1. Chapter 35 part 2
Cardiac Disorders 1

2. Electricity of the heart

3. Interpreting the Electrocardiogram
(Figure 33-15)
Interpreting the electrocardiogram (Table 33-10)
Rate
Rhythm
P waves
PR interval
QRS complex
T waves
Normal Sinus Rhythm
Sinus Bradycardia
Sinus Tachycardia
Sinus Dysrhythmia
Dysrhythmia (arrhythmia) is a disturbance of the heart rhythm caused by a problem in the conduction system

4. Sinus Rhythm Rhythm of normally functioning electrical system
Electrical tracing follows a normal pathway
There is no interference.

5. How do you know it’s Sinus Rhythm
Rhythm - interval between two P and two R waves occurs in the same pattern
Rate
P-wave look:
The same
Usually upright deflection (the bump goes up)
There is a P-wave before every QRS complex.

6. How you know continued PR interval QRS duration
Consistently between .12 and .20 seconds
QRS duration
Consistently between .06 and .10 seconds

7. How does the patient with Sinus Rhythm feel?
Cardiac output is normal
The patient is not symptomatic
Alert
Breathing normally
No chest pain or pressure
Stable blood pressure

8. Sinus Bradycardia
Less than 60 beats per minute and all other rhythm characteristics are the same as Sinus Rhythm

9. Is it Sinus Bradycardia?
P-wave
Looks the same
“Bump is usually up”
There is one before every QRS
Rate - 40 to 60 beats per minute
Rhythm – space between 2 P’s and 2 R’s occurs in a regular pattern

10. Sinus Bradycardia – more facts
PR interval
Between .12 and .20 seconds
QRS duration
Between .06 and .10 seconds

11. SB - How does the patient feel?
Patient may or may not exhibit signs of decreased cardiac output.
If symptoms are present, inform the physician
Rhythm may require drugs or pacemaker.

12. Decreased cardiac output?
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13. What is Sinus Tachycardia?
Rate more than 100 beats per minute.
All other rhythm characteristics are the same as SR.

14. More info on Sinus Tachycardia
Rate – 150 beats per minute
The interval between two P’s and two R’s is consistent
The P-wave:
Looks the same
“The bump is usually up”
The P-wave appears before every QRS complex.

15. Sinus Tachycardia continued
PR interval
Between .12 and .20 seconds
QRS duration
Between .06 and .10 seconds

16. How does the patient with ST feel?
Patients may complain of heart palpitations or a racing heart
Sinus tachycardia may be a normal response to exercise
It can also be a response to decreased cardiac output (there is less blood circulating with each beat so the heart beats faster)
ST may be life threatening in clients who recently had an MI
Medications may be necessary

17. Sinus Arrhythmia The rate is within normal limits. Rhythm is irregular
Irregular sinus rhythm can be caused by pressure on the heart from the respiratory cycle or changes in vagal nerve stimulation.

18. Sinus Arrhythmia (SA) - Criteria
Rhythm - irregular
Rate - 60 – 100
P-wave
Shaped the same
Usually “The Bump is Up”
P-wave appears proceeds every QRS complex.

19. Sinus arrhythmia cont. Patient usually shows no visible signs
Severe cases may slow the heart rate into the 40’s, causing dizziness, lightheadedness or palpitations
Place copy of rhythm strip in patient’s record and notify physician

20. Sinus Arrest
Condition where SA node (pace maker) stops firing, causing pause in electrical activity.
Atrial and ventricular contraction do not occur during the pause .

21. Sinus Arrest- Is it serious?
The seriousness depends on length of pause
Frequent pauses of two seconds will cause symptoms of decreased cardiac output
Immediate treatment is required
Notify the physician

22. Premature Atrial Contractions (PAC)
The electrical impulses originate in the atria and start an early impulse which disrupts regular rhythm.

23. Premature Atrial Contractions (PAC)
Rhythm – the overall regularity between P-P and R-R intervals is constant, with the exception of an occasional early complex
Rate - 60 to 100 depending on frequency of PAC’s

24. PAC’s- How do they look? P-wave PR interval
P-waves look the same, except for early beat
The early beat may be flattened, notched, biphasic or otherwise unusual.
The early P-wave may be hidden within the T-wave.
PR interval
Between .12 and .20 seconds
The early beat will have different PR measurements but within normal limits.

