Case 5
A 21-year-old boy with a history of atriopulmonary anastomosis at the age of two for tricuspid atresia and severe pulmonary stenosis underwent ablation procedure for the atrial tachycardia documented in 24 hours Holter ECG recordings. The EnSite™ NavX Precision system (St. Jude Medical St. Paul, MN, USA) is used as three dimensional mapping system and Advisor TM, HD grid mapping catheter and TacticathTM Quartz Contact Force (St. Jude Medical St. Paul, MN, USA) with Agilis™ NxT Steerable Introducer for mapping and ablation procedure. Confluence of coronary veins was absent and they drained to atria separately. Reference quadripolar esophageal (Esolo FIAB, Italy) catheter inserted to esophagus with close relation to left atria. During sinus rhythm voltage mapping, and tachycardia activation and propagation mapping was performed with high definition catheter by reference atrial signals receiving from esophageal recordings (figure 2b). Although atrial-sensing signals received perfectly, atrial capture could not be achieved from esophagus due to dextrocardia (figure 3). Therefore decapolar catheter was inserted to high atria for induction of tachycardia. Focal atrial tachycardia originating from free wall of right atria was detected and ablated successfully. Atrial activity was 130 ms earlier on target point when compared to esophageal signal.
Discussion :
Survival of complex congenital heart disease has improved dramatically over the last two decades. Improved survival leads to facing different types of arrhythmias developing due to hemodynamic effects of underlying disease or corrective surgery. Radiofrequency catheter ablation (RFCA) is an important therapeutic option for these arrhythmias. Accessing to the heart in cases with complex congenital heart defects may become a real obstacle for operators. Abnormalities of vascular structures (absence of hepatic part of inferior vena cava, coronary sinus anomalies, double superior vena cava without intercaval communication, left superior vena cava), surgical boundaries, and obstructed femoral veins are real challenges for electrophysiologists. Besides different electrical properties of complex congenital heart diseases altered myocardium acts as a substrate for atrial and ventricular arrhythmia. In complex congenital hearts reentries involving atria and ventricle scar areas are common with changing proportion to underlying disease or surgery as well as atrio-ventricular or nodal reentries or ectopic tachycardia. [4]
3D-electroanatomical mapping is recommended as class I for atrial and ventricular tachycardia in congenital heart diseases [5] which is reported to facilitate RFCA procedures for different types of arrhythmia mechanisms. All the mapping systems based on reference signal, and mapping catheter for electro anatomical mapping procedures. A stable positioned reference catheter is mandatory for performing such complex cases. Reference signal is generally acquired from intracardiac structures such as high right atria or coronary sinus, the latter is preferred mostly due to receiving signals both from atria, ventricle and extends to other side of atrioventricular groove. In cases with limited access resulting from congenital anomaly or size of the patient’s signals acquired from esophagus are very good alternative for intracardiac electrograms. Signals from esophagus have both atrial and ventricular potentials; additionally, close relation with left atria provides information about left sided structures.
Esophageal catheters are generally used for semi invasive electrophysiological studies in our center, which provides us useful information about palpitation complaints during pediatric age group, or overdrive pacing protocols for control of arrhythmia. A quadripolar catheter (Esolo FIAB, Italy) which is compatible with both Carto and EnSite™ NavX Precision system (St. Jude Medical St. Paul, MN, USA) with stimulation/sensing electrodes was inserted through the nares, and positioned, where the best atrial signals were received, approximately one cm above the cardiac portion of the stomach. The same protocol was applied during RFCA and mapping procedures successfully providing reference signals and pacing atria form left side. The demographic and clinical characteristics of patients are listed in Table 1, and mechanism and management of the arrhythmias are summarized in Table 2. Only in one patient atrial capture could not achieved due to dextroposition of heart. No complications associated with esophageal catheter were observed among our patients.