by Professor Douglas Chamberlain
This month in health hub we have the eminent cardiologist Professor Douglas Chamberlain explain heart conditions and how to treat them
The term ‘heart attack’ is in common use but has no specific meaning, other than that of an abrupt serious medical emergency relating to the heart. In most cases the event is one in which the blood supply to the heart, delivered in channels called coronary arteries, is either interrupted or suddenly becomes seriously inadequate. Typically, this causes chest pain that can be severe and can last one or more hours. Heart pain does not start instantly but builds up over seconds and minutes. Muscular chest wall pain that may follow awkward movement causes discomfort or pain that is usually at its worst in the first second; knowing this distinction can be reassuring! We should also consider angina of effort: chest pain or discomfort that occurs during exertion, and may limit activity over long periods of time. It has an underlying pathology usually similar to that of a heart attack, but causes symptoms only when the heart is stressed by the need to pump more blood.
In most cases, the cause of the inadequate blood supply is a build-up of fatty material (called atheroma) that narrows the passageway for flow. A heart attack may then occur if blood clots at the site where the lining has been rendered abnormal by this process. Atheroma develops over years; the resulting symptoms or events tend, therefore, to occur in older age-groups. There are exceptions: people who are diabetic, who have high blood pressure, abnormal metabolism involving cholesterol, who are overweight, or who smoke may have onset at appreciably earlier ages. Another much rarer cause in younger people can occur in women towards the end of pregnancy or in the few months after a birth. This is due to a sudden tear that occurs in the wall of one of the coronary arteries.
Heart attack can also refer to an unexpected cessation of effective pumping of the heart without any external cause that is called ‘sudden cardiac death’. Some who have suffered this way are resuscitated very rapidly leaving memory intact, so they have been able to describe what they felt at the time. Warning pain may indeed have occurred but no action has been taken, but in others pain is not a feature. Symptoms then are of light-headedness often described as dizziness, with loss of vision followed within a matter of seconds by loss of hearing and all sensation. Most sudden cardiac arrests are a result of the heart developing a malignant rhythm called ventricular fibrillation: its activity becomes totally uncoordinated and therefore ineffective, gradually fading to total inactivity over a few minutes. Sudden cessation of activity may also occur though this is rare.
Ventricular fibrillation is treatable by devices called defibrillators, and usually with a good outcome if they are applied within a few minutes; moreover, the time can be extended several-fold if the victim is given chest compressions (hands on the centre of the chest and push hard rhythmically at about 100 per minute, with any attempt better than none). Defibrillators are now small devices called Automated External Defibrillators (AEDs). Take note: they are very easy to use and require no training because once opened they speak and tell you what to do, repeated at each stage until you follow the simple instructions that they give. And incredibly, they can never do any harm to victim or user! Many AEDs are now in public places as many readers will know. For example, at least one has been placed on every railway station by Sussex Heart Charity and many local charities have purchased their own devices. They are also prominent in airports where many lives have been saved. Ventricular fibrillation can occur in apparently healthy people. You have nothing to fear in treating them. Success is not always possible but we should all be prepared to try!