Cardiovascular
Medicine - Education Center
Atrial fibrillation with premature ventricular complexes:
Atrial fibrillation is characterized by the disorganized
and chaotic excitation and recovery of the atria. A ragged baseline is the definitive diagnostic feature.
The rate at which these irregular impulses reach the atrio-ventricular node may range
from 400-600 impulses/min. The atrio-ventricular node cannot conduct all these impulses since it
is refractory for a certain period after each impulse. Hence, transmission to the ventricles is irregular.
Unfortunately, since the atrio-ventricular node is not as good a pacemaker as the sino-atrial node,
it occasionally fails to conduct and the ventricles fire spontaneously as a premature ventricular complex as
seen above. Atrial fibrillation usually occurs in coronary artery disease, thyrotoxicosis, mitral valve
disease (especially mitral stenosis), tricuspid valve disease, some cases of constrictive pericarditis and
also in the Wolff-Parkinson-White syndrome as paroxysmal atrial fibrillation. Atrial fibrillation in the absence of
any other pathological abnormality is termed as "lone auricular fibrillation" and usually occurs in young individuals or
in certain families.
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