Normal ECG Value Ranges
May 22, 2022
Source: Cainiu Health
Dr. Yang Shuwen
Introduction
The PR interval is 0.12–0.2 seconds. In adults, the QRS duration is less than 0.12 seconds. QRS amplitude must not exceed 1 mV in lead V₁, nor 2.5 mV in leads V₅ and V₆. In lead aVR, the amplitude is typically ≥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 fat tissue and thus closer proximity between the ECG electrode and the heart. - Hypertension, especially when blood pressure has been poorly controlled over a prolonged period. Chronic exposure to elevated afterload causes compensatory left ventricular hypertrophy and increased electrical potential—similar to the muscular hypertrophy seen in weightlifters’ upper limbs.
However, in advanced stages of myocardial hypertrophy, elastic fibers within the myocardium may rupture, leading to diminished contractility and progressive left ventricular chamber dilation—ultimately progressing to heart failure. We hope this article has been helpful to you!
