Pathophysiology of common arrythmias Flashcards
What is significant about the sinus node cells
Can spontaneously depolarise
What is the role of the AV node
delays conduction from the atria to ventricles
Features of an ECG
P PR interval QRS T QT interval
Why are cardiac arrhythmias brought about
abnormal a.p. mitiation
abnormal conductor
What are the extrinsic causes of bradycardia
normal SA node
hypothermia
Hypothyroidism
Drugs
Neurally mediated- carotid sinus syndrome + increased vagal tone
Intrinsic causes of bradycardia
Abnormal SA node
ischaemia/infarction
degeneration/fibrosis
What is first degree AV block
Prolonged PR interval >.0.2
What is second degree AV block
type 1 - 6 P waves only 5 QRS complexes ( always 1 less)
type 2- 2:1 ratio
What is third degree AV block
Complete heart block
no mathematical relationship
What is bundle branch block
QRS complex >0.10s
Symptoms of bradycardia
resulting from hypotension and decrease in cerebral blood flow
diziness
syncope
stokes-adams attacks
Management of bradycardia
Identify and treat extrinsic causes - sinus bradycardia
temp/perm pacemaker
What defines tachycardia
> 100 bpm
What are the stages of tachycardia
- accelerated automatically - increases the rate of depolarisation
- Triggered activity - after depolarisation
- re-entry
- number of pathways
- anterograde - conduction in one limb blocked
- retrograde- conduction maintained
What happens at sinus tachycardia
Normal P waves
What happens at supratrianlar tachycardia
p waves may be absent and palpitations and dizziness
What are features of AF
decrease in cardiac output
inadequate ventricular filling
stasis of blood - risk of thromboembolism
What is the atrial flutter
some organised activity
similar treatment to AF
What is ventricular tachyarrythmias
Includes ventricular fibrilation
originate in ventricular tissue life threatening
What is ventricular tachycardia and what can it lead to
Abnormal broad complexes
can degenerate to ventricular failure
Treatment for ventricular tachycardia
Antiarrhythmic drugs
DC cardioverision
What are examples of antiarrhythmic drugs
?
What are signs of ischaemia on an ECG
ST segment elevation
ST depression
T wave inversion
