ECG L

Left atrial enlargement
Burns E. Left Atrial Enlargement (April 16, 2017). Retrieved from
https://lifeinthefastlane.com/ecg-library/basics/left-atrial-enlargement/

Left atrial enlargement (LAE) is due to
pressure or volume overload of the
left atrium.
It is often a precursor to atrial
fibrillation!!!
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ECG features
DII
Bifid P wave with
>40 ms between the
two peaks!
Total P wave
duration >110 ms!
V1
Biphasic P wave with
terminal negative
portion >40 ms
duration!
Biphasic P wave with
terminal negative
portion >1 mm deep!

ECG features
DII V1
Bifid P wave with duration of 120 ms
and more than 40 ms between two peaks!
Biphasic P wave with negative portion
>40 ms duration (or >1 mm deep)!

Causes
Mitral stenosis
Systemic
hypertension
Aortic stenosis
Mitral
incompetence
Hypertrophic
cardiomyopathy

Left Anterior Fascicular Block
Burns E. Left Anterior Fascicular Block (April 16, 2017). Retrieved from
https://lifeinthefastlane.com/ecg-library/basics/left-anterior-fascicular-block/

LAFB

ECG features

LAFB
Left axis deviation!
qR in DI
rS in DII
rS in DIII
qR in aVL
rS in aVF

Left Bundle Branch Block
Burns E. Left Bundle Branch Block (April 16, 2017). Retrieved from
https://lifeinthefastlane.com/ecg-library/basics/left-bundle-branch-block/

LBBB
•In LBBB, the normal direction of
septal depolarisation is reversed
(becomes right to left), as the
impulse spreads first to the right
ventricle via the right bundle
branch and then to the left ventricle
via the septum.

ECG criteria
QRS duration of >120 ms.
Dominant S wave in V1.
Broad monophasic R wave in lateral leads (DI, aVL, V5-V6).
Absence of Q waves in lateral leads (DI, V5-V6).
Prolonged R wave peak time >60 ms in left precordial leads (V5-V6).

ECG criteria
• Appropriate discordance: the ST segments
and T waves always go in the opposite
direction to the main vector of the QRS
complex.
• Poor R wave progression in the chest leads
and left axis deviation.
rS
ST elevation and upright T wave

QRS morphology
The R wave in the lateral leads may be either:
•M-shaped
•Notched
•Monophasic
•RS complex

Causes

LMCA occlusion
Burns E. ST Elevation in aVR-LMCA occlusion (April 3, 2017).
Retrieved from https://lifeinthefastlane.com/ecg-library/lmca/

LMCA occlusion
Widespread horizontal ST depression,
most prominent in leads DI, DII and V4-V6!
ST elevation in aVR ≥1mm!
ST elevation in aVR ≥V1!

ST-elevation in aVR may also be seen with:
proximal left anterior descending artery
(LAD) occlusion
severe triple-vessel disease (3VD)
diffuse subendocardial ischaemia

ECG example
ST-elevation in aVR>V1

Left Posterior Fascicular Block (LPFB)
Burns E. Left Posterior Fascicular Block (April 16, 2017). Retrieved from
https://lifeinthefastlane.com/ecg-library/basics/left-posterior-fascicular-block/

LPFB
•In left posterior fascicular block (aka left
posterior hemiblock), impulses are
conducted to the left ventricle via the left
anterior fascicle, which inserts into the
upper, lateral wall of the left ventricle
along its endocardial surface.

ECG features
Right axis deviation (> +90 degrees)
Small R waves with deep S waves (rS complexes) in leads DI and aVL
Small Q waves with tall R waves (qR complexes) in leads DII, DIII and aVF
QRS duration normal or slightly prolonged (80-110ms)
Prolonged R wave peak time in aVF
Increased QRS voltage in the limb leads
No evidence of right ventricular hypertrophy
No evidence of any other cause for right axis deviation

LPHB
rS
rSqR
qR qR
Right axis deviation

Left ventricular aneurysm
Burns E. Left Ventricular Aneursym (April 3, 2017). Retrieved from
https://lifeinthefastlane.com/ecg-library/left-ventricular-aneursym/

ECG features
ST elevation seen after 2 weeks following an acute
myocardial infarction:
• most commonly seen in the precordial leads
• may exhibit concave or convex morphology
• usually associated with well-formed Q or QS
waves
• T-waves have a relatively small amplitude in
comparison to the QRS complex (unlike the
hyperacute T-waves of acute STEMI)

ECG features
Persistent ST elevation
qS waves
T-waves have smaller
amplitude than QRS complexes

Left ventricular hypertrophy
Burns E. Left Ventricular Hypertrophy (March 18, 2017). Retrieved from
https://lifeinthefastlane.com/ecg-library/basics/left-ventricular-hypertrophy/

ECG features
The most commonly used
are the Sokolov-
Lyon criteria: S wave depth
in V1 + tallest R wave
height in V5-V6 >35 mm.

ECG features
R wave in lead DI + S wave in
lead DIII >25 mm
R wave in aVL >11 mm
R wave in aVF >20 mm
S wave in aVR >14 mm
R wave in V4, V5
or V6 >26 mm
R wave in V5 or V6
plus S wave in V1
>35 mm
Largest R wave
plus largest S wave
in precordial leads
>45 mm

ECG features
Left axis deviation
ST elevation in the right precordial leads
V1-V3 (discordant to the deep S waves)
Prominent U waves (proportional to
increased QRS amplitude)

Lown-Ganong-Levine (LGL) Syndrome
Lifeinthefastlane.com

LGL
•Accessory pathway composed
of James fibres.
•ECG features are:
•PR interval <120ms
•Normal QRS morphology
•No delta wave

LOW QRS VOLTAGE

Low QRS voltage
•The amplitudes of all the QRS complexes
in the limb leads are <5 mm.
•The amplitudes of all the QRS complexes
in the precordial leads are <10 mm.

ECG L

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