Incessant Ventricular Tachycardia in an Infant Treated With Transmural Radiofrequency Ablation
A previously healthy, 7-month-old male infant weighing 7 kg presented to our institution with a 2-day history of incessant ventricular tachycardia (VT) unresponsive to defibrillation and medication. Echocardiography demonstrated a structurally normal heart and mild mitral regurgitation.
Percutaneous catheter mapping identified that the VT originated in the posterobasal left ventricle. Two attempts at catheter radiofrequency (RF) ablation using both standard and irrigated-tip catheters resulted in temporary slowing or cessation of VT with prompt recurrence.
A surgical approach using cardiopulmonary bypass was then tried. A yellowish plaque on the epicardial surface was noted over the posterobasal left ventricle (Figure 1). Epicardial mapping with a hand-held probe confirmed that the earliest activity occurred at this site (Figure 2). Tissue specimens demonstrated histiocytoid cardiomyopathy (Figure 3), which is a cardiomyopathy of infancy characterized by intractable tachycardia.
Temperature-controlled transmural RF ablation with a needle electrode to a 3×4-cm region of earliest activity and the visible lesion terminated the VT. The surrounding area was treated by cryoablation and the infant remained free of VT. Worsening of mitral regurgitation ultimately necessitated valve replacement. Subsequent follow-up over 6 months has been uneventful.
The editor of Images in Cardiovascular Medicine is Hugh A. McAllister, Jr, MD, Chief, Department of Pathology, St Luke’s Episcopal Hospital and Texas Heart Institute, and Clinical Professor of Pathology, University of Texas Medical School and Baylor College of Medicine.
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