Cardiac Arrhythmias

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  1. When does an arrhythmia become a problem during anesthesia?
    only if the hemodynamic status of the patient is being affected
  2. At what point do we start treatment for arrhythmia during anesthesia (after hemodynamic status is affected)?
    when cardiac output is reduced and causes sustained tachycardia or are progressing to life threatening cardiac electrical instability
  3. What can cause arrhythmias during anesthesia?
    • preexisting medical conditions
    • administration of premedications
    • anesthetic induction and maintenance agents
    • surgical stimulation
  4. What can anticholinergics cause?
    • sinus tachycardia
    • second degree AV block
  5. What can phenothiazine tranquilizers (acepromazine) cause?
    • sinus bradycardia
    • sinus tachycardia
    • first and second degree AV block
  6. What can alpha 2 agonists (xylazine, medetomidine) cause?
    • low cardiac output states
    • bradycardia
    • decreases the epinephrine threshold for premature ventricular contractions(VPCs)
  7. What can opioids (morphine, hydromorphone) cause?
    • bradycardia
    • second degree AV block
  8. What can induction with thiopental cause?
    bigeminy (a VPC following each normal beat)
  9. What is normal sinus rhythm?
    • a normal heart beat
    • nothing wrong with the conduction pattern
  10. Which animals have normal sinus arrhythmias?
    • dogs
    • not normal in cats
  11. What is a sinus arrhythmia?
    • cyclic slowing and speeding of the sinus rate that is usually assoicated with respiration
    • the rate tends to increase on inspiration and decrease on expiration because of changes in vagal tone
    • end of expiration there is a pause in the heart beat
  12. How do we diagnose a sinus arrhythmia?
    • need to watch the patient breath and listen to the heart at the same time
    • must be able to assoicate with the respiratory rate
  13. What is a sinus bradycardia?
    • slow heart rate, but has a regular rhythm
    • <60 bpm in large breed dogs
    • <80 bpm in small breed dogs
    • <120 bpm in cats
  14. What can cause sinus bradycardias?
    • drugs that increase vagal tone (alpha 2 agonists, opioids, xylazine, acepromazine)
    • mediated reflexes (pulling on ovarian pedicles, oculocardiac reflex)
    • hypothermia
    • hypothyroidism
    • Addison's disease
    • deep planes of anesthesia
  15. increase vagal tone = _____ heart rate
  16. What does transient mean?
    only happening from time to time
  17. What is a transient sinoatrial block?
    • pause in conduction in SA node
    • absent of PQRST from time to time
    • basically it is a missing heart beat because the SA node has to fire for anything  esle to happen so if it does not fire (arrested) then the beat is missing
  18. Is a transient sinoatrial block a problem?
    not usually a problem but can lead to something worse
  19. What do we often confuse transient sinoatrial block with?
    sinus arrhythmia
  20. What is another word for "block"?
  21. What is a first degree AV block?
    • PR interval is > 0.2 seconds
    • conduction block at the AV node
  22. Does first degree AV block affected cardiac function?
    no, but it is important to recognize because it can lead to second and third degree AV block
  23. What is a second degree AV block type 1?
    • PR interval becomes increasingly long with each heartbeat
    • the pattern accummulates until we lose a QRS complex and then it starts all over again
  24. What is another term for second degree AV block type 1?
    Mobitz 1
  25. What is second degree AV block type 2?
    • random absence of QRS complex and T wave
    • the PR interval is always the same and we just miss a QRS complex every now and then unlike type 1 where the PR interval gets longer with each beat until we miss a QRS complex
  26. What is another name for a second degree AV block type 2?
    Mobitz 2
  27. Does a second degree AV block compromise the patient?
    depends on how frequently it is happening
  28. What is a third degree AV block?
    • lots of P waves and no QRS waves
    • patient is about to die because the ventricles are not contracting therefore blood is not being circulated throughout the body
  29. What is sinus tachycardia?
    • normal conduction but happening fast
    • >160 bpm for large dogs
    • >180 bpm for small dogs
    • >220 bpm for cats
  30. When should we be concerned about sinus tachycardia?
    • when the rate becomes so high that there is insufficient time for ventriclar filling.
