The mechanism of synchronization in isorhythmic A-V dissociation. II. Clinical studies.
The electrocardiographic patterns recorded from seven patients with isorhythmic A-V dissociation fall into two distinct groups. In pattern I, the P wave fluctuates cyclically back and forth across the QRS complex. The mechanism responsible for this type of A-V synchronization represents a typical biologic feedback control system. The P-R interval is a determinant of stroke volume, which in turn influences the arterial blood pressure. The blood pressure has an inverse effect on the discharge frequency of the S-A node through the baroreceptor reflex. The S-A nodal frequency then affects the P-R interval, to close the feedback loop. In pattern II, the P wave is in a fairly constant position relative to the QRS complex. It is usually coincident with the QRS complex or appears on the ST segment or first half of the T wave. The mechanism producing synchronization in pattern II type of isorhythmic dissociation has not been established conclusively.
Levy
M N
MN
Departments of Investigative Medicine and Cardiology, Mt. Sinai Hospital, Cleveland, Ohio, USA.
Edflstein
J
J
D000328:Adult; D000368:Aged; D001283:Atrioventricular Node / Q000503:physiopathology; D001794:Blood Pressure; D002304:Cardiac Pacing, Artificial; D003327:Coronary Disease / Q000175:diagnosis; D004070:Digitalis / Q000009:adverse effects; D004562:Electrocardiography; D006327:Heart Block / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009205:Myocarditis / Q000175:diagnosis