1. Basic Principles of the Cardiovascular System
W. Lynne Clarke, Ed.D., RN

2. Objectives Describe the structures of the heart.
Explain the pumping mechanism of the heart and the path of blood flow through the heart.
Distinguish between pulmonary circulation and systemic circulation.
List the components of the conduction system and the sequence of impulse origination.
State four properties of cardiac cells.

3. Anatomy of the Heart 4 chambered pump Weighs less than 1 pound
Size of closed fist
Located in mediastinum – between lungs, sternum, spine

5. Chambers

6. Question
The right side of the heart pumps just as much blood as the left side – why are the walls of the right side thinner than those of the left?

7. Where are these valves? Tricuspid valve Mitral valve
Pulmonary semilunar valve
Aortic valve

8. Valves

9. Chordae tendoneae

10. Heart Layers

11. Heart Layers Endocardium – layer of smooth cells that line heart
Myocardium – layer of muscle that cause contraction (myocardial infarction)
Epicardium – fatty layer that protects heart
Pericardial sac – holds heart in place, reduces friction of beat

12. Circulation
Pulmonary
Systemic
Coronary

13. Pulmonary Circulation

14. Pulmonary Circulation

15. Systemic Circulation

16. Coronary Circulation

17. Coronary Circulation

18. Coronary Circulation
Anterior (A) and posterior (B) views of epicardial coronary circulation. LAD indicates left anterior descending coronary artery; AIV, anterior interventricular vein; CFX, circumflex coronary artery; RCA, right coronary artery; GCV, great cardiac vein; PDA, posterior descending artery; CS, coronary sinus; MCV, middle coronary vein; and SCV, small coronary vein.

20. Question
Where and when do coronary arteries fill?

21. Question Where and when do coronary arteries fill?
They fill ONLY during diastole from the pressure in the aorta. They branch from the aorta near where the aorta leaves the left ventricle.

22. Question
How can a fast heart rate be harmful to the heart muscle?

23. Question How can a fast heart rate be harmful to the heart muscle?
The only portion of the systole-diastole cycle that can shorten is diastole.

25. Coronary Sinus

26. Blood Vessels Define the following: Artery Arteriole Vein Venule
Capillary
Aorta
Vena Cava
Pulmonary artery
Pulmonary vein

27. Question
What vessels, structures and/or organs are included in each type of circulation?

28. Question
Show the path of a drop of blood from the right atrium back to the right atrium.
Be sure to include major vessels, organs, and valves.

29. Cardiac cycle Series of events that constitute complete heartbeat
Atrial systole - Contraction of atria to pump blood to ventricles
Ventricle systole – contraction of ventricles to pump blood to body
Atrial diastole – the atria begin refilling during ventricular systole
Ventricular diastole – blood from the atria begins refilling the ventricles during atrial systole.

30. Conduction Pathways Network of conducting tissue
Specialized cells – do not contract
Initiates each heartbeat and controls rhythm

32. Sinoatrial Node Located in right atrium Main cardiac pacemaker
Normally generates impulses at rate of 60 to 100 beats per minute

33. Atrioventricular Node
Receives impulse via internodal pathways
Located in floor of atrium near septum
Delay the impulse to allow ventricular filling
Intrinsic rate 40 to 60
Two basic functions
Protect ventricles from fast heart rate that may originate in atrium
Serves as pacemakers if SA node fails

34. AV Bundle or Bundle of His
Conducts impulse from AV Node
Intrinsic rate 40 to 60
Divides into right and left bundle branches at intraventricular septum
Right bundle branch supplies right ventricle
Left bundle branch splits
Anterior supplies upper portion of left ventricle
Posterior supplies lower portion of left ventricle

35. Purkinje Fibers Enlarged fibers
Spread along septum toward apex and over lateral walls of ventricles
Work with Bundle of His and bundle branches to contract ventricles
Intrinsic rate 20 to 40
May act as backup pacemaker

36. Cardiac Electrical System

37. Cool Website!

38. Special Properties of Cardiac Cells
Automaticity – ability to generate own impulse and maintain rhythmic activity
Excitability – ability of all heart cells to respond to impulse
Conductivity – cardiac cell able to relay impulse to neighboring cells and create wave of excitation
Contractility – ability to respond to electrical impulse with pumping action

39. Two Types of Cardiac Cells
Capable of contraction
Capable of conduction

40. Contraction of the Heart
Cell membrane must be electrically activated
Depolarization - Positive ions move into cell and negative ions move out of cell
Repolarization – negative ions return to inside of cell and positive ions move out of cell
This movement of ions is recorded by EKG

41. Cardiac Terminology Systole Diastole Electrical Cycle Depolarization
Repolarization
Activation
Recovery
Excitation
Mechanical Cycle
Contraction
Relaxation
Emptying
Filling
Shortening
Lengthening

