Anatomic Challenges In Pediatric Catheter Ablation

Abstract

Pediatric patients present unique anatomic challenges for catheter ablation. Small patient size requires special adaptation and understanding to perform safe procedures when clinically indicated. The anatomic variations of congenital heart disease also create problems that require pre-procedural preparation for each case in addition to a specialized understanding of a vast anatomic variation and surgical repairs. This understanding coupled with the knowledge of the pathophysiology of arrhythmia disorders and the biophysics of catheter ablation technology are required to perform successful and safe ablation procedures in this special population.

Figure 1.. Important Considerations for Abalation Procedures in Congenital Heart Disease.

Figure 2.. ECG of a 28y/o with Noonan’s syndrome ASD and pulmonary valve stenosis post repair in 2:1 IART. Note the discrete p waves and relatively slow tachycardia p-p interval of 270 msec.

Figure 3.. 3D mapping of a severely dilated right atrium in a 28 year old male with Ebstein Anomaly who is post tricuspid valve replacement and right atrial maze. The first panel shows a noncontact mapping image displaying the areas out of the 4cm accuracy range in red. The second panel shows a contact mapping geometry. In this case contact mapping revealed that the low voltage area and scar likely created by a right atrial maze procedure was a target for ablation that was out of range for noncontact mapping. Ablation in this area with a large (8mm) tip RF catheter resulted in arrhythmia termination, non-induciblilty and bidirectional conduction block.

Figure 4.. Relationship between mean lesion volume and flow rate for irrigated and large tip RF catheter types. Highest flow rate (3 L/min) corresponds to a flow velocity of 15.5 cm/s. (Data from Pilcher TA, Sanford AL, Saul JP, Haemmerich D. Convective cooling effect on cooled-tip catheter compared to large-tip catheter radiofrequency ablation. Pacing Clin Electrophysiol. 2006; 29: 1368-1374. With permission.)

Figure 5.. Ellipsoid graphs comparing the average lesion dimensions for cryoablation and RF ablation at each respective flow rate. The series shows decreasing lesion dimensions with increasing flow rate for cryoablation (P < 0.005) and increasing lesion dimensions for increasing flow rate for RF ablation (P < 0.005). Note the partial prolate ellipsoid shape of cryoablation lesions and the partial oblate ellipsoid shape of the RF ablation lesions. (Data from Pilcher TA, Saul JP, Hlavacek AM, Haemmerich D. Contrasting effects of convective flow on catheter ablation lesion size: Cryo versus radiofrequency energy. Pacing Clin Electrophysiol. 2008; 31: 300-307. With permission.)