Andy Baddeley’s description of his cardiac arrhythmia sounds as if he is suffering from supra ventricular intermittent tachycardia, a periodic extreme and disabling rapid heartbeat. This is the trouble that caused such problems to Tony Blair when he was Prime Minister and resulted in him having extreme breathlessness, chest discomfort and feelings of light-headedness.

If it is not treated with an operative implanted pacemaker or, as the former Prime Minister had, a relatively minor procedure that alters the conduction system of the heart, patients may collapse, occasionally fatally.

Supra ventricular tachycardia is often the result of an abnormality of the conduction system of the heart that has been present since birth, but may start to give problems only in adolescence and beyond. Normally the electrical impulses of the heart’s conduction system travel across the heart in well-defined bundles. These impulses control the beating of the chambers of the heart so that they work in a regular pattern. In some patients, possibly including Baddeley, the usual electrical conduction system has been disrupted because the heart’s network of conducting fibres has been disturbed by ancillary fibres forming small bypasses from the main route, similar to the bypasses off a trunk road.

As a result, the impulses reach the chambers of the heart out of time, out of schedule and the synchronisation of the beat is destroyed so that the heart beats dangerously quickly. Drugs are used in some cases to control the heartbeat, in others a pacemaker is fitted, but if the trouble is persistent ablation, the destruction of the ancillary bypassing pathways is necessary.