Arrhythmias and EKGs Part 1
Outline <ul><li>Normal Sinus Rhythm </li></ul><ul><li>Altered Automaticity </li></ul><ul><li>Reentry </li></ul><ul><li>Con...
Normal Sinus Rhythm Implies normal sequence of conduction, originating in the sinus node and proceeding to the ventricles ...
Mechanisms of Arrhythmogenesis
Recognizing altered automaticity on EKG <ul><li>Gradual onset and termination of the arrhythmia. </li></ul><ul><li>The P w...
Decreased Automaticity Sinus Bradycardia www.uptodate.com
Increased/Abnormal Automaticity Sinus tachycardia Junctional tachycardia Ectopic atrial tachycardia www.uptodate.com
Mechanism of Reentry
Mechanism of Reentry
Reentrant Rhythms <ul><li>AV nodal reentrant tachycardia (AVNRT) </li></ul><ul><li>AV reentrant tachycardia (AVRT) </li></...
Recognizing reentry on EKG <ul><li>Abrupt onset and termination of the arrhythmia. </li></ul><ul><li>The P wave of the fir...
Example of AVNRT
Mechanism of AVNRT
Atrial Flutter Most cases of atrial flutter are caused by a large reentrant circuit in the wall of the right atrium EKG Ch...
Unmasking of Flutter Waves In the presence of 2:1 AV block, the flutter waves may not be immediately apparent.  These can ...
Atrial Fibrillation Atrial fibrillation is caused by numerous wavelets of depolarization spreading throughout the atria si...
Atrial Fibrillation EKG Characteristics: Absent P waves Presence of fine “fibrillatory” waves which vary in  amplitude and...
What is this arrhythmia? Ventricular tachycardia Ventricular tachycardia is usually caused by reentry, and most commonly s...
Rhythms Produced by Conduction Block <ul><li>AV Block (relatively common)  </li></ul><ul><ul><li>1 st  degree AV block </l...
1 st  Degree AV Block EKG Characteristics: Prolongation of the PR interval, which is constant All P waves are conducted Th...
2 nd  Degree AV Block Type 1 (Wenckebach) EKG Characteristics: Progressive prolongation of the PR interval until a P  wave...
3 rd  Degree (Complete) AV Block EKG Characteristics: No relationship between P waves and QRS complexes Relatively constan...
Questions to answer in order to identify an unknown arrhythmia: <ul><li>1. Is the rate slow (<60 bpm) or fast (>100 bpm)? ...
Questions to answer in order to identify an unknown arrhythmia: <ul><li>4. Are there P waves? </li></ul><ul><li>Absent P w...
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Arrythmias and ek gs 1

  1. 1. Arrhythmias and EKGs Part 1
  2. 2. Outline <ul><li>Normal Sinus Rhythm </li></ul><ul><li>Altered Automaticity </li></ul><ul><li>Reentry </li></ul><ul><li>Conduction Block </li></ul><ul><li>Helpful hints for diagnosing arrhythmias </li></ul>
  3. 3. Normal Sinus Rhythm Implies normal sequence of conduction, originating in the sinus node and proceeding to the ventricles via the AV node and His-Purkinje system. EKG Characteristics: Regular narrow-complex rhythm Rate 60-100 bpm Each QRS complex is proceeded by a P wave P wave is upright in lead II & downgoing in lead aVR www.uptodate.com
  4. 4. Mechanisms of Arrhythmogenesis
  5. 5. Recognizing altered automaticity on EKG <ul><li>Gradual onset and termination of the arrhythmia. </li></ul><ul><li>The P wave of the first beat of the arrhythmia is typically the same as the remaining beats of the arrhythmia (if a P wave is present at all). </li></ul>
  6. 6. Decreased Automaticity Sinus Bradycardia www.uptodate.com
  7. 7. Increased/Abnormal Automaticity Sinus tachycardia Junctional tachycardia Ectopic atrial tachycardia www.uptodate.com
  8. 8. Mechanism of Reentry
  9. 9. Mechanism of Reentry
  10. 10. Reentrant Rhythms <ul><li>AV nodal reentrant tachycardia (AVNRT) </li></ul><ul><li>AV reentrant tachycardia (AVRT) </li></ul><ul><ul><li>Orthodromic </li></ul></ul><ul><ul><li>Antidromic </li></ul></ul><ul><li>Atrial flutter </li></ul><ul><li>Atrial fibrillation </li></ul><ul><li>Ventricular tachycardia </li></ul>
  11. 11. Recognizing reentry on EKG <ul><li>Abrupt onset and termination of the arrhythmia. </li></ul><ul><li>The P wave of the first beat of the arrhythmia is different as the remaining beats of the arrhythmia (if a P wave is present at all). </li></ul>
  12. 12. Example of AVNRT
  13. 13. Mechanism of AVNRT
  14. 14. Atrial Flutter Most cases of atrial flutter are caused by a large reentrant circuit in the wall of the right atrium EKG Characteristics: Biphasic “sawtooth” flutter waves at a rate of ~ 300 bpm Flutter waves have constant amplitude, duration, and morphology through the cardiac cycle There is usually either a 2:1 or 4:1 block at the AV node, resulting in ventricular rates of either 150 or 75 bpm www.uptodate.com
  15. 15. Unmasking of Flutter Waves In the presence of 2:1 AV block, the flutter waves may not be immediately apparent. These can be brought out by administration of adenosine. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine, 7th ed., 2005.