25. How does the patient with PAC’s feel?
The patient may experience symptoms of low cardiac output
Notify the physician if these symptoms occur

26. Atrial Flutter (A Flutter)
Occurs when a rapid impulse originates in the atrial tissue
The impulse may originate from ischemic areas or from the reentry pathway.
Reentry pathways provide faster routes for impulses.
AF may lead to more serious conditions if not treated

27. Atrial Flutter (A Flutter)

28. Atrial Flutter (A Flutter) -Criteria
Rhythm-
R-R interval is usually irregular, but may, occasionally be regular in the pattern.
flutter-to-flutter waves will be regular and stay constant throughout rhythm.
Rate beats per minute

29. Atrial Flutter - continued
P-wave configuration
P-wave’s are not seen, only flutter waves are present.
Flutter waves resemble saw-tooth or picket fence and are best seen in leads II and III
PR interval – can not be identified
QRS interval seconds

30. A Flutter – How does the patient feel?
Loss of atrial kick reduces cardiac output by %.
Patients with increased heart rate will demonstrate signs of low cardiac output because the heart chambers do not have time to refill with blood between each beat
Notify the physician
Treatment may include oxygen

31. Atrial Fibrillation (A Fib.)
Occurs when electrical impulses come from areas of reentry pathways or multiple ectopic foci.
Electrical impulse results in depolarization of small groups of cells, versus whole atria.
Multiple atrial activity is recorded as chaotic activity

32. Atrial Fibrillation (A Fib.)

33. A Fib. – Cont’. Rhythm Rate P-P interval can not be determined
R-R interval is irregular
Rate
Atrial rate beats per minute
Ventricular rate, prior to the administration of medication is

34. A Fib. - Criteria P-wave configuration
Cannot be identified
Chaotic electrical activity or fib. waves may be seen
PR interval - cannot be identified
QRS duration seconds and irregular

35. A Fib. – How does the patient feel?
Patient exhibits signs of decreased cardiac output
When the heart rate is controlled, the patient may be able to tolerate the loss of atrial kick
Blood collecting in atria can clot or form thrombus which increases risk of embolism; therefore, patients are given anticoagulants
Report complications or vital sign changes to the physician

36. Supraventricular Tachycardia (SVT)
Rapid heart beat makes identification of origin difficult.

37. Supraventricular Dysrhythmias
R-R usually regular
If identifiable, P waves usually regular
Rate
Ventricular rate is beats per minute.
Atrial rate is difficult to determine.

38. SVT – How does the patient feel?
Patient may be in stable or unstable condition
Observe patient for low cardiac output
Notify the physician

39. Heart Block Rhythms
Occur when electrical activity has difficulty traveling along normal conduction pathway
Ventricular depolarization is absent or delayed.
1st Degree Heart Block
2nd Degree AV Block Mobitz I (Wenckeback)
2nd Degree AV Block Mobitz II
3rd Degree Block

40. First Degree AV Block
Delay in electrical conduction from SA node to AV node
Electrical stimulus is prevented from traveling to ventricular conduction system.

41. First Degree AV Block - Criteria
Rhythm - regularity between P-P interval and R-R interval is constant.
Rate - normal, beats per minute
PR interval - greater than .20 seconds
P wave
Looks the same
P wave occurs before each QRS complex.

42. 1st Degree AV Block – How does the patient feel?
Patient can maintain normal cardiac output.
Monitor and report development of other heart blocks

43. 2nd degree AV Block, Mobitz I (Wenckeback)
Some electrical impulses are blocked from SA node to ventricles at AV junction region.
AV node conducts an electrical impulse to the ventricular conduction pathway until it fails, then resets in a repeat pattern

44. Second Degree AV Block, Mobitz I (Wenckeback) - Criteria
P wave
Normal size, upright
One P wave for every QRS, with additional P waves
PR interval - varies, starts short, gets progressively longer until QRS wave is dropped, then cycle is restarted
QRS duration - normal seconds

45. Wenckeback – How the patient feels
The patient may not exhibit signs of low cardiac output until rate decreases to 40 beats per minute, or lower
This condition usually results from inflammation around AV node and is often temporary
If patient exhibits signs of low cardiac output, the physician should be notified.
If no low cardiac output signs are exhibited, monitor patient for progression to third degree heart block

46. Second Degree AV Block, Mobitz II
Classical heart block
The AV node selects which electrical impulses to block
No pattern or reason for dropping QRS complex exists
Frequently progresses to third degree AV block

47. Second Degree AV Block, Mobitz II
P wave looks:
Normal size and upright
There is one P wave for every QRS complex, but additional P waves
PR interval - constant, even after QRS drop occurs
QRS duration - normal, seconds

48. 2nd Degree Mobitz II – How the patient feels
Observe patient for signs of low cardiac output
Condition can progress within seconds to third degree AV block or complete heart block

49. Third Degree AV BlockComplete heart block (CHB)
All electrical impulses originating above the ventricles are blocked.
No correlation exists between atria and ventricle depolarization.

