What are the causes of sudden cardiac arrest?
Sudden cardiac arrest is most often caused by heart disease. When blood vessels narrow, the heart muscle can become irritated because of lack of blood supply. In heart attack (acute myocardial infarction), a blood vessel becomes completely blocked by a blood clot, and there is enough irritability of the muscle to cause ventricular fibrillation. In fact, the reason many people with chest pain are admitted to the hospital is to monitor their heart rate and rhythm for signs that might lead to ventricular fibrillation. Sudden cardiac arrest may also be the first presentation of heart disease.
Congestive heart failure and heart valve problems, like aortic stenosis (narrowing of the aortic valve) also increase the risk of sudden cardiac arrest.
Cardiomyopathy is a broad category of heart disease where the heart muscle does not contract properly for whatever reason. Often it is ischemic, meaning part of the heart muscle doesn't get an adequate blood supply for a prolonged period of time and can no longer efficiently pump blood. People whose ejection fractions (the amount of blood pumped out of the heart with each heart beat) is less than 30% are at greater risk for sudden death (a normal ejection fraction is above 50%). In some people, cardiomyopathy may develop in the absence of ischemic heart disease.
Inflammation of the heart muscle, known as myocarditis (myo=muscle + card=heart + itis= inflammation), can also cause rhythm disturbances. Diseases like sarcoidosis, amyloidosis, and some infections can cause inflammation of the heart muscle.
Some people are born with electrical conducting systems that are faulty, which place them at higher risk for rhythm disturbances. Some are due to the wiring, or electrical conduction system, like Wolff-Parkinson-White syndrome, while others are due to the structural basic structural problems within the heart, like Marfan syndrome.
Pulmonary embolus, a blood clot to the lung, can also cause sudden death. Clots form in the leg or arm and may break off and flow to the lung where they decrease the lung's ability to get oxygen from the air to the body. Risk factors for blood clots include surgery, prolonged immobilization (for example, hospitalization, long car rides or plane trips. Even sitting for too long at a desk), trauma, or certain diseases like cancer.
Blunt chest trauma, such is in a motor vehicle accident, may result in ventricular fibrillation. This is because the heart sits directly behind the breast bone or sternum and when a direct blow is sustained it can short circuit the electrical system of the heart. This is called commotio cordis.
The only effective treatment for SCA is defibrillation within 4-6 minutes using an Automated External Defibrillator (AED) as part of the chain of survival.
For further information, please email: info@thedefibcentre.co.uk or call us on 0800 634 9745.
