| ventricular fusion beat | A fusion beat that occurs when the ventricles are activated partly by the descending sinus or A-V junctional impulse and partly by an ectopic ventricular impulse. (05 Mar 2000) |
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| parasystolic beat | A cardiac arrhythmia caused by the interaction of two foci independently initiating cardiac impulses at different rates. Generally one of the foci is the sinoatrial node (the normal pacemaker) and the ectopic focus is usually in the ventricle, but can occur in the sinus and av nodes, atrium and ventricle, and av junction. Each focus - and thus each rhythm - is protected from the influence of the other. (12 Dec 1998) |
| reciprocal beat | See: reciprocal rhythm. (05 Mar 2000) |
| retrograde beat | A beat occurring as an electrical activation of a portion of a heart chamber cephalad to the chamber of origin, e.g., an atrial beat triggered by an impulse originating in the ventricle. (05 Mar 2000) |
| mixed beat | A beat triggered by more than a single electrical impulse, when the wave fronts coincide to act together on a single final pathway of activity; in the electrocardiogram, the atrial or ventricular complex when either atria or ventricles are activated jointly by two simultaneous or nearly simultaneous invading impulses. Synonym: combination beat, mixed beat, summation beat. (05 Mar 2000) |
| combination beat | A beat triggered by more than a single electrical impulse, when the wave fronts coincide to act together on a single final pathway of activity; in the electrocardiogram, the atrial or ventricular complex when either atria or ventricles are activated jointly by two simultaneous or nearly simultaneous invading impulses. Synonym: combination beat, mixed beat, summation beat. (05 Mar 2000) |
| premature beat | A premature contraction of the heart that is independent of the normal rhythm and arises in response to an impulse in some part of the heart other than the sinoatrial node. Synonym: premature beat. (18 Nov 1997) |
| heart beat | A complete cardiac cycle, including spread of the electrical impulse and the consequent mechanical contraction. Synonym: ictus cordis. (05 Mar 2000) |
| pseudofusion beat | <cardiology, physiology> An electrocardiographic representation of a cardiac depolarisation produced by superimposition of an ineffectual electronic pacemaker spike upon a QRS-complex originating from a spontaneous focus within the heart. The pacemaker spike is ineffectual because the electronic discharge, which it represents graphically, occurred within the absolute refractory period of the spontaneous beat and is therefore not indicative of pacemaker malfunction. (21 Jun 2000) |
| summation beat | A beat triggered by more than a single electrical impulse, when the wave fronts coincide to act together on a single final pathway of activity; in the electrocardiogram, the atrial or ventricular complex when either atria or ventricles are activated jointly by two simultaneous or nearly simultaneous invading impulses. Synonym: combination beat, mixed beat, summation beat. (05 Mar 2000) |
| dependent beat | <cardiology, physiology> An extrasystole supposedly precipitated in some way by the preceding normal beat to which it is coupled, an extrasystole caused by artificial stimulation of the heart. Synonym: dependent beat. (05 Mar 2000) |
| Dressler beat | Fusion beat interrupting a ventricular tachycardia and producing a normally narrow QRS complex as a result of the fusion of two impulses, one impulse from the ventricular tachycardia and the other from a supraventricular focus; Dressler beat's strongly support the diagnosis of ventricular tachycardia by interruption of it. (05 Mar 2000) |
| dropped beat | A heart beat that fails to appear. (05 Mar 2000) |
| interference beat | Ventricular capture in forms of A-V dissociation due to interference. (05 Mar 2000) |
| echo beat | Extrasystole produced by the return of an impulse in the heart retrograde to a focus near its origin which then returns antegradely to produce a second depolorization. (05 Mar 2000) |