Time for atrial depolarization and conduction of SA to AV node
What is normal sinus rhythm?
Normal electrical conduction
between 60-100 bpm
What is sinus bradycardia?
< 60 bpm
What is sinus tachycardia?
> 100 bpm
What is sinus arrest?
Occasional complete absence of P or QRS interval
What is a Premature Atrial Contraction (PAC)?
Ectopic focus in atrium initiates impulse before SA node
**Usually harmless. > 9 = get a physician!**
What is Atrial Flutter
Ectopic Focus (1) - takes over normal pacemaker of the heart
Very rapid atrial tach
F wave ("saw tooth pattern")
What is Atrial Fib?
Ectopic Foci (1+)
Atria depolarized 350-600x/min
What is a Premature Ventricular Contraction (PVC)?
Ectopic focus (1) - premature ventricular depolarization
Bigeminy: every 2
Trigeminy: every 3
Couplet: 2 in a row
Unifocal PVC: look the same - coming from same spot
Multifocal PVC: look different - coming from different spots
What is Ventricular Tach?
Ectopic Focus (1)
3 or more PVCs at rate of > 150 bpm
**EMERGENCY: longer than 30 seconds = life threatening**
Common cause: MI, Cardiomyopathy, and Valvular Disease
What is Ventricular Fibrillation (v-fib)?
Ectopic Foci (1+)
Chaotic activity in ventricles
**EMERGENCY: pt in cardiac arrest!**
What is a 1st Degree Heart Block?
Consistent long PR interval
Consistent beat to beat
What is a 2nd Degree Heart Block - Mobitz Type I or Wenkebach?
progressively longer PR interval until one impulse DROPS
What is a 2nd Degree Heart Block - Mobitz Type II?
Consecutive normal PR intervals and then DROPPED segment
**No PT. Treat with meds or pacemaker**
What is a 3rd Degree (Complete) Heart Block?
Complete block of impulse for SA node
Atria and ventricles depolarizing independently
What causes ST Segment Depression?
- Subendocardial ischemia
- Dig toxicity
- Hypo or hyperkalemia
What causes ST segment eleveation?
Acute transmural infarction
What causes a T wave inversion?
- Occurs hours or days after MI
- May occur with R or L bundle branch blocks
If a patient has a PVC during treatment, what is the first thing you should do?