fusion beat

beat (bēt) a throb or pulsation, as of the heart or of an artery.

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apex beat  the beat felt over the apex of the heart, normally in or near the fifth left intercostal space.

atrioventricular (AV) junctional escape beat  a depolarization initiated in the atrioventricular junction when one or more impulses from the sinus node are ineffective or nonexistent.

atrioventricular (AV) junctional premature beat  see under complex.

capture beats  in atrioventricular dissociation, occasional ventricular responses to a sinus impulse that reaches the atrioventricular node in a nonrefractory phase.

ectopic beat  a heart beat originating at some point other than the sinus node.

escape beat , escaped beat heart beats that follow an abnormally long pause.

forced beat  an extrasystole produced by artificial stimulation of the heart.

fusion beat  in electrocardiography, the complex resulting when an ectopic ventricular beat coincides with normal conduction to the ventricle.

heart beat  heartbeat.

interpolated beat  a contraction occurring exactly between two normal beats without altering the sinus rhythm.

junctional escape beat  atrioventricular junctional escape b.

junctional premature beat  atrioventricular junctional premature complex.

postectopic beat  the normal beat following an ectopic beat.

premature beat  extrasystole.

pseudofusion beat  an ineffective pacing stimulus delivered during the absolute refractory period following a spontaneous discharge but before sufficient charge accumulates to prevent pacemaker discharge.

reciprocal beat  a cardiac impulse that in one cycle causes ventricular contraction, travels backward toward the atria, then reexcites the ventricles.

reentrant beat  any of the characteristic beats of a reentrant circuit.

retrograde beat  a beat resulting from impulse conduction that is backward relative to the normal atrioventricular direction.

ventricular escape beat  an ectopic beat of ventricular origin occurring in the absence of supraventricular impulse generation or conduction.

ventricular premature beat  (VPB) see under complex.

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fusion beat

n.

The atrial or ventricular complex in an electrocardiogram when either the atria or the ventricles are activated by two simultaneously invading impulses.

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fusion beat,

in an electrocardiogram, a P wave or QRS complex resulting from the concurrent activation of the atria or the ventricles by two stimuli in the same chamber. An atrial fusion beat results when the sinus beat coincides with an atrial ectopic beat, when two atrial ectopic beats coincide, or when an atrial or sinus beat coincides with retrograde conduction from a junctional focus. A ventricular fusion beat results when a ventricular beat coincides with a sinus beat, a ventricular ectopic beat, or a junctional beat.

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beat

a throb or pulsation, as of the heart or of an artery.

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apex beat

the palpable shock caused by the apex of the heart beating against the chest wall with each systole and felt over the apex of the heart, normally in the fifth left intercostal space. May be replaced by a thrill.

Palpitation of the apex beat. By permission from Hinchcliff KW, Kaneps AJ, Equine Sports Medicine and Surgery, Saunders, 2004

capture b's

occasional ventricular responses to a sinus impulse that reaches the atrioventricular node in a nonrefractory phase.

ectopic beat

a heartbeat originating at some point other than the sinus node.

escaped b's

heartbeats that follow an abnormally long pause.

forced beat

an extrasystole produced by artificial stimulation of the heart.

fusion beat

in electrocardiography, the complex resulting when an ectopic ventricular beat coincides with normal conduction to the ventricle.

premature beat

an extrasystole.

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fusion beat

Cardiology The superimposing of an ectopic beat on a paced natural sinoatrial node beat; an FB is usually narrower than a paced impulse and has various morphologies that reflect the relative contributions of the impulse to the venticular depolarization. See Pseudofusion beat.