1. Care of Patients with Dysrhythmias
Chapter 36
Care of Patients with Dysrhythmias
Automated external defibrillator with electrodes.

2. Learning Outcomes
1. Teach patients and their families about drug therapy used for common dysrhythmias.
2. Educate patients and families about procedures and other interventions for common dysrhythmias.
3. Identify typical physical assessment findings associated with common dysrhythmias.

3. 4. Analyze an ECG rhythm strip to identify normal sinus rhythm and common or life- threatening dysrhythmias.
5. Plan collaborative care for patients experiencing common dysrhythmias.
6. Explain how to perform emergency care procedures, such as cardiopulmonary resuscitation (CPR) and automated external defibrillation.
7. Differentiate between various ECG interpretations and their related signs and symptoms and appropriate interventions.

4. Normal Rhythms Normal sinus rhythm (NSR) Sinus arrhythmia Dysrhythmias Sinus dysrhythmias Sinus Tachycardia Sinus Bradycardia Atrial dysrhythmias Premature Atrial Complexes Supraventricular Tachycardia Atrial fibrillation (A Fib)

5. Dysrhythmias (Continued)
Ventricular dysrhythmias
Premature Ventricular Complexes (PVCs)
Ventricular Tachycardia (V Tach)
Ventricular Fibrillation (V Fib)
Ventricular Asystole
Atrial Ventricular blocks

6. Review of Cardiac Electrophysiology
Automaticity
Excitability
Depolarization
Conductivity
Contractility

7. Cardiac Conduction System

8. Cardiac Conduction System (cont’d)
Sinoatrial node
Electrical impulses beats/min
P wave on ECG
Atrioventricular junction
PR segment on ECG
Contraction known as “atrial kick”
Bundle of His
Right and Left bundle branch system
Pukinje fibers

9. Electrocardiographic Waveforms ECG waveforms are measured in amplitude (voltage) and duration (time).
ECG waveforms are measured in amplitude (voltage) and duration (time).

10. P wave PR segment PR interval QRS complex ST segment T wave U wave
ECG Complexes, Segments, & Intervals Study the next slide to learn the definitions.
P wave
PR segment
PR interval
QRS complex
ST segment
T wave
U wave
QT interval

11. Normal ECG
The components of a normal ECG.

12. ECG Rhythm Analysis Determine heart rate Determine heart rhythm
Analyze P waves
Measure PR interval
Measure QRS duration
Interpret rhythm

13. Electrocardiographic Waveforms
Each segment between the dark lines (above the monitor strip) represents 3 seconds when the monitor is set at a speed of 25 mm/sec. To estimate the ventricular rate, count the QRS complexes in a 6-second strip and then multiply that number by 10 to estimate the rate for 1 minute. In this example, there are 9 QRS complexes in 6 seconds. Therefore the heart rate can be estimated to be 90 beats/min.
Each segment between the dark lines (above the monitor strip) represents 3 seconds when the monitor is set at a speed of 25 mm/sec. To estimate the ventricular rate, count the QRS complexes in a 6-second strip and then multiply that number by 10 to estimate the rate for 1 minute. In this example, there are 9 QRS complexes in 6 seconds. Therefore the heart rate can be estimated to be 90 beats/min.

14. Normal Sinus Rhythm
1+ 2. Both atrial and ventricular rhythms are essentially regular (a slight variation in rhythm is normal). Atrial and ventricular rates are both 83 beats/min. 3. There is one P wave before each QRS complex, and all the P waves are of a consistent morphology, or shape. 4. The PR interval measures 0.18 second and is constant; 5. the QRS complex measures 0.06 second and is constant. 6. Normal sinus rhythm
Normal sinus rhythm. Both atrial and ventricular rhythms are essentially regular (a slight variation in rhythm is normal). Atrial and ventricular rates are both 83 beats/min. There is one P wave before each QRS complex, and all the P waves are of a consistent morphology, or shape. The PR interval measures 0.18 second and is constant; the QRS complex measures 0.06 second and is constant.

15. Normal Sinus Rhythm (cont’d)
Rate: beats/min
Rhythm: regular
P waves: Present, consistent configuration, one P wave before each QRS complex
PR interval : second and constant
QRS duration: second and constant

16. Sinus Arrhthmia Sinus arrhythmia is a variant of NSR.
Heart rate increases slightly during inspiration and decreases slightly during exhalation.
Frequently observed in healthy children as well as adults.
Sinus arrhythmia has all the characteristics of NSR except for its irregularity. The PP and RR intervals vary, with the difference between the shortest and the longest intervals being greater than 0.12 second (three small blocks).

