| ventricular arrhythmia | <cardiology> A cardiac arrhythmia which originates from within the ventricles. Isolated ventricular contractions are referred to as premature ventricular contractions. Frequent premature ventricular contractions can be potentially unstable and can degrade to a more serious rhythm or cardiac arrest. (12 Jan 1998) |
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| reentry | Return of the same impulse into a zone of heart muscle that it has recently activated; sufficiently delayed that the zone is no longer refractory, as seen in most ectopic beats, reciprocal rhythms, and most tachycardias. (05 Mar 2000) |
| reentry theory | That extrasystoles are due to reentry of an impulse initiated by the sinus impulse, to which the extrasystole is coupled, into the ectopic focus. (05 Mar 2000) |
| tachycardia, atrioventricular nodal reentry | A tachycardia characterised by rates between 150 and 250 beats per minute and a qrs complex of supraventricular origin. (12 Dec 1998) |
| tachycardia, sinoatrial nodal reentry | A tachycardia arising from the sinus node region and characterised by rates between 115 and 140 beats per minute. It is paroxysmal rather than constant. (12 Dec 1998) |
| anti-arrhythmia agents | Agents used for the treatment or prevention of cardiac arrhythmias. They may affect the polarization-repolarization phase of the action potential, its excitability or refractoriness, or impulse conduction or membrane responsiveness within cardiac fibres. Anti-arrhythmia agents are often classed into four main groups according to their mechanism of action: sodium channel blockade, beta-adrenergic blockade, repolarization prolongation, or calcium channel blockade. (12 Dec 1998) |
| arrhythmia | <cardiology, physiology> Any variation from the normal rhythm of the heart beat, including sinus arrhythmia, premature beat, heart block, atrial fibrillation, atrial flutter, pulsus alternans and paroxysmal tachycardia. Origin: Gr. Rhythmos = rhythm (18 Nov 1997) |
| arrhythmia, sinus | Irregularity of the heart rate related to functioning of the sinoatrial node. (12 Dec 1998) |
| cardiac arrhythmia | A disturbance the electrical activity of the heart that manifests as an abnormality in heart rate or heart rhythm. Patients with a cardiac arrhythmia may experience a wide variety of symptoms ranging from palpitations to fainting. (27 Sep 1997) |
| respiratory arrhythmia | Phasic sinus arrhythmia or any other rhythm fluctuation induced by respiratory fluctuation. (05 Mar 2000) |
| perpetual arrhythmia | An obsolete term for atrial fibrillation. (05 Mar 2000) |
| phasic sinus arrhythmia | Sinus arrhythmia in which the irregularity is related to the phases of respiration, the rate being faster in inspiration and slower in expiration. (05 Mar 2000) |
| sinus arrhythmia | <cardiology, physiology> An increase in heart rate during inspiration. A normal physiologic response, more pronounced in children. (27 Sep 1997) |
| nonphasic sinus arrhythmia | Sinus arrhythmia in which variations in rhythm are not related to the phases of respiration. (05 Mar 2000) |
| supraventricular arrhythmia | <cardiology> A cardiac arrhythmia which has its origin within the sinus node or atrium (above the ventricles). (27 Sep 1997) |