ARLC 2014 - Bradycardias

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Arrhythmias in Real Life Course, Khartoum, Sudan, August 2014

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  • Other definitions, failure to attain 85%, 75%
  • HR 46/min
    Put her on a treadmill reached HR of 137/min
  • 3.4 and 4.8 second pauses
    Patient had acute coronary syndrome with lesion in proximal RCA involving the branch to the SA node, placed a dual chamber pacemaker
  • ACC/AHA guidelines
  • Prolongation of of the PR interval > 200ms, 1:1 conduction, P before every QRS complex, both P and QRS are normal
  • Progressive prolongation of the PR interval terminated in a non conducted P wave
  • ARLC 2014 - Bradycardias

    1. 1. Bradycardias Salah Abusin, MD, MRCP, ABIM, ABIM (Card) Interventional Cardiologist Dubuque, IA, USA
    2. 2. Bradycardias • SA node dysfunction or Sick Sinus Syndrome – Inappropriate sinus bradycardia – Sinoatrial exit Block – Sinus Pause/Arrest – Tachycarda/Bradycardia syndrome – Persistent Atrial Standstill • AV Blocks – First Degree – Second Degree • Mobitz I • Mobitz II • 2:1 Block – Third Degree – High Grade AV Block
    3. 3. Sinoatrial Node dysfunction • Inappropriate sinus bradycardia • Sinoatrial exit Block • Sinus Pause/Arrest • Tachycarda/Bradycardia syndrome
    4. 4. Causes - Intrinsic • Idiopathic degenerative disease • Coronary Artery Disease • Cardiomyopathy • Hypertension • Infiltrative Disorders (amyloidosis etc..) • Collagen Vascular Disorders (scleroderma etc.) • Inflammatory Processes (myocarditis) • Surgical Trauma • Musculoskeletal disorders (myotonic dystrophy) • Congenital heart disease (postoperative or absence of correction)
    5. 5. Causes – Extrinsic - 1 • Medication – BBs, CCBs, digoxin – Clonidine, alpha methyldopa, reserpine – Antiarrhythmics Type • IA (quinidine, procainamide) • IC (flecainide) • III (amiodarone) – Lithium
    6. 6. Causes – Extrinsic - 2 • Autonomic influences – High vagal tone – Carotid sinus syndrome – Vasovagal syncope • Electrolyte abnormalities – Hyperkalemia, hypercarbia, hypothyroidism • Increase intracranial pressure • Hypothermia • Sepsis
    7. 7. Sinoatrial Node dysfunction • Inappropriate sinus bradycardia • Sinus Pause/Arrest • Sinoatrial exit Block • Tachycarda/Bradycardia syndrome
    8. 8. Inappropriate Sinus Bradycardia Chronotropic Incompetence • HR<60 that doesn’t increase appropriately with exercise • Usually defined as failure to attain 80% of maximal age predicted HR (MAHR) on exercise testing • MAHR = 220 – Age • e.g. failure to reach a HR of 120 in a 70 year old patient
    9. 9. Sinus bradycardia
    10. 10. Sinoatrial Node dysfunction • Inappropriate sinus bradycardia • Sinus Pause/Arrest • Sinoatrial exit Block • Tachycarda/Bradycardia syndrome
    11. 11. Sinus Pause/Arrest • Defined as absence of a sinus beat for >=3 seconds while AWAKE • SA node fails to discharge so no atrial activity occurs
    12. 12. Sinus Pause/Arrest
    13. 13. Sinoatrial Node dysfunction • Inappropriate sinus bradycardia • Sinus Pause/Arrest • Sinoatrial exit Block • Tachycarda/Bradycardia syndrome
    14. 14. Sinoatrial Exit Block • SA node discharges an impulse that does NOT result in atrial activity
    15. 15. Sinoatrial Exit Block
    16. 16. Sinoatrial Node dysfunction • Inappropriate sinus bradycardia • Sinus Pause/Arrest • Sinoatrial exit Block • Tachycarda/Bradycardia syndrome
    17. 17. Tachycardia-Bradycardia Syndrome • Bradycardia/sinus pauses interspersed with atrial arrhythmias (AFL, A fib, A tach) • Sinus arrest manifests after termination of atrial arrhythmia (spontaneously or after DCCV) • Sinus Node Recovery Time (SNRT) uses the above observation to assess SA node function in EP studies
    18. 18. Tachycardia-Bradycardia Syndrome Hurst the Heart 12th Edition
    19. 19. Indications for pacing in SND • Class I (recommended) – SND with documented symptoms – SND due to irreversible factors or due to essential drug therapy – Chronotropic incompetence • Class III (NOT recommended) – Asymptomatic
    20. 20. Bradycardias • SA node dysfunction or Sick Sinus Syndrome – Inappropriate sinus bradycardia – Sinoatrial exit Block – Sinus Pause/Arrest – Tachycarda/Bradycardia syndrome – Persistent Atrial Standstill • AV Blocks – First Degree – Second Degree • Mobitz I • Mobitz II • 2:1 Block – Third Degree – High Grade AV Block
