1. Heart Conduction System

2. Bell work
Define: Depolarization and Repolarization What is an EKG/ECG?

3. The Heart: Conduction System
The heart pumps blood through the body
This is accomplished by contraction and relaxation of the cardiac muscle tissue in the myocardium layer.

4. Conduction System Continued….
Cardiac conduction system: The electrical conduction system controls the heart rate
This system creates the electrical impulses and sends them throughout the heart. These impulses make the heart contract and pump blood.

5. CARDIAC CYCLE Creates Heart sounds Heard through stethoscope
“LUB-DUB” sound
1st sound, AKA S1 – longest and loudest (closure of atrioventricular (AV) valves)
Atrioventricular is Tricuspid and Mitral
What would Right AV valve be?
What would Left AV valve be?

6. 2nd sound – closure of aortic and pulmonary valves (AKA Semilunar Valves)
If valves do not close properly – you will hear an extra sound called a heart murmur

7. THE CARDIAC CYCLE
SYSTOLE – CARDIAC CONTRACTION THE BLOOD IS FORCED OUT OF THE HEART TO THE LUNGS FOR OXYGENATION AND TO THE BODY FOR CIRCULATION (CONTRACTION)
DIASTOLE – CARDIAC RELAXATION THE BLOOD IS RETURNED TO THE HEART FROM THE LUNGS AND THE BODY (RELAXATION)
What is this measuring?

8. Septum

9. Components of the Conduction System
Sinoatrial Node (Part I):
located in back wall of the right atrium near the entrance of vena cava
initiates impulses times per minute without any nerve stimulation from brain
establishes basic rhythm of the heartbeat
called the pacemaker of the heart
impulses move through atria causing the two atria to contract.
at the same time, impulses reach the second part of the conduction system

10. Components of the Conduction System Continued ….
Atrioventricular Node (Part II):
located in the bottom of the right atrium near the septum
cells in the AV node conduct impulses more slowly, so there is a delay as impulses travel through the node
this allows time for atria to finish contraction before ventricles begin contracting

11. Atrioventricular Bundle
A.K.A. “Bundle of His”
From the AV node, impulses travel through to the right and left bundle branches
These branches extend to the right and left sides of the septum and bottom of the heart.

12. Atrioventricular Bundle Continued….
These branch a lot to form the Purkinje fibers that transmit the impulses to the myocardium (muscle tissue)
The bundle of His, bundle branches and Purkinje fibers transmit quickly and cause both ventricles to contract at the same time
Like a “phone tree”

13. Atrioventricular Bundle Continued….
As the ventricles contract, blood is forced out through the semilunar valves into the pulmonary trunk and the aorta.
After the ventricles complete their contraction phase, they relax and the SA node initiates another impulse to start another cardiac cycle.

15. 1 - Sinoatrial node (SA node)
2 - Atrioventricular node (AV node)
3 – Bundle of His
4 - Right & Left Bundle Branches
which lead to Purkinje Fibers

17. Polarization
Depolarization and Repolarization 1. Cardiac cells at rest are considered polarized, meaning no electrical activity takes place 2. The cell membrane of the cardiac muscle cell separates different concentrations of ions, such as sodium, potassium, and calcium. This is called the resting potential.

18. Polarization
3.  Electrical impulses are generated by automaticity of specialized cardiac cells
4.  Once an electrical cell generates an electrical impulse, this electrical impulse causes the ions to cross the cell membrane and causes the action potential, also called depolarization
5.  The movement of ions across the cell membrane through sodium, potassium and calcium channels, is the drive that causes contraction of the cardiac cells/muscle

19. Polarization
6.  Depolarization with corresponding contraction of myocardial muscle moves as a wave through the heart
7.  Repolarization is the return of the ions to their previous resting state, which corresponds with relaxation of the myocardial muscle

20. Polarization
8.  Depolarization and repolarization are electrical activities which cause muscular activity
9.  The action potential curve shows the electrical changes in the myocardial cell during the depolarization – repolarization cycle
10.  This electrical activity is what is detected on ECG, not the muscular activity.

