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Atrial Flutter example one



Note the fairly regular, jagged baseline: a series of rapid atrial depolarizations.
These are flutter, or F-waves.  They make up what is often called a sawtooth
baseline.  Note that the F-waves following the QRS complexes are shaped
differently:  they are distorted by summation with the T-waves that follow
each QRS.  This is best seen in leads II and AVF.  The atrial rate here is 260
beats per minute, and the ventricular rate is 65 beats per minute, an exact
four to one ratio.  So, we call this atrial flutter with four to one capture.
The mechanism of atrial flutter is uncertain.  It may be caused by a single,
rapidly firing irritable focus in the atria, or by a reentrant pattern within a
small area of the atria.