ECG LP 03

Question 1

ATRIAL ENLARGEMENT

Answer 1

Can be caused by:
 volume overload (e.g. mitral/tricuspid valve insufficiency)
pressure overload (e.g. mitral/tricuspid valve stenosis)

Question 2

RIGHT ATRIAL ENLARGEMEN

Answer 2

Etiology: stenosis/ insufficiency of the tricuspid valve; atrial septal defect; RV failure.
Atrial depolarization: the RA has a larger mass, determines a larger depolarization vector, and the resultant atrial vector is moved downwards (verticalized) or even towards right.
The depolarization time of RA is increased, but usually it doesn’t increase the total atrial depolarization time (because the left atrium starts to activate later).

Question 3

RIGHT ATRIAL ENLARGEM (II)

Answer 3

On ECG: normal duration of P wave.
In frontal plane:
Tall P wave in inferior leads (LII, aVF, LIII), with amplitude > 2.5 mm in at least one of these 3 leads; this aspect = “P pulmonale”
P wave axis is deviated downward (around +90°).

In horizontal plane:
In V1 and/or V2 the first component of the P wave, the positive one, is taller;
it is significant for diagnosis is P wave is taller than 2 mm in V1 or V2.

Question 4

LEFT ATRIAL ENLARGEMEN

Answer 4

Etiology: stenosis (e.g. post-rheumatic), regurgitation of the mitral valve; LV failure.
Atrial depolarization:
Normal RA depolarization.
LAE generates a larger vector => the global depolarization vector is more horizontal
than normal (the electrical axis of atrial depolarization is deviated towards left); also it needs more time for depolarization and because the LA begins its depolarization after the RA and this determines a longer global atrial depolarization time.

Question 5

LEFT ATRIAL ENLARGEMENT (II)

Answer 5

On ECG: A longer duration of P wave: P wave ≥ 0.12’’
In frontal plane:
P wave is positive and bifid in LI, aVL, LII. This aspect and the P wave duration ≥ 0.12’’ = “P mitrale”
P wave axis is oriented towards 0°.
In horizontal plane:
In V1 and/or V2 the second part of the biphasic P wave, the negative one, is larger than the first positive one; it is significant for diagnosis if the negative phase of the P wave has a duration ≥ 0.04’’ and amplitude > 1mm.
In V5 and V6 it is a similar aspect with LI.

Question 6

VENTRICULAR ENLARGEMEN

Answer 6

Can be caused by:
pressure overloads (e.g. aortic stenosis);
volume overloads - usually dilations occurs (e.g. aortic regurgitation).
primary/secondary cardiomyopathies associated either with hypertrophy, either with dilation.

Question 7

RIGHT VENTRICULAR ENLARGEMENT (RIGHT VENTRICULAR HYPERTROPHY = RVH )

Answer 7

Etiology: pulmonary hypertension primary/secondary (e.g. long-standing mitral stenosis with narrow orifice); tricuspid regurgitation, stenosis of pulmonary artery;
congenital heart defects; cardiomyopathies.

Ventricular depolarization: larger RV vectors that counterbalance the left normal ones; usually the enlarged mass of RV is still smaller than the normal mass of left ventricle, so although the depolarization time for RV is longer, the total ventricular
depolarization time is normal, therefore QRS duration is normal.

Ventricular repolarization can be affected secondary to depolarization disturbances: secondary ST-T changes.

Question 8

RIGHT VENTRICULAR HYPERTROPHY = RVH

Answer 8

Voltage criteria (can be present 1 criterion or more):

In frontal plane:
White-Block index = (RI + SIII) – (SI + RIII) < - 14 mm

Horizontal plane: 
R in V1 > 7 mm
S in V5 > 7 mm
R in V1 + S in V5 or V6 > 11 mm (Sokolow-Lyon index)
R/S ratio > 1 in V1 and/or V2
R/S ratio < 1 in V5 and/or V6

Question 9

RIGHT VENTRICULAR HYPERTROPHY = RVH (II)

Answer 9

 Other criteria: if there are present, they are additional criteria for diagnosis; but their absence doesn’t exclude the RVH diagnosis based on voltage criteria!
Right QRS electrical axis deviation between 90°and 150°
R peak time ≥ 0.04 sec in V1 and/or V2
Secondary repolarization changes.
(ST and T wave in opposition to QRS complex).
P pulmonale

Question 10

RIGHT VENTRICULAR HYPERTROPHY = RVH (III)

Answer 10

Differential Diagnosis (esp. for V1, V2 aspect):

• RBBB (Right bundle branch block )
• Posterior wall MI
• WPW syndrome type A

Question 11

LEFT VENTRICULAR ENLARGEMENT (LEFT VENTRICULAR HYPERTROPHY = LVH)

Answer 11

Etiology: aortic stenosis/ insufficiency, mitral regurgitation, high systemic arterial
blood pressure.
Ventricular depolarization: The LV depolarization vectors are larger than normal.
Because there is more LV mass, the depolarization time of the LV (and the total ventricular depolarization time) can be increased.

Ventricular repolarization: can be also affected: if the stimulus has a long way from subendocardial to subepicardial cells, the subendocardial cells have the opportunity to repolarize first, so the repolarization vector is inverted.

Question 12

LEFT VENTRICULAR HYPERTROPY =LVH (I)

Answer 12

Voltage criteria (the most important criteria) :
In frontal plane:
R in aVL > 13 mm
White-Block index = (RI + SIII) – (SI + RIII) > +17 mm

In horizontal plane:
R in V5 or V6 > 25 (30) mm
S in V1 or V2 > 25 (30) mm
S in V1 + R in V5/V6 > 35 mm in adults, > 45 mm in children (Sokolow-Lyon index)

Question 13

LEFT VENTRICULAR HYPERTROPHY = LVH (II)

Answer 13

Other criteria:
Left QRS axis deviation (usually around -30°)
QRS duration 0.10 - 0.12 sec.
R peak time > 0.05 sec. in V5, V6
Secondary repolarization changes: depressed ST segment (but with J point on isoelectric line) and negative, asymmetrical T waves in left leads, where the QRS complex is predominantly positive.
LA enlargement

Question 14

LEFT VENTRICULAR HYPERTROPHY = LVH
Differential Diagnosis (esp. for V1, V2 aspect):

Answer 14

LBBB (left bundle branch block)
Septal MI
WPW syndrome type B
** In V1 the QRS aspect can be QS

Question 15

THE ROMHILT-ESTES POINT SCORE SYSTEM

(“DIAGNOSTIC” >5 POINTS; “PROBABLE” 4 POINTS):

Answer 15

LOOK AT THE LECTURE SLIDE 17

Question 16

REPOLARIZATION CHANGES:

Answer 16

Primary repolarization changes

• In ischemic heart disease: the earliest affected are the repolarization processes;
• ST depression or elevation, and pointed, negative or positive, symmetrical T wave.

Secondary repolarization changes
- In ventricular hypertrophies, RBBB or LBBB, WPW syndrome repolarization changes
are present secondary to the depolarization abnormalities;
- ST and T are opposed to QRS (= where QRS complex is predominantly positive, ST is depressed and T is negative); j point is isoelectric; the depressed ST is descending; T wave is asymmetrical.

Mixed repolarization changes

• Combinations of primary and secondary repolarization changes
• For example: LVH and ischemic heart disease;