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
What are the ventricular arrhythmias?
- Premature ventricular complex (PVC)
- Ventricular tachycardia (v-tach)
- Ventricular fibrillation (v-fib)
- Ventricular asystole
What is seen on ECG for PVC’s?
- Absent P wave
- Wide QRS complex with aberrant shape
Common causes of PVCs
- Anxiety
- Caffeine
- Stress
- Smoking
- All forms of heart disease
ECG of v-tach
- Absent P wave
- QRS complexes wide and aberrant
V-tach longer than ____ is a life-threatening arrhythmia and requires immediate medical intervention
30 seconds
V-tac may degenerate into this
Ventricular fibrillation
Common causes of v-tach
- MI
- Cardiomyopathy
- valvular disease
V-fib results in
- No cardiac output
- patient becomes unconscious
V-fib
Clinical significance
lethal tachyarrhythmia, requires IMMEDIATE defibrillation
Common causes of v-fib
- any type of heart disease
- MI
- cocaine use
Clinical significance of ventricular asystole
requires immediate CPR and meds to stimulate cardiac activity
Common causes for ventricular asystole
- acute MI
- ventricular rupture
- cocaine use
- lightning strikes
- electrical shock
Signs of myocardial ischemia and infarction
- ST segment depression
- ST segment elevation
- Q wave
- T wave insertion
ST segment depression may be indicative of
- ischemia
- digitalis toxicity
- hypokalemia
Earliest sign of acute transmural infarction
Can also indicate a benign early repolarization pattern in a normal heart
ST segment elevation
A characteristic marker of infarction. Signifies the loss of positive electrical voltages due to necrosis
Q wave
Occurs hours or days after an MI as the result of a delay in repolarization produced by the injury
T wave inversion
ECG strip: determine heart rate
For regular rhythm
Divide 300 by number of large squares between two consecutive p waves
Includes fractions of squares
ECG strip: determine heart rate
For irregular rhythm
Count number of QRS complexes in a 6 second strip
Multiply by 10
How to evaluate rhythm
Compare R to R intervals
Evaluating rhythm: regular
R to R intervals are within 0.04 seconds
Evaluating rhythm: irregular
Should ask…
Is there a pattern or is it totally irregular?
Normal PR interval
0.12 to 0.20 seconds
ECG: purpose of looking at QRS complexes
Determine if conduction is normal through the ventricles
Normal QRS width
0.04-0.10 seconds in all leads
Assess ST segment where?
0.08 seconds after J point
