L12 - ECG 2 Flashcards
What constitutes a normal sinus rhythm?
Regular rhythm
Initiated at SA node
P waves upright (in lead II) and present
QRS less than or equal to 3 small boxes (0.12 secs)
PR intervals 3-5 small boxes (0.12-0.2seconds)
Every p wave followed by a QRS complex
What is a common cause of heart block?
Acute mi/degenerative changes
Define a first degree heart block as per ECG
Prolonged PR interval (>0.2 seconds)
Describe the differences between mobitz type 1 and mobitz type 2 second degree heart block
Type 1. - successively longer PR intervals until loss of one QRS
Type 2 - PR intervals do not lengthen but sudden loss of QRS complex
In 3rd degree (‘complete’ heart block), a ventricular ‘escape’ rhythm takes over because the ventricles are depolarising independently. Describe this rhythm on an ECG
Slow (30-40bpm), wide QRS complexes, no congruency between p and QRS because both are depolarising independently
What is the range for a normal HR?
60-100bpm
Describe a characteristic ECG of a bundle branch block
Wide QRS, p wave and PR interval normal
What is a supraventricular rhythm?
Any rhythm which arises above the ventricles
How can you easily distinguish between a supraventricular and ventricular rhythm?
Narrow or wide QRS complexes
Describe an ECG of atrial fibrillation
No p waves, wavy baseline. Narrow QRS complexes with irregular R-R intervals
Heart rate and pulse irregular
Explanation - p waves are reaching AV node but not all are conducted because of AB refractory period
What condition is described by random wide QRS complexes followed by normal rhythm?
Ventricular ectopic beats
When do ventricular ectopic beats becomes ventricular tachycardia?
When there is a run of three or more consecutive ectopic
What does a ventricular fibrillation look like?
Complete loss of organisation. Rapid, irregular rhythm that can lead to cardiac arrest
In a blood test how would you distinguish between whether a patient has angina or has had an MI
Presence of cardiac troponins indicating muscle necrosis in MI
Which kind of MI is
a) the full thickness of the myocardium involved
b) the sub endocardium affected only
a) STEMI
b) NSTEMI
STEMIs are the result of a complete occlusion of coronary artery by a thrombus, ST elevation is the earliest sign, then Q wave gets deeper and T wave inverts. Which symptom of these three persists in patients post STEMI?
Deep Q wave
What ECG changes are seen in an NSTEMI and severe ischaemia (unstable angina) (look the same - differentiated by blood test)
ST depression and T wave inversion
In NSTEMI, the coronary vessel isn’t completely occluded so deep q waves don’t occur, what is the difference between stable and unstable angina?
Stable - ST depression seem during exercise but normal at rest
Describe an ECG of someone who is hyperkalaemic
Resting membrane potential is less negative
Tall peaked T wave (earliest sign)
Flattened p wave/ absent p waves depending on how severe
Prolonged PR interval, wide QRS
‘Sine wave pattern’ in severe
Describe a hypokalaemic ECG
Flat T wave
Low ST segment
High U wave (after t wave)
explain how you would calculate HR from a regular and irregular ECG differently
Regular - 300/number of big boxes in R-R interval
Irregular - 30 big boxes, number of R waves x 10
