Basic EKG Interpretation

1. Basic EKG Interpretation AV Blocks

2. Atrioventricular Blocks • Can be temporary or permanent • Temporary due to: • Digoxin toxicity • Ischemia or infarction (inferior) due to edema formation • Permanent due to: • Degeneration of conduction system • Anterior infarction due to anoxic destruction of conduction system

3. Atrioventricular Blocks • Partial: All or some of sinus impulses are conducted to ventricle • First degree AV Block • Second degree AV Block • Complete: No sinus impulses are conducted to ventricles • Third degree AV Block • Effects depend on heart rate: May decrease cardiac output and BP

4. First degree AV Block • Partial block due to slowing of conduction at AV node • All impulses are conducted to ventricle • PR interval longer than 0.20 seconds • Usually well tolerated unless bradycardia develops • Usually not treated unless prophylactically • Observe for worsening of AV block

6. First Degree AV Block • Causes: medications (quinidine, digoxin), MI, Hyperkalemia, increased vagal tone • Characteristics: • PR prolonged • PR constant • 1:1 P:QRS • Rate is that of the underlying rhythm

7. Second Degree AV Blocks • Partial blocks: Not all impulses are conducted to ventricles • Mobitz, Type I: Wenckebach phenomenon - partial block at AV node • Mobitz, Type II: Partial block at bundle branches - more serious since block is lower in conduction system • Effects on client depend on number of nonconducted beats

8. Second degree AV Block, Type I • Progressively prolonged PR interval until QRS complex is dropped • More P waves than QRS complexes • Rhythm described in ratio of P waves to QRS complexes (e.g. 4:3, 5:4) • QRS duration may be normal or prolonged

11. Second Degree, Mobitz I • Characteristics • PR varies • PR progressively lengthens until a QRS is dropped • Regular atrial rhythm • Irregular ventricular rhythm • Usually transient and reversible but can progress to a higher degree of block

12. Treatment • Asymptomatic • Oxygen • Close observation • Symptomatic • Oxygen • Atropine 0.5-1 mg IV bolus • Transcutaneous pacing • Dopamine or epinephrine if hypotensive

13. Second degree AV BlockType II • PR interval is constant until QRS complex is dropped • There are more P waves than QRS complexes • Rhythm described in ratio of P waves to QRS complexes • QRS duration usually prolonged due to bundle branch block

14. Second degree, Mobitz II • Characteristics • PR constant • PR normal or prolonged • 2,3,4 (etc) P waves to each QRS • Regular atrial rhythm • Regular ventricular rhythm unless conduction ratios vary

15. Second Degree, Mobitz II

16. Treatment • Asymptomatic • Oxygen • Transcutaneous pacing • Symptomatic • Oxygen • Transcutaneous pacing • Dopamine or epinephrine if hypotensive

17. Second Degree 2:1 • 2:1 ratio (every other QRS is dropped)

18. Third degree AV Block • Complete block: No sinus conduction to ventricles • Atria and ventricles beat independently (AV dissociation) • Junctional or ventricular escape mechanism results • Atrial and ventricular rates different with atrial rate usually higher • P waves may be hidden by QRS

19. Third Degree AV Block • Both atrial and ventricular rhythms usually regular but not related • No identifiable pattern to PR intervals • QRS duration normal in junctional escape with rate 40 - 60 • QRS duration wide in ventricular escape with rate 20 - 40 • Most serious; potential life-threatening, can be temporary or permanent

25. Treatment for AV Blocks • Goal is to maintain HR • Administer O2 • Treat if hypotensive • Atropine 0.5 - 1 mg IV up to 2-3 mg if narrow complex QRS • Transcutaneous pacer as bridge • Transvenous pacemaker • Dopamine or epinephrine if hypotension persists after bradycardia is resolved • Unresolved, permanent pacemaker