17. 4 Types of Dysrhythmias Sinus Dysrhythmia
Problem originates in SA node
Atrial Dysrhythmia
Problem originates in the atrial tissue
Ventricular Dysrhythmia
Problem originates in the ventricular tissue
Atrial Ventricular Blocks
Problem originates in the AV node

18. Sinus Dysrhythmias A Sinus tachycardia (heart rate, 110 beats/min; PR interval, 0.12 second; QRS complex, 0.08 second). B Sinus bradycardia (heart rate, 52 beats/min; PR interval 0.18 second; QRS complex, 0.08 second).
Sinus rhythms. A, Sinus tachycardia (heart rate, 110 beats/min; PR interval, 0.12 second; QRS complex, 0.08 second). B, Sinus bradycardia (heart rate, 52 beats/min; PR interval 0.18 second; QRS complex, 0.08 second).

19. Sinus Tachycardia heart rate, 110 beats/min.

20. Sinus tachycardia
When the rate of SA node discharge is more than 100 beats per minute, the rhythm is called sinus tachycardia.
Sympathetic nervous system stimulation or vagal (parasympathetic) inhibition results in an increased rate of SA node discharge, which increases the heart rate.

21. Increased sympathetic stimulation is a normal response to physical activity but may also be caused by …..
Anxiety, pain, stress, fear, fever, anemia, hypoxemia, hyperthyroidism, and pulmonary embolism.
Drugs such as epinephrine, atropine, caffeine, alcohol, nicotine, aminophylline, and thyroid medications may also increase the heart rate.
In some cases, sinus tachycardia is a compensatory response to decreased cardiac output or blood pressure.

22. The patient may be asymptomatic except for an increased pulse rate
The patient may be asymptomatic except for an increased pulse rate. However, if the rhythm is not well tolerated, he or she may have symptoms.
For patients with sinus tachycardia, assess for
fatigue, weakness, shortness of breath, orthopnea, decreased oxygen saturation, and decreased blood pressure.
Also assess for restlessness and anxiety from decreased cerebral perfusion and for decreased urine output from impaired renal perfusion.
The patient may also have anginal pain and palpitations.
The desired outcome is to treat the underlying cause.
Bedrest if the tachycardia is causing hypotension or weakness.

23. Sinus Bradycardia Sinus bradycardia; heart rate, 40 beats/min.

24. Sinus Bradycardia
When the sinus node discharge rate is less than 60 beats/min, the rhythm is called sinus bradycardia
What can cause Sinus Bradycardia?
Excessive vagal (parasympathetic) stimulation to the heart
Increased parasympathetic stimuli may also result from hypoxia or an inferior wall MI
Drugs such as beta-adrenergic blocking agents, calcium channel blockers, and digitalis.

25. Just a low HR or is there more?
Patient may be asymptomatic or symptomatic.
Assess the patient for:
• Syncope (“blackouts” or fainting)
• Dizziness and weakness
• Confusion
• Hypotension
• Diaphoresis (excessive sweating)
• Shortness of breath
• Chest pain

26. Possible interventions for patients with Sinus Bradycardia
If the patient has any of these symptoms and the underlying cause cannot be determined, the treatment is to administer
drug therapy,
increase intravascular volume via IV fluids
apply oxygen.
pacing may be needed to increase the heart rate.

27. Premature Atrial Complexes (PACs) Supraventricular Tachycardia (SVT)
Atrial dysrhthmias
Focus of impulse generation shifts away from the sinus node to the atrial tissues. The shift changes the axis (direction) of atrial depolarization, resulting in a P- wave shape that differs from normal P waves.
Premature Atrial Complexes (PACs)
Supraventricular Tachycardia (SVT)
Atrial fibrillation (A Fib)

28. Premature Atrial Complexes
A premature atrial complex (PAC) occurs when atrial tissue becomes irritable.
This ectopic focus fires an impulse before the next sinus impulse is due.

29. The premature P wave may not always be clearly visible because it can be hidden in the preceding T wave.
Examine the T wave closely for any change in shape, and compare with other T waves. A PAC is usually followed by a pause.

30. PAC symptoms and interventions
The patient usually has no symptoms except for possible heart palpitations.
No intervention is needed except to treat causes such as heart failure.
Antidysrhythmic drugs if PAC severe
Teach the patient measures to manage stress and substances to avoid, such as caffeine and alcohol, that are known to increase atrial irritability.

