Introduction:

Antidromic atrioventricular (AV) reentry is a cardiac arrhythmia characterized by the presence of an accessory pathway that conducts electrical impulses in a retrograde fashion from the ventricles to the atria, resulting in a reentrant circuit. This article provides an overview of antidromic AV reentry, including its pathophysiology, clinical manifestations, diagnosis, and treatment strategies.

Pathophysiology:

Antidromic AV reentry typically occurs in individuals with an accessory pathway connecting the atria and ventricles, known as the bundle of Kent. In this arrhythmia, electrical impulses travel antegradely from the atria to the ventricles through the normal AV conduction system and retrogradely from the ventricles to the atria through the accessory pathway. The retrograde conduction through the accessory pathway completes the reentrant circuit, leading to repetitive depolarization and contraction of the atria and ventricles.

Clinical Manifestations:

The clinical presentation of antidromic AV reentry varies depending on the rate of ventricular response and the presence of underlying cardiac conditions. Common manifestations include:

• Palpitations: Patients may experience palpitations or a sensation of rapid, irregular heartbeat due to the arrhythmia.
• Tachycardia: Antidromic AV reentry often presents as paroxysmal supraventricular tachycardia (PSVT) with a rapid ventricular rate.
• Chest discomfort: Some individuals may report chest discomfort, chest pain, or tightness during episodes of arrhythmia.
• Dyspnea: Shortness of breath or dyspnea may occur, especially in individuals with compromised cardiac function.
• Syncope: In severe cases or in patients with underlying structural heart disease, antidromic AV reentry may lead to syncope or loss of consciousness.

Diagnosis:

The diagnosis of antidromic AV reentry is based on a combination of clinical evaluation, electrocardiographic findings, and electrophysiological studies. Diagnostic modalities include:

• Electrocardiogram (ECG): ECG findings during arrhythmia episodes typically reveal a narrow-complex tachycardia with a regular rhythm and no discernible P waves.
• Holter monitoring: Ambulatory ECG monitoring may be used to capture episodes of arrhythmia over an extended period, aiding in diagnosis and assessment of arrhythmia burden.
• Electrophysiological study (EPS): EPS is the gold standard for diagnosing antidromic AV reentry and identifying the location and properties of the accessory pathway. During EPS, catheters are placed in the heart to induce and characterize arrhythmia.

Treatment Strategies:

The management of antidromic AV reentry aims to control symptoms, restore sinus rhythm, and prevent recurrent arrhythmia episodes. Treatment strategies may include:

• Vagal maneuvers: Vagal maneuvers, such as the Valsalva maneuver or carotid sinus massage, may be attempted to terminate episodes of PSVT by stimulating the parasympathetic nervous system.
• Pharmacological therapy: Antiarrhythmic medications, such as adenosine, verapamil, or beta-blockers, may be used to terminate acute episodes of antidromic AV reentry and prevent recurrence.
• Catheter ablation: Radiofrequency catheter ablation is the definitive treatment for antidromic AV reentry, particularly in patients with recurrent or symptomatic arrhythmia. During ablation, the accessory pathway is targeted and ablated to interrupt the reentrant circuit.
• Implantable devices: In individuals with refractory antidromic AV reentry or recurrent arrhythmia despite medical therapy and ablation, implantable devices such as pacemakers or implantable cardioverter-defibrillators (ICDs) may be considered to manage arrhythmia and prevent sudden cardiac death.

Conclusion:

Antidromic AV reentry is a form of cardiac arrhythmia characterized by retrograde conduction through an accessory pathway, leading to reentrant tachycardia. Diagnosis is based on clinical evaluation, electrocardiographic findings, and electrophysiological studies. Treatment options include vagal maneuvers, pharmacological therapy, catheter ablation, and implantable devices, with the goal of symptom control and arrhythmia prevention.

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