Hypertrophy

Hypertrophy is defined as the enlargement of an organ or tissue due to the increased size of its cells.

Cardiac hypertrophy then, denotes the increased mass of the heart’s constituent chamber walls. This enlargement is due to an overload, in response to which the chamber in question dilates so as to handle the increased volume of blood within it.

An ECG can pick up the physiological changes in the corresponding area of the heart suffering from hypertrophy, so knowing what area of the heart each section of the PQRST wave corresponds to can help in determining the variety of enlargement.

Left Atrial Enlargement – LAE
- Increased volume/ muscle mass
- Walls thicken
- Can be caused by:
  - Mitral stenosis/ aortic valve disease
  - Cardiomyopathy
  - Atrial fibrillation (LAE is also often a precursor to AF)
  - Hypertension
LAE on ECG

Lead II:
- P mitrale
- >0.04s between peaks.
- >0.1s total
  - P wave is the sum of atrial depolarisation, so a visible difference is depolarisation speeds in lead II shows LAE
Lead V1
- Biphasic P wave, terminal negative portion:
  - >1mV deep
  - >0.04s

Right Atrial Hypertrophy – RAH
- Can be caused by:
  - Tricuspid stenosis/ pulmonary valve disease
  - Chronic lung disease
  - Pulmonary hypertension, primary
RAH on ECG

P pulmonale
- Inferior leads:
  - >2.5mV
- V1, V2
  - >1.5mV
- P pulmonale displays as a tall, peaked wave and can often be seen throughout whole trace

Left Ventricular Hypertrophy
Can be caused by:
- Aortic valve disease
- Aortic coarctation
- Hypertension

LVH on ECG

Dx can be made using a number of formulae, but we will look at the Sokolov-Lyon and Cornell criteria:
- Sokolov-Lyon
  - V1 S wave depth + V5 or V6 R wave_Tallest = >35mV
  - LVH present
- Cornell
  - aVL R wave + V3 S wave =
    - Males >28mV
    - Females >20mV
  - LVH present