Repetitive reentrant and non-reentrant ventriculoatrial synchrony in dual chamber pacing.
Repetitive retrograde ventriculoatrial (VA) conduction in patients with dual chamber pacemakers may cause two forms of VA synchrony. (1) Endless loop tachycardia (pacemaker-mediated tachycardia) or repetitive reentrant VA synchrony occurs when the pacemaker senses retrograde P waves. Appropriate programming can prevent pacemaker reentrant tachycardia in almost all cases. However, the measures used to control tachycardia may themselves create new problems. (2) AV desynchronization arrhythmia or repetitive non-reentrant AV synchrony occurs when the pacemaker does not sense retrograde P waves. In this form of VA synchrony, the atrial stimulus is ineffectual because it falls in the atrial myocardial refractory period generated by the preceding unsensed retrograde P wave. A long atrioventricular interval and a relatively fast lower rate (or sensor-driven rate with DDDR pacing) favor the development of AV desynchronization arrhythmia and its unfavorable hemodynamic consequences.
Barold
S S
SS
Department of Medicine, Genesee Hospital, Rochester, NY 14607.
D005117:Cardiac Complexes, Premature / Q000503:physiopathology*; D004562:Electrocardiography; D006325:Heart Atria / Q000503:physiopathology; D006329:Heart Conduction System / Q000503:physiopathology; D006352:Heart Ventricles / Q000503:physiopathology; D006801:Humans; D010138:Pacemaker, Artificial; D013610:Tachycardia / Q000503:physiopathology* / Q000628:therapy