31. Supraventricular Tachycardia
Rapid stimulation of atrial tissue occurs at rate of beat/min Paroxysmal supraventricular
SVT may occur in healthy young people, especially women.

32. During SVT, P waves may not be visible, especially if there is a 1:1 conduction with rapid rates, because the P waves are embedded in the preceding T wave.

33. SVT Symptoms and Interventions
Palpitations, chest pain, weakness, fatigue, shortness of breath, nervousness, anxiety, hypotension, and syncope
If SVT occurs in a healthy person and stops on its own, no intervention may be needed other than eliminating identified causes.
Possible interventions
electrophysiology study (EPS)
radiofrequency catheter ablation
treat the cause
dysrhythmia drugs ( Fill in your chart 36-2)

34. Atrial fibrillation
Atrial fibrillation. Note wavy baseline with atrial electrical activity and irregular ventricular rhythm.
Note wavy baseline with atrial electrical activity and irregular ventricular rhythm.

35. Atrial Fibrillation
Associated with atrial fibrosis and loss of muscle mass
Client at risk for decreased CO
Common in heart disease such as hypertension, heart failure, and coronary artery disease
Cardiac output can decrease by as much as 20% to 30%

36. Atrial Fibrillation Signs and Symptoms
fatigue weakness shortness of breath dizziness anxiety syncope palpitations chest discomfort pain hypotension

37. Atrial Fibrillation Interventions
Patient-centered collaborative care
Risk for PE, VTE
Anti-dysrhythmic drugs
Cardioversion

38. Atrial Fibrillation Interventions(cont’d)
Percutaneous radiofrequency catheter ablation
Bi-ventricular pacing
Maze procedure

39. Ventricular Dysrhythmias
More life-threatening than atrial dysrhythmias because the left ventricle pumps oxygenated blood through the body to perfuse vital organs.
Premature Ventricular Complexes (PVCs)
Ventricular Tachycardia (V Tach)
Ventricular Fibrillation (V Fib)
Ventricular Asystole

40. A, Normal sinus rhythm with unifocal premature ventricular complexes (PVCs). B, Normal sinus rhythm with multifocal PVCs (one negative and the other positive).
Ventricular dysrhythmias. A, Normal sinus rhythm with unifocal premature ventricular complexes (PVCs). B, Normal sinus rhythm with multifocal PVCs (one negative and the other positive).

41. Premature Ventricular Complexes
Result of increased irritability of ventricular cells—early ventricular complexes followed by a pause
PVCs are common and their frequency increases with age

42. Premature Ventricular Complexes S+S
The patient may be asymptomatic or experience palpitations or chest discomfort caused by increased stroke volume of the normal beat after the pause.
Peripheral pulses may be diminished or absent with the PVCs themselves because the decreased stroke volume of the premature beats may decrease peripheral perfusion.

43. PVC Interventions
If there is no underlying heart disease, PVCs are not usually treated other than by eliminating any contributing cause (e.g., caffeine, stress).
With acute myocardial ischemia or MI, PVCs are managed by administering oxygen and amiodarone (Cordarone) as prescribed.
Potassium is given for replacement therapy if hypokalemia is the cause.
People with more than 5000 PVCs in a 24- hour period are usually placed on beta blockers.

44. Ventricular Tachycardia
Also called V tach—repetitive firing of irritable ventricular ectopic focus, usually at beats/min
Sustained ventricular tachycardia at a rate of 166 beats/min.
Sustained ventricular tachycardia at a rate of 166 beats/min.

45. Ventricular tachycardia may occur in patients with ischemic heart disease, MI, cardiomyopathy, hypokalemia, hypomagnesemia, valvular heart disease, heart failure, drug toxicity, hypotension, or ventricular aneurysm.
In patients who go into cardiac arrest, VT is commonly the initial rhythm before deterioration into ventricular fibrillation (VF) as the terminal rhythm!

46. V-Tach Interventions
Current Advanced Cardiac Life Support (ACLS) guidelines state that elective cardioversion is highly recommended for stable VT.
The physician may prescribe an oral antidysrhythmic agent, such as mexiletine (Mexitil) to prevent further occurrences.
Unstable VT without a pulse is treated the same way as ventricular fibrillation.

