- 期刊
- OpenAccess
Mechanisms Underlying Cardiac Pacemaker Activity
並列摘要
Generally, the pacemaker activity is equated to diastolic depolarization. However, there is no agreement about the mechanisms underlying the pacemaker potential either in the sino-atrial node (SAN) or in Purkinje fibers. In fact, even within the SAN, there are dominant and subsidiary pacemakers and this raises the question as to whether there are two (dominant and subsidiary) pacemaker mechanisms and whether each of them can sustain spontaneous discharge. Also, both mechanisms appear to be present in subsidiary cells depending on the degree of polarization. In addition, it is becoming apparent that diastolic depolarization is only part of the mechanism leading to spontaneous discharge. This is not too surprising since DD is an afterpotential (it follows an action potential) and therefore it could not be responsible for the initiation of pacemaker activity after a period of standstill. In fact, both in SAN and in Purkinje fibers there are oscillatory pre-potentials (ThVos) that are responsible for the initiation of spontaneous discharge. These same oscillatory potentials are also needed for the maintenance of spontaneous activity, since they are the obligatory link between diastolic depolarization and the threshold for the upstroke. Another oscillatory after-potential (Vos) appears involved in spontaneous activity. Vos appear to contribute to the faster discharge of the sino-atrial node under normal conditions and to that of Purkinje fibers under abnormal conditions. The aim of this review is to evaluate the different mechanisms that have been proposed for diastolic depolarization in the sino-atrial node and in Purkinje fibers and illustrate the findings that show the importance of voltage oscillations in the initiation and maintenance of pacemaker discharge in SAN and in Purkinje fibers.
被引用紀錄
延伸閱讀
- Chan, Y. C. (2008). Cellular electrophysiology of cardiac pacemaker channel-implications on novel drug and gene therapies development [doctoral dissertation, The University of Hong Kong]. Airiti Library. https://www.airitilibrary.com/Article/Detail?DocID=U0029-1812201200016113
- Chen, H. M., & Chao, Y. F. (2002). Change in Quality of Life in Patients With Permanent Cardiac Pacemakers: A Six-month Follow-up Study. The Journal of Nursing Research, 10(2), 143-150. https://www.airitilibrary.com/Article/Detail?DocID=16823141-200206-10-2-143-150-a
- Kerkhof, P. L. M. (2015). Characterizing Heart Failure in the Ventricular Volume Domain. Clinical Medicine Insights: Cardiology, 2015(S1), 11-31. https://doi.org/10.4137/CMC.S18744
- Lai, Y. H., Lo, C. I., Wu, Y. J., Hung, C. L., & Yeh, H. I. (2013). Cardiac Remodeling, Adaptations and Associated Myocardial Mechanics in Hypertensive Heart Diseases. Acta Cardiologica Sinica, 29(1), 64-70. https://www.airitilibrary.com/Article/Detail?DocID=10116842-201301-201302180006-201302180006-64-70
- Luqma, N., Wang, C. L., Sung, R. J., & Kuo, C. T. (2008). Emerging Role of Cardiac Resynchronization Therapy in Heart Failure. Acta Cardiologica Sinica, 24(1), 1-14. https://www.airitilibrary.com/Article/Detail?DocID=10116842-200803-24-1-1-14-a