unipolar lead of electrocardiogram

例句：

1. 1.The unipolar lead is used to record the electrical activity in the heart.
   单极导联用于记录心脏的电活动。
2. 2.In a unipolar lead, the electrodes are positioned on either side of the heart.
   在单极导联中，电极位于心脏的两侧。
3. 3. The unipolar lead is essential for accurate interpretation of ECG readings.
   单极导联对于准确解读心电图读数至关重要。