Atrial tachycardia

Atrial TachycardiaAtrial Tachycardia

蔡佳醍醫師蔡佳醍醫師台大醫院心臟內科台大醫院心臟內科

Atrial tachycardias (ATs) are an uncommon cause of supraventricular 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

Atrial TachycardiaAtrial Tachycardia

(Zipes DP, Jalife J. Cardiac Electrophysiology: From cell to bedside, 4th edition. 2004; pg. 500)

Atrial TachycardiasAtrial Tachycardias

Locations: Locations: Tachycardia originating in Tachycardia originating in

atrial muscle at a site(s) atrial muscle at a site(s) other than the sinus node or other than the sinus node or the AV node.the AV node.

Mechanisms: Mechanisms: Abnormal automaticity, Abnormal automaticity,

trigger activities, or reentrytrigger activities, or reentry

Focal AT: activation spreading from a single focus either radially, circularly or centrifugally without an electrical activation spanning the tachycardia cycle length.

Mechanisms based on AblationMechanisms based on Ablation

(Zipes DP, Jalife J. Cardiac Electrophysiology: From cell to bedside, 4th edition. 2004; pg. 500-501)

Macroreentrant : reentry occurring over fairly large well-defined circuits that span the entire tachycardia cycle length(>70%). Also the earliest and latest atrial activations 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)

Classification of MechanismsClassification of Mechanisms

Focal Atrial TachycardiasFocal Atrial Tachycardias

• Focal atrial tachycardia has three mechanisms: Focal atrial tachycardia has three mechanisms: automaticity, triggered activity and microreentryautomaticity, triggered activity and microreentry. .

• Automatic atrial tachycardia is identified by the presence Automatic atrial tachycardia is identified by the presence of the following characteristics:of the following characteristics:

• AT can be initiated by an isoproterenol infusionAT can be initiated by an isoproterenol infusion• PES cannot initiate or terminate the ATPES cannot initiate or terminate the AT• AT can be gradually suppressed with overdrive pacing, but AT can be gradually suppressed with overdrive pacing, but

then resumes with a gradual increase in the atrial ratethen resumes with a gradual increase in the atrial rate• AT is terminated by propranololAT is terminated by propranolol• AT episodes have a “warm up” and/or “cool down AT episodes have a “warm up” and/or “cool down phenomenonphenomenon• AT cannot be terminated by adenosineAT cannot be terminated by adenosine

Triggered activity is identified by the presence of the following characteristics:

• AT can be initiated with rapid atrial pacing •No entrainment is observed, but overdrive suppression or

termination occurs• Delayed afterdepolarizations can be recorded near the origin

using a monophasic action potential catheter before the AT onset, but not at sites remote from the tachycardia• AT terminated by adenosine, propranolol, verapamil,

, Valsava maneuvers and carotid sinus pressure

Microreentry is identified by the presence of the following characteristics:

• AT can be reproducibly initiated and terminated by atrial pacing and extrastimuli

• No delayed afterdepolarizations can be recorded using a monophasic action potential catheter

• Manifest and concealed entrainment observed while pacing during the tachycardia

Focal Atrial TachycardiaFocal Atrial Tachycardia

Focal AT in a post-open heart patient with the focus originating in Focal AT in a post-open heart patient with the focus originating in the right atrial free wall with centrifugal spread of the activation.the right atrial free wall with centrifugal spread of the activation.

MOST COMMON SITESMOST COMMON SITES Right AtriumRight Atrium

– Right Atrial AppendageRight Atrial Appendage– Coronary Sinus OstiumCoronary Sinus Ostium– Crista TerminalisCrista Terminalis

Left AtriumLeft Atrium– Pulmonary Vein OstiaPulmonary Vein Ostia– Left Atrial AppendageLeft Atrial Appendage

Right Atrial Appendage

Focal Atrial Tachycardia - Right Focal Atrial Tachycardia - Right Atrial AppendageAtrial Appendage

AP ViewAP View

LAO VIEW

Tricuspid Valve

Effective Site

LAO ViewLAO View

Focal Atrial Tachycardia – Coronary Focal Atrial Tachycardia – Coronary Sinus OstiumSinus Ostium

PA VIEW OF RA

SEPTUM

PA ViewPA View

Focal Atrial Tachycardia – Left Sided Focal Atrial Tachycardia – Left Sided Focus (RA Septum is Early)Focus (RA Septum is Early)

• 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 tachycardia.

Electrocardiographic Localization of Focal ATElectrocardiographic Localization of Focal AT

Focal AT Sites at RAFocal AT Sites at RA

(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

Electrocardiographic Localization of Focal ATElectrocardiographic Localization of Focal AT

(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

Short-PRShort-PR

• The CT is a common site for ATs (as much as 75% of right The CT is a common site for ATs (as much as 75% of right ATs). ATs).

• CT demonstrates marked anisotropy due to poor transverse cell CT demonstrates marked anisotropy due to poor transverse cell to cell coupling. This may create slow conduction and thus to cell coupling. This may create slow conduction and thus microreentry. Also the CT contains a cluster of cells with microreentry. Also the CT contains a cluster of cells with automaticity. automaticity.

• If superolateral, they will have positive P-waves in leads, II, III If superolateral, they will have positive P-waves in leads, II, III and aVF. If inferolateral, they will have negative P-waves in and aVF. If inferolateral, they will have negative P-waves in leads, II, III and aVF. leads, II, III and aVF.

AT Arising from the Crista TerminalisAT Arising from the Crista Terminalis

• 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.

AT Arising from the AV AnnulusAT Arising from the AV Annulus

• 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.

