Paroxysmal Atrial Tachycardia (PAT) with Block

1. The P wave morphology is different than that of a normal sinus rhythm (NSR).
2. The atrial rate is between 150 and 250 beats per minute (BPM).
   • It is less than 200 in most cases.
   • In atrial flutter the rate is > 250 BPM in most cases.
3. There is an isoelectric baseline between P waves in all leads.
   • In atrial flutter there is a sawtooth appearance to the P waves.
4. AV block
   • Usually 2:1, but can be 3:1, and can even be variable and resemble atrial fibrillation.
5. Digoxin toxicity caused 73% of cases in the Lown series. Other reports put the number at 40 to 82%.

• Atrial flutter
• Atrial tachycardia
• Atrial fibrillation
• Multifocal atrial tachycardia

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