ECG Interpretation Flashcards
What are the two atrioventricular valves in the heart?
Mitral and tricuspid valves = open with ventricular diastole, close with ventricular systole
What are the two semilunar valves in the heart?
Aortic and pulmonary valves = open with ventricular systole, close with ventricular diastole
Where do the left and right coronary arteries originate?
From the coronary ostia = openings at the base of the aorta behind the aortic valve leaflets
When does passive filling of the ventricles take place?
During diastole = fill to 70% capacity
What is the normal range for stroke volume?
60-130ml
What is preload?
Volume and stretch of ventricular myocardium at the end of diastole
What is afterload?
Amount of pressure against which the left ventricle must work during systole to open the aortic valve
Where is the brown lead placed?
Lower sternum in the 5th intercostal space
Where is the red lead placed?
Left mid-axillary line in the 5th intercostal space
Where is the black lead placed?
Upper sternum just below the sternal angle
Where is the white lead placed?
Right mid-axillary line in 5th intercostal space
Where is the green lead placed?
Anywhere
How much time does a small square represent on an ECG?
0.04 seconds
How much time does a large square on an ECG represent?
0.2 seconds
What are some features of the U wave?
Usually not visible
Smaller than the T wave when present
May indicate hypovolaemia
What are some reasons for interference during an ECG?
Patient movement, loose or defective electrode, improper grounding, faulty ECG apparatus
Where do all sinus rhythms originate from?
The SA node
What are the variants of sinus rhythm?
Normal sinus rhythm Sinus bradycardia Sinus tachycardia Sinus arrhythmia Sinus pause
What are some examples of circumstances where sinus bradycardia may occur?
In athletes, during sleep or in response to a vagal manoeuvre
What can sinus tachycardia precipitate?
Myocardial ischaemia or infarct
How does respiration impact sinus arrhythmias?
Rate increase with inspiration and decreases with expiration
What is a sinus pause?
Transient absence of P waves that lasts anywhere from 2s to several minutes
What can be used to treat a sinus pause?
Atropine or a pacemaker
Where do impulses originate from to cause atrial rhythms?
Atrial tissues or internodal pathways
What age group is most at risk of developing atrial flutter?
Age > 60
What is the first line treatment for atrial flutter?
Cardioversion
What are the atrial rhythms?
Atrial flutter, atrial fibrillation, supraventricular tachycardia, premature atrial contraction
What is the most common arrhythmia?
Atrial fibrillation
What drugs can be used to control rate in atrial fibrillation?
Digoxin, beta blockers, verapamil
What does the term supraventricular tachycardia encompass?
All tachycardias where heart rate is > 150 bpm
How is a supraventricular tachycardia treated?
Vagal manoeuvres or adenosine
What is a premature atrial contraction?
Not a rhythm but an ectopic beat = may need beta blocker or calcium channel blocker
How can you spot a ventricular rhythm on an ECG?
Absence of P waves and wide QRS complexes
What is the most common ventricular rhythm?
Premature ventricular contractions
What are the lethal ventricular rhythms?
Idioventricular rhythm Accelerated idioventricular rhythm Ventricular tachycardia Ventricular fibrillation Torsades de pointes Pulseless electrical activity Agonal rhythm Asystole
What are the different patterns of premature ventricular contractions?
Ventricular bigeminy = occur every other beat Ventricular trigeminy Ventricular quadrigeminy Couplets Runs of ventricular tachycardia
What is the treatment of choice for premature ventricular contractions?
Lidocaine
What is the rate of an agonal rhythm?
< 20 bpm
What is the most common cause of pulseless electrical activity?
Hypovolaemia
