[Phenomenon of a complete interventricular (interatrial) block]

In 21 cases of separate cardiac cavity excitation (20 of separate ventricular excitation (SVE) and one of separate atrial excitation), 40 right and left QRS complexes were obtained by routine, prolonged and synchronous ECG recording in various standard leads. A differential diagnosis was made between fusion QRS complexes and right and left QRS complexes. Three criteria of fusion ventricular complexes were found to be undiagnostic for right and left ventricular complexes in SVE. SVE has its own electrocardiographic criteria: (1) heterodirectional P waves or QRS complexes separated and unseparated from each other by an isoelectrical interval of less than 0.15 or less than 0.25 s, respectively; (2) in SVE, P-R interval may be no more than 0.06 s shorter than sinus P-R interval; (3) the end vector may be different from or similar to the sinus one. The basis for separate cardiac cavity excitation is functional longitudinal interatrial or interventricular blockade.