Certified Rhythm Analysis Technician (CRAT) Practice Exam 2026 - Free CRAT Practice Questions and Study Guide

In the context of ECG graph paper, each large box is designed to represent specific voltage levels for accurate reading and interpretation of the cardiac electrical impulses. When looking at the standard calibration of ECG paper, two large boxes correspond to a voltage representation of 1 millivolt. This standard allows technicians and medical professionals to assess the amplitude of the electrical activity of the heart with precision.

Understanding this measurement is crucial for identifying abnormal heart rhythms or conditions. The way the large boxes are divided into smaller boxes and their defined measurements further aids in consistently interpreting the amplitude of ECG signals across different recordings. An accurate assessment of voltage is essential for diagnosing and monitoring patients’ cardiac health effectively.