ECG Of Ventricular Hypertrophy (Will be updated)

Introduction
In this modern age where urbanization and sedentary life has become more common than previously thought possible, there is an increase of numerous health problem such as hypertension, obesity, diabetes, etc while at the same time a decreasing prevalence of infectious disease. Left Ventricle Hypertrophy is an enlargement of myocardium tissue that is strongly related to systemic hypertension. Because of the high prevalence of untreated hypertension, both from undiagnosed patient or poor patient compliance, we can expect an increase of LVH incidence now and in the future. The significance is even greater when we realize that LVH is associated with excess risk of cardiovascular morbidity.

Pathology

Normal, Dilated, and Hypertrophy Heart 

The middle heart is a normal heart. As we can see here, the left ventricle is much more thicker than the right ventricle due to the requirement to pump blood against systemic resistance. Interestingly, infants have their right ventricle thicker due to different hemodynamic physiology during pregnancy (high pulmonary resistance and low systemic resistance). Consequently, this makes the normal ECG interpretation of infants different, a topic that will be discussed in the future. The left ventricle of infant becomes progressively thicker during growth, reaching normal heart structure at teenage years.

The left heart has a hypertrophy of the myocardium, the heart muscle. LVH happens when the required force to pump blood to systemic circulation isn't enough. For example, in systemic hypertension, the muscle of heart requires much greater force to contract than normal in order to counter elevated blood pressure. Another mechanism that can cause LVH is aortic stenosis, an obstruction of blood flow due to narrowing of aortic valve. The obstruction will then make the left ventricle to harder. 

The right heart is a dilated heart, a completely different mechanism yet indistinguishable from hypertrophy in ECG. 

ECG Finding

  

Under normal condition of heart, the left ventricle is electrically more dominant than its right counterpart (negative S waves in right leads and positive R waves in left leads) due to larger mass. So what happens when the left ventricle become really enlarged like from a very long hypertension? Generally, the increase mass of left ventricle will produce an electrical imbalance causing the vector to move even further to left. Because of this, S wave in right precordial leads will have an increase in amplitude (become deeper). Consequently, the leads facing the left ventricle such as I, AVL, V4-V6 are higher than normal.

Repolarization of the left ventricle may also be affected shown by ST segment depression and/or elevation in tall R leads. The T wave is often inverted asymmetrically in left precordial leads. In right ventricle hyperthrophy, the QRS vector is moved to the right

In this illustration, we can see the increased amplitude from Left Ventricle Hypertrophy. Note the high R wave in V6, deep S wave in V1, secondary ST changes in left leads. Also note the high aVL and deep aVR. 

Diagnostic Criteria 

Currently, there are many criteria devised by experts such as from Sokolow to Cornell. This reflect the imperfection of ECG in diagnosing LVH.

Left Ventricle Hyerthropy Criteria
Sokolow-Lyon Voltages	SV1 + RV5 > 3.5mV             RAVL > 1.1mV
Romhilt-Estes point score system See note for score system	Any limb lead R wave or S wave > 2.0 mV (3 points) or SV1 or SV2 ≥ 3.0 mV (3 points) or RV5 to RV6 ≥ 3.0 mV (3 points) ST-T wave abnormality, no digitalis therapy (3 points) ST-T wave abnormality, digitalis therapy (1 point) Left atrial abnormality (3 points) Left axis deviation ≥ −30 degrees (2 points) QRS duration ≥ 90 msec (1 point) Intrinsicoid deflection in V5 or V6 ≥ 50 msec (1 point)
Cornel voltage criteria	SV3 + RaVL ≥ 2.8 mV (for men) SV3 + RaVL >2.0 mV (for women)
Cornell regression equation	Risk of LVH = 1/(1+ e−exp)†
Cornel voltage duration measurement	QRS duration × Cornell voltage > 2,436 mm-sec3 QRS duration × sum of voltages in all leads > 1,742 mm-sec

Note: Probable left ventricular hypertrophy is diagnosed if 4 points are present and definite left ventricular hypertrophy is diagnosed if 5 or more points are present.

Romhilt seems to be the easiest to remember. If you don't like the above criteria, you can use the improvised criteria adapted from above. Below is the summary of them:

1. Amplitude of R wave in V5 OR V6 > 26 mm/2.6mV 
2. Amplitude of R wave in V5 or V6 + S wave in V1 is>35mm/3.5mV
3. Amplitude of highest R wave + S wave in precordial lead is > 45 mm/4.5mV
4. R wave in aVL > 11 mm/1.1mV 
5. R wave in aVF > 20 mm/2 mV
6. S wave in aVR > 14 mm/1.4mV
7. ST wave depression in left precordial
8. Asymmetrical T wave inversion in left precordial 
9. Left axis deviation 

Example 

This ECG fulfills many LVH criteria. Notice in V6, the R wave amplitude exceed 26 mm (more than 5 medium boxes) and of course when we combined the v6 as the highest R wave with V2 as the deepest S wave, the result is more than 45 mm. R wave in AVL more than 11mm.  Not to mention the asymmetrical T wave inversion in V5 and V6. There is a very slight ST segment elevation in V1-V3. This a the kind of ST elevation that may accompany LVH