Effective Refractory Period

In electrocardiography, during a cardiac cycle, once an action potential is initiated, there is a period of time that a new action potential cannot be initiated. This is termed the effective refractory period (ERP) of the tissue. This period is also termed the absolute refractory period (ARP). During this period, depolarization on adjacent cardiac muscles does not produce a new depolarization in the current cell as it has to refract back to phase 4 of the action potential before a new action potential can activate it. ERP acts as a protective mechanism and keeps the heart rate in check and prevents arrhythmias and coordinates muscle contraction. Anti-arrhytmic agents used for arrhythmias usually prolong the ERP. For the treatment of Atrial fibrillation, it is a problem that the prolongation of the ERP by these agents also affects the ventricles, which can induce other types of arrhythmias.

Cardiovascular system, physiology: cardiovascular physiology
  • Stroke volume = End-diastolic volume – End-systolic volume
  • Afterload
  • Preload
  • Frank–Starling law of the heart
  • Cardiac function curve
  • Venous return curve
  • Aortic valve area calculation
  • Ejection fraction
  • Injection fraction
  • Cardiac index
  • Fractional shortening = (End-diastolic dimension – End-systolic dimension) / End-diastolic dimension
Interaction diagrams
  • Cardiac cycle
  • Wiggers diagram
  • Pressure volume diagram
  • Chronotropic (Heart rate)
  • Dromotropic (Conduction velocity)
  • Inotropic (Contractility)
  • Bathmotropic (Excitability)
  • Lusitropic (Relaxation)
Conduction system /
Cardiac electrophysiology
  • Cardiac action potential
    • Atrial action potential
    • Ventricular action potential
  • Effective refractory period
  • Pacemaker potential
  • EKG
    • P wave
    • PR interval
    • QRS complex
    • QT interval
    • ST segment
    • T wave
    • U wave
  • Hexaxial reference system
Chamber pressure Central venous pressure/right atrial pressure → Right ventricular pressure → Pulmonary artery pressure → Pulmonary wedge pressure/left atrial pressure → Left ventricular pressure → Aortic pressure
  • Ventricular remodeling
Vascular system/
Blood flow
  • Compliance
  • Vascular resistance
    • Total peripheral resistance
  • Pulse
  • Perfusion
Blood pressure
  • Pulse pressure
    • Systolic
    • Diastolic
  • Mean arterial pressure
  • Portal venous pressure
Regulation of BP
  • Baroreflex
  • Kinin–kallikrein system
  • Renin–angiotensin system
  • Vasoconstrictors/Vasodilators
  • Autoregulation
    • Myogenic mechanism
    • Tubuloglomerular feedback
    • Cerebral autoregulation
  • Paraganglia
    • Aortic body
    • Carotid body
    • Glomus cell



noco/cong/tumr, sysi/epon, injr

proc, drug (C1A/1B/1C/1D), blte


anat (a:h/u/t/a/l,v:h/u/t/a/l)/phys/devp/cell/prot

noco/syva/cong/lyvd/tumr, sysi/epon, injr

proc, drug (C2s+n/3/4/5/7/8/9)

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