    • this decreases cardiac output and blood pressure and can have serious hemodynamic consequences for the patient
  31. What does supraventricular mean?
    happening above the ventricles in the heart
  32. What are some supraventricular (atrial) arrhythmias?
    • atrial flutter
    • atrial fibrillation
  33. What is atrial flutter?
    • multiple P waves
    • sometimes seen in cats, post induction
    • we usually don't worry about it
  34. Is the patient compromised with atrial flutter or atrila fibrillation?
    no because there is still a QRS complex so the patient is still having regular ventricular contractions
  35. What are premature ventricular complexes (PCVs or VPCs)?
    • absence of a P wave and heart beat makes a different sound
    • will have a pulse deficit - no pulse associated with a heart beat
    • not a normal, healthy ventricular contraction - it is weak, poor, and pushes no blood out dispite being large on the EKG
  36. What is the most common ventricular arrhythmia?
  37. When do we often see VPCs?
    trauma patients who have sustained myocardial bruising and dogs presenting for correction of gastric dilation and colculus (GDV) surgery
  38. When do VPCs become a problem for the patient?
    • if they are happening every no and then they are not a problem
    • they become a problem when there are "runs" of VPCs - this can lead to ventricular fibrillation and death
  39. What is a bigeminy?
    • every other beat is a VPC
    • only 50% of the beats are produces perfusion to the patient
  40. What is trigeminy?
    every 3rd beat is a VPC
  41. What are "runs of VPCs"?
    • normal beats and then a bunch of VPCs back to back
    • frequency of the runs determines if it compromises the patient
    • can lead to worse problems - more than 6 in a run with increasing frequency
  42. What is unifocal ventricular tachycardia?  Multifocal?
    • ventricular tachycardia means the patient is dieing
    • Unifocal:  VPCs are firing all from one spot and they all look the same
    • Multifocal:  VPCs are firing from different places
  43. What does ventricular tachycardia lead to?
    ventricular fibrillation
  44. What is ventricular fibillation?
    • no pulse, no mechanical activity
    • ventricles are fluttering but not contracting of pushing out any blood
  45. What is asystole?
    flat line
  46. Image Upload
    What is this?
    normal sinus rhythm
  47. Image Upload
    What is this?
    • sinus arrhythmia
    • normal in dogs, not normal in cats
    • pause in heart beat at the end of expiration
  48. Image Upload
    What is this?
    • sinus bradycardia
    • conduction/pattern is normal just happening slower
  49. Image Upload
    What is this?
    • transient sinoatrial block
    • pause in conduction at the SA node
    • absent PQRST in an otherwise normal rhythm strip
  50. Image Upload
    What is this?
    • first degree AV block
    • PR interval is > 0.2 seconds
  51. Image Upload
    What is this?
    • second degree AV block type 1 (mobitz 1)
    • PR interval becomes increasingly long with each heartbeat until a heartbeat is skipped (QRS) and then it starts back over
  52. Image Upload
    What is this?
    • second degree AV block type 2 (mobitz 2)
    • PR interval is always the same instead of getting longer with each beat - the heart just skips a beat every now and then
  53. Image Upload
    What is this?
    • sinus tachycardia
    • normal conduction/pattern just happening faster
  54. Image Upload
    What is this?
    • atrial flutter
    • multiple P waves
  55. Image Upload
    What is this?
    atrial fibrillation
  56. Image Upload
    What is this?
    • premature ventricular contraction (PCV or VPC)
    • contraction is weak and poor with not blood being pushed out
    • will have a pulse deficit - no pulse associated with a heart beat
  57. Image Upload
    What is this?
    • bigeminy
    • a VPC every other beat
  58. Image Upload
    What is this?
    • Run of VPCs
    • normal beats and then a bunch of VPCs back to back
  59. Image Upload
    What is this?
    • ventricular tachycardia - unifocal
    • VPCs are firing from one spot and all look the same
  60. Image Upload
    What is this?
    • ventricular tachycardia - multifocal
    • VPCs firing from different places
  61. Image Upload
    What is this?
    • ventricular fibrillation
    • no pulse or mechanical activity
    • ventricles are just fluttering but not contracting or pushing out any blood
  62. What questions do we ask ourselves when evaluating an EKG?
    • what is the rate and is it normal? (sinus tachycardia or sinus bradycardia)
    • normal rhythm?  regular rhythm?  irregular rhythm (does the irregularity follow a regular pattern like a sinus arrhythmia)? 
    • is there a P wave prior to each QRS? (if no...VPCs)
    • is there a QRS to follow every P? (if no...second or third degree AV block)
Card Set:
Cardiac Arrhythmias
2012-10-14 02:40:03

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