atrial tachycardia

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  • 1. Atrial Tachycardia 1

2. Atrial Tachycardia Atrial tachycardias (ATs) are an uncommon cause ofsupraventricular tachycardia (SVT): Adults - 5% of all SVTs subject to EP studies Pediatric patients: 10-15% of the SVTs in pediatric patients without congenital heart defects (CHD) More in those who have undergone a surgical correction of their CHD(Zipes DP, Jalife J. Cardiac Electrophysiology: From cell to bedside, 4th edition. 2004; pg. 500)2 3. Atrial Tachycardias Locations:Tachycardia originating inatrial muscle at a site(s) otherthan the sinus node or the AVnode. Mechanisms:Abnormal automaticity,trigger activities, or reentry3 4. Mechanisms based on Ablation Focal AT: activation spreading from a singlefocus either radially, circularly or centrifugallywithout an electrical activation spanning thetachycardia cycle length. 4(Zipes DP, Jalife J. Cardiac Electrophysiology: From cell to bedside, 4th edition. 2004; pg. 500-501) 5. Classification of Mechanisms Macroreentrant : reentry occurring over fairly largewell-defined circuits that span the entire tachycardiacycle length(>70%). Also the earliest and latest atrialactivations are in close proximity. The various patterns are: Single loop (like typical atrial flutter) Figure of eight (made up of two loops) Reentry through narrow channels adjacent to scar,anatomic barriers (i.e. tricuspid annulus) 5(Zipes DP, Jalife J. Cardiac Electrophysiology: From cell to bedside, 4th edition. 2004; pg. 500-501) 6. Focal Atrial Tachycardias6 7. Focal Atrial Tachycardias Focal atrial tachycardia has three mechanisms:automaticity, triggered activity and microreentry. Automatic atrial tachycardia is identified by the presence of the following characteristics: AT can be initiated by an isoproterenol infusion PES cannot initiate or terminate the AT AT can be gradually suppressed with overdrive pacing, butthen resumes with a gradual increase in the atrial rate AT is terminated by propranolol AT episodes have a warm up and/or cool downphenomenon AT cannot be terminated by adenosine 7(Zipes DP, Jalife J. Cardiac Electrophysiology: From cell to bedside, 4th edition. 2004; pg. 500-501) 8. Focal Atrial Tachycardias Triggered activity is identified by the presence of the followingcharacteristics: AT can be initiated with rapid atrial pacingNo entrainment is observed, but overdrive suppression ortermination occurs Delayed afterdepolarizations can be recorded near the originusing a monophasic action potential catheter before the ATonset, but not at sites remote from the tachycardia AT terminated by adenosine, propranolol, verapamil,, Valsava maneuvers and carotid sinus pressure 8(Zipes DP, Jalife J. Cardiac Electrophysiology: From cell to bedside, 4th edition. 2004; pg. 500-501) 9. Focal Atrial TachycardiasMicroreentry is identified by the presence of the following characteristics: AT can be reproducibly initiated and terminated byatrial pacing and extrastimuli No delayed afterdepolarizations can be recorded usinga monophasic action potential catheter Manifest and concealed entrainment observed whilepacing during the tachycardia 9(Zipes DP, Jalife J. Cardiac Electrophysiology: From cell to bedside, 4th edition. 2004; pg. 500-501) 10. Focal Atrial Tachycardia Focal AT in a post-open heart patient with the focus originating in theright atrial free wall with centrifugal spread of the activation.10(Zipes DP, Jalife J. Cardiac Electrophysiology: From cell to bedside, 4th edition. 2004; pg. 502) 11. MOST COMMON SITES Right Atrium Right Atrial Appendage Coronary Sinus Ostium Crista Terminalis Left Atrium Pulmonary Vein Ostia Left Atrial Appendage11 12. 12 13. Focal Atrial Tachycardia - RightAtrial AppendageRight AtrialAppendage13AP View 14. Focal Atrial Tachycardia Coronary Sinus OstiumLAO VIEWTricuspid Valve Effective Site14 CS Os LAO View 15. Focal Atrial Tachycardia Left Sided Focus (RA Septum is Early)PA VIEW OFRA SEPTUM HISCS OS15PA View 16. Electrocardiographic Localization of Focal AT Focal atrial tachycardia is characterized by P waves separated by an isoelectric interval in all ECG leads. The P-wave can often be obscured by the T wave or QRS complexes during the 16tachycardia. 17. Focal AT Sites17(Tada H, et al. Simple Electrocardiographic Critera for Identifying the Site of Origin of Focal Right Atrial Tachycardia. PACE 1998;21[Pt. II]:2431-2439 18. Electrocardiographic Localization of Right Focal AT Short-PR18(Tada H, et al. Simple Electrocardiographic Critera for Identifying the Site of Origin of Focal Right Atrial Tachycardia. PACE 1998;21[Pt. II]:2431-2439 19. AT Arising from the Crista Terminalis The CT is a common site for ATs (as much as 75% of right ATs). CT demonstrates marked anisotropy due to poor transverse cell to cell coupling. This may create slow conduction and thus microreentry. Also the CT contains a cluster of cells with automaticity. If superolateral, they will have positive P-waves in leads, II, III and aVF. If inferolateral, they will have negative P-waves in leads, II, III and aVF.