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The Heart

The heart, although one of the most important organs in the body, is simply a muscular pump. It pumps blood containing oxygen and other essential nutrients around the body, and delivers waste products to the kidneys and lungs. For the heart to pump effectively it requires its own blood supply, which it receives from the three coronary arteries, and a regular and reliable heart beat, which it derives from its own electrical conduction system.
A problem with the coronary arteries or the electrical regulation of the heart can translate into physical symptoms such as:

  • Chest Pain
  • Breathlessness
  • Palpitations, Dizzy Spells and Blackouts

Coronary artery disease is caused by atheroma, an accumulation in the arteries of fatty deposits made up primarily of lipids and calcium. As the diagram opposite demonstrates, over time the build-up of these deposits makes it more difficult for blood to pass through the vessels, and may even cause a complete blockage which may in turn lead to a heart attack.

Symptoms - Chest Pain

With exercise or emotional stress, more blood is needed through the coronary arteries to supply the heart muscle with the blood and oxygen it requires to beat faster. Over the years the coronary arteries may become narrowed and furred up, initially causing no symptoms whatsoever. As the furring up process continues there comes a time when the heart cannot get enough blood through the coronary arteries to cope with stress or increased activity, when walking uphill or climbing stairs, for example. This reduction in blood supply can cause chest pain, pressure, heaviness or tightness (angina) which rapidly disappears with rest or certain medication (a GTN spray or tablets).

If the furring up in an artery is so great that a blockage occurs, the patient experiences a heart attack, or myocardial infarction. The pain is particularly intense and is not relieved adequately by rest or GTN. This is a medical emergency and the patient should be admitted to hospital immediately to unblock the artery and treat the consequences of the heart attack.

Symptoms - Breathlessness

Breathlessness, or dyspnoea, is a common symptom of several medical disorders. Increasing age and lack of physical activity can cause some degree of breathlessness, but difficult or painful breathing should always be fully investigated by a doctor to look for an underlying heart or lung disorder.

If the heart muscle is not pumping effectively, pressure can build up within the lungs and the chambers of the heart, creating the sensation of breathlessness. If the muscle impairment is mild, breathlessness is only felt with significant exercise, but increasing muscle damage causes breathlessness with even mild activity and is perhaps more noticeable when lying down in bed, such that a patient may start to sleep with more pillows than before.

The most common cause of breathlessness in the Western world is ischaemic heart disease or atherosclerosis, the furring up of the coronary arteries. If an artery blocks completely and causes a heart attack, the heart muscle that was supplied by that artery will die, healing with time to leave a scar. The larger the scar, the greater the effect on the remaining healthy heart muscle, and the more likely it is that a patient may feel breathless.

Other causes of breathlessness include malfunctioning heart valves that may narrow down and/or leak, and various abnormalities of the heart muscle itself, which may be inherited, or acquired (e.g. following a viral infection of the heart or a long period of alcohol excess).

Symptoms - Palpitations, Dizzy Spells and Blackouts

Palpitations are a common symptom that may or may not signify an important underlying heart problem. An awareness of occasional heart beats is common and normal. We all experience extra heart beats from time to time and in most cases this is not dangerous, although it may initially be concerning to the patient. Sometimes the heart rhythm can change significantly and this needs careful investigation, for example with an ECG or 24 hour heart monitor.

Occasionally a small device, an implantable loop recorder, may be inserted under the skin on the front of the chest to monitor the heart beat continuously for a year or longer. The device can store precise information about the heart rhythm at the time of a patient's symptoms and the information can be downloaded at a later time for analysis. There are many different types of heart rhythm change, which, depending on the precise rhythm abnormality, can be treated in several different ways, for example with regular medication, a permanent pacemaker, or an implantable defibrillator.

Some heart rhythms can be successfully treated, often permanently, with the brief application of radiofrequency energy through small catheters (tubes) passed through the veins into the heart chambers. This is a technique called radiofrequency ablation.

Dizzy spells and blackouts may be caused by a drop in blood pressure, which temporarily reduces the supply of oxygen to the brain. This may occur when getting up quickly from a lying or sitting position (postural hypotension), and can be exacerbated by certain medications, such as those to control high blood pressure. Many dizzy spells and faints do not have a significant underlying cause but they should always be investigated, particularly if they are accompanied by other symptoms, as they can sometimes be indicative of a cardiovascular disorder such as a heart rhythm disturbance or a heart valve problem.

Investigations and Treatments

For more information on the following forms of investigation and treatment, please click on a title to be taken to a pdf information booklet for you to download and print:

* ECG (electrocardiogram)
* Echocardiogram
* 24 hour ECG
* 24 hour Blood Pressure Monitoring
* Exercise Tolerance Test
* Chest X-ray
* Angiography
* Angioplasty
* Myocardial Perfusion Scanning