内部控制制度审计办法.doc

内部控制制度审计办法.doc心律失常(Cardiac Arrhythmia)
Dr. Wei Meng, MD,
Department of cardiology, affiliated 6th people’s hospital, Shanghai Jiao Tong University
Mechanism of arrhythmia
Property of cardiac elctrophysiology
兴奋性(Excitability)
自律性(automaticity)
传导性(Conductivity)
Excitability
Excitability indicates that myocardial cell has electrical activity when it is stimulated
Electrical activity of single myocardial cell is called action potential(AP)
Electrical activity of whole heart makes ECG
0
-60
-90
+20
Threshold voltage
mv
0
1
2
3
4
ARP
ERP
RRP
Super-conductive period
ARP: Absolute Refractory period; ERP: Effective Refractory period; RRP: Relative Refractory period
Conductivity
Electrical impulse can conduct in myocardial tissue bidirectionally
Normal conduction pathway:
sinus node→intranode bundle →atrioventricula node and intraatrial bundle→His bundle→right and left bundle branch(including left anterosuperior and posteroinferior)→Purkinje fiber→myocardium
automaticity
Cells spontaneously discharging (spontaneous AP, diastolic depolarization)
Automaticity increases from high to low as follows:
Physiological status:SN、AVN、HIS、Purkinje
pathological:diseased myocardial and conductive tissue, etc.
Property of normal rhythm
Impulse from SN
Heart rate is within 60~100/min
Regular rhythm,PP in