Podcheko Alexey, MDUpd Fall 2014

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HYPERTROPHY & ENLARGEMENTOF HEART CHAMBERS

Intended Learning Outcomes

To know ECG criteria for : 1. “Left Ventricular Hypertrophy”

2. “Right Ventricular Hypertrophy”

3. “Right and Left Atrial Enlargement”

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Precordial leads V1-V6 (horizontal plane)

V1-V2 Right ventricle

V3 Septum

V4-V6 Left Ventricle

Why should I know signs of LVH and RVH?LVH and RVH frequently

misdiagnosed as acute Myocardial Infarct and as result patient may incorrectly treated

“Left ventricular depolarization” is responsible for the prominent R waves in the left sided chestprominent R waves in the left sided chest leads and the S S waves of the right sided chestwaves of the right sided chest leads.

“Left Ventricular

Hypertrophy”

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 The VoltageVoltage developed by depolarizing cardiac muscle is proportional is proportional to the Mass Mass of muscle of muscle present

During hypertrophy as the left ventricular muscle mass increases, greater depolarization voltages are produced in the thickened ventricular wall

The amplitude of the R wave The amplitude of the R wave in the left lateral leads in the left lateral leads becomes progressively becomes progressively higher higher while the S waves in the S waves in the right sided chest leads the right sided chest leads become progressively become progressively deeperdeeper.

“Left Ventricular

Hypertrophy”

“Voltage CriteriaVoltage Criteria”, the best known of which is the

“Sokolow-Lyon criteriumSokolow-Lyon criterium”:

If the sum of the depth of the S wave in lead S wave in lead V1V1 and the height of the R wave in lead R wave in lead V5 or V5 or V6V6, which ever is the taller, is greater than 35 greater than 35 mm mm (35 small squares) the patient has left left ventricular hypertrophyventricular hypertrophy

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Criteria to diagnose left Criteria to diagnose left ventricular hypertrophyventricular hypertrophy

If a subject meets the Sokolow-Lyon Criterion on their ECG they have a high probability of underlying LVH.

o However, a high proportion of individuals with underlying LVH do NOT meet the criterium on their ECG.

o This pattern of high specificity but low sensitivity, is This pattern of high specificity but low sensitivity, is observed with almost all voltage criteria and probably observed with almost all voltage criteria and probably reflects the fact that factors other than muscle mass reflects the fact that factors other than muscle mass influence the amplitude of deflections in the leadsinfluence the amplitude of deflections in the leads.

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Sokolow-Lyon criteriumSokolow-Lyon criterium

In obese individuals the increased distance of the leads from the heart tends to dampen down the amplitude of deflections produced

If the voltage criteria are present on the ECG this is strong evidence of underlying LVH; however, if they are not, this does not reliably outrule hypertrophy. 

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Sokolow-Lyon criterium, exceptionsSokolow-Lyon criterium, exceptions

LVH can produce striking changes in the ST segments and T waves on the ECG, with T wave inversion and ST segment depression in the “left” sided leads.

ST elevation may be present in the “right” sided chest leads. In the setting of LVH, these T wave and ST segment changes are referred to as an “LV strain pattern”.

The ‘LV strain pattern’ [Chronic] is seen on the ECG of a proportion of LVH cases.

It is clinically important as it is easily confused with the ECG changes of acute coronary artery thrombosis11

LVH and changes in the ST segments and T waves

LVH and changes in the ST segments and T waves ST elevation may be present in the “right” sided

chest leads. In the setting of LVH, these T wave and ST segment changes are referred to as an “LV

strain pattern”.

LV strain pattern may result from reversal of the normal transmural dispersion of repolarization in the thickened ventricular wall with consequent loss of T wave /QRS concordance.

The ECG changes of ‘LV strain’ are chronic and do Not reflect underlying acute ischemia.

Most common causes of LVH: HTN, Athletic Heart, AS, Coarctation of Aorta

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LV strain pattern and LVH

Summary: EKG Voltage Criteria for LVH

1. Height of R-wave in V5 or V6 V5 or V6 + Depth of S-wave in V1V1 > 35 mm (35 small sq. or 7 Large Squares)(or)R-wave in V5 or V6 V5 or V6 > 27 mm(or)R-wave in aVL aVL > 11 mm(and)2. LV Strain Pattern: ST segment Depression & Asymmetrical T-wave Inversion in “Left”-sided Leads, such as Leads I, aVL, V5, & V6;3. ST segment elevation may be present in the “Right”-sided Leads4. Heart Axis – Horizontal

Remember: in LVH Heart Axis is horizontal, but there is no LAD!!!

