The heart as a pump blood in the human body, beating because of the electrical impulses within the heart itself, which stimulates contractions of the heart muscle. The study of cardiac conduction system is electrocardiography. Description of cardiac electrical strip is recorded in the electrocardiogram (ECG).
With the ECG we can assess:
- cardiac arrhythmias
- atrial and ventricular hypertrophy
- ischemic and myocardial infarction
- drug effects
- disorders of fluid and electrolyte balance, especially potassium
- assessment of pacemaker function
Cardiac Conduction System
Sinoatrial Node (SA Node)
SA Node consists of a group of special cells that act as automatic “pacemaker”.
Responsible for starting the electrical impulse stimulates the heart muscle to contract regularly.
SA Node is located in the upper right atrium near the superior vena cava.
SA Node under the influence of the autonomic nervous system.
Symphatis system stimulates the heart and causes increased heart rate through B1 adrenergic receptor
Parasympathetic system, via the vagus nerve, making the heart beat slows down and keep it at rest with pulses of about 60-70 times per minute.
If parasympatis activity on the block / inhibition, by anti-cholinergic drugs or cutted vagal nerve at the heart rate will increase.
If stimulation parasympatis increased, for example due to carotid sinus activity can lead to decreased heart rate
Rytme derived from the SA node due to depolarization of SA node is faster (60-100 beats a minute) from the AV node (40-60 beats per minute) and ventricular conduction system (30-40 beats per minute) so that the AV node and conduction sytem ventricular “will be stricken” by the sinus impulse
Atrioventricular Node
Atrioventicular Node (AV node) located in the interatrial septum near the tricuspid valve
Receive the SA node impulses and delivers an impulse into HIS Bundle.
Electrical impulses from the SA must connect through the AV due to atrial and ventricular tissue were separated by fibrous which has low conductivity.
AV node and HIS Bundle together with AV junctional rhythm made.
AV junctional have intrinsic pacemaker activity of 40-60 beats per minute. If the SA nodes had injuries the AV junctional take over for heart rhythm and the beats.
HIS Bundle
HIS Bundle located in intraventricular at proximal septum.
Bundle of HIS very important stream of the AV node impulse to the ventricles.
HIS Bundle branch consists of the right and left anteriorsuperior, and left posteriorinferior
Here, we can see how to cardiac conduction have became :
