A 28-year-old patient, 37-weeks pregnant, with no relevant priors or regular medication, was consulted by her gynecologist due to a long-lasting history of palpitations and pre-syncope aggravated since the twentieth week of pregnancy.
A 12-lead electrocardiogram and a 24-h Holter monitoring were requested that demonstrated repetitive, almost incessant, narrow QRS complex tachycardia alternating with rare sinus beats, suggestive of atrial tachycardia (Figs. 1 and 2). The average heart rate was 155 beats per minute (bpm), maximum of 234 bpm and a minimum of 84 bpm. A cardiology consultation was then requested, and the patient was immediately admitted for initiation of antiarrhythmic therapy under close monitoring.
At admission the patient was hemodynamically stable with an unremarkable physical examination, except for a rapid and irregular rhythm. A transthoracic echocardiogram (Additional File 1: Video S1) demonstrated a dilated left ventricle with diffuse hypokinesis and moderately compromised ejection fraction (35% by Simpson Biplane) and a diagnosis of tachycardia-induced cardiomyopathy was assumed.
Administration of adenosine with complete atrioventricular block demonstrated monomorphic P waves and resumption of clinical arrhythmia. The patient was started on propranolol in uptitrating doses and flecainide which were ineffective. Digoxin was then administered with some reduction in the average heart rate while maintaining frequent symptomatic episodes of atrial tachycardia.
The patient evolved in acute congestive cardiac failure at third day of admission and, after multidisciplinary meetings, an emergency cesarean delivery was decided on and performed. Perioperative hemodynamically instability occurred with transient need of vasopressor therapy. The patient was admitted in an intensive care unit achieving clinical stability at 24 h. The newborn was admitted in a neonatal intensive care unit as a precaution.
Given the poor response to pharmacological treatment the patient was submitted to an electrophysiological study. The study confirmed a focal atrial tachycardia (Fig. 3) and, using a 3D mapping system (CARTO ©3D Mapping system), identified the earliest local activation at the lower left pulmonary vein (Fig. 4 and Additional File 2: Video S2). An electrical isolation of the vein with radiofrequency catheter ablation was performed with total suppression of the ectopic foci (Fig. 5). There was no recurrence, even after infusion of isoprenaline.
Upon clinical improvement, the patient was discharged, asymptomatic, and without recurrence of the arrhythmia. The newborn evolved clinically well, without sequelae.
In the follow-up at 4 months the patient was asymptomatic, without drug therapy, with normal resumption of everyday activity. There was no recurrence of arrhythmia or supraventricular extrasystoles on a 24 h Holter monitoring and the transthoracic echocardiogram (Additional File 3: Video S3) showed a non-dilated left ventricle, without regional wall motion abnormalities, and a complete recovery of left ventricular function (64% by Simpson Biplane).