Pathology Of Dysrhythmia Flashcards
Arrhythmia vs dysrhythmia
Mean the same thing
Both include the following terms
- Brady cardia
- tachycardia
- chaotic/sporadic depolarization of ventricles (ventricular fibrillation)
- no electrical activity at all (asystole)
Possible causes of general dysrhythmia
Ischemia
Hypoxia
Acidosis
Autonomic changes (more parasympathetic/sympathetic)
Electrolyte imbalances
Genetic defects in ion channels
Administration of drugs
Ectopic foci
A possible cause for abnormal automaticity to cause dysrhythmia.
Essentially means that myocytes depolarize in an improper fashion, causing depolarization in the wrong direction
- more problematic in the ventricles
Recently currents
Cells depolarize in an improper fashion, causing cells nearby to depolarize in a paracrine fashion.
Causes a cycle of improper depolarization
- usually marked by random ventricular depolarizations on ECG with non-associated atrial depolarizations
Sick sinus syndrome
Dysfunctional SA or AV (usually SA) node of the heart
- causes Brady or tachycardia
What happens if the SA node dies?
The AV node takes over, however it beats at a much slower rate and always results in bradycardia with lowered cardiac output.
Types of atrial dysrhythmia
Premature atrial contractions
Paroxysmal atrial tachycardia
Atrial flutter
Atrial fibrillation
- all lead to an increased risk for blood clotting due to pooling/immobile blood*
Fibrillation definition
Loss of synchrony
What is the most common form of dysrhythmia?
Ventricular premature beats
- leads to ventricular fibrillation
What happens to cardiac output in ventricular fibrillation?
Falls to zero since the ventricle cant beat hard enough to actually get the blood out and the preload from the atria is not high.
Long QT syndrome (LQTS or Torsades de pointes)
Type of ventricular tachycardia that possesses a long QT interval.
- is congenital and results in polymorphism of K+/NA+ channels (different makeups of the same channels)
also can be caused by hypokalemia/ quinidine (or other slowing myocardial drugs)
Shows elongated QT interval followed by ventricular tachycardia
- leads to v. Fib if not treated
Symptoms of LQTS
Syncope
Chest fluttering
Abnormal rhythms
can lead to sudden cardiac arrest and/or deafness
Heart blocks
Usually occurs via ischemia along the conduction pathways
- severity determines on position and length of heart block
- generally do not cause dysrhythmia but can lower C.O*
Primary AV block
PR interval is greater than 200ms
- no treatment required
2nd AV block (mobitz’s type 1)
Lengthening of the PR interval w/ occasional skipping of the QRS
- often asymptomatic
