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.