Complete (third-degree) heart block: symptoms, emergency signs and pacemaker treatment

In a healthy heart, electrical impulses travel from the atria, the upper chambers, to the ventricles, the lower chambers, and trigger each heartbeat. The British Heart Foundation explains that in AV heart block these impulses are delayed or blocked on the way. Third-degree, or complete, heart block is the most advanced of the three degrees.

The NHS describes heart block in general as a condition in which the heart beats too slowly or the heartbeat is not steady. Of the AV heart blocks, the NHS says third-degree often needs treatment. In complete heart block, the signals between the upper and lower chambers do not get through in the usual way, which is why symptoms from a slow heart rate are more likely than in the milder degrees.

The British Heart Foundation also describes other conditions that affect the electrical pathways, such as bundle branch blocks and tachy-brady syndrome, which are different problems and are not the same as AV block.

The British Heart Foundation says second and third-degree heart blocks can cause symptoms: feeling faint or dizzy, feeling tired and sometimes confused, feeling pressure or pain in the chest, and being short of breath. Some people have a very low heart rate. In some people the block is always there, while in others it can come and go. Sometimes there are no symptoms at all.

The NHS recommends getting help from NHS 111 if you feel dizzy all the time or it keeps coming back, you have fainted, or you have shortness of breath that gets worse when you have been doing normal activities or when you lie down.

It says to call 999 straight away if you have been diagnosed with heart block and have chest pain, you have severe difficulty breathing (gasping, choking or not able to get words out), you feel sweaty, sick or lightheaded, or someone faints and is not breathing or cannot be woken within 1 minute, because you may need immediate treatment in hospital. You should not drive yourself to A&E; the 999 call handler will advise you.

The NHS says heart block is most often caused by a heart condition such as coronary heart disease or a heart attack, and that babies are sometimes born with it (congenital heart block). Other causes of AV heart block include taking some types of medicine, infection and inflammation of the heart caused by another condition, and having heart surgery. Sometimes there is no obvious cause.

The British Heart Foundation lists coronary heart disease, congenital heart disease, cardiomyopathy, ageing of the electrical pathways, thickening of the heart muscle and some medicines, and says it can also happen naturally in people with an otherwise normal heart. Knowing the cause matters because it affects treatment: block caused by medicines or electrolyte imbalances is managed by reversing the medicine effect or correcting the imbalance.

The main test is an electrocardiogram (ECG), which measures the electrical activity of the heart. The NHS says it usually takes only a few minutes, but you may be asked to wear a portable ECG for 1 or 2 days. The British Heart Foundation says the ECG can show the type of heart block you have.

The NHS lists other tests that may help: an echocardiogram or MRI scan to get a picture of the heart and nearby blood vessels, exercise tests using a bike or treadmill, and blood tests. These help find an underlying cause, such as coronary heart disease or cardiomyopathy, which may need treatment in its own right.

The British Heart Foundation says that if you are diagnosed with second or third-degree heart block you may need to have a pacemaker fitted. If your heart block was caused by a heart attack you may only need a temporary pacemaker in hospital, but if the heart does not return to a normal rhythm shortly afterwards you might need a permanent one.

A pacemaker is a small device put under the skin of the chest that sends out electrical signals to help control the heartbeat. According to the NHS, it is fitted in hospital by a cardiologist in a procedure that usually takes about an hour.

• The NHS says that the battery for a pacemaker usually lasts 6 to 7 years and the device is checked more often as it nears replacement.

• You will be given a pacemaker ID card to show to healthcare professionals and airport security, and the NHS says you must tell the DVLA and your insurance company.

• The NHS says that if you have a slow heartbeat you may be offered a leadless pacemaker, which is put into a vein and guided directly to the heart so there are no wires and no cuts to the chest.

The NHS says having a pacemaker fitted is a common procedure and that it is unlikely that anything will go seriously wrong, although an infection is sometimes possible. It advises contacting your pacemaker clinic or NHS 111 if your wound becomes more swollen, tender or redder, if blood, pus or clear liquid leaks from it, if your temperature is very high or you feel hot, cold or shivery, or if symptoms you had before the procedure return or get worse.

It advises calling 999 or going to A&E if you have severe difficulty breathing, a tight or heavy chest, pain spreading to the arms, back, neck or jaw, lips or skin turning very pale, blue or grey, or sudden confusion. Do not drive to A&E; ask someone to drive you or call 999.

Complete heart block with symptoms is usually managed through emergency services and hospital cardiology on the NHS, with ECG monitoring, any temporary pacing needed and permanent pacemaker implantation. This care is free at the point of use, and you will be followed up in a pacemaker clinic.

Some people with a known heart block pursue a private cardiology opinion, particularly for a second view on whether a pacemaker is needed. Because the situation can change quickly, new fainting or breathlessness should still be treated as described above rather than waiting for a routine appointment.