supraventricular arrhythmias jerry john july 29, 2009

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  • Supraventricular arrhythmias Jerry John July 29, 2009
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  • Objectives Supraventricular Arrhythmias How do supraventricular arrhythmias manifest? What are the common supraventricular arrhythmias? What is the mechanism of atrioventricular arrhythmias? Which drugs are used in the management of supraventricular arrhythmias? Which patients should be offered catheter ablation? Atrial Fibrillation and Atrial Flutter What are the incidence and prevalence of atrial fibrillation? What are the major sequelae of atrial fibrillation? What are the risk factors for stroke in atrial fibrillation? What are the treatment options for patients with atrial fibrillation?
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  • History F > M (2:1) AVNRT M >F AVRT Posture Menses 3 rd trimester pregnancy Neck pulsations (Frog sign) Age of onset (10 year difference AVNRT(39) vs. AVRT (26) Thyroid symptoms Acute precipiants (post op, PE, drug withdrawal, ischemia) JACC 2009; 53:2353-58
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  • EKG AV node dependent (Y/N) Re-entrant circuit (Y/N) Circuit (Macro/Micro) Anatomic (e.g. previous ASD repair, CVTI) Accessory pathway ( WPW, Mahaim, etc. ) P wave Rate Morphology (Sinus/Retrograde/abnormal): look at the T waves and the psuedo R (V1) and psedo S (inferior leads) Conduction (2:1; 3:1, etc.) Response to AV Block VA conduction (i.e. R-P relationship): (short/long) Initiation (PAC or PVC) & Termination (P wave or QRS)
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  • Anatomy & Physiology SA node 1 mm subendocardial near RSPV AV node Decremental conduction properties His-Purkinje Accessory pathways No decremental conduction AV conduction 10-20 ms
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  • AVNRT Atach (reentry or automaticity) ORT Non paraoxysmal junctional tach
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  • AV Node Depdendence (Y/N) AV nodal dependent arrhythmias AVNRT (micro-reentrant circuit) AVRT (macro-reentrant circuit): anti/orthodromic JET (junctional ectopic tachycardia) - childhood and associated with congenital heart disease AV nodal independent arrhythmias Atrial tachycardia Inappropriate Sinus Tachycardia Sinus Node Reentrant Tachycardia Atrial flutter Atrial fibrillation
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  • RP relationship Short RP Tachycardias: Typical AVNRT AVRT Long RP Tachycardias: Atrial Tachycardia Atypical AVNRT AVRT with long retrograde conduction PJRT
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  • Wheres the P wave Valsalva Carotid sinus massage Slows SA nodal; and/or AV nodal conduction Adenosine Slows sinus rate Increases AV nodal conduction delay T 5 seconds 6 or 12 mg bolus Effect blocked by theophylline, methylxanthines (caffeine); and potentiated by dipyridamole
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  • P waves Rate Morphology (Sinus/Retrograde/abnormal) Conduction (2:1; 3:1, etc.) Response to AV Block VA conduction (i.e. R-P relationship): (short/long)
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  • P waves (-) Inferior leads atrial activation from low to high: AVNRT, atypical AVNRT; AVRT Right atrial focus: 1) (-/+) in aVL right atrium activated first and then left atrium) 2) (-) or biphasic in V1 Left atrial focus: 1) (-) or isoelectric in aVL 2) (+) V1 suggests back to front
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  • Tachycardia onset Most SVTs triggered by a PAC If the PAC conducts with a long PR, dual AV nodal physiology is suggested with the conduction being through the slow pathway If a PVC initiates SVT, it is likely to be AV node dependent
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  • Tachycardia termination Ends with a P wave: suggests an AV nodal dependent arrhythmia because the generation of the P wave without a QRS suggests block in the AV node this is more likely to be AVNRT or AVRT AVNRT p waves however can be buried in the QRS if VA conduction is very short Ends with a QRS : almost always atrial tachycardia (some rare AV node dependent tachycardias can terminate in this manner)
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  • AVNRT Most common cause of a regular narrow complex tachycardia Involves a slow and a fast pathway in the region of the AV node Turn around point appears above the bundle of His 160-190 bpm but may exceed 200 bpm Slow-fast form accounts for 90% of AVNRT Fast-slow or slow-slow AVNRT accounts for 10% Pseudo r in V1, pseudo S wave in 2,3,avf, and p wave absence help distinguish AVNRT from AVRT and atrial tachycardia
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  • AVNRT Initiation and termination by APDs, VPDs or atrial pacing during AVW Dual AVN physiology Initiation depends on critical A-H delay Concentric retrograde atrial activation(V-A -42 to 70 msec) Retrograde P wave within QRS with distortion of terminal portion of the QRS Atrium, His bundle and ventricle not required, vagal maneuvers slow and then terminate SVT
