Normal ECG Value Ranges
Aug 19, 2022
Source: Cainiu Health
Dr. Zhang Jianbin
Introduction
The PR interval is 0.12–0.2 seconds. In adults, the QRS duration is less than 0.12 seconds; its amplitude must not exceed 1 mV in lead V₁, nor 2.5 mV in leads V₅ and V₆. In lead aVR, the amplitude is generally ≥0.5 mV; in lead aVL, it is <1.2 mV; and in lead aVF, it is <2.0 mV.
An electrocardiogram (ECG) reflects the processes of atrial and ventricular depolarization and repolarization. Some patients wish to understand the normal reference ranges for ECG parameters—so what are these normal values?
Normal ECG Reference Ranges
Typically, a normal ECG consists of the P wave, ST segment, and T wave. The normal duration of the P wave is less than 0.12 seconds; its amplitude in limb leads is generally less than 0.25 mV and less than 0.2 mV in precordial leads. The PR interval ranges from 0.12 to 0.20 seconds. In adults, the QRS complex duration is less than 0.12 seconds. Its amplitude must not exceed 1 mV in lead V1, nor 2.5 mV in leads V5 and V6. In lead aVR, amplitude is typically ≥0.5 mV; in lead aVL, it should be <1.2 mV; and in lead aVF, it should be <2.0 mV.
Left ventricular high voltage may be observed in the following conditions: - Healthy young individuals, particularly those who are slender—this is attributable to reduced chest wall adipose tissue and closer proximity of the ECG electrode to the heart. - Hypertension, especially when blood pressure has been poorly controlled over a prolonged period. Chronic exposure to elevated afterload induces compensatory left ventricular hypertrophy, thereby increasing electrical potential—somewhat analogous to the upper-limb muscle hypertrophy seen in weightlifters.
However, in advanced stages of myocardial hypertrophy, elastic fibers within the myocardium may rupture, resulting in diminished contractility and progressive left ventricular chamber dilation—ultimately leading to heart failure. We hope this article has been helpful to you!
