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slowness of the heartbeat, so that the pulse rate is less than 60 per minute. This can occur in normal persons, particularly during sleep; trained athletes also usually have slow pulse and heart rates. adj., adj bradycar´diac.
fetal bradycardia a fetal heart rate of less than 120 beats per minute, generally associated with hypoxia; it is usually due to placental insufficiency; it may also result from transfer of local anesthetics or beta-adrenergic blocking agents, and rarely to heart block associated with congenital heart disease or maternal collagen vascular disease.
nodal bradycardia bradycardia in which the stimulus of the heart's contraction arises in the atrioventricular node or common bundle.
sinoatrial bradycardia (sinus bradycardia) a slow sinus rhythm, with a heart rate of less than 60 beats per minute in an adult; it is common in young adults and in athletes but is also a manifestation of some disorders.
bradycardia originating in the normal sinus pacemaker.
sinus bradycardiaA heart rhythm caused by sinus-node dysfunction (sick sinus syndrome), which is characterised by a rhythm of less than 60 beats/minute.
Lightheadedness, dizziness, hypotension and syncope.
Vagal hypertonicity, hypothermia, hypothyroidism, SA node disease, drugs (e.g., digitalis, beta blockers, calcium channel blockers), viral myocarditis or bacterial endocarditis.
Normal P waves, P-R interval of 0.12–0.20 seconds, QRS complex < 0.12 seconds.
sinus bradycardiaCardiology Sinus-node dysfunction–sick sinus syndrome characterized by a normal P-wave axis of < 60 beats/min EKG Every P wave is followed QRS complexes , or at < 50 beats/min. See Sick sinus syndrome. Cf Sinus tachycardia.
si·nus bra·dy·car·di·a(sī'nŭs brad'ē-kahr'dē-ă)
A heart rate less than 60 beats per minute with a normal rhythm.