PT Tests And Measures 4 Flashcards
Normal PR interval
0.20 seconds
Normal QRS interval
- 20 to 0.40 seconds
* depends on HR
What are the atrial dysrhythmias?
- Premature atrial contractions (PAC)
- Atrial flutter
- Atrial fibrillation
Indication of PAC
Premature P wave with abnormal configuration
PAC clinical significance
- Very common, generally benign
- May progress to atrial flutter, tachycardia, or fibrillation
PAC: may happen in normal heart with:
- Caffeine
- Stress
- Smoking
- Alcohol
Atrial flutter = atrial rate of
250-350 bpm
Atrial flutter is commonly seen with:
- Valvular disease (esp mitral)
- Cardiomyopathy
- HTN
- Acute MI
- COPD
- Pulmonary emboli
S/s atrial flutter
- Palpitations
- Lightheadedness
- Angina due to rapid rate
What are the AV conduction blocks?
- 1st degree AV block
- 2nd degree AV block
- 3rd degree AV block (complete heart block)
This type of conduction block is considered a medical emergency and requires a pacemaker
3rd degree AV block
Types of 2nd degree AV blocks
Mobitz I (Wenckebach block) Mobitz II
Mobitz I block
Progressive prolongation of PR interval until one impulse is not conducted
Generally benign
Mobitz II block
Consecutive PR intervals are the same and normal followed by nonconduction of one or more impulses
May progress to 3rd degree block
With 3rd degree AV block, what happens to atria and ventricles?
Atria and ventricles paced independently
Atrial rate greater than ventricular rate
3rd degree AV block: ventricular rate too slow
Leads to drop in cardiac output and pt may faint
3rd degree AV block: common causes
- Degenerative changes of conduction systems
- Digitalis
- Heart surgery
- Acute MI