Diagnosis of tachycardia mechanism with cryomapping in a toddler with complex congenital heart disease.

A 2.5-year-old patient with complex congenital heart disease involving dextrocardia, atrioventricular and ventriculoarterial discordance, pulmonary stenosis, ventricular septal defect (VSD), atrial septal defect (ASD), and paroxysmal supraventricular tachycardia (SVT) underwent electrophysiological study. The tachycardia mechanism was diagnosed with cryomapping. The ability of cryomapping to have transient and reversible effect on the tissue, unlike radiofrequency (RF) ablation, helped in the establishment of diagnosis in this toddler with typical atrioventricular nodal reentrant tachycardia. Cryomapping can be an additional safe diagnostic utility in young patients with complex congenital heart disease.