Your house has plumbing and electrical wiring – so does your heart. The plumbing pipes are your arteries which bring oxygenated, nutrient rich blood to your heart muscle. These arteries can become clogged with cholesterol deposits, leading to angina or a heart attack. The electrical wiring is also built in to the heart: this ensures that the four heart chambers beat regularly and in unison. Many things can affect the electrical system of the heart, e.g. some medications, smoking and thyroid hormones to name but a few. These can cause the conduction of electrical impulses to be disturbed, leading to an irregular heartbeat. Other factors, notably heart attacks, heart valve problems, smoking and ageing, can cause damage or degeneration in the actual electrical fibres: this will have a similar effect, but which may be irreversible.
Conduction problems which affect the receiving chambers of the heart – the atria – can lead to a condition called atrial fibrillation (AF). Here, the atria do not contract normally: instead of regular, forceful contractions which propel the blood onwards to the pumping chambers, the atria just quiver in a totally disorganized way. Just as your car cannot perform at its best when the timing is wrong, your heart function will be compromised when its timing is wrong.
In AF, blood flow through the atria is thus sluggish, and can result in the formation of clots within the heart: this is a high risk factor for pulmonary embolus and stroke. In addition, there is ineffective filling of the ventricles, leading to a reduced cardiac output. AF is thus important because of the increased risk of mortality.
Because AF usually occurs against a background of existing heart disease, the symptoms may be overlooked or attributed to the existing problem. Even without underlying heart disease, the irregular rhythm itself can cause
• Palpitations ( awareness of an unpleasant, usually fast and irregular) heartbeat
• Decreased exercise tolerance
• Shortness of breath
• Weakness and dizziness
• Sudden drop in blood pressure
Diagnosing AF is done with by an electrocardiogram (ECG). Restoring a normal heart rhythm (cardioversion) is the ideal solution but not always possible. If the rhythm remains abnormal, then you must be protected against stroke. Warfarin prevents clots forming in the atria thereby protecting you against stroke and lung embolus.
If you suspect you may have a heart rhythm disorder, please consult your doctor for a referral to a cardiologist.