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KEY FEATURES

ESSENTIALS OF DIAGNOSIS

  • Heart rate typically 160–220 bpm, occasionally as slow as 120 bpm

  • Most commonly a narrow QRS tachycardia

  • Occasionally, retrograde P waves seen after the QRS complex or buried within the end of the QRS complex. Because of this, P waves not visible in 90% of cases

  • Short RP tachycardia (RP interval shorter than PR interval)

  • In atypical atrioventricular (AV) nodal reentrant tachycardia (< 20% of cases), long RP tachycardia (RP interval > PR interval) may be seen

GENERAL CONSIDERATIONS

  • More common in females

  • Polyuria not uncommon secondary to elevated atrial natriuretic peptide

  • Age distribution is bimodal; initial episode during second decade of life, only to disappear and then reappear during the fourth and fifth decades

  • Antegrade (slow pathway) and retrograde (fast pathway) limbs are within the AV node

  • In atypical cases, fast pathway is antegrade limb

  • Sudden death is reported in rare instances

CLINICAL PRESENTATION

SYMPTOMS AND SIGNS

  • Rapid, regular pounding in the neck

  • Palpitation

  • Dizziness

  • Occasionally syncope

  • Polyuria

PHYSICAL EXAM FINDINGS

  • Tachycardia: 120–220 bpm but usually > 160

  • Occasionally hypotension

  • Neck pulsations corresponding to the heart rate

  • Tachycardia may occasionally terminate with vagal maneuver and carotid sinus pressure

DIFFERENTIAL DIAGNOSIS

  • AV reentrant tachycardia

  • Atrial tachycardia

DIAGNOSTIC EVALUATION

LABORATORY TESTS

  • CBC, basic metabolic panel

ELECTROCARDIOGRAPHY

  • ECG and rhythm strip usually show a narrow QRS complex tachycardia without p waves. When p waves are visible, they are seen near the end of the QRS complex (lead V1 is best) and usually a short RP (RP < PR) interval is noted

  • Ambulatory cardiac monitoring to detect tachycardia

  • Event recorder to detect tachycardia

IMAGING STUDIES

  • In otherwise healthy patient, no imaging required, although echocardiography is commonly performed to exclude structural heart disease

DIAGNOSTIC PROCEDURES

  • Invasive electrophysiology (EP) study to confirm mechanism of tachycardia and its suitability for ablation

TREATMENT

CARDIOLOGY REFERRAL

  • EP referral is recommended for all patients, although some physicians may try medications initially

HOSPITALIZATION CRITERIA

  • If the diagnosis is certain and posttermination ECG is normal, hospitalization is not required

MEDICATIONS

  • Acute termination occurs with adenosine 6-mg or 12-mg bolus injection. Note that some atrial tachycardias are also adenosine sensitive

  • Maintenance therapy includes beta blockers or calcium channel blockers to inhibit the slow pathway

  • Class IC drugs may be used to inhibit the fast pathway; however, they are less commonly used due to efficacy of catheter ablation

THERAPEUTIC PROCEDURES

  • EP study followed by slow AV nodal pathway ablation offers definitive cure in > 95% of patients

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