With the first ribs fixed by neck muscles (scalene muscles and sternocleidomastoid muscle), the intercostals muscles (especially external intercostal muscles and interchondral part of internal intercostal muscles of opposite side), elevate the 2nd to 12th ribs and thus act as inspiratory muscles.
Medical Dictionary. arrhythmia. play. noun arÂ·rhythÂ·mia \Ä-Ërith-mÄ-É\. Medical Definition of arrhythmia. : an alteration in rhythm of the heartbeat either in time or force.
An arrhythmia is an abnormal heart rhythm caused by a problem in the heart's electrical system, also called the cardiac conduction system. When a child has SVT, the heart suddenly starts to beat very fast, at rates of 180 to 280 beats a minute and up to 300 beats a minute in infants.