Flashcards in ECG Interpretation Deck (31):
Placement of the 6 chest electrodes?
V1, V2 4th ICS R/L SE
V4 5th ICS MCL
V3 between V2&V4
V6 5th ICS MAL
V5 between V6&V4
Placement of the 4 limb electrodes?
What do each of the main components of the ECG represent?
P wave: atrial depolarisation
QRS: ventricular depolarisation
T wave: ventricular repolarisation
How many seconds are in a small square?
How many seconds are in a large square?
0.2 (5 small squares)
How many squares make up a second?
5 large squares
How many squares make up a minute?
What does the PR interval represent and what is normal range?
Start of P wave to start of QRS
Depolarisation of atria with AVN delay
0.12 - 0.2sec (3-5 small squares)
What is depolarisation?
Wave of positive charge
What is a segment on the ECG and main examples?
Region between two waves
PR segment - end of P wave to start of QRS (depolarisation of AVN)
ST segment - end of QRS to start of T wave (all of ventricular myocardium depolarised)
What is an interval on an ECG and main examples?
A duration of time that includes a segment and one or more waves
PR interval - start of P wave to start of QRS
QT interval - start of QRS to end of T wave
RR interval - R wave to R wave
What does QT interval indicate?
Ventricular systole (ventricular depolarisation through to ventricular repolarisation)
What are each of the QRS waves?
Q wave - septal depolarisation
R wave - major muscle depolarisation
S wave - basal depolarisation (base up by ventricles)
When does ventricular diastole start?
When the T wave ends
What is normal time of QRS?
<0.12secs (3 small squares)
Step 1 of ECG interpretation?
Details - (patient, date/time, calibration speed 25mm/s)
STATE IF ELECTRICAL ACTIVITY IS PRESENT
Step 2 of ECG interpretation?
Rate - Use paper trick:
This rhythm is regular at (300/r-r large squares) bpm
This rhythm is irregular at approx (QRS's x6) bpm
STATE IF BRADY OR TACHY
Step 3 of ECG interpretation?
P waves not present: AF, Atrial flutter (saw tooth baseline)
P waves present, every one followed by QRS every QRS preceded by P wave: Sinus rhythm
P waves present but not always followed by QRS: HB
P waves present but not every QRS preceded by one: HB
Types of heart block?
Type 1: PR >0.2 (5 small squares) no lengthening (Conduction problems between SAN and AVN)
Type 2: M1: PR progressively lengthening then dropped QRS. (Conduction problem in AVN itself, can't keep up with SAN and sometimes drops a beat) M2: PR constant at >0.2 but randomly dropped QRS (Conduction problem in bundle of HIS dropping a beat with no warning)
Type 3: No relationship between P waves and QRS (Complete HB with no relationship between ventricles and atria, rhythm maintained at ventricular rate)
BBB: L and R (Conduction problem within the L or R bundles)
Management of T1 and M1 HB?
Monitoring, can be normal
Stop offending drugs (BB, CCB)
If severe symptoms such as dizziness, syncope, slow heart rate then pacemaker
Treatment of M2 and T3 HB?
Need intervention with pacing
How to identify BBB?
V1 and V6
LBBB: rS, R
RBBB: rSR, qRs
Step 4 of ECG interpretation?
Mean axis - I, aVF
both positive: normal
I+, aVF- RAD (RVH)
I-, aVF+ LAD (Heart conduction defects)
Step 5 of ECG interpretation?
PR interval -
>0.2 (5 small squares) HB
<0.12 (3 small squares) Electrical impulse is travelling quicker to the AVN (Normal - some SAN closer in distance) (Accessory pathway e.g WPW)
What is WPW and the main risk of it?
Congenital accessory pathway between the atria and ventricles called bundle of Kent
Depolarisation doesn't have to pass through the AVN so can allow the ventricular rate to get very high
What is the main ECG finding in WPW?
Delta wave (QRS with kink)
Management of WPW?
Ablation of accessory pathway
Step 6 of ECG interpretation?
<0.12 (3 small squares): narrow/normal
>0.12: broad (abnormal depolarisation - BBB, ventricular ectopic)
<5mm in LL/<10mm in CL: small
>5mm in LL/>10mm in CL: tall (ventricular hypertrophy)
Abnormal waves: Delta wave (WPW), Pathological Q wave (>25% of R wave)(previous MI)
Step 7 of ECG interpretation?
ST segment - elevated, depressed
When to consider pericarditis on an ECG?
Wide spread STE in a young patient with accompanied PR depression