Electrocardiogram & rhythm disorders Flashcards by rachael a

why is ECG used?

cheap
easy to undertake
reproducible
quick turnaround on results/reporting

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what is ECG used to view/diagnose?

conduction abnormalities
structural abnormalities
perfusion abnormalities

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what are ECG electrodes?

sticky pads placed on body

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what are ECG cables/wires?

cables with coloured ends attached to machine and body

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what are ECG leads?

heart perspectives based on where the electrodes are placed

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what do the characteristics of deflections on the leads mean?

width of deflection - duration of event
steepness of line - velocity of action potential
downward deflection - towards -ve electrode
upward deflection - towards +ve electrode

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what are the normal deflections on an ECG?

P wave - small upwards
QRS complex - tiny down large up tiny down
T wave - small but long upwards

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what does the P wave of an ECG tell you?

conduction of sinoatrial node and atrial depolarisation

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what does the pause between P and Q on an ECG represent?

atrioventricular node depolarisation

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what is represented by the isoelectric line just before Q on an ECG?

rapid conduction down bundle of His

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what is represented by the Q complex on an ECG?

bundle branches depolarisation/septal depolarisation

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what is represented by the R wave of an ECG?

apex of heart purkinje fibre depolarisation

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what is represented by the S wave of an ECG?

purkinje fibres depolarising up the side of the myocardium

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what is represented by the isoelectric line between S and T waves on an ECG?

fully depolarised ventricles

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what represents the T wave on an ECG?

ventricular repolarisation

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what is the electrode placement for an ECG?

V1 - right sternal border of 4 IC space
V2 - left sternal border of 4 IC space
V3 - midway between V2/4
V4 - mid clavicular line of 5 IC space
V5 -  midway between V4/6
V6 - mid axillary line of 5 IC space
electrodes on both limbs on both sides

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what lead goes between right and left arm?

rule of Ls - lead I

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what lead goes between right arm and left leg?

rule of Ls - lead II

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what lead goes between left arm and left leg?

rule of Ls - lead III

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how do you read ECG findings?

rate&rhythm
P wave/P-R interval
QRS duration
QRS axis
ST segment
QT interval
T wave

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what is sinus rhythm on an ECG?

each P wave followed by QRS
normal and regular rate
otherwise unremarkable

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what is sinus bradycardia on an ECG?

each P wave followed by QRS
rate is regular and slow
healthy, caused by medication or vagal stimulation

what is sinus tachycardia on an ECG?

each P wave followed by QRS
rate is regular and fast
often due to physiological response

what is sinus arrythmia?

each P wave followed by QRS
rate is irregular and normal
R-R varies with breathing cycle

what is atrial fibrillation on an ECG?

oscillating baseline - atria contracting asynchronously | rhythm may be irregular and rate slow

what is atrial flutter on an ECG?

regular saw tooth pattern in baseline (II,III,aVF) not always in all leads atrial to ventricular beats at a 2:1 ratio, 3:1 ratio or higher

what is first degree heart block on an ECG?

prolonged P-R interval/segment regular rhythm and rate P waves followed by QRS complexes

what is second degree heart block mobitz I on an ECG?

gradual prolongation of PR interval until a beat skips some P waves not followed by QRS regularly irregular rhythm

what is second degree heart block mobitz II on an ECG?

regular P waves, only some are followed by QRS no P-R prolongation regularly irregular

what is third degree (complete) heart block on an ECG?

P waves regular, QRS regular but no relationship to each other P waves can be hidden by other, larger vectors non-sinus rhythm

what is ventricular tachycardia on an ECG?

P waves hidden rate is regular and fast no isoelectric line but shockable rhythm

what is ventricular fibrillation on an ECG?

rate irregular and 250bpm+ | shockable rhythm

what heart rhythms are shockable?

ventricular tachycardia | ventricular fibrillation

what is ST elevation on an ECG?

P waves visible followed by QRS regular rate and rhythm ST segment depressed >2mm below isoelectric line in leads related to obstructed vessel myocardial infarction

what is ST depression on an ECG?

regular rate rhythm ST segment depressed 2mm below isoelectric line myocardial ischaemia - not infarction

what does a saw tooth pattern in II, III and aVF indicate?

atrial flutter

what does a gradual prolonging of PR interval until a beat dropped indicate?

2nd degree heart block Mobitz I

what does a prolonged PR interval with some dropped QRS indicate?

2nd degree heart block mobitz II

what does an ECG with no isoelectric baseline, no P waves indicate? massive waves with small wave on top

ventricular tachycardia

how to read cardiac axis

lead I and aVF

what is right axis deviation

lead I negative lead aVF positive +90°- +180° right reaching

what is left axis deviation

lead I positive lead aVF negative −30° - −90° left leaving

what is normal cardiac axis

lead I positive | aVF positive

when may left axis deviation be normal

tall thin people | due to lungs rotating heart straighter

when may right axis deviation be normal

short wide people | due to more space in the mediastinum

what may be a cause of left axis deviation

left ventricular hypertophy - more working cardiac muscle to have electrical activity myocardial infarction in right side - muscle dies so less activity on that side, shifts left

what is a long PR interval

bigger than 1 big square

investigations for suspected blocked coronary artery

coronary angiogram

treatment for coronary artery blockage

CABG - coronary artery bypass graft (harvest another vessel and pop it on) PCI - percutaneous coronary intervention (basically a stent)

what does a STEMI/NSTEMI in lead II, III and aVF indicate

inferior ischaemia/infarction | right coronary artery involvement

what does a STEMI/NSTEMI of lead I, aVL and V5,V6 indicate

lateral ischaemia/infarction | left circumflex artery

what does a STEMI/NSTEMI in V1 2 indicate

septal ischaemia/infarction | left anterior descending artery

what does a STEMI in V3, V4 indicate

damage to anterior heart | left anterior descending artery blockage

How to calculate rate if ecg is irregular rhythm

Rhythm strip QRS complexes x 6