50. 3rd degree AV Block Rhythm Rate P-P interval is regular.
R-R interval is regular, but different from P-P interval.
Rate
Atrial rate is beats per minute.
Ventricular is beats per minute. P wave configuration .

51. 3rd degree block- a look at the P’s
P wave looks:
Normal size, but may be buried in QRS complex
Number of P waves will not correlate to number of QRS complexes
P waves will outnumber QRS complexes
PR interval will vary
A long PR interval followed by a short PR interval indicates complete heart block

52. 3rd Degree AV Block – How does the patient feel?
Patient will show signs of low cardiac output and may be unconscious
Immediate medical intervention may be required
Initiate Code Blue when patient shows first signs of low cardiac output
Rhythm strips should be mounted and identified in patient’s record

53. Rhythms Originating from the Ventricles
Rate beats per minute.
Electrical Current is initiated in the Purkinje fibers
Rhythm is longer than normal depolarization of ventricles.

54. Premature Ventricular Contractions (PVC)
Ectopic beat that occurs early in the cycle and originates from the ventricles

55. Premature Ventricular Contraction (PVC)
Rhythm
P-P and R-R intervals are regular with early QRS complexes
The early complex has a full compensatory pause
Rate
Atrial and ventricular rates are the same for the underlying rhythm
Early complexes make ventricular rhythm faster than normal rhythm

56. Premature Ventricular Contraction (PVC) –The P-wave
The shape is that of the underlying rhythm
P waves not identified on early ventricular complex
PR interval
Follows underlying rhythm
The P wave not present in early complex

57. Premature Ventricular Contraction (PVC) – the QRS
QRS duration
Follows underlying rhythm
Duration of early complex greater than .12
QRS shape is unusual, with T wave in opposite direction from QRS wave

58. Types of Premature Ventricular Contractions (PVC)
Unifocal - early beat (has similar shape and size suggesting only one irritable focus present)
Multifocal - varied shapes and forms of the PVCs
Interpolated - PVC occurs during the normal R-R interval without interrupting the normal cycle.
Occasional - more than one to four PVCs per minute
Frequent - more than five to seven PVCs per minute minute

59. Types of Premature Ventricular Contractions (PVC)
Bigeminy - every other beat is a PVC.
Trigeminy - every third beat is a PVC.
Quadgeminy -every fourth beat is a PVC.
R on T PVC’s - PVC occurs on the T wave or the vulnerable period of the ventricle refractory period.
Coupling - two PVCs occur back to back.

60. PVC – How does the patient feel?
Frequency of PVCs determines their significance
More complex PVCs indicate increased risk of developing more serious ventricular dysrhythmias
Watch for symptoms of low cardiac output
Notify licensed practitioner if they occur
Treatment includes oxygen

61. Ventricular Tachycardia (Vtach) the picture
Three or more PVCs occur in a row.
Ventricles are in continuous state of contraction-relaxation.

62. Ventricular Tachycardia (Vtach)
Rhythm
P-P interval usually not identifiable.
R-R interval usually regular, can be slightly irregular, at times
Rate
Atrial rate cannot be determined.
Ventricular rate beats per minute
P wave is usually absent
PR interval cannot be determined
QRS duration
Greater than .12 seconds
T wave in opposite direction (usually down) from QRS complex

63. Vtach – How does the patient feel?
If patient is unresponsive, issue code blue, begin CPR, use emergency equipment and notify the physician
Mount rhythm strips in patient’s medical record and record code proceedings

64. Ventricular Fibrillation (Vfib)
Chaotic electrical activity within ventricular tissue results in no cardiac output.

65. Ventricular Fibrillation (Vfib) - Criteria
P wave configurations - not identifiable
PR interval - cannot be identified
QRS duration - cannot be determined

66. Vfib – Call a code blue! The patient will be unresponsive
Code blue situation is present
Begin CPR and emergency measures immediately
Advanced cardiac life support (ACLS) should begin immediately
If patient is conscious and talking it is not Vfib, leads are loose or detached.

67. Asystole Straight line or flat line
No electrical activity is present in the myocardium.

68. Asystole – Initiate CPR
The situation is life-threatening
The patient is in cardiac arrest; initiate emergency procedures immediately

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70. Electronic Pacemaker Rhythms
Deliver electrical impulse to myocardium, causing cells to depolarize
Can pace the atria, ventricles, or both
If the SA nodefires…the pacemaker will not
Approximately 115,000 permanent pacemakers are implanted each year

71. Is the pacemaker working?
Pacing spike
There is a thin spike on ECG tracing indicating electrical current from pacemaker
After the spike, either a P wave or QRS complex will appear