• Re-entry and Supraventricular Tachycardia
• Intra-Atrial Reentry Tachycardia
• ECG and Intra-Atrial Reentry Tachycardia
• Differential Diagnosis

Re-entry and Supraventricular Tachycardia

• In supraventricular tachycardia (SVT), impulses originate in the atria or in the AV junction
• Re-entry is one of the mechanisms of tachycardia
• where the impulse circulates in a loop, most often around an anatomical obstacle (scar tissue)

• Sinoatrial Nodal Reentry Tachycardia
• Re-entry is in the SA node
• or re-entry passes through the SA node
• Intra-atrial Reentry Tachycardia
• Re-entry occurs somewhere in the atria
• most commonly around scar tissue (post-myocardial infarction)
• or re-entry occurs without an obstacle
• AV Nodal Re-entry Tachycardia
• Re-entry is in the AV node
• AV Re-entry Tachycardia
• It is macro re-entry, with the impulse circulating between:
• the atria and the ventricles through the AV node and an accessory pathway
• We recognize 3 accessory pathways:
• Kent bundle (WPW syndrome)
• James bundle (LGL syndrome)
• Mahaim bundle (Mahaim syndrome)
• Atrial Flutter
• It is macro re-entry, with the impulse circulating
• through the entire most commonly right atrium

ECG and Intra-Atrial Reentry Tachycardia

• Frequency 100-250/min.
• It is a narrow-complex supraventricular tachycardia (SVT)
• QRS complex width < 0.12s
• P waves are abnormal in shape
• Because they do not originate in the SA node
• It is paroxysmal (sudden onset and sudden termination)
• As with all reentry SVT tachycardias

Intra-Atrial Reentry Tachycardia

• Frequency > 100/min. (115/min.)
• Narrow QRS complexes (< 0.12s)
• Abnormal P wave (before each QRS)
• P wave in lead II should not be negative

Focal Atrial Tachycardia

• There is an ectopic focus in the atrium that generates impulses instead of the SA node
• Frequency 100-250/min.
• P waves have a different shape compared to sinus rhythm
• In this case, P waves are negative in lead II
• Electromechanism of the ectopic focus can be
• Increased automaticity (the tachycardia is "warming up")
• Triggered activity (tachycardia is paroxysmal)

Intra-Atrial Reentry Tachycardia (IART)

• It concerns a 40-year-old patient who is post-surgical correction of a congenital heart defect (Fallot's tetralogy)
• The patient experienced paroxysms of the mentioned supraventricular tachycardia
• Frequency: 120/min.
• Non-physiological P wave
• Negative (II, III, aVF), positive (V1)
• Does not originate from the SA node
• Exactly the same EKG pattern can be seen in focal atrial tachycardia
• Anamnesis (cardiac surgery, paroxysms) suggests IART
• Definitive diagnosis is made with electrophysiological examination