HOCM

42 years old male patient with hypertrophic cardiomyopathy.

– Septum (2.9cm).
– Posterior wall (2.7cm).

What is HCM?

In HCM the muscular walls of the heart’s ventricles become thickened.

HCM generally affects the left ventricle and particularly the septum. However, it can also affect the right ventricle.

The average thickness of the left ventricle wall in an adult is 12mm, but in HCM the thickness is 15mm or more.

The thickening of the muscle makes the ventricle stiffer, which makes it harder for the heart to relax and fill with blood, and contract to pump blood out.

Depending on the area and amount of thickening, the volume of the ventricle may be normal, or may be reduced.

What causes HCM?

HCM is usually caused by a genetic mutation, and usually by a single mutation (rather than several mutations happening together).

It is often inherited as an autosomal dominant trait. This means that the mutated gene is found on one of the non-sex chromosomes (called the autosomes).

A child of an affected parent will have a 50% chance of inheriting the mutation.

So although someone is born with the mutation, they may not develop the condition, or any symptoms, until teenage years or their early 20s.

Some people have minor or even no symptoms. In some cases, the condition occurs later in life, known as ‘late onset HCM’.

For the reasons above, it is important that first-degree relatives (children, siblings and parents) of the person with HCM are also screened for HCM.