The Electrocardiogram (ECG) is one of the safest and most useful diagnostic medical tests. Being able to read and interpret the Electrocardiogram correctly is vital for all Health professionals. However, to achieve this objective it is necessary to know the Electrocardiogram paper and their characteristics.
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Characteristics of the Electrocardiogram Paper.
The Electrocardiogram Paper is a graph paper in which there are large squares made up of small squares (5×5). The paper is millimeter. Each small square measures 1 millimeter. While each large square measures 5 millimeters.

Axes of the Electrocardiogram Paper
The Paper used for Electrocardiograms has 2 axes; one horizontal and one vertical. The Horizontal Axis is used to measure time.
On an EKG at a standard speed of 25 millimeters per second (25 mm / s). Every 1 millimeter or every small square equals 0.04 seconds. A large square is made up of 5 small frames, its value is 0.20 seconds. This axis is used in the interpretation and reading of the Electrocardiogram, for example when calculating the heart rate.
The Vertical Axis is used to measure the voltage of the electric current. In other words, it measures the amplitude of the electrical current in the heart. Its unit of measurement is expressed in milli volts (mV).
Every 10 millimeters or every 2 large squares in height equals 1 mV. This means that each small square or every 1 millimeter in height equals 0.1 mV, and each large square or every 5 millimeters equals 0.5 mV.
Standard or normal electrocardiogram
As a standard, the Electrocardiogram should go at a speed of 25 millimeters per second. However, it is possible to increase or decrease the paper speed as required.
Certain diseases such as disorders wave may require a higher speed. While rhythm disturbances may require a reduced speed for proper analysis.
The voltage can also be increased or decreased as needed. It is possible to increase the amplitude of the Electrocardiogram in the event of microvoltages or decrease it if, for example, there are too high QRS complexes.
Normally the velocity and amplitude values can also be seen printed on the Electrocardiogram Paper. They are usually on the top or bottom edge of the paper.
Electrocardiogram Calibration
The EKG machine automatically performs a calibration at the start of each recording. This calibration can be seen on the Electrocardiogram Paper as a rectangle.

The electrocardiograph makes an electric pulse of 1 mV for exactly 0.2 seconds. What is reflected in the Electrocardiogram Paper as can be seen in Figure 2.
The formed Rectangle must be 10mm high and 5mm wide. If the electrocardiograph is correctly calibrated, the rectangle formed should not have deviations.
Verificar que el Electrocardiograma a realizar se encuentra calibrado resulta esencial para una prueba fiable y para evitar falsos resultados en la prueba.
Video of the Electrocardiogram Paper
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MD. University teacher. Passionate about internal medicine. Biochemistry and Pathophysiology are my favorite subjects. I have created this website as a portal to help understand certain topics and as a source of review.