Electrophysiological and Electroanatomic Characterization of the Atria in Sinus Node Disease

Abstract

Background-The normal sinus pacemaker complex is an extensive structure within the right atrium. We hypothesized that patients with sinus node disease (SND) would have evidence of diffuse atrial abnormalities. Methods and Results-Sixteen patients with symptomatic SND and 16 age-matched controls were studied. The following were evaluated: effective refractory periods (ERPs) from the high and low lateral right atrium (RA), high septal RA, and distal coronary sinus (CS); conduction time along the CS and lateral RA; P-wave duration; and conduction at the crista terminalis. Electroanatomic mapping was performed to define the sinus node complex and determine regional conduction velocity, double potentials, fractionated electrograms, regional voltage, and areas of electrical silence.Patients with SND demonstrated significant increase in atrial ERP at all right atrial sites, increased atrial conduction time along the lateral RA and CS, prolongation of the P-wave duration, and greater number and duration of double potentials along the crista terminalis. Electroanatomic mapping demonstrated the sinus node complex in SND to be more often unicentric, localized to the low crista terminalis at the site of the largest residual voltage amplitude. There was significant regional conduction slowing with double potentials and fractionation associated with areas of low voltage and electrical silence (or scar). Conclusions-SND is associated with diffuse atrial remodeling characterized by structural change, conduction abnormalities, and increased right atrial refractoriness. There was a change in the nature of sinus pacemaker activity with loss of the normal multicentric pattern of activation, caudal shift of the pacemaker complex, and abnormal and circuitous conduction around lines of conduction block.

EHRA/HRS/APHRS/SOLAECE expert consensus on atrial cardiomyopathies: definition, characterization, and clinical implication

“…Electroanatomic mapping has been used to image the electroanatomic substrate of atrial cardiomyopathy associated with sinus node disease, 432 rheumatic MS, 215 atrial septal defect, 218,431 CHF, 433 obstructive sleep apnoea, 117 and ageing. 167 It has been a powerful research tool that has enhanced our understanding of the atrial substrate in patients with paroxysmal and persistent atrial fibrillation and 74,434 those who have failed initial PV antrum isolation.…”

Surgical Treatment of Chronic Atrial Fibrillation—Unipolar Radiofrequency Ablation versus Cryoablation, and Left Atrial versus Bi‐atrial Maze Procedures

“…28) Sinus node disease also shows similar observations and low atrial voltage causing pathophysiological change. 29) Degeneration and/or fibrosis of atrium including sinus node and conducting fiber cause tissue inhomogeneity and nonuniform atrial excitement. Fibroblast which is fairly depolarized influences adjacent cell depolarization by an electrotonic interaction.…”

Biology of the Sinus Node and its Disease

“…42 In order to account for these changes in function, multiple processes and widespread remodelling are likely to be taking place, evidence for which is discussed below and summarised in Table 1 and Figure 5.…”