42. EKG Representation of Heartbeat

43. The Normal Electrocardiogram

44. Detection and Recording
Transmembrane potential – electrical difference between the inside and outside of the cell
Action potential – changes that occur during the process of depolarization and repolarization within a cell as activated by electrical impulse
Refractory period – time during which the cell is unable to respond to a stimulus
Vector – path of impulse displaying the direction and magnitude of the electrical current

45. Normal Heart
Vector proceeds in same sequence
Vector is predictable

46. EKG machine Writing arm Recording device (galvanometer) Lead wires
Stylus needle responds by heat or pressure
Lead wires
Attaches electrodes to machine
Electrodes
Provides direct contact with skin

47. EKG
Tracing of electrical voltage produced by continual depolarization and repolarization of heart
Shows direction and magnitude of electrical current produced by the heart

48. Waves
Deflections from the baseline
Designated as: P, QRS, T

49. Waves P wave – depolarization of atria
Q wave – (may be absent) activation in intraventicular septum, first negative deflection of QRS
R wave – impulse progression through right and left ventricles, first upward deflection of QRS
S wave – completion of left ventricular activation
T wave – repolarization of ventricles

50. Waves

51. Segments Straight lines or spaces between waves ST segment
Measured from end of S wave to beginning of T wave
0.35 to 0.45 seconds
Isoelectric (flat)

52. Segments

53. Intervals Consists of wave and a connecting straight line
P-R Interval - measured from onset of P wave to beginning of QRS
Normal 0.12 to 0.20 seconds
QT Interval - measured from start of Q to end of T wave

54. Intervals

55. Complexes Groups of related recorded waves QRS complex
Represents depolarization or contraction of the ventricles
Normal length to 0.10

56. Complexes

58. Explanation of EKG paper

59. Measuring Time

60. Normal cycle 0.8 seconds

61. Heart Rate Calculation #1
Count the number of large squares between R waves and divide into 300

62. Heart Rate Calculation #2
Count number of small squares between
r waves and divide that number into 1500
Most accurate method but can only be used for regular rhythms.
Example : If there were 12.5 small boxes between two successive R waves, then the heart rate would be : 1500/12.5 small boxes = 120 bpm.

63. Heart Rate Calculation #3
Get 6 second strip
Count number of complete complexes
Multiply by 10 (6 x 10 = 60 seconds or 1 minute)
Special Note: Only method that can be used for irregular rhythm

64. Normal Rhythm Identification
All P waves appear like all other P waves
QRS complexes resemble each other
P-R intervals are constant
P-P intervals are constant
R-R intervals are constant
P before every QRS
Rate is between 60 to 100 beats per minute

65. Normal Sinus Rhythm Regular
P before every QRS, every complex looks the same
P-R int. = 0.20
QRS = 0.10
Rate = approx. 75

66. Five Step Method Step 1 Rate or speed of the rhythm
Atrial ______ Ventricular _________
Step 2 Regularity of rhythm
Step 3 Is there a P wave before every QRS?
Step 3 PR Interval
Step 4 QRS duration
Step 5 Interpretation
**Be sure to include underlying rhythm

67. Abnormal Rhythms – Sinus Bradycardia
Less than 60 beats per minutes
May be normal in athletes
Other aspects of EKG normal

68. Abnormal Rhythms - Tachycardia
Over 100 beats per minute
May be caused by exercise or fever
Other aspects of EKG are normal

69. Neat Websites

70. Lead Systems

71. Objectives Describe the purpose of an EKG lead
Differentiate between unipolar and bipolar leads
Describe the orientation of all 12 leads
Explain chest and limb lead placement

72. Leads Each lead views the heart at a unique angle
Each lead has a positive and a negative pole – measures the electrical difference between the poles

73. Limb Leads Placed on arms and legs
Reflect impulses moving in vertical or frontal plane
Six leads: I, II, III, AVR, AVL, AVF

74. Remember
Right and left refers to the patient’s right and left

75. Limb Lead Placement RA right arm between elbow and shoulder
LA left arm between elbow and shoulder
RL right leg a few inches above ankle
LL left leg a few inches above ankle
Alternate placement for leg leads
upper legs as close to torso as possible

76. Chest Leads
Demonstrate forces moving anteriorly and posterior in a tranverse plane

77. Precordial Lead Placement
V1 – right sternal border at 4th intercostal space
V2 – left sternal border at 4th intercostal space
V3 – Midway between 2nd and 4th V leads
V4 – 5th intercostal space straight down from midclavicular notch
V5 – at anterior axillary line at same horizontal level as V4
V6 – at midaxillary line on the same horizontal level as V4 and V5