    21. 21. AV Blocks • First Degree • Second Degree – Mobitz I – 2:1 Block – Mobitz II • Third Degree • High Grade AV Block
    22. 22. First Degree AV Block • PR interval > 200msec • If QRS is normal, block is usually at the level of the AV node • If QRS shows bundle branch block, block maybe in His-Purkinje System
    23. 23. First degree AV block
    24. 24. Management • Usually no specific therapy is required
    25. 25. Second Degree Heart Block Mobitz I or Wenchebach • Progressive Prolongation of the PR interval and shortening of the RR interval until a P wave is blocked • RR interval containing the non conducted P wave is less than two PP intervals • PR interval longer after the non conducted P wave • Grouped beating
    26. 26. Second Degree – Mobitz I P P P P P P
    27. 27. Causes • Normal • Athletes • Medications • Myocardial Infarction (inferior wall) • Acute rheumatic fever • Myocarditis Features • Usually asymptomatic • Usually narrow QRS complex  block at AV node • The presence of bundle branch block suggests the possibility of block below the AV node in His Purkinje system
    28. 28. Management • Usually do not require permanent pacing
    29. 29. Second Degree – Mobitz II • Constant PR interval with intermittent nonconducted P wave and no evidence for PACs • RR interval between non conducted P waves is equal to two PP intervals • Each QRS is preceded by multiple P waves • 3:1, 4:1 also called high grade AV block • Other variations include 3:2 • 2:1 block maybe Mobitz I or Mobitz II
    30. 30. High Grade AV Block
    31. 31. PP PP Second Degree Heart Block 2:1 Block
    32. 32. Management • Usually require permanent pacing especially if symptomatic due to high likelihood of progression to high grade AV block and third degree AV block
    33. 33. Differentiating mechanism of 2:1 block Feature Mobitz I Mobitz II QRS duration Narrow Wide Response to increasing HR & AV conduction i.e. exercise, atropine Improves Worsens Response to decreasing HR & AV conduction i.e. carotid sinus massage Worsens Improves Acute MI Inferior Anterior
    34. 34. Third Degree AV block • Atrial impulses consistently fail to reach the ventricles, resulting in atrial and ventricular rhythms that are independent of each other • PR interval varies • PP and RR intervals are constant • Ventriculophasic sinus arrhythmia – PP interval containing QRS is shorter than PP interval without a QRS complex
    35. 35. Third Degree AV block P P P P P P P P P PP
    36. 36. Escape Rhythms • Junctional – Usually narrow (may be wide if underlying BBB) – 40-60/min • Ventricular Escape Rhythm – Wide complex – 30-40/min (range 20-50)
    37. 37. Causes • Myocardial Infarction – Inferior wall, usually transient, associated with a stable junctional escape rhythm – Anterior wall, usually permanent • Degenerative Disease • Infiltrative Disease (amyloid, sarcoid) • Endocarditis (Aortic Root abscess) • Hyperkalemia • Medication • Post Cardiac Surgery
    38. 38. Management • Usually require permanent pacing
    39. 39. Acclerated Idioventricular rhythm
    40. 40. Acclerated Idioventricular rhythm • Regular Wide complex rhythm • 60-110/min • AV dissociation • Benign phenomenon • Causes – Normal – Coronary reperfusion – Digoxin toxicity
    41. 41. Problems
    42. 42. 3rd degree AV block, junctional escape
    43. 43. Second Degree Mobitz I
    44. 44. P P P P P P P P P P P 3rd degree AV block, junctional escape
    45. 45. P P P P P P P P P P 3rd degree AV block, junctional escape or high grade AV block
    46. 46. Problem • 50 year old female with no PMH presents with acute onset of shortness of breath on exertion of 4 days duration • HR 50/min, BP 140/80 • Initial ECG sinus bradycardia • TropI 1.2
    47. 47. Sinus arrest with ventricular escape
    48. 48. Sinus arrhythmia
    49. 49. Problem • 65 year old male presented with 4 day history of shortness of breath on exertion, orthopnea and PND • HR 50/min, regular, BP 150/70
    50. 50. Atrial Fibrillation with 3rd degree AV block & junctional escape
    51. 51. Single Chamber Ventricular Pacing at 45/min with complete heart block
    52. 52. Dual Chamber Pacing with marked anterolateral ST depression
    53. 53. Sick Sinus Syndrome Sinus pauses with interspersed short runs of Atrial Fibrillation
    54. 54. Thank You

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