Properties of Cardiac Muscle

• Excitability• Conductivity• Contractility• Automaticity

0. quick depolarization1.Quick initial repolarization2. Platoe phase3. Quick final repolarization

4. Slow diastolic depolarization (SDD)Develops in pace-makers during heart diastole

4.Slow diastolic depolarization (SDD)Develops in pace-makers during heart diastole

The dynamics of changing in cardiac muscle excita-bility (3), compared withphases of contraction (1)and excitation (2).A - absolute refractory phaseB - relative refractory phaseC - period of supernormality

A - sinus extrasystole B - ventricular extrasystole CP - compensatory ventricular pause

Cardiac cycle• Atrium systole + ventricle

systole + common pause• duration = 1 minute/ bpm

ATRIAL SYSTOLE 0,1sec

Ventricle systole 0,33sec

VENTRICLE SYSTOLE 0,33sec

VENTRICLE SYSTOLE 0,33sec

COMMON PAUSE 0,37sec

COMMON PAUSE 0,37sec

COMMON PAUSE 0,37sec