From time to time, we hear of promising young athletes who unexpectedly collapse and die on the field.
Though in itself a rare condition, ARVD (arrhythmogenic right ventricular dysplasia) is a major cause of this sort of tragedy, responsible for around one-fifth of such instances. And a disorder where sudden death may be the first symptom noticed, has to be taken very seriously.
What the tongue-twisting name means is this. Dysplasia means that there is some fault in the maturation and development of some cells, in this case heart muscle cells in the right ventricle, a major section of the heart; and the disordered heart muscle is irritable and liable to cause sudden arrhythmias when the heart's normal rhythm goes wrong, with the heartbeat often becoming erratic or too rapid.
There is major disruption to the muscular wall of the right side of the heart, and muscle fibres become replaced by fat and fibrous tissue; often the heart wall bulges and enlarges, while its ability to contract properly and keep normal blood circulation going, fails. The tissue is irritable, the ECG (a recording of the pattern of electrical activity of the heart) is abnormal, and there tend to be both extra beats and episodes of very rapid and disorganised beating of that section of the heart.
There are many causes for both extra beats and for having a rapid heartbeat, and many of them are brief and not serious, so we must not all rush to assume that we have this condition. Many healthy people have occasional extra heart beats, and are well. Palpitations are normal when one gets a fright, or exerts oneself significantly. If one's heart rate speeds up to over 120 beats a minute more than briefly, and with no obvious reason, medical help may be advisable.
The symptoms can vary, as many people don't recognise the typical arrhythmias as such. As the heart with an arrhythmia is less efficient at pumping the blood round normally, one may feel light-headed or dizzy, or may even faint. There can be chest pain, angina, too (again, there are multiple possible causes for each of these symptoms - doctors look for the particular patterns of combinations of symptoms and personal history in order to make a diagnosis.)
Sometimes the person develops heart failure, when the heart is being ineffective at maintaining the circulation properly, and other symptoms may show, such as swelling of legs, feet, abdomen or elsewhere; shortness of breath even when exercising, and, when at its worst, even when lying down; and feeling extremely fatigued.
Who gets it?
There is often a family history - and even if the condition hasn't been diagnosed previously, there may be a history in the family of people dying suddenly, and under the age of 35.
It is genetic, and once it has been identified, it is worth checking whether any other family members may also be affected, though it does not appear in all members of a family, and solitary cases can arise. It affects around one person in 5,000.
Diagnosis and treatment
The diagnosis can be difficult to make, and needs a careful physical examination and a range of tests, including an ECG,and a cardiac MRI scan done by a unit experienced at understanding the complex images this produces.
Treatment aims at controlling the arrhythmias and heat failure, usually by medication. Some use an implantable cardioverter defibrillator (ICD),a gadget which monitors the heart rhythm, and can recognise and give a small electric shock if it becomes abnormally fast or irregular. Otherwise, the person may need a short admission to hospital for cardioversion, where a similar electric shock is carefully administered in the ward.
Sometimes, if one specific area of heart muscle is found to be causing most of the trouble, it is possible to operate and remove that specific part.
Some people can be maintained pretty well using such methods, for years. The person needs to avoid significant exercise, as soon as the condition is recognised. But the disorder is progressive, and worsens slowly or rapidly. And the ultimate treatment may be a heart transplant, though I notice that some authorities, especially American ones, call this rare.
An affected person has a chance of passing the disorder on to be inherited by their children - one hopes that Melanie and her brother will receive good genetic counselling about such issues. The different influences of an inherited predisposition to the disorder (which is not enough to cause it) with factors such as exposure to certain viruses, and to an athletic lifestyle, are not yet properly understood. All first-degree relatives ought, ideally, to be screened every 2 to 5 years - brothers and sisters, parents, and children. Genetic testing is beginning to become available, including a test for one of the genes involved in ARVD, plakophilin-2 (PKP2).
Afflicted persons should avoid substantial exercise, stimulants including nicotine and caffeine, and most cough or cold remedies, and should be cautious about alcohol intake.
(Professor M.A. Simpson, Health24, December 2008)