SADS – Sudden Arrhythmic (Adult) Death Syndrome

Causes of Sudden Arrhythmic (Adult) Death Syndrome (SADS):

The main causes of SADS fall in to three different types of categories (conditions). These are:

1. Arrhythmias
2. Cardiomyopathies (conditions which affect the muscle of the heart)
3. Channelopathies (conditions and diseases that are inherited and affect the muscle cells of the heart and subsequently its electrical activity)

Arrhythmias

The heart contracts to pump blood by the help of its electrical system, the electrical currents run through the heart muscle to allow this to happen, this is in effect our “heart rhythm”.

Any disruption to the electrical mechanisms in the heart can cause disruption to the heart rhythm and this leads to an abnormal rhythm, something that is called an arrhythmia. Some arrhythmias are life threatening and some are not.

The top chambers of the heart are called atria; these are the chambers of the heart that receive blood coming from the body. Arrhythmias that affect the top chambers of the heart cause atrial fibrillation (AF), and this can usually be treated with medication or specialist treatment.

The lower chambers of the heart are called ventricles and are responsible for the pumping of blood. Ventricular Tachycardia (VT) occurs when the electrical impulses coming from the heart muscle are fired too often and the pathway of these impulses is affected, causing a very fast heart rate. Sometimes this only lasts for a short time but in others it can be prolonged and cause other symptoms such as chest pain, shortness of breath and general weakness and in some cases can lead to Ventricular Fibrillation (VF). VF is highly dangerous as the impulses become so confused that the heart may not be able to beat and in this case the person can collapse and their pulse may stop. VF can be fatal unless prompt defibrillation and Cardio Pulmonary Resuscitation (CPR) are started.

Although VT and VF are most commonly associated with people with underlying coronary heart disease, they can also cause deaths without warning, where there are other underlying conditions that may place a person at higher risk of VT and VF; this is called Sudden Arrhythmic Death Syndrome (SADS).

Cardiomyopathies

Cardiomyopathies are conditions which affect the muscle of the heart and mostly these are inherited conditions. There can however be causes which may not be inherited; these include a history of high blood pressure, a history of coronary artery disease or viral infections.

Persons with Cardiomyopathies may have little or no symptoms or may present with chest pain, shortness of breath, weakness and palpitations.

Cardiomyopathy Conditions include:

• Hypertrophic Cardiomyopathy (enlargement of the heart because the muscle becomes abnormally thick)
• Arrhythmogenic Right Ventricular Cardiomyopathy (disruptions to the heart muscle where the muscle becomes abnormally thin)
• Dilated Cardiomyopathy (enlargement of both sides of the heart, mainly the ventricles, which affects its ability to pump blood

Channelopathies

Many deaths dues to SADS are thought to be caused by Channelopathies. Channelopathies are conditions which occur through inherited diseases. These diseases usually affect the hearts cells which interpret and distribute the electrical signals through the heart muscle, allowing the heart to contract and pump blood. Although they often affect the electrical activity they do not always affects the hearts structure. Disruption to this activity leads to arrhythmias and these often cause collapse without warning. Cardiomyopathies can often only be detected when the person is alive as they do not show up on a post mortem. They can however be detected through changes on the persons ECG (heart tracing) or through examining existing family members.

Common Channelopathy Conditions include:

• Arrhythmias (abnormal heart rhythms)
• Long QT Syndrome (LQTS) (a condition which affects the channels of potassium and sodium regulation in the heart through its affect on electrical activity and the force and contraction of the heart).
• Burgada Syndrome (a condition which causes abnormal sodium regulation in the heart, which also affects electrical activity and the force and contraction of the heart)

Other Causes of SADS

• Structural Heart Disease
• Epilepsy (research has shown that this can be a cause but it is rare)
• Severe asthma Attacks (research has shown that this can be a cause but it is rare)
• Pulmonary Embolism (a clot in the lungs)

Sudden Arrhythmic Death Syndrome During Pregnancy

Arrhythmias during pregnancy are common and may cause concern of health for both the mother and the fetus. For some pregnant women the arrhythmias can be a recurrence of a previously diagnosed arrhythmia or may be she is suffering with structural heart disease.

Diagnosis of arrhythmia in pregnancy

There are three ways to the diagnosis of arrhythmia in pregnancy:

1. Get the accurate diagnosis of the arrhythmia
2. Diagnose any other heart disease associated with the arrhythmia
3. Exclude systemic disorders that may present with arrhythmias

Pregnancy can be associated with ventricular and supraventricular arrhythmias. It can be handled at very low risk to mother and fetus.

Doctors and you yourself should start treatment of arrhythmia before conceiving your baby, but during pregnancy treatment should only be initiated for severe symptoms or haemodynamic compromise.

In general, arrhythmias during pregnancy can be safely managed medically with little risk to mother or fetus. Avoid using Drugs during your first trimester and under go as your doctors advice.