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.
Arrhythmias are abnormal heart rhythms. Some arrhythmias are normal variants (such as the respiratory sinus arrhythmia in dogs). Dangerous arrhythmias are those that result in clinical signs and/or put the animal risk of sudden cardiac death. Sinus node disease results in too low of heart rate (bradycardia).