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Tachycardia: Difference between revisions
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====Clinical diagnosis:==== | ====Clinical diagnosis:==== | ||
If an accessory bundle excites the ventricle earlier than normal AV-conduction, thus has antegrade conduction properties, and can activate the ventricles, pre-excitation is visible on the ECG. This is a can be visible on the ECG by a shortened PQ interval and a widened QRS complex of >120ms due to slurring of the QRS complex (delta wave). This is also called the Wolf-Parkison-White symptom and can occur intermittently. If a patient has pre-excitation and complaints of arrhythmia caused by an AVRT the combination of these two is called the Wolf-Parkinson-White syndrome. Some patient have an AVRT, but no traces of pre-excitation. The bundle is then called a concealed bundle. Patients can be asymptomatic if they only have pre-exitation and this ECG pattern is commonly an incidental finding.<cite>Wellens, Robles</cite> When an arrhythmia develops using the accessory bundle, both types of AVRT can develop depending on the conduction characteristics of the bundle: | If an accessory bundle excites the ventricle earlier than normal AV-conduction, thus has antegrade conduction properties, and can activate the ventricles, pre-excitation is visible on the ECG. This is a can be visible on the ECG by a shortened PQ interval and a widened QRS complex of >120ms due to slurring of the QRS complex (delta wave). This is also called the Wolf-Parkison-White symptom and can occur intermittently. If a patient has pre-excitation and complaints of arrhythmia caused by an AVRT the combination of these two is called the Wolf-Parkinson-White syndrome.<cite>WPW</cite> Some patient have an AVRT, but no traces of pre-excitation. The bundle is then called a concealed bundle. Patients can be asymptomatic if they only have pre-exitation and this ECG pattern is commonly an incidental finding.<cite>Wellens, Robles</cite> When an arrhythmia develops using the accessory bundle, both types of AVRT can develop depending on the conduction characteristics of the bundle: | ||
* Orthodrome AV re-entry tachycardia: There is a P-wave (other morphology than sinus rhythm) followed by small QRS-complex | * Orthodrome AV re-entry tachycardia: There is a P-wave (other morphology than sinus rhythm) followed by small QRS-complex | ||
* Antidrome AV re-entry tachycardia: This is a broad-complex tachycardia, where the broad QRS complex is followed by a retrograde P-wave originating from the AV-node. | * Antidrome AV re-entry tachycardia: This is a broad-complex tachycardia, where the broad QRS complex is followed by a retrograde P-wave originating from the AV-node. | ||
====Management:==== | ====Management:==== | ||
The circuit of the arrhythmia uses the AV node, therefore vagal maneuvers are able to terminate the AVRT. However adenosine should be used with care, as it may induce AF and cause 1:1 conduction. Anti-arrhythmic drugs (Class IC, II, III, IV) can be useful to prevent paroxysms of arrhythmia, and a pill-in-the-pocket approach can be used for patients with infrequent episodes.<cite>Alboni</cite> Catheter ablation can target the accessory pathway and destroy the bundle. The success of the procedure is dependent on the location of the bundle as not all anatomical positions are easily targeted with ablation.<cite>jackman, calkins5</cite> It is controversial if patients with an asymptomatic WPW ECG pattern and no co-morbidities should have an ablation. To determine the risk of 1:1 conduction, an exercise test can be performed to determine the response of the accessory bundle to an increased atria rate. If the pre-exitations persists an electrophysiological procedure can be performed to assess the conduction properties of the accessory bundle. While the characteristics of the bundle predict the risk for an event, the life-style and\or profession of the patient can influence the decision for ablation.<cite>cohen, pappone, priori</cite> | The circuit of the arrhythmia uses the AV node, therefore vagal maneuvers are able to terminate the AVRT. However adenosine should be used with care, as it may induce AF and cause 1:1 conduction. Anti-arrhythmic drugs (Class IC, II, III, IV) can be useful to prevent paroxysms of arrhythmia, and a pill-in-the-pocket approach can be used for patients with infrequent episodes.<cite>Alboni</cite> Catheter ablation can target the accessory pathway and destroy the bundle. The success of the procedure is dependent on the location of the bundle as not all anatomical positions are easily targeted with ablation.<cite>jackman, calkins5</cite> It is controversial if patients with an asymptomatic WPW ECG pattern and no co-morbidities should have an ablation. To determine the risk of 1:1 conduction, an exercise test can be performed to determine the response of the accessory bundle to an increased atria rate. If the pre-exitations persists an electrophysiological procedure can be performed to assess the conduction properties of the accessory bundle. While the characteristics of the bundle predict the risk for an event, the life-style and\or profession of the patient can influence the decision for ablation.<cite>cohen, pappone, priori</cite> | ||