Conducting system Flashcards
Conducting system
SA node — AV node – Bundle of His – right & left bundle branches – Purkinje fibers
Specialized cardiac muscle cells for conduction
both ventricular muscles contract
at the same time
action potential travels down right & left bundle branched to purkinje fibers causing
muscles to contract
Heart has ______ rythmicty
Inherent
-it continues to beat indefinitely with proper input
If SA node stops pacing other part of heart can take over pacing can be
Problematic
pacing by other part of heart than SA node can be problematic because
may create dual pacers
may not be synchronized
fire before threshold met
may not extinguish signal before new one coming
Normal SA rythm
approximately 70 bpm
Bradycardia
less than approximately 60 bpm
Tachycardia
more than approximately 100 bpm
Arrhythmia (dysrythmias
- abnormal pulse generation or conduction
- abnormal HR & or rythm
- alter cardiac cycle (filling/emptying)
- ——CO & perfusion affected
- several types
arrythmia’s alter
cadiac cycle (filling/emptying) which then affects Cardiac output and perfusion
Types of arrythmia’s
- atrial flutter
- atrial fibrillation
- heartblock
- Ventricular fibrillation
Etiology of arrythmias
- congenital heart defects
- myocardial ischemia
- MI
- stimulant drugs (pharmaceutical & recreational)
- fluid-electrolyte imbalance (k+)
Atrial flutter
- fairly regular
- accelerated rate of contraction (not enough time to fill and pump
- regular atrial tachycardia (approx 300 bpm)
- aprox 150 bpm in ventricles
- 2:1 (A:V)
with atrial flutter there is accelerated rate of _______ which then causes
contraction
not enough time to fill and pump
