Cardiac arrhythmias are a general term describing collective group of disorders of the normal heart rhythm. Importance of the disturbances from the regular cardiac pattern arises when consider the wide range of underlying causes as well as the serious sometimes life-threatening complications of these rhythmical disarrangements. In terms of nursing management of arrhythmias, proper diagnosis of the disorder is achieved with reading of the electrocardiography (ECG), and general rules of appropriate nursing interventions are necessary once the diagnosis is affirmed.
Understanding of the arrhythmias, however, requires knowledge of the heart conductive system. To start with, the heart has two type of cells - mechanical (responsible for cardiac contraction), and electrical (transferring an electrical impulse). The electrical activity occurs first and it is registered on the ECG before the palpation of the peripheral pulse. All myocardial cells have electrical activities; however, it is the electrical cells, clustered in particular areas, that assure the formation and firing the impulses (automacy), response to electrical impulses (excitability), rapid transfer an impulse to the juxtaposing cells (conduction), and no response to further impulses within specific period after stimulation (refraction).
These properties of the electrical cells are due to different concentration of three major ions across the membranes: Na+, K+, and Ca2+. Put in simple, K+ is a predominant ion inside the cells when they are in rest, as opposite for the Ca2+ and Na+. Once the electrical impulse is initiated, there is a shift of K+ out of cells, and Na+ and Ca2+ into the cells. The areas of the heart with greater concentration of electrical cell form the cardiac conductive system. The travel of the electrical impulses normally goes after of the track displaced bellow. The cells of the sinoatrial (SA) node (found in the right atrium) generates of rate of 60-100 per minute.