Catheter Ablation in Neonate with Heart Failure Due to Incessant Atrioventricular Reentrant Tachycardia

Abstract The atrioventricular (AV) reentrant tachycardia (AVRT) is the most common cause of supraventricular tachycardia (SVT) in the young pediatric population. Some newborns might present with congestive heart failure and require interventional treatment. Catheter ablation in small infants (<6 months and <5 kg) is still poorly performed and controversial due to high complications rate in this group of patients.1 We report a case of a 28 days old infant (3,5 kg) with a drug-refractory left accessory pathway mediated tachycardia and severe hemodynamic compromise, who underwent catheter ablation. Radiofrequency ablation should be part of the therapeutic arsenal in a context of drug-resistant supraventricular tachycardia with hemodynamic compromise, despite the greater risks of complications in this special population.

Randomized study of propofol effect on electrophysiological properties of the atrioventricular node in patients with nodal reentrant tachycardia.

BACKGROUND: Atrioventricular nodal reentrant tachycardia (AVNRT) is probably the most common form of paroxysmal supraventricular tachycardia. Percutaneous catheter ablation is a technique to interrupt cardiac conduction pathways selectively. The anesthetist is challenged to provide a safe anesthetic which takes into account the electrophysiologist's requirements for minimal cardiac conduction interference. Propofol is an ideal drug. However, previous studies have shown that the infusion of propofol has sometimes been associated with bradyarrhythmias or conversion of arrhythmias to sinusal rhythm. The purpose of this report is to verify the interferences of propofol in the electrophysiological properties of the atrioventricular (AV) node conduction system in patients with AVNRT. METHODS: Patients were randomly assigned to receive either a placebo or propofol at sedative doses. An electrophysiological study was performed consisting of measuring the anterograde (AERPFP) and retrograde effective refractory period of the fast (RERPFP) and the anterograde effective refractory period of the slow (AERPSP) AV nodal pathway. Reciprocating tachycardia was induced and the cycle length (CL) and atrial-His (AH), His-ventricular (HV), and ventriculoatrial (VA) intervals were measured. RESULTS: Propofol did not cause alteration (P > 0.05) in the AERPFP or RERPFP and the AERPSP AV nodal pathway. The AH, HV, and VA intervals were not affected. Sustained reciprocating tachycardia could be induced in the all patients. All slow pathways were successfully identified and ablated. CONCLUSION: Propofol has no effect on the electrophysiological properties of the AV node conduction system. It is thus a suitable anesthetic agent for use in patients undergoing ablative procedures.

[Clinical and electrophysiological characteristics of patients with atrioventricular nodal reentry tachycardia who underwent slow pathway ablation]. / Características clínicas y electrofisiológicas de pacientes fulgurados con radiofrecuencia por taquicardia por reentrada nodal típica.

BACKGROUND: AV nodal reentry tachycardia (AVNRT) is the most common cause of paroxysmal supraventricular tachycardia. Radiofrequency ablation is today the treatment of choice. AIM: To report our experience in patients who underwent slow pathway ablation. PATIENTS AND METHODS: Fifty six consecutive patients (68% female, mean age 43 years old) that underwent slow pathway ablation are reported. RESULTS: Sixty four percent of patients had failed drug therapy. During electrophysiological study, AVNRT was induced in 55 patients. Isoproterenol was required for induction in 36%. Programmed atrial stimulation revealed dual AV nodal pathway in only 64% of the patients; 29% had AVNRT with single nodal curve and 7% only prolongation of AH interval. The slow pathway was ablated in 55 patients. One patient refused ablation because of risk of AV block. All patients had immediate success post ablation. Sixty four percent of patients persisted with partial evidence of dual curve manifested by sudden AH prolongation and single echoes. CONCLUSIONS: Isoproterenol is essential for ruling out AVNRT, since 29% of the patients had baseline single nodal curve and in only 64% was tachycardia induced without isoproterenol. Persistence of residual dual physiology does not rule out the success of ablation.

Supraventricular tachycardia: diagnosis and treatment.

Specific mechanisms of supraventricular tachycardia include sinoatrial, intra-atrial, atrioventricular (AV) nodal as well as concealed and manifest bypass tract reentry. In dual pathway reentry, at least one of the pathways involves the AV node, usually the slow pathway and the other pathway, perinodal fibers within the atria. Localization of the perinodal fibers is critical for ablative procedures to eliminate AV nodal tachycardias. Other mechanisms of supraventricular tachycardia include chaotic atrial tachycardia and automatic atrial tachycardia with and without AV block. However, drug therapy includes intravenous adenosine 6 mg, as well as the older standbys of digoxin, calcium and beta-blocking agents, and type 1a and 1c antiarrhythmias. In resistance cases, amiodarone is usually effective. However, for incessant supraventricular mechanisms, catheter or surgical ablative techniques are recommended to eliminate long-term drug administration.