tachycardia with 2:1 AV block due to digitalis intoxication (note diminutive
P waves, barely visible even in V1)
B. Multifocal atrial tachycardia. Note the constantly changing form of
ectopic P waves.
R.J., MD, Kessler, K.M., MD, Castellanos, A., MD, Recognition, Clinical
Assessment, and Management of Arrhytmias and Conduction Disturbances,
Hurst's The Heart, 8th edition, p 705-758.