Case Report
An 84-year-old woman was referred to our hospital due to heart failure with wide QRS tachcardia associated with AF. She was diagnosed as Wolf-Parkinson-White syndrome in 1996, however catheter ablation of the right posterolateral accessary pathway at that time was unsuccessful under fluoroscopy. She was not taking anticoagulants because her AF had not been noted. After administration of medication for heart failure and oral anticoagulant, transoesophageal echocardiography showed the presence of a thrombus in the left atrium. We decided to perform catheter ablation under AF.
An electrophysiological study (EPS) was performed under local anaesthesia, and the position of the tricuspid valve was mapped using the CARTO (Biosense Webster, Diamond Bar, CA) ICE catheter (Sound Star Biosense Webster) to evaluate the functional tricuspid anulus (TA). The functional TA was significantly deviated to the right ventricular side (Figure 1-A-1). The location of the functional TA was tagged using ICE (Figure 1-A-2,3). After insertion of the His-RV catheter, a high-density mapping catheter (penta-ray Biosense Webster) and a ablation catheter (ThermoCool Smarttouch Surroundflow catheter (STSFc), Biosense Webster) were advanced into the right atrium and right ventricle, and activation maps were generated using an electroanatomical mapping system (CARTO 3 System Version 7, Biosense Webster). Mapping was done under AF and both ventricular and atrial electrogram were recorded on the tricuspid annulus. The activation timing was automatically annotated using a local activation time (LAT) annotation tool integrated in the CARTO system.
Activation mapping was performed concerning the body surface advanced referenced annotation (ARA) algorithm. The window of interest was set to cover the earliest V-wave of the endocardial ECG. Because of the mixture of narrow QRS via atrioventricular node and wide QRS complex with pre-excitation (Figure 2), the CARTO3 Confidence Module with pattern matching was used to acquire the points of the QRS automatically. The QRS morphology of maxmum pre-excitation was acquired, and the correlation threshold was set to ≥0.97. Position stability was set to 3 mm, and the mapping density was set to maximum. One thousand eight hundred forty-three points of maximum prepexcitation patterns were mapped in 15 min. Since the AF electrogram was recorded simultaneously, the earliest ventricular activity could not be detected by mapping using a LAT map (Figure3-A). We used 3D intra-cardiac electrograms visualisation (Ripple map (RM) module), which does not require annotation of the timing of excitation and reflects all excitations on the map even if there are multiple excitations in the window of interest. The RM clearly visualized the consistent propagation around TA via the accessary pathway (Figure3-B, supplemental movie). The fusion point of the ventricular and atrial activity was more to the right atrial side than the functional anulus mapped using ICE (Figure 1 B-2) and coincided with the location of the earliest ventricular activity expressed by RM (Figure 3 B-1,2,3). When the the fusion point was energised at a maximum of 35W, the wide QRS wave disappeared, and only the irregular narrow QRS beats were observed after 5 seconds of ablation (Figure 1 B-1). Postoperative echocardiography showed improvement in left ventricular ejection fraction, and the patient was confirmed with an Ebstein anomaly on transbusturacic echocardiography.