78. Overview by Lead

79. Identifying Rhythms

80. Clinical Significance of EKG’s
PCT must recognize abnormal patterns and alert MD

81. Sinus Rhythms Rhythms beginning in the SA node Characteristics
1:1 relationship between P and QRS
P, QRS, T are in order and consistent in configuration
P-R interval is within 0.12 to 0.20 seconds
QRS interval is within 0.04 to 0.10
Heart rate is 60 to 100
P-R, P-P, R-R intervals are regular

82. Terminology Question
What’s the difference?
Arrhythmia
Dysrhythmia

83. Dysrhythmias Occur When
Disturbance in automaticity – rate to slow or too fast
Disturbance in conductivity – site of impulse formation is not in SA node
Combination of altered automaticity and conductivity – impulse conduction is abnormal

84. Late or Early?

85. Sinus Tachycardia Impulse formation faster than normal
Rate is beats per minute
Faster than normal but not fast enough to decrease cardiac output
Causes: exercise, fever, anxiety, hypovolemia (decreased fluid volume)
Same characteristics as Normal Sinus Rhythm except rate

86. Sinus Bradycardia Rate is 30 to 60 beats per minute
Slow rate can decrease cardiac output
Can be caused by vomiting, tracheal suctioning, valsalva maneuver, drug side effects

87. Sinus Arrhythmia
Impulses originate in SA node but speed up with inspiration and slow with expiration
P-P and R-R intervals vary

88. Sinus Arrest or Pause Potentially lethal SA Node fails
Beats dropped but bets that do occur appear normal
Sudden decrease in cardiac output can cause dizziness, syncope or angina
Patient may need permanent pacemaker

89. Atrial Arrhythmias
Abnormal electrical activity occurring in the atria before the sinus impulse can occur

90. Premature Atrial Contractions
Early firing from ectopic focus in the atria
Appear earlier than normal in cycle
Have abnormal P wave and abnormal P-R
QRS usually normal
May be caused by alcohol, caffeine, nicotine, low potassium, heart or lung disease

91. Arial Tachycardia Heart rate is 150 to 200
P wave may be abnormal or hidden in preceding T wave
Decreased cardiac output due to rate and increased oxygen demand

92. Atrial Fibrillation Possibly lethal No P waves, P-R can’t be measured
QRS normal but R-R irregular
Causes: underlying heart disease
May be chronic
Danger of clots (pulmonary or cerebral) – patient may be on blood thinner to prevent

93. Atrial Flutter
Ectopic atrial focus takes over - generates impulse faster than SA node
Multiple P waves in sawtooth pattern
QRS normal
Atrial rate 250 to 350, regular
Ventricular rate varies but is regular
AV node blocks some impulses

94. Junctional Rhythms
Impulses originating from ectopic focus in AV node region – fire earlier than SA node
P wave is negative and may occur before, during, or after the QRS
P-R may be shortened or not measurable
QRS usually normal
May predispose heart to more serious dysrhythmias

95. Junctional Rhythm

96. Ventricular Rhythms
Impulse originates from an ectopic in the bundle branches, Purkinje fibers, or ventricular muscle before SA node
Beat caused by this impulse does not produce adequate cardiac output
P wave is absent – no P-R interval
QRS is premature, wide, bizarre
May be caused by hypoxemia, stress, electrolyte imbalance, caffeine, nicotine, alcohol, medication toxicity, myocardial infarction
MAY BE NORMAL FOR PATIENT

97. Premature Ventricular Contractions
Wide, bizarre complex which occurs early
Example: Unifocal

98. Premature Ventricular Contractions
Wide, bizarre complex which occurs early
Example: Multifocal

99. Premature Ventricular Contractions
Wide, bizarre complex which occurs early
Example: Couplet

100. Premature Ventricular Contractions
Wide, bizarre complex which occurs early
Example: Salvo or triplet

101. Premature Ventricular Contractions
Wide, bizarre complex which occurs early
Example: Bigemeny

102. Premature Ventricular Contractions
Wide, bizarre complex which occurs early
Example: Trigeminy

103. R-on-T Occurs when R of PVC falls on T of preceeding beat
Heart vulnerable to electrical stimulation
Usually does not produce a sustained ventricular dysrhythmia

104. Ventricular Tachycardia
Three ectopic ventricular beats
Rate 100 to 250 per minute, regular
Possible lethal arrhythmia
No P waves, no P-R
QRS consecutive, wide, bizarre
Decreased or NO cardiac output
Will deteriorate into V Fib if not treated

105. Ventricular Fibrillation
CHECK LEADS!!!!!
Ventricular rhythm is chaotic
Results from multiple ectopic foci in ventricles
Ventricles quiver instead of contracting – NO CARDIAC OUTPUT
Will deteriorate into asystole

