Submitted by Dr T on June 24, 2011 – 8:34am
Question:
Hi Dr T:
My Pre-op ECG read vertical axis unusual for age but other wise normal. Can you tell me what this means (vertical axis)?
My Pre-op ECG read vertical axis unusual for age but other wise normal. Can you tell me what this means (vertical axis)?
I cannot identify what the unusual feature is of course, but this explains the vertical axis of an EKG:
EKG paper is a grid where time is measured along the horizontal axis.
- Each small square is 1 mm in length and represents 0.04 seconds.
- Each larger square is 5 mm in length and represents 0.2 seconds.
Voltage is measured along the vertical axis.
- 10 mm is equal to 1mV in voltage.
- The diagram below illustrates the configuration of EKG graph paper and where to measure the components of the EKG wave form
![](https://www.cardiachealth.org/wp-content/uploads/tracer.gif)
Heart rate can be easily calculated from the EKG strip:
- When the rhythm is regular, the heart rate is 300 divided by the number of large squares between the QRS complexes.
- For example, if there are 4 large squares between regular QRS complexes, the heart rate is 75 (300/4=75).
- The second method can be used with an irregular rhythm to estimate the rate. Count the number of R waves in a 6 second strip and multiply by 10.
For example, if there are 7 R waves in a 6 second strip, the heart rate is 70 (7×10=70).
Hope this helps,
(From: How to Read an EKG Strip)