Coronary artery disease
Coronary artery disease (also known as ischaemic heart disease) is due to ‘furring up’ of one or more of the 3 major arteries that supply blood to the heart. During the early stages of the disease symptoms do not occur, but as the narrowings progress (typically causing obstruction to the blood flow down an artery by 70% or more), symptoms of chest pain may develop. This ‘furring up’ is due to a combination of factors including
lifestyle issues such as smoking. However, genetic factors such as a family history of heart disease (especially in relatives below the age of 65 years), high blood cholesterol, high blood pressure and diabetes all contribute.
Heart failure is due to reduced heart muscle function. Usually, this is due to a reduction in the squeezing ability of the heart muscle (systolic dysfunction) which normally acts like a pump to squeeze blood around the body. The commonest cause is damage to the heart muscle secondary to a myocardial infarction (heart attack) where a blockage of one or more of the coronary arteries causes scarring to the heart muscle. Other causes include poorly controlled blood pressure, a viral attack (viral myocarditis), excessive alcohol or a genetic cause (dilated cardiomyopathy). Less commonly the problem is of a failure of the heart muscle to relax properly (diastolic dysfunction). The commonest cause is high blood pressure, but a genetic cause may include hypertrophic cardiomyopathy or restrictive cardiomyopathy.Whatever the cause of heart failure the symptoms and signs may include breathlessness and swollen ankles.
An arrhythmia is any fast and abnormal rhythm of the heart. There are many different types of arrhythmias, but they basically divide into those originating from the atria (upper chambers of the heart) and those from the ventricles (main pumping chamber of the heart).
Atrial Fibrillation (AF)
This is a common rhythm problem and is often found in association with other problems such as high blood pressure, thyroid problems or excessive alcohol. Occasionally it can occur is isolation and is termed lone AF. The heart beat is usually fast and is always irregular. The rhythm problem may be intermittent (paraoxysmal AF) or longterm (chronic or established AF). Treatment may be aimed at either slowing the heart down with drugs, or getting the heart back into regular rhythm using a brief electric shock (cardioversion) or a keyhole operation (an ablation). Most patients with atrial fibrillation will need either aspirin or warfarin to thin the blood to prevent stroke.
Ventricular ectopic beats
Extra heart beats originating from the ventricles are common and are almost always benign. They are usually experienced as a pause then an extra heavy beat and occur particularly at night. If they are very frequent, are associated with sustained palpitations or with dizziness or collapse they need further investigation.
Ventricular tachycardia (VT)
This is occasionally found in patients with normal hearts, but is more likely to be found secondary to coronary artery disease or a cardiomyopathy. All cases of VT need to be carefully investigated as it may be life threatening and need drug treatment or implantation of a cardiac defibrillator.
A cardiomyopathy is a heart muscle problem that is often due to a genetic cause.
There are 3 main types:
This is an inherited cardiac disease that affects up to 1 in 500 of the population. The genetic problem is due to a ‘spelling mistake’ in one of the genes that makes the heart muscle proteins. This leads to excessive thickening of the heart muscle (between 15 to 30mm). This ‘spelling’ mistake can be passed onto offspring in an autosomal dominant fashion, meaning there is a 50:50 chance of passing it on to the next generation. However, due to complex genetic factors there is usually a less than 100% chance of getting the disease even if the gene is passed on. Family screening is recommended in all first degree relatives. Most patients can lead a relatively normal life with little in the way of symptoms and achieve a normal life expectancy. However, for a proportion of patients there is a risk of sudden death. Risk stratification by a cardiologist with experience in this disease can determine which patients are at risk and thus who should be referred on for a cardiac defibrillator device to protect from sudden collapse.
Dilated cardiomyopathy refers to an enlarged heart due to thinning and reduced function of the heart muscle. There are many causes (see heart failure), but in around 40% of cases the cause is genetic. The condition can be passed on in either an autosomal dominant (50:50 chance) or autosomal recessive (1in 4 chance) fashion.
Thus family screening is recommended when no clear underlying cause is found. The management is similar to that of heart failure from other causes, and centres on drug treatment which aims to alleviate symptoms and improve heart function.
Arrhythmogenic right ventricular dysplasia
This is an inherited cardiac disease that predominantly affects the right side of the heart and may present with problems of palpitations, dizziness or collapse. Patients are usually investigated with an ECG, Echo, 24 hour tape and cardiac MRI scan. The diagnosis can be difficult to confirm and thus patients and their relatives should be referred to a specialist clinic with expertise in the inherited cardiac diseases. Family screening is recommended in all first degree relatives.
This is a group of genetic disorders in which the heart is structurally normal, but the electricity of the heart is abnormal. In both the Long QT and Brugada syndromes there is a genetic defect in the proteins that regulate the electrical signalling within the heart making the heart vulnerable to tachycardias. In some cases there is a significant risk of collapse and sudden death. Once detected these conditions can however be successfully treated with either drugs, or quite commonly, the implantation of a sophisticated pacemaker known as an internal cardiac defibrillator (ICD).
Occasionally vigorous athletic training can lead to detectable changes of the heart. These can manifest as abnormalities of both the ECG and occasionally the echo scan of the heart (Athlete’s heart). These changes arise as a result of an enhanced, but normal thickening response of the heart to high level sports. These findings are not predictable and can occur more commonly in some ethnic groups than others. The condition is, however, benign and reversible. Where confusion sometimes lies is in discriminating this normal response to exercise from the abnormal conditions that these changes sometimes mimic i.e. the cardiomyopathies (see above). Thus, when screening athletes it is important to have a cardiologist with expertise in both the cardiomyopathies and the Athlete’s heart.