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  • Atypical AVNRT Initiation and termination by APDs, VPDs, or ventricular pacing during retrograde AVW Dual retrograde AVN physiology Initiation dependent on critical H-A delay Earliest retrograde activation at CS os Retrograde P wave with long R-P interval Atrium, His bundle, and ventricle not required, vagal, maneuvers slow and then terminate SVT, always in the retrograde slow pathway
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  • AVNRT Treatment Low threshold for catheter ablation given long term success rate > 90% and low risk of complications AV nodal blocking agents (diagnosis/treatment) Adenosine BB/CCB Digoxin Anti-arrhythmics (third choice) Procainamide Amiodarone Disopyramide Flecainide/Propafenone
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  • AVRT Activation sequence is ventricle via atria; therefore P wave often in the ST or T Left lateral AP: (+) Delta V1; (-) Delta I Right sided AP: (-) Delta V1 {QS pattern}; (+) Delta I Concealed AP implies only retrograde conduction; i.e. no pre-excitation and only orthodromic AVRT. Rapidly conducted Afib occurs may occur for 2 reasons: 1) AP may have a short refractory period ; 2) AP does not exhibit decremental conduction properties like the AV node Flecainide and Propafenone preferred as they prolong the effective refractory period
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  • BBB on tachycardia Interval development of BBB and increased tachycardia cycle length suggests contralateral AVRT Pre-existing BBB Rate related BBB: will look like a conventional BBB Accessory pathway
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  • AVRT Use of Adenosine or Verapamil There is a small risk (3-5%) of preferential conduction down the accessory pathway, and ibutilide or procainamide, or electric cardioversion should be immediately available
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  • Asymptomatic WPW 165 children (5-12 years) screened 60 randomized, 3 withdrew: 20 ablation and 27 no ablation 1 child in ablation group had arrhythmia (5%) and 12 of 27 in control group ( 44% ) 2 children in control group had VF and one died Pappone et al; NEJM 2004;351:1197-05
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  • AVRT Treatment Low threshold for catheter ablation given long term success rate > 90% and low risk of complications Posteroseptal pathways have less success rates L sided AV nodal blocking agents (diagnosis/treatment) Adenosine BB orCCB in conjunction with Flecainide or Propafenone
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  • Atrial tachycardia Older patients - related to atrial stretch or scarring If conduction to the ventricle via the AV node, variable AV block may occur A bystander (accessory) pathway may be used to conduct antegrade to the ventricles; i.e. the accessory pathway is not what is causing the atria to beat so fast Tachycardia may be incessant: the ventricle is a slave to the atrium Procainamide may be considered to achieve immediate control AV nodal blocking agents and sotalol may be considered for chronic treatment
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  • Irregular SVT AV block Wenckebach Variable block (e.g. atrial tachycardias) 2:1 with typical flutter; odd multiples with atypical flutter Multifocal atrial tachycardia (MAT) Atrial Fibrillation (with or w/o pre-excitation)
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  • Focal Atrial Tachycardia Incessant or paroxysmal atrial rhythms 120-250 bpm Demographic profile similar to reentrant AT, but less likely to have cardiac surgery Typically 1:1 conduction P wave morphology different from sinus Typically terminate or transiently suppress with adenosine Centrifugal activation Cannot be entrained
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  • Focal Atrial Tachycardia Three Subgroups: 1.Cristal Tachycardia - Initiated and terminated with PES - Arise along crista - P wave similar to NSR - Terminates with adenosine 2.Repetitive monomorphic AT - Repetitive runs of nonsustained AT - Suppress with adenosine - Variable locations 3.Automatic AT - Incessant AT - Transient suppression with adenosine
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  • Macroentrant Atrial Tachycardia Incessant or Paroxysmal atrial rhythms 120-250 bpm Demographic similar to focal atrial tach but more likely to have had cardiac surgery P wave morphology usually differs from sinus Typically are insensitive to adenosine Demonstrate features specific for reentry - concealed or manifest entrainment - fractionated mid diastolic EGMs - concealed activation during diastole
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  • Junctional Tachycardia Nonparoxysmal Junctional Tachycardia Junctional Ectopic Tachycardia Congenital Automatic Junctional Tachycardia


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