Three-dimensional distribution of bipolar atrial electrogram voltages in patients with congenital heart disease

Voltage differences might be used to distinguish normal atrial tissue from abnormal atrial tissue. This study was aimed at identifying lowest voltage areas in patients with atrial tachycardia after surgical correction of cong enital heart disease and to evaluate if identification of these areas in di seased hearts facilitates selection of critical conduction pathways in reen trant circuits as target sites for catheter ablation. Ten patients (four me n, age 39 +/- 15 years) with normal sized atria and atrioventricular recipr ocating tachycardia (control group) and ten patients (5 men, 32 +/- 7 years ) with congenital heart disease and postoperative atrial tachycardia (CL 28 1 +/- 79 ms) referred for radiofrequency catheter ablation were studied. Ma pping and ablation was guided by a three-dimensional electroanatomic mappin g system (CARTO) in all patients. In the control group, voltage maps were c onstructed during sinus rhythm and during tachycardia to evaluate the volta ge distribution. The amplitude of bipolar signals was 1.90 +/- 1.45 mV (0.1 1-8.12 mV. n = 660) during sinus rhythm and 1.45 +/- 1.66 mV (0.12-5.83 mV, n = 440, P < 0.05) during atrioventricular reciprocating tachycardia. In t he study group, the amplitude of 1,962 bipolar signals during tachycardia w as 1.01 +/- 1.19 mV (0.04-9.40 mV), which differed significantly from the c ontrol group during tachycardia (P < 0.0001). No significant difference in the tachycardia cycle length was found (P < 0.05) between the control and s tudy groups. As the lowest voltage measured in normal hearts was 0.1 mV, th is value was used as the upper limit of the lowest voltage areas in the pat ients with congenital heart disease. These areas were identified by detaile d voltage mapping and represented by a gray color. Activation and propagati on maps were then used to select critical conduction pathways as target sit es for ablation. These sites were characterized by fragmented signals in al l patients. Ablation resulted in termination of the tachycardia in eight (8 0%) of ten patients. Complications were not observed. Identification of the lowest voltage areas using a cut-off value of 0.1 mV in congenital heart d isease patients with postoperative atrial reentrant tachycardia facilitated the selection of critical conduction pathways as target sites for ablation .