Progressive cardiac conduction defect (PCCD)

Progressive cardiac conduction defect (PCCD) is a rare condition. In people with PCCD, the heart’s electrical impulses are conducted very slowly and this results in the gradual development over time of heart block. (Heart block is a failure of the heart’s electrical impulse to conduct properly from the top chambers [the atria] to the bottom chambers [the ventricles]). The severity of the condition and its associated risk can vary. PCCD can cause arrhythmias – either because the heart’s rhythm is too sluggish (bradycardia and asystole), or because of rapid rhythm disturbances (tachycardia) arising from parts of the heart that have escaped normal regulation. In some people PCCD has been associated with sodium channel mutations that cause changes in channel behaviour similar to those found in people with Brugada syndrome.

What are the symptoms?

Dizziness and blackouts are the usual symptoms, cardiac arrest may also occur.

Are there any physical signs?

There are no physical signs usually except if there is heart block when the doctor may feel a slow pulse.

How is PCCD diagnosed?

The ECG abnormalities may be detected either on a standard ECG or with Holter monitoring. An electrophysiological study may also help the doctor make a diagnosis.  If a sodium channel mutation is identified in affected members of a family then it may also be found in other relatives.

Treatment and advice

If you have PCCD you will need to have a pacemaker fitted in order to stop dangerous bradycardia from occurring. You may also need to take antiarrhythmic drugs. Some people may need to have an implantable cardioverter defibrillator (ICD) fitted instead of a pacemaker. Medication alone does not help.