ARHINENCCPHALIA ARRHYTHMIA

refers to the abnormal rhythm of the heartbeat. The specific nature of the change in heart rhythm is relatively important in terms of diagnosis and therapy. Normal rhythm for an infant may be as high as 150 beats per minute, whereas this would be considered to be tachycardia (any rate above 100 per minute) and perhaps a sign of a cardiac emergency for an adult. A rate of less than 60 beats per minute (bradycardia) may also signal the presence of heart disease. Other specific types of arrhythmias include premature beats- atrial flutter, in which one of the upper chambers contracts at a rate of as much as 400 times per minute- and heart block. The latter is indicated by a marked failure of the heart to contract because of the interruption or delay of an electrical stimulus needed to trigger the contraction.