Pharmacology: dysrhythmias Flashcards
What are 2 ways of categorising dysrhythmias?
- Site of abnormality
- Whether the heart is beating faster or slower
Differentiate (in terms of beats/minute)
- Tachycardia
- Flutter
- Fibrillation
Tachycardia: 100-150 beats/minute
Flutter: 150-300 beats/minute
Fibrillation: >350 beats/minute
Atrial fibrillation: is it irregular?
Supraventricular tachycardia: which part of heart does it affect? Is it regular?
Ventricular tachycardia: is it common?
Yes
Atria, yes
No
How is AF a risk factor for stroke?
Blood can pool and clot in the atria, and then get dislodged in brain vessels
What are the 2 main mechanisms of cardiac dysrhythmia?
Abnormal impulse generation
Abnormal impulse conduction/repolarisation
2 main types of abnormal impulse generation?
Altered normal automaticity
Premature (ectopic) beats
Are ectopic beats benign?
Yes
Label the following
3 types of abnormal impulse conduction/repolarisation?
Conduction (heart) block
Re-entry circuits
After depolarisations
What are 1st, 2nd, and 3rd AV blocks?
Re entry circuits
- How can ischemia impact how impulses travel from SA to AV node?
After depolarisation
- What effect do they have on HR?
Delay HR
Early after depolarisation
- What causes it?
- What do we see on ECG?
Decreased K+ outflow
QT prolongation, torsades de pointes (twisting of peaks)
Late after depolarisation
- What causes it?
- What drugs can contribute to it?
Ca2+ overload
Cardiac glycosides, catecholamines
Can the following factors cause or exacerbate dysrhythmias?
* Ischemia, MI
* Cardiac surgery
* Electrolyte disturbances
* Hypoxia
* Valvular disease
* Catecholamines
Some drugs
Yes
