who are identified by an abnormal terminal P-V 1 index. An increased P P -R segment ratio is often a nonspecific finding. Unusual negativity of the P wave in Lead V 1, as indicated by an abnormal terminal P-V 1 index, correlates quite well with roentgenographic evidence of increased left atrial size. To date, abnormal negativity of the P wave in Lead V 1 is the sole electrocardiographic measure of left atrial enlargement which has this advantage.