Sinus node modification with an ultra high-density electroanatomical mapping system in inappropriate sinus tachycardia

A 45-year-old woman without overt heart disease or significant comorbidities with a longstanding history for inappropriate sinus tachycardia since adolescence presented in our hospital. She had undergone consecutive treatments with verapamil, beta-blockers, and ivabradine without success. Clinical manifestations were symptomatic tachycardia, dizziness, and near syncope. Different causes for sinus tachycardia, e.g. hyperthyroidism, had been excluded. The patient presented with a sinus tachycardia showing a heart rate of 110 b.p.m. in the 12-lead electrocardiogram (ECG). Holter ECG showed heart rate variability from minimum 59 b.p.m. to maximum 171 b.p.m. with a mean heart rate of 102 b.p.m. Exercise testing revealed an acceleration in rate with minimal exercise until a maximum heart rate of 180 b.p.m. We decided to perform an electrophysiology study and catheter ablation. Electroanatomical maps of the right atrium (RA) were created using the Rhythmia system (Boston Scientific, Inc.). Mapping data were collected with a mini basket (1.8 cm diameter), containing eight splines of eight electrodes (total 64 electrodes, 2.5 mm spacing). The system automatically acquires electrograms and location information based on predefined set of beat acceptance criteria. Activation mapping and determination of earliest atrial activation were performed as described previously.