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Ectopic Complexes: Difference between revisions
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[[Image:Rhythm_premature.png|thumb| An [[Atrial_Premature_Complexes|atrial]] with a noncompensatory pause.]] | [[Image:Rhythm_premature.png|thumb| An [[Atrial_Premature_Complexes|atrial]] with a noncompensatory pause.]] | ||
[[Image:Rhythm_ventricular_premature.png|thumb|A [[Premature ventricular beats(PVB) / Venticular extrasystoles (VES)|ventricular extrasystole]] with a compensatory pause]] | [[Image:Rhythm_ventricular_premature.png|thumb|A [[Premature ventricular beats(PVB) / Venticular extrasystoles (VES)|ventricular extrasystole]] with a compensatory pause]] | ||
[[Image:pacemaker_rates. | [[Image:pacemaker_rates.svg|thumb|Mycoardial cells with pacemaker activity]] | ||
The pacemaker cells in the sinus node are not the only cells in the heart that can depolarize spontaneously. Actually all cardiomyoctyes have this capacity. The only reason why the sinus node 'rules' is that it is the fastest pacemaker of the heart. All healthy cardiomyocytes from the sinus node to the ventricles can function as ectopic pacemakers. Ectopic pacemaker activity can originate from the atria (60-80 bpm), AV-node (40-60 bpm) and the ventricles (20-40 bpm). So, as the sinus rate drops (e.g. during atrial infarction), other cells can take over. The configuration of ectopic | The pacemaker cells in the sinus node are not the only cells in the heart that can depolarize spontaneously. Actually all cardiomyoctyes have this capacity. The only reason why the sinus node 'rules' is that it is the fastest pacemaker of the heart. All healthy cardiomyocytes from the sinus node to the ventricles can function as ectopic pacemakers. Ectopic pacemaker activity can originate from the atria (60-80 bpm), AV-node (40-60 bpm) and the ventricles (20-40 bpm). So, as the sinus rate drops (e.g. during atrial infarction), other cells can take over. The configuration of ectopic complexes, or extrasystoles, as seen on the ECG, reveals its origin, whether they are [[Atrial_Premature_Complexes|atrial]], nodal or [[ves|ventrical]]. | ||
==Ectopic pacemakers== | ==Ectopic pacemakers== | ||
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==Compensatory or noncompensatory pause== | ==Compensatory or noncompensatory pause== | ||
The duration of the interval following a premature | [[File:comppause.svg|thumb|A ladder diagram showing a non-compensatory pause following an atrial premature beat that resets the sinus node and fully compensatory pause following a ventricular premature beat that does not reach the sinus node.]] | ||
The duration of the interval following a premature complex can help in the differentiation of a atrial or ventricular premature complex. | |||
===Non-compensatory pause, following an atrial premature complex=== | ===Non-compensatory pause, following an atrial premature complex=== | ||
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===Fully compensatory pause, following a ventricular premature complex=== | ===Fully compensatory pause, following a ventricular premature complex=== | ||
The electrical activity of a ventricular premature complex is usually not conducted through the AV node towards the atria. The sinus node will not be reset. If the next sinus complex finds the AV nodal tissue still refractory (and thus not conducting) there will be a pause until the next sinus complex follows. The interval between the premature ventricular complex and the next sinus complex will be longer (longer than 1 second in the above sample of a heart rate of 60/min). This is called a fully compensatory pause. With the use of a caliper, the preceding sinus rate can be tracked beyond the ventricular premature complex. This is a telltale sign of a ventricular premature complex without retrograde conduction. | The electrical activity of a ventricular premature complex is usually not conducted through the AV node towards the atria. The sinus node will not be reset. If the next sinus complex finds the AV nodal tissue still refractory (and thus not conducting,) there will be a pause until the next sinus complex follows. The interval between the premature ventricular complex and the next sinus complex will be longer (longer than 1 second in the above sample of a heart rate of 60/min). This is called a fully compensatory pause. With the use of a caliper, the preceding sinus rate can be tracked beyond the ventricular premature complex. This is a telltale sign of a ventricular premature complex without retrograde conduction. | ||
==Parasystole== | ==Parasystole== | ||
[[Image:parasystole_12lead.jpg|thumb|An example of parasystole on a 12 lead ECG]] | [[Image:parasystole_12lead.jpg|thumb|An example of parasystole on a 12 lead ECG]] | ||
[[Image:Paraystole_rhythmstrip.jpg|thumb|This rhythm strip shows clear parasystole. Here the origin of the ectopic beats is somewhat distal to the HIS bundle.]] | [[Image:Paraystole_rhythmstrip.jpg|thumb|This rhythm strip shows clear parasystole. Here the origin of the ectopic beats is somewhat distal to the HIS bundle.]] | ||
Parasystole is the phenomenon that results from two competing pacemakers in the heart. Usually a supraventricular and nodal/ventricular pacemaker compete. For example, sinus rhythm might be interfered with by ventricular ectopic beats. The basic rhythm in this example would be sinus rhythm with a rate of 60/min. Ectopic ventricular complexes can be seen interfering with this rate and rhythm. Parasystole is diagnosed when the ectopic | Parasystole is the phenomenon that results from two competing pacemakers in the heart. Usually a supraventricular and nodal/ventricular pacemaker compete. For example, sinus rhythm might be interfered with by ventricular ectopic beats. The basic rhythm in this example would be sinus rhythm with a rate of 60/min. Ectopic ventricular complexes can be seen interfering with this rate and rhythm. Parasystole is diagnosed when the ectopic complexes have a constant RR interval, e.g. 1500ms, resulting in a rate of 20 ventricular ectopic complexes per minute. [[Fusion complexes]] are often present as the two rhythms are dissociated. | ||
{{clr}} | {{clr}} | ||