47. Stable or Unstable V-Tach?
Unstable patients have signs or symptoms of insufficient oxygen delivery to vital organs as a result of the tachycardia. Such manifestations may include the following:
Chest pain
Dyspnea
Hypotension
Altered level of consciousness

48. Ventricular Fibrillation
Also called V fib—result of electrical chaos in ventricles and is life threatening!
Coarse ventricular fibrillation.
Coarse ventricular fibrillation.

49. Ventricular Fibrillation
There is no cardiac output or pulse and therefore no cerebral, myocardial, or systemic perfusion. This rhythm is rapidly fatal if not successfully ended within 3 to 5 minutes.

50. What can lead to V-fib?
Patients with myocardial infarction (MI) are at great risk for VF.
It may also occur in those with
hypokalemia,
hypomagnesemia,
hemorrhage,
antidysrhythmic therapy,
rapid supraventricular tachycardia (SVT)
shock.
Surgery or trauma may also cause VF.

51. V-fib Emergency Care. Client is pulseless and apneic
V-fib Emergency Care! Client is pulseless and apneic. What are you going to do?
Call a CODE BLUE. Get your team!
The priority is to defibrillate the patient immediately according to ACLS protocol.
CPR must be continued until the defibrillator arrives.
Defibrillator shocks, high-quality CPR and provide airway management.
Oxygen and drug therapy (ie: vasopressin, epinephrine, amiodarone, lidocaine, and magnesium sulfate

52. Ventricular Asystole
Also called ventricular standstill—complete absence of any ventricular rhythm
Ventricular asystole with one idioventricular complex.
Ventricular asystole with one idioventricular complex.

53. Ventricular Asystole
The patient is in full cardiac arrest
Usually results from myocardial hypoxia
Prognosis for patients with asystole is poor
Consider ending resuscitation efforts
Consider allowing family members to be present

54. Atrioventricular (AV) blocks
Atrioventricular (AV) blocks exist when supraventricular impulses are excessively delayed or totally blocked in the AV node or ventricular conduction system.
Read about the AV Block family in the handouts.

55. Atrioventricular Blocks
Differentiated by their PR interval
First-degree—all sinus impulses eventually reach ventricles
Second-degree—some sinus impulses reach ventricles, others do not
Third-degree—no sinus impulses reach ventricles

56. Is this a 1st, 2nd or 3rd degree AV Block?
The SA node continues to function normally, and atrial depolarizations and P waves occur regularly. Because of the conduction dysfunction, ventricular depolarizations and QRS complexes are either delayed or blocked.
Is this a 1st, 2nd or 3rd degree AV Block?

57. Dysrhythmias: Nonsurgical Management
Drugs Drugs Drugs (Chart 36-2)
Vagal maneuvers
Temporary Pacing
CPR
ACLS

58. Dysrhythmias: Nonsurgical Management (continued)
Cardioversion
Defibrillation
AED
Radiofrequency Catheter Ablation

59. Surgical Management
• Permanent pacing • Coronary artery bypass grafting (CABG) • Aneurysmectomy • Implantable cardioverter/defibrillator • Open-chest cardiac massage

60. Teaching for self-management
Community-Based Care
Home care management
Teaching for self-management
See chart 36-5 in the handouts about how to prevent or decrease dysrhthmias
Health care resources

61. A 28-year-old woman with a history of hypertension and tachycardia comes to the hospital clinic stating that she doesn’t feel well. You connect her to a cardiac monitor and observe that she is in SVT with a rate varying between She reports shortness of breath, palpitations, and weakness. She appears very nervous and anxious, and her BP is 88/56 mm Hg. What is your first priority intervention?
Oxygen should be administered at 2 L per nasal cannula.

62. Oxygen should be administered at 2 L per nasal cannula.

63. Lidocaine (Xylocaine) 75 mg IVP Mexiletine (Mexitil) 300 mg PO q8h
(cont’d)
The patient’s SVT returns after 30 minutes. What medication do you anticipate will be ordered for the patient?
Lidocaine (Xylocaine) 75 mg IVP
Mexiletine (Mexitil) 300 mg PO q8h
Magnesium sulfate 1 g IVP
Adenosine (Adenocard) 6 mg IVP
ANS: D
The appropriate medication to administer is adenosine (Adenocard), which is the drug used for SVT. The nurse should give the medication as ordered to include 6 mg IV over 1 to 3 seconds followed by 20 mL saline flush. It may be repeated in 1 to 2 minutes if necessary. The nurse should monitor the patient’s heart rate and rhythm carefully after administration of the medication. Be sure to have the crash cart available because a short period of asystole is common after administration. Bradycardia and hypotension may also occur.

