Section I. DYSRHYTHMIA
a. Dysrhythmia is a disturbance in cardiac rhythm. Ninety percent of patients with acute myocardial infarction (heart attack) will experience a form of cardiac dysrhythmia during the first couple of weeks after their attack. Half of these will be life threatening and will lead to cardiac arrest (sudden stoppage of adequate cardiac output) unless properly treated. In order to analyze and treat a dysrhythmia correctly, you must have a systematic approach to the electrocardiogram (EKG). Only after this process has been completed can you make sound judgments as to which cardiac drug to administer and when to defibrillate or use cardioversion.
b. When monitoring a patient's EKG, remember that you are monitoring electrical activity of a heart, not mechanical activity. A pulse is always taken to assure you of the heart's pumping action. Information learned from the EKG will be used to help determine the treatment of the dysrhythmia. Dysrhythmia treatment could be defibrillation, cardioversion, intravenous cardiac drugs, and/or cardiopulmonary resuscitation (CPR).
DYSRHYTHMIA -- a disturbance in cardiac rhythm
ELECTROCARDIOGRAM -- monitors electrical activity of the heart
1-2. DYSRHYTHMIA CAUSES/SIGNIFICANCE
a. Causes of Dysrhythmia. Dysrhythmias develop for various reasons, including acute myocardial infarction (heart attack), trauma, and drug reactions.
Drowning, near drowning, asphyxiation, and the patient's underlying medical conditions can also cause dysrhythmias.
b. Significance of Dysrhythmia. There are several reasons why cardiac dysrhythmias may be clinically significant. Heart rates below 40 to 50 beats per minute lead to inadequate cardiac output and often precede electric instability of the heart. If the sinus rate falls below 60 beats per minute, another conduction system may take over. The atrial-ventricular junction (AV junction) has an inherent rate of 40 to 60 beats a minute. The ventricle has an inherent rate of 20 to 40 beats a minute. This may lead to premature ventricular contractions and ventricular dysrhythmias. If a heart rate is over 120 to 140 beats per minute, the heart must work harder. This causes further myocardial ischemia (diminished blood flow). Tachycardia may be linked with a drop in cardiac output which is secondary to decreased stroke volume, this lowered volume being caused by the ventricles having less time to fill between heartbeats. Finally, ectopic beats (beats located away from the normal position) could be a sign of electric instability of the ventricles. Such heartbeats are an important sign since they may indicate that more serious dysrhythmias, such as ventricular tachycardia or ventricular fibrillation, may develop.