Cardiac Dysrhythmias

  1. 4 Stable Tachycardia Categories:
    • 1. Atrial fibrillation/flutter
    • 2. Narrow-complex tachycardia
    • 3. Stable wide-complex tachycardia, unknown type
    • 4. Stable monomorphic VT and/or stable polymorphic VT
  2. Image Upload 1
    Atrial Fibrillation/Flutter
  3. Atrial Fib/Flutter: Evaluation Focus
    4 Clinical Features
    • 1. Is patient clinically unstable?
    • 2. Is cardiac function impaired?
    • 3. Is WPW present?
    • 4. Is duration of AF <48 or >48 hours?
  4. Atrial Fib/Flutter: Treatment Focus
    4 Treatment Considerations
    • 1. Treat unstable patients urgently
    • 2. Control rate
    • 3. Convert rhythm
    • 4. Provide anticoagulation if indicated
  5. Image Upload 2
    Atrial Flutter 
  6. Image Upload 3
    Paroxysmal Supraventricular Tachycardia
  7. Image Upload 4
    Sinus Tachycardia
  8. Image Upload 5
    Ventricular Tachycardia
  9. Unstable Tachycardias:
    • 1. Atrial fibrillation/flutter
    • 2. Narrow-complex tachycardias
    • 3. Wide-complex tachycardias of unknown type
    • 4. Ventricular Tachycardia
  10. Unstable Tachycardias:
    Narrow-Complex Tachycardias
    • Paroxysmal supraventricular tachycardia (PSVT)
    • Junctional tachycardia
    • Multifocal atrial or ectopic atrial tachycardia
  11. Unstable Tachycardias:
    Wide-Complex Tachycardia of unknown type
    • Wide-complex tachycardia - not specified
    • Aberrant conduction of an SVT
  12. Unstable Tachycardias:
    Ventricular Tachycardia
    • Stable monomorphic VT
    • Stable polymorphic VT (baseline QT interval normal)
    • Stable polymorphic VT (baseline QT interval prolonged = torsades de pointes)
  13. Image Upload 6
    Sinus Tach: PSVT (Paroxysmal Supraventricular Tachycardia)
  14. Image Upload 7
    Atrial Flutter:

    • Atrial Rate = 250 bpm
    • Ventricular Rate = 125 bpm
  15. Image Upload 8
    Sinus Bradycardia
  16. Bradycardias: Sinus Bradycardia
    Heart Blocks
    • 1st Degree
    • 2nd Degree type 1
    • 2nd Degree type 2
    • 3rd Degree
  17. Image Upload 9
    Cardiac Conduction System 2:

    Relationship of ECG to anatomy
  18. Approximately what percentage of Wide-Complex Tachyarrhythmias are what?
    Approximately 80% of wide-complex tachyarrhythmias are V. Tach
  19. Typical Post-cardioversion med therapy of VT?
    • Lidocaine
    • Procainamide
    • Bretylium
  20. Determining The Rate:
    Image Upload 10
    • 1. Find where the R-S junction of a QRS complex fall on one of the darker 5-mm lines
    • 2. Note the next R-S junction; mark it
    • 3. Label each of the darker 5-mm lines between the first R-S junction and the next one in the following sequence:  300 - 150 - 100 - 75 - 60 - 50
    • This number is the rate of beats per minute
  21. Analyzing Rhythm Strips:
    Key Questions
    • Are QRS complexes present?
    • Are P waves present?
    • How is the P wave related to the QRS complex?
  22. Relationship of P waves and QRS Complexes:
    • Every P wave is followed by a QRS complex w/ normal P-R interval
    • Every P wave is followed by a QRS complex but the P-R interval is prolonged
    • Some P waves are NOT followed by a QRS complex; more P waves than QRS complexes
  23. Clinically Blocks occur with?
    Slow rates and more P waves than QRS complexes
  24. Image Upload 11
    First-Degree AV Block
  25. Definition of "Prolonged P-R interval":
    P-R interval is equal to or greater than 0.2 seconds
  26. First-Degree AV Block has?
    The P-R interval is prolonged. It is 0.31 seconds
  27. The P-R interval lengthens in 1st-degree AV block because?
    The impulse is slowed getting through the AV node
  28. Sinus Bradycardia:
    Rate & PathologyImage Upload 12
    Rate = 48 bpm; regular


