Congenital Sick Sinus Syndrome With Atrial Inexcitability and Coronary Sinus Flutter

Abstract

ongenital sick sinus syndrome has been described sporadically. The syndrome may comprise various components of sinus bradycardia, atrial fibrillation, and right atrial inexcitability. [1][2][3][4][5][6][7] In the current case, detailed electrophysiological evaluation was undertaken with electroanatomic mapping of the right atrium and coronary sinus (CS) and of associated supraventricular arrhythmias. CaseA 37-year-old asymptomatic male physician from Mexico without any previous medical problems was referred after routine physical examination for evaluation of atrial fibrillation with a slow ventricular rate. Arrhythmia duration was unknown. He stated that bradycardia had been consistently noted on previous clinical examinations and had been attributed to competitive long-distance running since childhood. Heart rates in the "40s" had been noted since age 10 to 11 years when he had been informed of a "heart murmur." Subsequent echocardiographic examination had been normal. The patient denied any family history of sudden death or arrhythmias. He had no siblings and no children. His prior records (and those of his parents) were unavailable.Physical examination was normal except for a regular bradycardia of 45 beats/min. Twelve-lead ECG showed fixed R-R intervals. No clear P-wave activity was identified. However, there was small-amplitude baseline electric activity of debatable origin, interpreted variously by experienced electrocardiographers as standstill, artifact, or atrial fibrillation waves ( Figure 1A). A transthoracic echocardiogram showed normal ventricular volume and function (left ventricular end-diastolic diameter, 52 mm; left ventricle end-systolic diameter, 34 mm) and mild tricuspid regurgitation with estimated pulmonary artery systolic pressure of 40 mm Hg. Both atria were severely enlarged (left atrial volume index, 58 mL; right atrial area, 41 cm 2 ). Doppler echocardiographic examination of both tricuspid and mitral atrioventricular (AV) inflow showed complete absence of A waves, indicating lack of left and right atrial contractile activity (Figure 2). A transesophageal echocardiogram did not reveal any evidence of an intracardiac shunt. A Bruce protocol exercise treadmill test was stopped at 10 minutes and 26 s because of patient shortness of breath. Heart rate accelerated gradually to a maximum of 131 beats/min and always remained regular. Baseline atrial activity (if any) was not interpretable because of exercise artifact. Isolated premature ventricular contractions were observed during exercise. A 24-hour Holter monitor showed regular rhythm (mean heart rate, 47 beats/ min; range, 35-95 beats/min; maximum R-R interval, 1.8 s) with 56 ventricular bigeminal cycles. The only symptom during recording periods was an abnormal lateral chest sensation that corresponded with heart rates between 30 and 40 beats/min. The patient underwent an external cardioversion without appreciable change in heart rate (44 beats/min), although electrocardiographic intervals between QRS-T complexes became completely isoel...

Electroanatomic Mapping and Late Gadolinium Enhancement MRI in a Genetic Model of Arrhythmogenic Atrial Cardiomyopathy

“…Patients with primary atrial disease may show the entire spectrum of atrial arrhythmias; data documenting the arrhythmogenic substrate in humans are few. 6,7 In this study, the detailed 3D reconstruction of atrial anatomies with accurate estimation of volumes and shapes, the electroanatomic mapping of low voltages and scar areas, and the LGE-MRI identification of fibrosis provided in vivo demonstration of the pathologic substrate of atrial arrhythmias in primary atrial disease. The second contribution of our observation is the correlation between the extent of low voltages and scarring/fibrosis with the type of atrial arrhythmias.…”

“…Unfortunately, monogenic arrhythmogenic atrial diseases are rarely identified. Current knowledge is still limited to and based on electrophysiological studies done in cell and animal models or with computational simulation and on electrophysiological evaluation in 2 single patients …”

“…Current knowledge is still limited to and based on electrophysiological studies done in cell and animal models or with computational simulation and on electrophysiological evaluation in 2 single patients. 6,7 In a previous study we documented the genetic origin of an atrial cardiomyopathy due to a Natriuretic Peptide Precursor A (NPPA) gene mutation and we defined its clinical phenotype. 8 In this study, we integrated electroanatomic mapping, tomography, and late gadolinium enhancement magnetic resonance imaging (LGE-MRI) to test the hypothesis that fibrosis is the substrate of atrial arrhythmias and that the progression of fibrosis is associated with the worsening of atrial arrhythmias in this human monogenic model of arrhythmogenic atrial cardiomyopathy.…”

Electrical Isolation of Both Left Pulmonary Veins by a Single Left Atrial Endocardial Radiofrequency Energy Application: Ablation of Marshall Bundle Bypass

“…It was abolished by ablation at the ostium of the coronary sinus and not within the muscular CS at the origin of the vein of Marshall. This may reflect propensity for arrhythmogenesis throughout the embryologic left sinus horn which yields the coronary sinus as well as the vein of Marshall 10 …”

Fundamental Concepts in Electrophysiology in Cases and Reviews

“…Varma et al present a teaching rounds case of congenital atrial disease with sinus node dysfunction, areas of atrial tachycardia and atrial electrical inexcitability, consistent with extensive fibrosis illustrating the coexistence of multiple brady and tachyarrhythmias in this rare congenital atrial disease. 23 Cavotricuspid isthmus ablation guided by real-time magnetic resonance imaging. Piorkowski C,et al 24 Achieving conduction block in the common cavotricuspid isthmus is difficult in some patients due to anatomic constraints, as can also be encountered in other areas of the heart.…”