Monitoring III Cardiac Rhythms

Question 1

Mean electrical vector tends to point towards…

Answer 1

areas of hypertrophy (more tissue undergoing depolarization)

Question 2

Mean electrical vector tends to point away from…

Answer 2

areas of myocardial infarction (vector has to move around these areas)

Question 3

What are causes of right axis deviation?

Answer 3

• COPD
• acute bronchospasm
• Cor pulmonale
• Pulmonary HTN
• PE

Question 4

What are causes of left axis deviation?

Answer 4

• Chronic HTN
• LBBB
• Aortic stenosis
• Aortic insufficiency
• Mitral regurg

Question 5

What are drugs to avoid in antidromic AVNRT (WPW)?

Answer 5

• avoid drugs that block conduction through the AV node
• adenosine
• digoxin
• CCB (diltiazem & verapamil)
• beta-blockers
• lidocaine
• amiodarone or cardioversion are safe for both orthodromic and antidromic AVNRT

Question 6

What is the treatment of Afib with WPW?

Answer 6

• procainamide is treatment of choice
• if hemodynamically stable, cardioversion is the best tx
• avoid drugs that increase the refractory period of the AV node

Question 7

What is the definitive treatment of WPW?

Answer 7

• ablation of the accessory pathway

Question 8

What causes torsades de pointes?

Answer 8

• long QT interval

Question 9

What is the treatment of torsades de pointes?

Answer 9

• its w/ long QT may require beta-blocker prophylaxis and/or ICD placement
• avoid SNS stimulation
• Acute tx includes reversing underlying cause and/or shorten the QT interval:
  - Mg sulfate
  - cardiac pacing