    is a decrease in the rate of atrial depolarization secondary to sinus node disease, increased parasympathetic tone, or the effects of drugs such as digoxin, β-blockers, or calcium channel blockers.
  29. Image Upload 13
    Second-Degree Type 1 AV Block
  30. Second-Degree Type 1 AV Block:
    • Progressive lengthening of the P-R interval until a P wave is NOT followed by a QRS complex
    • Atrial rhythm is regular
    • Ventricular rhythm has pauses b/c every 4th P wave fails to conduct into the ventricles. (4 P waves to 3 QRS complexes = a 4:3 cycle)
  31. Progressive prolongation of the P-R interval means?
    Increasing conduction delay in AV node before the non-conducted beat
  32. Characteristic of 2nd-Degree Type 1 AV Block?
    Lengthening of the P-R interval
  33. Image Upload 14
    Second-Degree Type 2 AV Block
  34. Second-Degree Type 2 AV Block:
    • 3 conducted beats are followed by 2 non-conducted P waves
    • The P-R interval of conducted beats remains constant
    • Block is usually located at the level of the bundle branches
    • QRS is wide because of the block location near the bundle branches
  35. Second-Degree Type 2 AV Block:
    Cause, Prognosis, Risk
    Cause: A serious organic lesion in the conduction pathway

    Prognosis: Usually poor

    Risk: High risk for complete heart block to develop
  36. Characteristic of Second-Degree Type 2 AV Block:
    Fixed P-R interval until a beat is dropped
  37. Differentiation of 2nd and 3rd-Degree AV Blocks:
    More P's than QRS's? → YES → PR fixed? → YES 2nd-degree AV block, Fixed Mobitz II

    PR fixed? → NO → QRS's that look alike regular? → YES 3rd-degree AV Block

    QRS's that look alike regular? → NO 2nd-degree AV Block, Variable, Mobitz I Wenckebach
  38. Defining Symptomatic Bradycardia Key Points:
    Do NOT treat a slow heart rate in a Stable patient

    Treating the symptoms is the most important concept

    Relative bradycardia exists when a hypotensive patient "needs" a faster HR. but the rate cannot accelerate due to sinus node disease, conduction system disease, or β-blockers
  39. Symptomatic Bradycardia in Resting Athletes and Patients w/ inferior MI
    Resting Athletes may have sinus rate <40 bpm and still be completely asymptomatic

    Patients with inferior MI frequently have sinus bradycardia w/ or w/out chest pain
  40. Will ischemia be alleviated or worsened by increasing the rate?
    Usually the bradycardia is NOT the cause of the chest pain.

    Treat if clearly detrimental symptoms are present: Hypotension/shock, decreased level of consciousness, sudden increased pain associated w/ decreased rate, CHF, or adrenergic symptoms such as pallor and cool, clammy periphery
  41. Image Upload 15
    Third-Degree AV Block at the level of the AV node

    (Supra-nodal or supraventricular level)
  42. Third-degree AV block at the level of the AV node (supra-nodal or supraventricular level)
    Atrial rhythm is irregular due to sinus arrhythmia at a rate of 48-70 bpm

    There is no constant P-R interval. The narrow QRS complex indicates that the block is occurring above the ventricles (supraventricular) at an upper level of the AV node.
  43. Third-degree AV block at the level of the AV node (supra-nodal or supraventricular level):
    Rate, Pathology, Prognosis
    Rate: Atrial Rate = 45-70 bpm; Ventricular Rate = 44 bpm

    Pathology: (A) = increased parasympathetic tone, which can result from drug effects such as digoxin, or β-blockers; 


    (B) = damage to the AV node

    Prognosis: Third-degree AV block with a narrow junctional escape rhythm is usually transient and is associated with a favorable prognosis.
  44. Characteristic of Third-Degree AV Block:
    Variable P-R interval w/ regular R-R interval

    Look at similar QRS complexes to assess the regularity of the R-R interval
  45. Image Upload 16
    Third-Degree AV Block
  46. Image Upload 17
    Third-Degree AV Block at the infra-nodal (bundle branch) level
  47. Third-Degree AV Block at the infra-nodal (bundle branch) level:
    The wide QRS indicates that the block is occurring at the ventricular level

    • There is no relation between the atrial and ventricular rhythm
    • Ventricular rhythm is regular and very slow (38 bpm)
    • The QRS is wide b/c block is at the bundle branch level, usually involving both bundle branches. 
    • The ventricular pacemaker is downstream from that level
  48. Third-Degree AV Block at the infra-nodal (bundle branch) level:
    Damage, Cause, Tx?
    Damage: To both bundle branches indicates extensive conduction system disease below the AV node. 