  16. 16. Atrial Fibrillation Atrial fibrillation is caused by numerous wavelets of depolarization spreading throughout the atria simultaneously, leading to an absence of coordinated atrial contraction. Atrial fibrillation is important because it can lead to: Hemodynamic compromise Systemic embolization Symptoms www.uptodate.com
  17. 17. Atrial Fibrillation EKG Characteristics: Absent P waves Presence of fine “fibrillatory” waves which vary in amplitude and morphology Irregularly irregular ventricular response www.uptodate.com
  18. 18. What is this arrhythmia? Ventricular tachycardia Ventricular tachycardia is usually caused by reentry, and most commonly seen in patients following myocardial infarction.
  19. 19. Rhythms Produced by Conduction Block <ul><li>AV Block (relatively common) </li></ul><ul><ul><li>1 st degree AV block </li></ul></ul><ul><ul><li>Type 1 2 nd degree AV block </li></ul></ul><ul><ul><li>Type 2 2 nd degree AV block </li></ul></ul><ul><ul><li>3 rd degree AV block </li></ul></ul><ul><li>SA Block (relatively rare) </li></ul>
  20. 20. 1 st Degree AV Block EKG Characteristics: Prolongation of the PR interval, which is constant All P waves are conducted The Alan E. Lindsay ECG Learning Center ; http://medstat.med.utah.edu/kw/ecg/
  21. 21. 2 nd Degree AV Block Type 1 (Wenckebach) EKG Characteristics: Progressive prolongation of the PR interval until a P wave is not conducted. As the PR interval prolongs, the RR interval actually shortens EKG Characteristics: Constant PR interval with intermittent failure to conduct Type 2
  22. 22. 3 rd Degree (Complete) AV Block EKG Characteristics: No relationship between P waves and QRS complexes Relatively constant PP intervals and RR intervals Greater number of P waves than QRS complexes www.uptodate.com
  23. 23. Questions to answer in order to identify an unknown arrhythmia: <ul><li>1. Is the rate slow (<60 bpm) or fast (>100 bpm)? </li></ul><ul><li>Slow  Suggests sinus bradycardia, sinus arrest, or conduction block </li></ul><ul><li>Fast  Suggets increased/abnormal automaticity or reentry </li></ul><ul><li>2. Is the rhythm irregular? </li></ul><ul><li>Irregular  Suggests atrial fibrillation, 2 nd degree AV block, multifocal atrial tachycardia, or atrial flutter with variable AV block </li></ul><ul><li>3. Is the QRS complex narrow or wide? </li></ul><ul><li>Narrow  Rhythm must originate from the AV node or above </li></ul><ul><li>Wide  Rhythm may originate from anywhere </li></ul>
  24. 24. Questions to answer in order to identify an unknown arrhythmia: <ul><li>4. Are there P waves? </li></ul><ul><li>Absent P waves  Suggests atrial fibrillation, ventricular tachycardia, or rhythms originating from the AV node </li></ul><ul><li>5. What is the relationship between the P waves and QRS complexes? </li></ul><ul><li>More P waves than QRS complexes  Suggests 2 nd or 3 rd degree AV block </li></ul><ul><li>More QRS complexes than P waves  Suggests an accelerated junctional or ventricular rhythm </li></ul><ul><li>6. Is the onset/termination of the rhythm abrupt or gradual? </li></ul><ul><li>Abrupt  Suggests reentrant rhythm </li></ul><ul><li>Gradual  Suggests altered automaticity </li></ul>

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