Certified Pulmonary Function Technologist (CPFT) Practice Exam

When lead II is correctly placed in an electrocardiogram (ECG), it is positioned so that the positive electrode is on the left leg and the negative electrode is on the right arm. This configuration allows for the electrical activity of the heart to be recorded in a way that it typically aligns with the heart's physiological electrical conduction pathway.

As the depolarization wave moves through the heart, it propagates from the atria to the ventricles, following a specific directional path. Since lead II is oriented in a manner that captures the heart's electrical activity moving from the right atrium to the left ventricle, the resulting waveform is characterized by upward deflections on the ECG.

Therefore, the primary reason for upward peaks in lead II is the alignment of the positive electrode capturing the electrical activity traveling towards it, thus producing a peak that moves up on the ECG tracing. This upward movement indicates the direction and strength of the heart's electrical signals as they travel through the different structures of the heart.