P-Wave Duration Calculator

How to calculate P-wave duration?

P-wave duration represents the time taken for electrical impulses to travel through the atria, indicating the efficiency of atrial depolarization.

Formula: Duration (ms) = (Boxes / Paper Speed) * 1000

Using the P-wave calculator: an example

Example: A P-wave spanning 2.5 small boxes on a strip recorded at 25 mm/s paper speed.

Step-by-step calculation:

1. Count the horizontal small boxes (2.5)
2. Identify the recording speed (25 mm/s)
3. Apply the formula: (2.5 / 25) * 1000 = 100 ms

Frequently Asked Questions

What is a normal P-wave duration?

A normal P-wave duration is typically less than 120 milliseconds (3 small boxes at 25 mm/s).

What causes a prolonged P-wave?

Prolonged duration (>= 120ms) often indicates left atrial enlargement or intra-atrial conduction delay.