Unit 2: Heart Blocks

Question 1

Heart Blocks

Answer 1

> First Degree AV Block
Second Degree AV Block Type I
Second Degree AV Block Type II
Third-Degree AV Block

Question 2

First-Degree AV Block

Answer 2

-similar to NSR
-PR interval is prolonged (> 0.2 or 5 blocks long)
-d/t atrial depolarization being delayed in AV node
TX: not required unless symptomatic

Question 3

Second Degree AV Block Type I

Answer 3

(Wenckebach or Mobitz I)
-occurs when not all atrial impulses get through the AV node to the ventricles
-more P waves than QRS complexes
-PR interval gets progressively longer until a QRS complex is dropped (Dropping QRS)
>”longer, longer, longer, dropped; then you have a Wenckebach”
-not life-threatening
>TX: only if symptomatic (dizziness, lightheadedness, SOB)
-tx = atropine 0.5 mg IVP to stimulate the heart to beat faster

Question 4

Second Degree AV Block Type II

Answer 4

(Mobitz II)
-drops QRS complexes
-unlike type I, PR intervals are exactly the same length with each complex
-more life-threatening b/c it can turn into Third-degree Heart block
>Tx: dependent on symptoms
-if symptomatic, temporary pacing is treatment of choice; Transcutaneous Pacing (TCP) is fastest option

Question 5

Third Degree AV Block

Answer 5

“complete heart block (CHB)”

• occurs when the AV node is completely blocked and prevents any impulses from entering or exiting
• requires pacing if unable to treat cause
• QRS complexes march out regularly and independent of P waves
• P waves march throughout strip at a regular rate
• TX: treating symptoms (hypotension or SOB)
• attempts are made to reverse cause if possible
• Transcutaneous pacing if symptomatic CHB
• long-term tx is insertion of permanent pacemaker