Postmaze Atrial Tachycardia: Case Submitted by: Berardo Sarubbi, MD, PhD

Case Synopsis

AR was the only daughter of normal parents, with no family history of cardiac abnormalities.

A cardiac murmur was heard at 8 days. At 3 years, palpation confirmed a thrill, and investigations confirmed the presence of a huge ostium secundum atrial septal defect with moderate pulmonary stenosis.

At the age of 10 years she underwent an uncomplicated atrial septal defect closure and pulmonary valvotomy.

She remained well until she was admitted, aged 32 years, in a peripheral hospital, for a first episode of atrial fibrillation. Severe pulmonary regurgitation was noted at the time.

When she was 34 years old, she suffered repeated episodes of atrial fibrillation and atrial flutter, which were hard to control despite various antiarrhythmic treatments (propafenone or sotalol alone, than amiodarone alone and in combination with propranolol).

When she was 36 years old, she underwent radiofrequency catheter ablation (RFCA) for atrial fibrillation consisting of pulmonary vein isolation. However, she soon had recurrences despite ongoing treatment with amiodarone.

She was referred to our cardiac tertiary center when she was 44 years old and underwent surgical operation for pulmonary valve replacement and surgical ablation of atrial arrhythmias through a tailored approach. She was discharged with sotalol treatment, which was discontinued 6 months after the operation.

She remained free of palpitations with routine periodic follow-up until age 48 when she suffered a new occurrence of atrial arrhythmias with no associated hemodynamic impairment.

At admission to our department, she reported dyspnea only with moderate to severe exertion.

Physical examination was remarkable only for a grade 1–2/6 systolic murmur at the left sternal border. Transcutaneous oxygen saturation was 99% and arterial blood pressure was 110/70 mmHg.

Electrocardiogram showed a narrow QRS tachycardia with a mean HR of 105 bpm and slight irregularity in the RR interval. Negative P-waves were seen in II, III, and aVF leads, with 2:1 atrioventricular (AV) conduction, leading to a diagnosis of intraatrial reentrant tachycardia ( Fig. 9.1 ).

Transthoracic echocardiogram revealed normal left ventricular dimensions and normal global left ventricular systolic function (left ventricular end-diastolic diameter [LVEDD] 45 mm; left ventricular ejection fraction [LVEF] 60%), along with moderate biatrial enlargement (Left atrial volume index [LAESV A-L index] 36 ml/m2 BSA), right ventricular hypertrophy and moderate dilation (right ventricular end-diastolic diameter [RVEDD] 42 mm), mild right ventricular dysfunction (TAPSE:14 mm), and severe pulmonary regurgitation. There was no right ventricular outflow tract obstruction.

After a detailed 3-D electroanatomic activation mapping (EnSite NavX Velocity technology), the patient underwent RFCA using a multielectrode dedicated catheter (Intella Tip Mifi XP Boston Scientific 8F 8 mm).

Three-dimensional mapping showed that the intraatrial reentry tachycardia involved a circuit around an atriotomy scar along the lateral right atrium wall ( Fig. 9.2 and 9.3 ), so it was decided to perform the extension of surgically created lines of conduction between the caval veins in a manner that could divide any corridors of myocardial tissue needed to sustain reentry. During radiofrequency application the arrhythmia stopped ( Fig. 9.4 ) and it was not possible to induce it again. A complete bidirectional conduction block was then demonstrated across the ablated region.