    Cause: This is most often caused by extensive anterior myocardial infarction. The ventricular escape pacemaker is slow (<40 bpm) unstable and may lead to episodes of ventricular asystole

    Tx?: New 3rd-degree AV block demands urgent pacing, likely w/ TCP. This is why TCP shoiuld be readied while atropine is tried
  49. Image Upload 18
    Third-Degree AV Block at the Supra-nodal level
  50. Third-Degree AV Block at the Supra-nodal level:
    Third-degree AV block w/ narrow junctional escape rhythm is usually transient and associated w/ a favorable prognosis
  51. Image Upload 19
    Third-Degree AV Block w/ Ventricular Asystole
  52. Third-Degree AV Block w/ Ventricular Asystole:
    Patient has acute anterior myocardial infarction.

    He developed right bundle branch block (see wide-QRS complex on left side of strip).

    Complete heart block abruptly developed: only P waves seen on right side of strip. P waves are not followed by a ventricular escape focus, resulting in ventricular asystole.
  53. Third-degree AV block with ventricular asystole:
    Lidocaine Issue
    Escape rhythms are less likely w/ Lidocaine
  54. Third-degree AV block at the infra-nodal (bundle branch) level: 
    Transcutaneous Pacing
    The advantage of TCP over catecholamine infusion is significant.

    A transvenous pacemaker often takes too long to place.

    The key focus is on the unstable patient and the value of TCP as a bridge while transvenous pacing is organized.

    Note the use of pacing to allow the use of lidocaine in stable second-degree AV block with PVC or runs of VT.

    This is a good place to reinforce this contraindication to lidocaine for ventricular escape rhythms.

    Standby pacing (pads applied but not in pacing mode) is the reason for understanding intranodal AV blocks.
  55. Image Upload 20
  56. Asystole:
    A cardiac arrest rhythm associated w/ no discernible electrical activity on ECG "Flat Line"
  57. Asystole:
    Successful Resuscitation
    Successful resuscitation of a person in asystolic cardiac arrest occurs RARELY.

    It happens only when rescuers stop, think, and ask “Why did this person have this cardiac arrest at this time?” Only if the cause of asystole is identified and treated in a timely manner will there be any reasonable possibility of survival.
  58. Survival of Asystolic Patients:
    A large % of Pt's will NOT survive.
  59. Asystole occurs almost exclusively in?...
    Severely ill patients.

    Often this rhythm represents the terminal rhythm of patients who have deteriorated from organ failure. Cardiac function has diminished until cardiac electrical and functional activity finally stop.
  60. Asystole:
    The person has died
    In such scenarios resuscitation fades as a high-priority action.

    Prolonged efforts are unnecessary, futile, often unethical, and ultimately dehumanizing if not demeaning.

    The asystole case therefore provides the most appropriate setting to discuss and understand more about ethics, when not to start resuscitative efforts, and indications for termination of the resuscitation attempt.
  61. Causes: H's & T's
    • Hypoxia (CNS events)
    • Hypokalemia/Hyperkalemia (and other electrolytes)
    • Hypothermia/Hyperthermia
    • Hypoglycemia/Hyperglycemia
    • Hypovolemia (tank/anaphylaxis, gravid)
  62. Causes: H's & T's
    • Trauma
    • Tamponade
    • Thrombosis (pulmonary)
    • Thrombosis (coronary)
    • Tablets (OD's, drugs, etc.)
    • Tension (pneumothorax, asthma)
  63. PEA
    • Electromechanical dissociation (EMD)
    • Idioventricular rhythms
    • Pulseless asystolic rhythms
    • Bradyasystolic rhythms
    • Ventricular junctional escape rhythms
    • "Pseudo-EMD" (All these terms have been replaced by the term PEA.)
  64. QRS complexes in PEA:
    Can be fast or slow, narrow or wide.

