What are Inherited Cardiovascular Conditions?
ICCs are conditions that affect around 1 in 250 people worldwide - around 260,000 people in the UK. ICCs cover a broad range of conditions affecting the heart muscle, the heart's electrical system and major blood vessels, and sometimes the skeletal muscles as well. Many patients are unaware of their condition and can often lead a normal life. But some patients can experience symptoms that affect their quality of life, and sometimes be at risk of major complications such as heart failure and stroke. ICCs are also a leading cause of sudden death in young people, and around half of all heart transplants are needed because of a inherited heart muscle disease.
ICCs can often be difficult to diagnose and may require a range of investigations to establish an accurate diagnosis.
These conditions can often run in families, and therefore establishing an accurate diagnosis is essential not just for a patient, but for their relatives who may also be at risk.
Screening close relatives is therefore really important when assessing families.
There are four broad groups of inherited cardiovascular conditions.
Cardiomyopathies
Cardiomyopathies are a group of conditions that can affect the heart muscle. Different cardiomyopathies can cause the heart muscle to thicken, weaken, or develop fatty tissue and scarring. These conditions can ultimately affect the ability of the heart to pump blood around the body and they can also cause abnormal rhythms. Common symptoms can include breathlessness and fatigue, and sometimes chest pain, palpitations and occasionally fainting.
Examples of cardiomyopathies include:
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Hypertrophic cardiomyopathy (HCM) - when the heart muscle becomes thick and stiff
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Dilated cardiomyopathy (DCM) - when the heart muscle becomes enlarged and weak
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Arrhythmogenic right ventricular cardiomyopathy (ARVC) or arrhythmogenic cardiomyopathy (ACM) - caused when the heart muscle becomes weakened, and the muscle is replaced with fat and scar tissue
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Restrictive cardiomyopathy (RCM) - when the heart becomes stiff
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Non-dilated left ventricular cardiomyopathy (NDLVC) - although the heart isn't enlarged, there are clear abnormalities within the heart muscle
Channelopathies
Channelopathies are a group of conditions that affect how electrical impulses spread across the heart and can lead to sudden changes in the heart's rhythm (arrhythmias).
Many patients experience no symptoms (and therefore be unaware they have the condition), but some can experience palpitations, sudden dizziness or sudden loss of consciousness.
Examples of channelopathies include:
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Long QT syndrome (LQTS) - when the heart takes too long to relax after each heartbeat
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Brugada syndrome (BrS) - associated with a specific pattern on the ECG (heart trace) caused by abnormal spread of impulses across the heart
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Catecholaminergic polymorphic ventricular tachycardia (CPVT) - where arrhythmias are usually triggered by exercise or emotional stress
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Short QT syndrome (SQTS) - a very rare condition, where the heart relaxes too quickly
Vascular Disorders (aortopathies)
Aortopathies are disorders of the main blood vessel leaving the heart, called the aorta. The aorta may become enlarged in some patients (thoracic aortic aneurysm), and can be associated with a risk of sudden rupture (aortic dissection). Some patients with an aortopathy can have signs that other parts of the body are affected.
Examples of aortopathies include:
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Marfan syndrome
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Loeys-Dietz syndrome
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Thoracic aortic aneurysm and dissection (TAAD)
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Ehlers-Danlos syndrome (vascular form)
Neuromuscular Conditions
Several genetic conditions affect both the heart muscle and the skeletal muscles throughout the rest of the body. Sometimes patients experience muscle aches, or muscle weakness as well as more typical heart symptoms including breathlessness and symptoms related to arrhythmias.
Examples of neuromuscular conditions include:
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Duchenne muscular dystrophy
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Becker muscular dystrophy
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Myotonic dystrophy
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Mitochondrial disorders
Sudden Arrhythmic Death Syndrome (SADS)
SADS is not a specific condition itself, but is a term used when a young person dies suddenly with no cause identified after a post-mortem examination. There are a number of conditions that can cause SADS including some of the genetic conditions mentioned above, but there are also some causes that don't run in families. Often, despite extensive investigations, the cause of SADS remains unknown. There are now established pathways to ensure that families are referred for further assessment following a SADS death.
What causes inherited cardiac conditions?
ICCs are often caused by a fault or change in a specific gene. Genes control the production of proteins that have specific functions in the body, and how the body grows and develops. If a genetic change disrupts a protein which is important in the heart, this can lead to an inherited cardiac condition developing. We know that there are many genes associated with inherited heart conditions - a change in any one of those genes may be sufficient to cause the condition.
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