64. ANS: D
The appropriate medication to administer is adenosine (Adenocard), which is the drug used for SVT. The nurse should give the medication as ordered to include 6 mg IV over 1 to 3 seconds followed by 20 mL saline flush. It may be repeated in 1 to 2 minutes if necessary. The nurse should monitor the patient’s heart rate and rhythm carefully after administration of the medication. Be sure to have the crash cart available because a short period of asystole is common after administration. Bradycardia and hypotension may also occur.

65. (cont’d)
The SVT resolves immediately after IV adenosine (Adenocard) is administered. Because the patient has experienced repeated episodes of symptomatic SVT, a cardiologist has been consulted and treatment options discussed.
ANS: B
If SVT is continuous, the patient should be studied in the electrophysiology laboratory. The preferred treatment is radiofrequency catheter ablation. Radiofrequency ablation is a procedure that can cure many types of fast heart rates. Using special wires or catheters that are threaded into the heart, radiofrequency energy (low-voltage, high-frequency electricity) is targeted toward the area(s) causing the abnormal heart rhythm, permanently damaging small areas of tissue with heat. The damaged tissue is no longer capable of generating or conducting electrical impulses. If the procedure is successful, this prevents the dysrhythmia from being generated, thereby curing the patient.

66. What is the preferred treatment for recurrent SVT?
Atrial overdrive pacing
Radiofrequency catheter ablation
Synchronized electrical shock
Daily administration of diltiazem (Cardizem)

67. ANS: B
If SVT is continuous, the patient should be studied in the electrophysiology laboratory. The preferred treatment is radiofrequency catheter ablation. Radiofrequency ablation is a procedure that can cure many types of fast heart rates. Using special wires or catheters that are threaded into the heart, radiofrequency energy (low-voltage, high-frequency electricity) is targeted toward the area(s) causing the abnormal heart rhythm, permanently damaging small areas of tissue with heat. The damaged tissue is no longer capable of generating or conducting electrical impulses. If the procedure is successful, this prevents the dysrhythmia from being generated, thereby curing the patient.

68. Ventricular fibrillation Atrial fibrillation
Question 1
Patients with which type of dysrhythmia make up the largest group of those hospitalized with dysrhythmias?
Sinus tachycardia
Sinus bradycardia
Ventricular fibrillation
Atrial fibrillation
Answer: D
Rationale: Atrial fibrillation (AF) is the most common dysrhythmia seen in clinical practice. It is responsible for a third of hospitalizations for cardiac rhythm disturbances. Patients can live with this dysrhythmia, but most are treated with anticoagulation therapy to avoid possible blood clots.

69. ANS: B
If SVT is continuous, the patient should be studied in the electrophysiology laboratory. The preferred treatment is radiofrequency catheter ablation. Radiofrequency ablation is a procedure that can cure many types of fast heart rates. Using special wires or catheters that are threaded into the heart, radiofrequency energy (low-voltage, high-frequency electricity) is targeted toward the area(s) causing the abnormal heart rhythm, permanently damaging small areas of tissue with heat. The damaged tissue is no longer capable of generating or conducting electrical impulses. If the procedure is successful, this prevents the dysrhythmia from being generated, thereby curing the patient.

70. Question 2
On a telemetry monitor, the nurse observes that a patient’s heart rhythm is sustained ventricular tachycardia (VT). The nurse checks the patient and finds him alert and oriented with no reports of chest pain, but feeling slightly short of breath. His blood pressure is 108/70. What is the nurse’s first action?
Administration of oxygen and observation of the heart rhythm
Administration of IV amiodarone (Cordarone) and dextrose
Synchronized cardioversion
CPR and immediate defibrillation
Answer: A
Rationale: Current advanced cardiac life support (ACLS) guidelines recommend administration of oxygen and observation of heart rhythm first, followed by administration of an IV antidysrhythmic agent such as amiodarone mixed with dextrose 5%. Synchronized cardioversion would be the next step. CPR and immediate defibrillation would be used only to treat unstable VT.

71. Answer: A
Rationale: Current advanced cardiac life support (ACLS) guidelines recommend administration of oxygen and observation of heart rhythm first, followed by administration of an IV antidysrhythmic agent such as amiodarone mixed with dextrose 5%. Synchronized cardioversion would be the next step. CPR and immediate defibrillation would be used only to treat unstable VT.