    Tx approach, and ultimately the patient's prognosis, may vary based on fast V.S. slow and narrow V.S. wide complexes
  65. Pulseless Electrical Activity:
    Image Upload 21
    Any pulseless rhythm that looks as if it could produce a pulse is considered a PEA

    THEREFORE, any pulseless rhythm that is not VF, VT, or asystole should be considered PEA. This rhythm—sinus tachycardia with unifocal PVCs and no pulse—is one form of PEA that could be EMD or pseudo-EMD
  66. Sinus Tachycardia W/ No Pulse:Image Upload 22
    This rhythm is another form of PEA that could be EMD or pseudo-EMD. This patient also has first-degree AV block.
  67. Bradyasystolic Rhythm W/out a Pulse:
    Image Upload 23
    Another form of PEA.
  68. 2 Drugs used for Non-specific PEA:
    Epinephrine = administered every 3-5 mins during cardiac arrest

    Atropine = used to treat relative bradycardia. One of the standard agents for treating PEA, w/out reference to the rate of the electrical activity. Until specific evidence accumulates otherwise, limit atropine to absolute or relative bradycardia.

    The shorter dosing interval (every 3mins) is possibly helpful (Class IIb) in cardiac arrest.
  69. Idioventricular Rhythms W/out a Pulse:
    Image Upload 24
    Another form of PEA.
  70. Agonal Rhythms W/out a Pulse:
    Image Upload 25
    Another form of PEA.

    May be due to true EMD. A rapid search for treatable causes is KEY! Only a few reversible causes exist, & must be found and treated quickly.
  71. Cardiac Tamponade:
    Clinical Signs
    • Pulsus paradoxus
    • Pericardial friction rub may be present
    • Heart size on x-ray may be normal or enlarged
    • Echocardiogram
  72. Although rare, Tamponade may cause?
  73. Pericardial Tamponade:
    Chest X-ray & Electrical Alternans
    • Chest X-ray:
    • Image Upload 26
    • Widened mediastinum
    • Pneumo- or hemothorax
    • Note rounded bottle shape to left side of heart

    • Electrical Alternans:
    • Image Upload 27
  74. Cardiac Tamponade:
    • Impairment of ventricular diastolic filling caused by pressure of pericardial sac
    • & by bulging of ventricular septum into LV
    • Stroke volume and cardiac output fall
  75. Tension Pneumothorax:
    Image Upload 28
    • Air under tension in left thorax
    • Pleural margin; partial lung collapse

    Although rare, tension pneumo may cause PEA

    Hx may include: Trauma, recent CPR, prior chest surgery, central venous lines, or other reason for a pneumo
  76. Tension Pneumothorax:
    Air under pressure

    • Venous return inhibited
    • Mediastinum displaced 
    • Vena cava kinked
    • Cardiac output decreased
    • Cardiovascular collapse developed
  77. Tension Pneumothorax:
    Clinical manifestations in Pt. W/
    • Spontaneous breathing
    • Respiratory distress
    • Florid face
    • Trachea deviation
    • Distended neck veins
    • Tachycardia
    • Hypotension
  78. Tension Pneumothorax:
    • Provide as soon as diagnosis is apparent to prevent cardiovascular collapse and cardiac arrest
    • Do not wait for x-ray confirmation
    • Use large-bore needle tap
  79. Tension Pneumothorax:
    Equipment & Technique

    • Povidone-iodine solution
    • 14-gauge catheter-over-needle device


    • Cleanse overlying skin
    • Insert needle at 2nd or 3rd intercostal space, midclavicular line, over top of rib
    • Leave catheter in pleural space open to air
  80. Tension Pneumothorax:
    Complications of Tx
    • Misdiagnosis - pneumothorax created
    • Lung laceration
    • Internal mammary or intercostal vessel laceration
    • Hemothorax
  81. Image Upload 29
    Ventricular Fibrillation
  82. Characteristics of Ventricular Fibrillation:
    • Organized QRS complexes and absent P waves
    • Wavy, chaotic, inconsistent baseline
    • Irregular rhythm

    VF may occur spontaneously or be preceded by VT
  83. Image Upload 30
    Pulseless Ventricular Tachycardia
  84. Characteristics of VT:
    • Wide, bizarre QRS complexes
    • Regular rhythm and mostly uniform in shape
    • Absent Pwaves
    • Ventricular rate is 150 bpm
Card Set
Cardiac Dysrhythmias
Cardiac Dysrhythmias Week 3 A.C.C