(Zipes DP, Jalife J. Cardiac Electrophysiology: From cell to bedside, 4th edition. 2004; pg. 504)19 20. Representative Focal AT 12-Lead ECGs A: A CT-AT that originated from segment 1. B: A CT-AT that originated from segment 2.20(Tada H, et al. Simple Electrocardiographic Critera for Identifying the Site of Origin of Focal Right Atrial Tachycardia. PACE 1998;21[Pt. II]:2431-2439 21. AT Arising from the AV Annulus ATs arising for the tricuspid annulus are relatively uncommon, accounting for only about 13% of right atrial ATs. The P-wave will be negative in the precordial and inferior leads. ATs may also arise form the mitral valve annulus. In that case the P-waves are negative in aVL and positive in V1. The demonstration of cells with AV nodal EP properties lacking connexin43 near the annulus, the mechanism is believed to be microreentry involving these nodal-like cells.(Zipes DP, Jalife J. Cardiac Electrophysiology: From cell to bedside, 4th edition. 2004; pg. 504)21 22. Representative Focal AT 12-Lead ECGs A: A TA-AT that originated from segment 1. B: A TA-AT that originated from segment 3. C: A Sep-AT that originated from near the apex of Kochs triangle, showing narrow P waves with an initial large negative and a late small positive component in leads II, III and aVF. 22(Tada H, et al. Simple Electrocardiographic Critera for Identifying the Site of Origin of Focal Right Atrial Tachycardia. PACE 1998;21[Pt. II]:2431-2439 23. AT Arising from the CSos Musculature Focal ATs of up to 12% of right ATs occur in the area around the CSos, outside or just inside the os. In very rare cases, AT can occur from deep in the CS and arises from the CS musculature. These cannot usually be ablated from the left atrial endocardium and need to be ablated from within the CS. A negative P-wave in V6 is often seen in ATs originating from the CSos.(Zipes DP, Jalife J. Cardiac Electrophysiology: From cell to bedside, 4th edition. 2004; pg. 504)23 24. AT Arising from the Atrial SeptumThese ATs are sensitive to lower doses of adenosine than ATs arising from the crista terminalis. These also more often require the use of isoproterenol to induce than right atrial free wall ATs.In up to 10% of ATs in the right atrium can arise from the apex of Kochs triangle (para-hisian). These are adenosine sensitive and can be induced with isoproterenol. These can usually be ablated without damage to the AV node.The P-wave duration for these ATs is on average 20 msec shorter during AT than sinus rhythm.In these patients it is important to map both the right and left atria. In patients with a left-sided origin, the P-waves can be either positive or negative in V1, so it is misleading. Up to 40% of patients with the earliest activation recorded in Kochs triangle have a left atrial focus.(Zipes DP, Jalife J. Cardiac Electrophysiology: From cell to bedside, 4th edition. 2004; pg. 504)24 25. Sinus Node Reentrant TachycardiaSinus Node Reentrant Tachycardias are presumed to bedue to microreentry in the tissue near the sinus node or theperinodal region (superior crista terminalis). The P-Wavemorphology is identical to that during sinus rhythm.Focal ATs may also arise from the superior vena cava(SVC). Those ATs arising from around the SVC mayconduct to the right atrium (RA).(Zipes DP, Jalife J. Cardiac Electrophysiology: From cell to bedside, 4th edition. 2004; pg. 505)25 26. Inappropriate Sinus Tachycardia The hallmark feature of inappropriate sinus tachycardia (IST) isa consistently elevated resting heart rate and exaggerated heartrate response to low levels of physical activity.Some patients may have primary autonomic abnormalities,including postural orthostatic tachycardia syndrome. Others mayhave primary abnormalities of the sinus node. These patients show a blunted response to adenosine (0.1 to 0.15mg/kg) with less of a sinus cycle length prolongation than age-matched controls. Thus structural abnormalities of the sinusnode are the cause of IST in those patients.(Zipes DP, Jalife J. Cardiac Electrophysiology: From cell to bedside, 4th edition. 2004; pg. 505)26 27. ECG Differential Diagnosis of AT ATs, especially septal ATs, need to be differentiated fromconcealed septal bypass tracts, AV node reentry (fast-slow atypicalAVNRT).1. When AV block occurs, a bypass tract can be ruled out (AV block also observed in AV node reentry).2. Adenosine may also terminate AT.3. Only AT patients experienced oscillations in the atrial cycle length.(Zipes DP, Jalife J. Cardiac Electrophysiology: From cell to bedside, 4th edition. 2004; pg. 505)27 28. ECG Differential Diagnosis of AT Burst pacing from the right ventricle for 3-6 beats duringthe tachycardia at a cycle length faster than thetachycardia results in:1) tachycardia termination; 2)entrainment of the tachycardia; 3) dissociation of theventricle from the tachycardia. If the ventricles are dissociated from the tachycardia, ab

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