Arrhythmias

In this session, we’re going to look at cardiac arrhythmias. Cardiac arrhythmias may be defined as a disturbance of the normal heart rhythm. Arrhythmias are important because they’re a major cause of sudden cardiac arrests in this country. And currently, there are about 100,000 people each year that die from sudden cardiac arrest. When this occurs, the only chance to save the victim is to combine CPR with a defibrillator. Arrhythmias are significant because they reduce the efficiency of the heart and significantly reduce cardiac output. They may be classified as either fast or tachyarrhythmias, or they may be described as slow bradyarrhythmias, or they may be chaotic in nature, in which case they are described as fibrillation.

So what are the main causes of arrhythmias? They may occur in response to heart failure, coronary artery disease, high blood pressure. They may occur in response to mutations (genetic mutations) or even following a fever. The easiest way to diagnose arrhythmias is using the electrocardiogram, or the ECG. That measures the electrical activity of the heart. Arrhythmias always result in alterations to the electrical activity of the heart that will be detectable used in this method. Tacchyarrhythmias, or fast arrhythmias, usually occur as a result of reentry currents that reactivate either the atria or the ventricles. These can cause the atria or the ventricles to contract very fast. And when these contract very fast, these are referred to as flutters.

When they are more chaotic in nature, these are described as fibrillation.

Bradyarrhythmias tend to occur either as a result of problems associated with the pacemaker, in which there are changes in ionic currents within the sinoatrial node, the pacemaker on the right atrium. Or there may be problems associated with conduction of the electrical signal through the heart. Bradyarrhythmias may also occur in response to changes in the conduction pathways, and this may affect the rate and the speed with which the electrical activity can pass through the heart. This usually occurs in response to damage following coronary artery disease that can damage different regions of the heart. The electrocardiogram will enable the position of any damage to be determined.

In addition to significant changes to cardiac output as a result of arrhythmias, patients with arrhythmias are also at risk from blood clots, and may require anticoagulation therapy. The presence of clots increase significantly the risk of strokes. If the problem associated with the heart is due to the pacemaker or the sinoatrial node on the right atrium of the heart, it’s possible that pacemaker therapy can be used to treat this condition.