Final answer:
The 'precordial leads' are the first six leads of an ECG, named as such because they are positioned on the chest to directly measure the heart's electrical activity. Key to diagnosing heart conditions, these leads, along with limb leads, form part of the standard 12-lead ECG which provides detailed heart function analysis.
Step-by-step explanation:
The first six leads of an ECG are called 'precordial leads' because they are placed directly on the chest, around the heart's area. These leads measure voltage differences created by the cardiac activity specifically across the chest, hence providing a direct view of the heart's electrical function. On a 12-lead ECG, ten electrodes are placed on the patient's body: six of them are positioned on the chest (V1-V6, representing the precordial leads) and four on the limbs.
Each of these leads captures electrical signals from different angles, offering a comprehensive representation of the heart's electrical activity. This is crucial for diagnosing conditions like myocardial infarctions, where certain leads will show changes reflecting damage to specific regions of the heart. ECG technology has advanced significantly, allowing for portable monitoring devices, such as the Holter monitor, which continuously record the heart's electrical activity.