0°

-30°

+60°

In the presence of gross RVH, when the RV wall has increased to at least twice its normal thickness, the depolarizing voltage generated in the enlarged right ventricular muscle mass can produce:

a. abnormally tall R waves in the “right” sided chest leads (V1V1)

b. persistent large S waves in those on the “left” (V6V6).

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ECG Criteria for Right Ventricular Hypertrophy

V1V6

“EKG Voltage Criteria for RVH”:

An R wave in lead V1V1 higher than 7 small squares in amplitude (or)If the R wave in lead V1V1 is higher in amplitude than the S wave (R:S ratio > 1)(or)R wave in lead V1V1 + S wave in lead V6V6 > 11 mm

Criteria for RVHSome cases of RVH may be associated with an “RV

strain pattern” on the ECG with ST depression and asymmetrical deep T wave inversion in leads V1 to V3. In this situation, this does NOT reflect underlying acute ischemia.

Sensitivity of the ECG in the diagnosis of RVH is poor:

20% (RVH) primarily “Cor Pulmonale” – Pulmonary

HTN, COPD, Emphysema, PS, etc.18

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SUMMARY: ECG SIGNS OF RVHSUMMARY: ECG SIGNS OF RVH

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Right and Left Atrial Enlargement

Characteristics of the Normal Sinus P Wave:•Smooth contour•Monophasic in lead II•Biphasic in V1Axis•Normal P wave axis is between 0° and +75°•P waves should be upright in leads I and II, inverted in aVRDuration< 120 msAmplitude< 2.5 mm in the limb leads,< 1.5 mm in the precordial leadsAtrial abnormalities are most easily seen in the inferior leads (II, III and aVF) and lead V1, as the P waves are most prominent in these leads.

The Atrial Waveform – Relationship to the P wave

Atrial depolarisation proceeds sequentially from right to left, with the right atrium activated before the left atrium.

The right and left atrial waveforms summate to form the P wave.

The first 1/3 of the P wave corresponds to right atrial activation, the final 1/3 corresponds to left atrial activation; the middle 1/3 is a combination of the two.

In most leads (e.g. lead II), the right and left atrial waveforms move in the same direction, forming a monophasic P wave.

However, in lead V1 the right and left atrial waveforms move in opposite directions. This produces a biphasic P wave

Right Atrial Enlargement – Look at the Lead II

In right atrial enlargement, right atrial depolarisation lasts longer than normal and its waveform extends to the end of left atrial depolarisation.

Although the amplitude of the right atrial depolarisation current remains unchanged, its peak now falls on top of that of the left atrial depolarisation wave.

The combination of these two waveforms produces a P waves that is taller than normal (> 2.5 mm), although the width remains unchanged (< 120 ms, 3 s sq).

Right Atrial Enlargement – Lead V1

Right atrial enlargement causes increased height (> 1.5mm) in V1 of the initial positive deflection of the P wave.

“Right Atrial Enlargement”:

P waves in any inferior lead taller than 2.5 mm or small squares(Sensitivity 7%, Specificity 100%)Initial positive deflection of P waves > 1.5mm in V1

Causes of RA Enlargement: “P. PulmonaleP. Pulmonale” – Chronic lung diseases (cor pulmonale), Pulmonary HTN, Tricuspid valve stenosis, Tricuspid valve regurgitation,etc.

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Left Atrial Enlargement – Lead II

In left atrial enlargement, left atrial depolarisation lasts longer than normal but its amplitude remains unchanged.

Therefore, the height of the resultant P wave remains within normal limits but its duration is longer than 120 ms (>3 s. sq.)

A notch (broken line) near its peak may or may not be present (“P mitrale”).

Left Atrial Enlargement – Lead V1

Left atrial enlargement causes widening (> 40ms wide, 1 s sq) and deepening (> 1mm deep) in V1 of the terminal negative portion of the P wave.

“Summary: Left Atrial Enlargement”:P waves in “any” lead broader than 2.5 small squares in “duration”. {Sensitivity 84%, Specificity 35%}

Negative P terminal force in lead V1 greater than 1 small square in “Depth” and “Duration”. (Sensitivity 37%, Specificity 88%)

Notched P waves Notched P waves with peak separation of greater than 1 small square (“P. MitraleP. Mitrale”). (Sensitivity 8%, Specificity 99%Specificity 99%)…………..28

Causes of Left Atriam Enlargement: “P. Mitrale” – Mitral Stenosis, Mitral Regurgitation,

Remember, when applying “voltage criteria” for chamber enlargement always check that the calibration box is two large squares in height and one large square in width………………….indicating the machine is recording at a needle speed of 25 mm/sec.

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Biatrial Enlargement

Biatrial enlargement is diagnosed when criteria for both right and left atrial enlargement are present on the same ECG.

Review of Cases