13. Rhythm and Arrhythmias Flashcards
What is sinus rhythm?
Normal HR
60-100bpm
What is sinus tachycardia?
Activation of sympathetics
Exercise, baroreflex
What is sinus bradycardia?
Low heart rate
Athletes
What is sinus arrhythmia caused by?
Deep breathing
What are ectopic beats?
Premature contractions due to abnormal impulses from outside pacemaker
Causes of ectopic beats
Ischaemia
Excessively stretched fibres
Drug actions
What are premature atrial contractions?
Common in healthy people
Pulse is weak on that beat
Atria hasn’t filled enough yet so there is a decreased stroke volume
What are AV node premature contractions?
AV depolarisation goes to atria and ventricles
Both contract at the same time
P wave is lost in QRS
What is the cause of a prolonged QRS complex?
Impulse was conducted slowly rather than through the fast purkinje system
What is the cause of an increased QRS?
One side depolarises before the other
Depolarisation occurs over a longer time period
What is the cause of an inverted T wave?
Current flow goes from apex to base instead of usual base to apex
What allows atrial tachycardias to spread to the ventricles?
Anomalous pathways between atria and ventricles
What is paroxysmal tachycardia?
Bursts of tachycardia
Long pathway or slow conduction causes one impulse to keep travelling around
