[Allorhythmias (classification and differential diagnosis)]

Allorhythmia in the broad sense is defined as a regular sequence of similar groups of ECG-complexes associated with various disorders of cardiac rhythm and conduction. The following classification of allorhythmias is suggested. A. True allorhythmias. I. Due to extrasystoles: 1) noncomplicated; 2) complicated by disorders of conduction. II. Allorrhythmias due to ectopic rhythms with capture beats: 1) paroxysmal or nonparoxysmal ectopic tachycardia; 2) escaping rhythms. III. Allorrhythmias due to impulse conduction block: 1) II degree S--A block; 2) II degree A--V-block; 2, atrial flutter and atrial tachycardia with A--V-block 3 : 2, 4 : 2, etc. B. Pseudoallorrhythmias due to regular alterations in the shape of the QRS complex: 1) transient bundle-branch block; 2) transient WPW syndrome; 3) bidirectional tachycardia. Differential diagnosis of various types of allorrhythmia is of great importance in choosing the measures and methods for antiarrhythmic therapy.