21. EKG COMPONENTS
P WAVE – INDICATES ATRIAL DEPOLARIZATION CAUSING ATRIAL CONTRACTION
QRS COMPLEX – INDICATES VENTRICULAR DEPOLARIZATION CAUSING VENTRICULAR CONTRACTION
ST SEGMENT – INDICATES MYOCARDIAL DAMAGE
T WAVE – INDICATES VENTRICULAR REPOLARIZATION CAUSING VENTRICULAR RELAXATION

23. EKG

24. How To Read EKG
EKG paper is a grid where time is measured along the horizontal axis.
Each small square is 1 mm in length and represents 0.04 seconds.
Each larger square is 5 mm in length and represents 0.2 seconds
In order to correctly identify heart rhythms, you will need to print off 6 second strips

25. How to Read EKG Can determine HR from EKG strip
Each strip is 6 seconds
To determine HR:
Count R waves and multiply by 10

26. HEART RHYTHMS NORMAL SINUS RHYTHM (NSR) SINUS TACHYCARDIA
between 60 – 100 BPM, regular rhythm
SINUS TACHYCARDIA
> 100 BPM, regular rhythm
SINUS BRADYCARDIA
< 60 BPM, regular rhythm

27. Normal Sinus Rhythm
60 – 100 Beats per minute

28. Sinus Tachycardia
 A fast heart rhythm with a rate of more than 100 beats per minute.

29. Sinus Bradycardia
A slow heart rhythm with a rate below 60 beats per minute.

30. Arrhythmias
Abnormal heart rhythms that can be mild to life threatening.

31. Irregular Rhythm

32. HEART RHYTHMS PREMATURE ATRIAL CONTRACTION (PAC) ATRIAL FLUTTER
ATRIAL FIBRILLATION (A-FIB)
PREMATURE VENTRICULAR CONTRACTION (PVC)
DANGEROUS PVCs
VENTRICULAR TACHYCARDIA (V-TACH)
VENTRICULAR FIBRILLATION (V-FIB)
ASYSTOLE

33. PAC Premature atrial contraction (PAC)
Can occur in anyone but usually goes unnoticed.
Most common forms of arrhythmias. 
the premature discharge of an electrical impulse in the atrium, causing a premature contraction. 
A PAC is premature, because the it occurs earlier than the next regular beat should have occurred.

34. Atrial Flutter
the electrical signal travels along a pathway within the right atrium. It moves in an organized circular motion, or "circuit," causing the atria to beat faster than the ventricles of your heart.

35. Atrial Fibrillation
Many impulses begin and spread through the atria, competing for a chance to travel through the AV node. The resulting rhythm is disorganized, rapid and irregular. Because the impulses are traveling through the atria in a disorderly fashion, there is a loss of coordinated atrial contraction.

36. Premature Ventricular Contraction (PVC)
Early, extra heartbeats that originate in the ventricles. Most of the time, PVCs don’t cause any symptoms or require treatment. This type of arrhythmia is common and can be related to stress, too much caffeine or nicotine, or exercise. They can be also be caused by heart disease or electrolyte imbalance.

37. Ventricular Tachycardia
A rapid heartbeat that originates in the ventricles. The rapid rhythm keeps the heart from adequately filling with blood, and less blood is able to pump through the body. V-tach can be serious, especially in people with heart disease.

38. Ventricular Fibrillation
An erratic, disorganized firing of impulses from the ventricles. The ventricles quiver and cannot generate an effective contraction, which results in a lack of blood being delivered to the body. This is a medical emergency that must be treated with cardiopulmonary resuscitation (CPR) and defibrillation (delivery of an energy shock to the heart muscle to restore a normal rhythm) as soon as possible.

39. Superventricular Tachycardia SVT
Supraventricular tachycardia (SVT) is a cardiac arrhythmia characterized by very rapid or erratic beating. 
heart racing/palpitations, dizziness or light-headedness, chest pain, breathlessness

40. Asystole
Asystole is defined as a cardiac arrest rhythm in which there is no discernible electrical activity on the ECG monitor. 

41. Artifact