Causes and Types of dysrhythmias Flashcards
what is a dysrhythmia?
Any of a group of conditions in which the electrical activity of the heart is irregular or is consistently faster or slower than normal
What causes dysrhythmias
- altered impulse formation
- altered impulse conduction
Describe what altered impulse formation can lead to
- Tachyarrhythmias
- Increased automaticity of SAN
- Increased automaticity of latent pacemakers
- Abnormal automaticity
- Triggered activity - Bradyarrhythmias
- decreased automaticity of SAN
Describe what altered impulse conduction can lead to
- Tachyarrhythmias
- unidirectional block and re-entry - Bradyarrhythmias
- conduction block
what can altered automaticity lead to
- Sick sinus syndrome- automaticity in the SAN can be both faster or slower than normal
- Thyrotoxicosis
- infection
- anaemia
- drug therapy
What is an ectopic beat
Usually nothing to worry about
- increased automaticity of a latent pacemaker
What are the causes of ectopic beats
- exercise, stress, pregnancy, menopause and ageing
- fluctuations in K+ and Mg levels in blood
- intake of caffeine, alcohol, recreational drugs or some prescribed medications (decongestants, asthma)
- conditions affecting heart muscle, including prior MI and heart failure
How does abnormal automaticity occur
these cells don’t normally have pacemaker activity
- damage (eg. following MI) causes these cells to spontaneously depolarise
what is triggered activity
abnormal action potentials which can be either early or late afterdepolarisations
What is a conduction block
the electrical signal that controls the heartbeat is partially or completely blocked from reaching the ventricles
What is heart block classified as
Classified as type 1, 2 or 3 with 3 being most serious
What can heart block be caused by
can be caused by damage to AV node or drug therapy