106. Agonal
Wide bizarre complexes from multiple ventricular pacemakers

107. Asystole
CHECK LEADS
No electrical activity

108. S-T elevation Rhythm - Regular Rate - varies QRS Duration - Normal
P Wave - Normal
S-T Element does not go isoelectric which indicates infarction

109. A-V Block – First Degree
Caused by a conduction delay through the AV node but all electrical signals reach the ventricles
Rarely causes any problems by itself – may be seen in athletes
Rhythm - Regular
Rate - Normal
QRS Duration - Normal
P Wave - Ratio 1:1
P Wave rate - Normal
P-R Interval - Prolonged (>5 small squares)

110. A-V Block – Second Degree Type I
Also called Wenckebach
Conduction block of some, but not all atrial beats getting through to the ventricles
Progressive lengthening of the PR interval and then failure of conduction of an atrial beat, this is seen by a dropped QRS complex.
Rhythm - Regularly irregular
Rate - Normal or Slow
QRS Duration - Normal
P Wave - Ratio 1:1 for 2,3 or 4 cycles then 1:0.
P Wave rate - Normal but faster than QRS rate
P-R Interval - Progressive lengthening of P-R interval until a QRS complex is dropped

111. A-V Block – Second Degree Type II
Electrical excitation sometimes fails to pass through the A-V node or bundle of His
Constant P-R interval but not regularly followed by ventricular contraction
Rhythm - Regular
Rate - Normal or Slow
QRS Duration - Prolonged
P Wave - Ratio 2:1, 3:1
P Wave rate - Normal but faster than QRS rate
P-R Interval - Normal or prolonged but constant

112. A-V Block – Third Degree
Atrial contractions are 'normal' but no electrical conduction is conveyed to the ventricles.
Ventricles then generate their own signal through an 'escape mechanism' from a focus somewhere within the ventricle.
Ventricular escape beats are usually 'slow'
Rhythm – Regular P and Regular QRS but they are not related!
Rate - Slow
QRS Duration - Prolonged
P Wave - Unrelated
P Wave rate - Normal but faster than QRS rate
P-R Interval - Variation

113. Paced Rhythms

114. Acquiring the EKG

115. Equipment Modern machines are multichannel
Can transmit EKG via telephone lines
Machine may store EKGs
Has 10 lead wires
Always follow manufacturers directions for use, cleaning, storage

116. Other considerations
Drape lead wires over machine – do not fold or tie
Inspect lead wires for breaks/frays
Do not put food or liquids on cart
Do not put anything on screen
Be sure machine stays plugged in when not in use
Store electrodes properly – gel can dry out

117. Question
What are beginning actions for any procedure?

118. Patient Preparation Check physician order or be familiar with protocol
Check patient ID with two identifiers
Wash hands
Explain procedure
Provide privacy

119. Patient Position Place patient in supine position
Patient may be at 45 degree angle if short of breath
Have patient uncross legs

120. Skin Preparation Electrode contact with skin important
May have to wash dirty/scaly skin –
Epidermis is poor conductor
Chest hair should be shaved
Use alcohol to remove skin oils
Wipe excess perspiration with 4 x 4
Apply pressure to edges of electrode – not center

121. Recognizing Artifact Extraneous electrical activity
Can be reduced by having patient touch only the mattress – not bed rails
Keep patient quiet and calm
Keep patient warm
Position electrodes high on extremities if patient has tremor
Be sure all leads are attached

122. Wandering Baseline

123. 60 cycle interference

124. Patient Movement

125. BE SURE THAT YOU ARE TREATING THE RHYTHM -
NOT THE ARTIFACT!

126. Special Situations Dextrocardia – reverse precordial leads
Large breasts – do NOT place electrodes on top of breast
Bilateral breast implants you should apply V4, V5, and V6 close to the midaxillary line.
Note patient abnormalities on EKG
Do not place electrodes on open wounds, burns, or clear dressings
Do not allow electrodes to touch one another

127. Other types of EKG’s Telemetry Holter Monitor Event Monitor
Stress Tests
Exercise
Drug Induced
Nuclear

128. Lethal Arrhythmias Ventricular Fibrillation Ventricular Tachycardia
Asystole
Bradycardia
Tachycardia

129. Signs and Symptoms of Cardiopulmonary Distress
Tachycardia or bradycardia
Pallor or Cyanosis
Lightheadedness or weakness
Diaphoresis
Low blood pressure
Fast, labored, slow, or shallow respirations
Anxiety or confusion
Nausea and/or vomiting
Chest pain or tightness - may radiate to arms, neck, jaw
Shortness of breath
Syncope