Download Heart Conduction System

HEART CONDUCTION
SYSTEM
• Cardiac Muscle cells contract as a unit
– Designed to conduct electrical signals
• SA (Sinoatrial) Node (pacemaker)- - located in wall of Rt Atrium generates an electrical impulse
that
spreads out over both atria.
• Both atria contract (syncytium) and
stimulate the AV (atrioventricular) node
to send an impulse.
• AV (atrioventricular) node– located in the wall of the interatrial septum.
– sends a signal down the A-V Bundle ( bundle
of His) (interventricular septum).
• A-V Bundle ( bundle of His) branches into
(Purkinje Fibers) that spread out over the
ventricles and stimulate simultaneous
contraction (vent. syncytium).
CARDIAC CONDUCTION SYSTEM ANATOMY VIDEO
MEDLINEPLUS
HTTP://WWW.YOUTUBE.COM/WATCH?V=BXKBQQE_BO0
• When Problems start to arise…..
• SA Node – stimulates contraction at a rate of 60-100
beats/minute
– *If the SA Node fails, the AV Node can take over
• AV Node – stimulates contraction at a rate of 40-60
beats/minute
– *If the AV Node fails, the Purkinje Fibers can take over
• Purkinje fibers – stimulate contraction at a rate of 15-40
beats/minute
NEED FOR THE ARTIFICIAL PACEMAKER…..
GETTING A PACEMAKER SURGERY
HTTP://WWW.YOUTUBE.COM/WATCH?V=WNN4FW2EWXI
EKG/ECG
• Electrocardiogram – records electrical impulses of the
myocardium
• SA Node – triggers impulse – atrial depolarization (PWave)
• Ventricular depolarization – (QRS complex) – atrial
repolarization occurs at the same time – but it is smaller
than the QRS deflection and is not seen
• Ventricular repolarization – (T wave)
• Cardiac conduction system and relation to EKG
http://www.youtube.com/watch?v=v3b-YhZmQu8
CARDIAC RATE
• Tachycardia – increased heart rate
(greater than 100 BPM)
• Bradycardia – decreased heart rate
(less than 60 BPM)
• Flutter – very rapid HR (250-300 BPM)
• Fibrillation – rapid, uncoordinated
heart actions