Welch Allyn Means ECG Physicians Manual for CP Series Electrocardiographs - User Manual - Manual (Page 34)

MEANS Physicians Manual
Welch Allyn
34
3.3 Decision tree
The decision tree for the rhythm analysis is shown in Figure 1 on page 36. The program starts
at the top decision node and proceeds depending on the value of the test. If the condition in
the decision no
de is met, the branch marked by “yes” is taken. If not, the “no”-branch is
followed. First, the activity of an artificial pacemaker, the occurrence of more than one type of
QRS complexes (non-dominant complexes), and the presence of atrial flutter waves is tested.
In presence of pacemaker spikes or flutter waves, an appropriate statement is issued and the
rhythm analysis stops. If non-dominant complexes are also present, the type of arrhythmia is
described. The non-dominant complexes are then discarded from further consideration and
the analysis proceeds. Thus, after this first phase, only one type of QRS complex (the
dominant complexes) is analyzed.
Second, regular rhythms are distinguished from irregular ones based on the consistency of
the RR intervals. Both types of rhythm are subdivided in to different groups depending on the
number of P waves versus the number of QRS complexes (P/QRS ratio) and on the
consistency of the PR interval (PR range). The irregularity of a rhythm may be brief local. The
program then describes the abnormality and discards the relevant complexes, similar to the
way non-dominant complexes are handled. If the resultant rhythm, after removal of the
atypical complexes, is regular, the rhythm is analyzed in the regular rhythm part of the
program.
In Table 3 the various groups are listed together with a characterization of the types of
arrhythmia in each group.