Electrodes are placed in different parts of the human body and connected to the positive and negative electrodes of the electrocardiograph electrometer through a lead wire. This circuit connection method for recording electrocardiograms is called electrocardiogram lead. The widely adopted international lead system is called the conventional 12 lead system, which includes limb leads connected to the limbs and chest leads connected to the chest.
Monitoring significance:
12 lead monitoring system can timely reflect myocardial ischemia events, with 70% to 90% of myocardial ischemia detected through electrocardiogram and often asymptomatic in clinical practice.
For patients at risk of myocardial ischemia, such as unstable angina and myocardial infarction, continuous 12 lead ST segment electrocardiogram monitoring can timely detect acute myocardial ischemia events, especially asymptomatic myocardial ischemia events, providing reliable basis for timely clinical diagnosis and treatment.
It is difficult to accurately distinguish between ventricular tachycardia and supraventricular tachycardia with differential conduction within the ventricle using lead II alone. The best leads to correctly distinguish between the two are V and MCL (with the most clear morphology of P-wave and QRS complex).
When evaluating abnormal cardiac rhythms, using multiple leads is more accurate than using a single lead.
12 lead monitoring system is more accurate and timely than traditional single lead monitoring systems to understand whether patients have arrhythmia, as well as the type, incidence rate, occurrence time, duration, and changes before and after drug treatment of arrhythmia.
12 lead electrocardiogram monitoring is crucial for determining the nature of arrhythmias, selecting diagnostic and treatment methods, and observing treatment outcomes.
12 lead monitoring system also has its limitations in clinical applications and is susceptible to interference. When the patient's position changes or the electrode is used for a period of time, many interference waves will appear on the screen, which will affect the judgment and analysis of the electrocardiogram.