Right atrial enlargement is usually due to pulmonary hypertension.

右心房增大通常由肺动脉高压引起。

Unusual morphology of P waves is indicative of atrial enlargement.

P波形态异常提示心房扩大。

Left atrial enlargement is commonly due to mitral stenosis.

左房增大通常是由于二尖瓣狭窄引起的。

In left atrial enlargement, depolarization of the left atrium lasts longer than normal.

左房扩大时，左房去极化持续时间比正常长。

In right atrial enlargement, depolarization of the right atrium lasts longer than normal and its waveform extends to the end of that of the left atrium.

右心房扩大时，右心房除极持续时间比正常长，波形延伸至左心房末端。