Function and Dysfunction of Human Sinoatrial Node.
10.4070/kcj.2015.45.3.184
- Author:
Boyoung JOUNG
1
;
Peng Sheng CHEN
Author Information
1. Division of Cardiology, Department of Medicine, Yonsei University College of Medicine, Seoul, Korea.
- Publication Type:Review
- Keywords:
Calcium;
Sinoatrial node;
Adrenergic beta-agonists;
Sick sinus syndrome;
Biological pacemaker
- MeSH:
Adrenergic beta-Agonists;
Atrial Fibrillation;
Biological Clocks;
Calcium;
Heart Atria;
Heart Failure;
Humans;
Isoproterenol;
Membranes;
Models, Animal;
Sarcoplasmic Reticulum;
Sick Sinus Syndrome;
Sinoatrial Node*
- From:Korean Circulation Journal
2015;45(3):184-191
- CountryRepublic of Korea
- Language:English
-
Abstract:
Sinoatrial node (SAN) automaticity is jointly regulated by a voltage (cyclic activation and deactivation of membrane ion channels) and Ca2+ clocks (rhythmic spontaneous sarcoplasmic reticulum Ca2+ release). Using optical mapping in Langendorff-perfused canine right atrium, we previously demonstrated that the beta-adrenergic stimulation pushes the leading pacemaker to the superior SAN, which has the fastest activation rate and the most robust late diastolic intracellular calcium (Cai) elevation. Dysfunction of the superior SAN is commonly observed in animal models of heart failure and atrial fibrillation (AF), which are known to be associated with abnormal SAN automaticity. Using the 3D electroanatomic mapping techniques, we demonstrated that superior SAN served as the earliest atrial activation site (EAS) during sympathetic stimulation in healthy humans. In contrast, unresponsiveness of superior SAN to sympathetic stimulation was a characteristic finding in patients with AF and SAN dysfunction, and the 3D electroanatomic mapping technique had better diagnostic sensitivity than corrected SAN recovery time testing. However, both tests have significant limitations in detecting patients with symptomatic sick sinus syndrome. Recently, we reported that the location of the EAS can be predicted by the amplitudes of P-wave in the inferior leads. The inferior P-wave amplitudes can also be used to assess the superior SAN responsiveness to sympathetic stimulation. Inverted or isoelectric P-waves at baseline that fail to normalize during isoproterenol infusion suggest SAN dysfunction. P-wave morphology analyses may be helpful in determining the SAN function in patients at risk of symptomatic sick sinus syndrome.
