It’s a leak back through one of the inlet valves of the heart, usually the mitral valve which controls blood flowing between the left sided heart chambers.

The inlet valves do not form normally in people with this condition, with often just one valve forming rather than the usual two. The surgeon repairs the valve(s) at the time of the surgery, but in some people the left valve in particular can become gradually more leaky over time.

The valve leak means that the main pumping chamber of the heart (the left ventricle) has to do extra work pumping more blood than usual. If the valve leak is severe, the left ventricle can become enlarged and potentially become weakened over time.

If the leak gets severe and causes progressive enlargement of the left ventricle, we may recommend an operation to repair or sometimes replace the valve. The surgery is done to prevent long-term damage to the left ventricle.

There isn’t usually anything you can do to stop this from happening, but this complication only occurs in a minority of people with this condition.

If you notice a deterioration in your exercise tolerance or you are getting more breathless, then get in touch with your heart team so that we can check you out.

Left ventricular outflow obstruction is narrowing of the way out from the left ventricle, where the blood is pumped out of the heart to flow around the body.

The left ventricular outflow is longer than usual in people with this condition, and can sometimes be narrower than normal. There can be extra muscle causing the narrowing, or extra valve material causing the narrowing.

The muscle of the left ventricle has to work harder to pump the blood out of the heart past the narrowed area. This means that the muscle becomes thicker than normal and with time the heart muscle can become weakened as a result.

If the narrowing gets tight enough then we may recommend an operation to open up the narrowed area.

There isn’t anything you can do to prevent this from happening, but it’s important that you come to your clinic appointments so that we can do regular echo scans to look out for these sorts of complications occurring.

Heart block is a problem with the electrics of the heart, such that the heart beat is not transmitted in the normal way from the upper heart chambers to the lower heart chambers.

The electrical pathways of the heart do not develop in a completely normal way in people with this condition, and sometimes there can be a gradual deterioration of the electrical conduction of the heart over time.

Some people will eventually develop “complete heart block”, where the electrics of the upper and lower heart chambers do not “talk” to each other at all.

This means that the heart beat may be much slower than normal, which makes people feel tired or have dizzy spells and is a potentially dangerous situation.

For complete heart block we would usually recommend implanting a pacemaker to help the heart rate to be more normal and to prevent dangerously slow heart rhythms.

A pacemaker is a small device that sits under the skin of your upper chest and connects to your heart through one of the big veins. The pacemaker detects if your heart goes too slow and gives a tiny electrical signal to your heart that makes it speed up.

Click here to find out more about pacemakers.

There isn’t usually anything you can do to prevent this happening, but it is important that you let us know if you notice that you are tiring more easily than usual, or particularly if you have major dizzy spells or blackouts.