Final answer:
Lead II in an ECG represents the vector of depolarization across the heart from the right arm to the left leg, showing the movement of the impulse. It illustrates the heart's electrical activity during various stages of the heartbeat and helps identify the condition of cardiac tissue.
Step-by-step explanation:
Lead II of an electrocardiogram (ECG) is significant for its ability to display well-defined upright waveforms. The role of Lead 2 in an ECG is to monitor the heart's electrical activity, specifically to show the movement of the impulse as it travels from the top of the heart through the atria, down to the ventricles. This is critical in diagnosing different cardiac conditions and understanding the heart's overall function.
Three electrodes, labeled RA (right arm), LA (left arm), and LL (left leg), are placed on the patient to measure electrical activity across the heart from different angles, forming leads I, II, and III. Lead 2 usually identifies upright waveforms that are easily identified and corresponds to the vector of heart's depolarization that travels from the right arm (RA) to the left leg (LL), capturing the heart's electrical activity in this plane. Depolarization begins with the P wave (atrial depolarization), followed by the QRS complex (ventricular depolarization), and ends with the T wave (ventricular repolarization).
These waveform components correspond to different stages of the heartbeat and provide information on the state of the cardiac tissue. For example, damaged heart tissue, such as that caused by infarcts, can be detected by changes in these waveforms across one or more of the 12 ECG leads. Modern ECG technology allows for portable monitoring, which can be useful in ambulances, hospitals, or even in patient-oriented wearable devices.