Welch Allyn Means ECG Physicians Manual for CP Series Electrocardiographs - User Manual - Manual (Page 33)

MEANS Physicians Manual
Welch Allyn
33
Basic parameters such as the consistency of the RR interval, the P/QRS ratio, and the
consistency of the PR interval are not the only characteristics upon which a diagnosis is
based. Other features are used to form a statement, such as heart rate, type of the non-
dominant complexes, QRS duration, and PP interval. Through combinations, it is possible to
form more than ISO statements concerning the type of rhythm that is present.
The subsequent paragraphs in this chapter will describe the parameters that are used in
rhythm analysis, the general structure of the decision tree, the categories of rhythm
statements that have been distinguished, and the diagnostic criteria for the rhythm statements
grouped according to category. A cross-reference list is provided for ease of finding the
criteria for a specific statement.
3.2 Rhythm parameters
The following parameters are used in the criteria for documenting rhythms

P/QRS ratio: ratio of the number of P waves to the number of dominant QRS complexes.
(If used as a measure for atrial activity).

PR range: difference between the maximum and minimum PR interval (in ms). It is used
as a measure for the constancy of the PR interval.

Type of QRS complex: classification of QRS complexes according to their morphology.
Complexes with the same morphology belong to one type. A basic distinction is between
the dominant and non-dominant types of QRS complexes. The latter group may consist of
one or more types of non-dominant QRS complexes.

RR interval: interval between two consecutive QRS complexes (in ms).

PP interval: interval between two consecutive P waves (in ms).

PR interval: interval between a dominant QRS complex and a preceding P wave (in ms).

atrial rate: number of atrial contractions (in beats per minute, BPM).

Ventricular rate: number of ventricular contractions (in BPM).

Rate variation: difference between the maximum and minimum RR interval, normalized to
the average RR interval. (If used as a measure for regularity of the rhythm).

QRS duration: difference between the global onset and end of the QRS complex (in ms).

P axis: axis of the P wave in the frontal plane, using the areas under the P waves in lead I
and II (in degrees).

negative P amplitude (in µV): absolute value of the negative deflection of the P wave.