AT Arising from the CSos MusculatureAT Arising from the CSos Musculature

•These 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 Koch’s 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 Koch’s triangle have a left atrial focus.

AT Arising from the Atrial SeptumAT Arising from the Atrial Septum

Sinus Node Reentrant TachycardiaSinus Node Reentrant Tachycardia

•Sinus Node Reentrant Tachycardias are presumed to be due to microreentry in the tissue near the sinus node or the perinodal region (superior crista terminalis). The P-Wave morphology 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 may conduct to the right atrium (RA).

Inappropriate Sinus TachycardiaInappropriate Sinus Tachycardia

• The hallmark feature of inappropriate sinus tachycardia (IST) is a consistently elevated resting heart rate and exaggerated heart rate response to low levels of physical activity.

•Some patients may have primary autonomic abnormalities, including postural orthostatic tachycardia syndrome. Others may have primary abnormalities of the sinus node.

• These patients show a blunted response to adenosine (0.1 to 0.15 mg/kg) with less of a sinus cycle length prolongation than age- matched controls. Thus structural abnormalities of the sinus node are the cause of IST in those patients.

ECG Differential Diagnosis of ATECG Differential Diagnosis of AT

• ATs, especially septal ATs, need to be differentiated from concealed septal bypass tracts, AV node reentry (fast-slow atypical AVNRT).

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.

ECG Differential Diagnosis of ATECG Differential Diagnosis of AT

• Burst pacing from the right ventricle for 3-6 beats during the tachycardia at a cycle length faster than the tachycardia results in:1) tachycardia termination; 2) entrainment of the tachycardia; 3) dissociation of the ventricle from the tachycardia.

• If the ventricles are dissociated from the tachycardia, a bypass tract is excluded.

• If burst RV pacing reproducibly terminates the tachycardia, without conduction to the atrium, AT is excluded.

RV overdrive pacing to DD septal AT from septal RV overdrive pacing to DD septal AT from septal AP or atypical AVNRT AP or atypical AVNRT

• Ventricular burst pacing can also be performed for longer periods of time at a rate just slightly faster than the tachycardia cycle length.

• If the atrial activation sequence during pacing is different than that during tachycardia, an AT is present.

• When pacing is stopped, and the ECG sequence following the last paced ventricular beat demonstrates a V-A-A-V response, an AT is present.

28(Zipes DP, Jalife J. Cardiac Electrophysiology: From cell to bedside, 4th edition. 2004; pg. 1061)

AT with a VAAV PatternAT with a VAAV Pattern

Immediately after the last paced ventricular beat (S), atrial tachycardia Immediately after the last paced ventricular beat (S), atrial tachycardia with a variable degree of atrioventricular (AV) block is demonstrated, with a variable degree of atrioventricular (AV) block is demonstrated, with a typical VAAV pattern. with a typical VAAV pattern.

RA overdrive pacing to DD septal AT from septal RA overdrive pacing to DD septal AT from septal AP or atypical AVNRT AP or atypical AVNRT

• Overdrive right atrial pacing during the tachycardia at a cycle length slightly faster than the tachycardia cycle length can cause termination or tachycardia continuation upon cessation of pacing.

• VA interval measured from the onset of the surface QRS VA interval measured from the onset of the surface QRS on the first postpacing ventricular beat to the onset of the on the first postpacing ventricular beat to the onset of the atrial electrogram on the His catheter of the return cycle.atrial electrogram on the His catheter of the return cycle.

• If the VA interval is within 10 msec of the VA interval during the tachycardia, the tachycardia is due to AVNRT or a bypass tract. If the AV interval is variable or different, AT is present.

DD septal AP from atypical AVNRT DD septal AP from atypical AVNRT

Mechanisms of Macroreentrant ATMechanisms of Macroreentrant AT

Macroreentrant Atrial TachycardiaMacroreentrant Atrial Tachycardia

LIPVLIPV

Macroreentrant AT originating near the LIPV and propagating Macroreentrant AT originating near the LIPV and propagating around the Mitral valve.around the Mitral valve.

Specific Types of Macroreentrant ATSpecific Types of Macroreentrant AT

• Sites of macroreentrant ATs:• Right atrium• Left atrium• Biatrial• Left atrial septum• Right pulmonary veins (single loop and figure of eight)• Between 2 areas of low voltage or around one such area• Left atrial flutters• Reentry involving the CS and its musculature

Entrainment: Fusion Entrainment: Fusion This is a demonstration of pacing with fusion.This is a demonstration of pacing with fusion.

Concealed EntrainmentConcealed EntrainmentThis is a demonstration of concealed entrainment.This is a demonstration of concealed entrainment.

Concealed Entrainment

PPI :Post pacing interval FCL: Flutter cycle lengthPPI :Post pacing interval FCL: Flutter cycle length

15. Lesh et al.15. Lesh et al. JCE JCE Vol.7,No 4, April 1996Vol.7,No 4, April 1996

Concealed EntrainmentConcealed Entrainment

Post Pacing Interval (PPI) in Post Pacing Interval (PPI) in Entrainment with FusionEntrainment with Fusion

= pacing site= pacing site

The reentry circuit = Tachycardia cycle length (TCL) The reentry circuit = Tachycardia cycle length (TCL)

Time from pacing site to the circuitTime from pacing site to the circuit

Return cycle length= (Time from pacing site)x2 +TCLReturn cycle length= (Time from pacing site)x2 +TCL

PLUSPLUS

Time from circuit to the pacing siteTime from circuit to the pacing site

=Return Cycle Length=Return Cycle Length

Return cycle length= (Time from pacing site)x2 +TCLReturn cycle length= (Time from pacing site)x2 +TCL

= pacing site= pacing site

If the pacing occurred inside of the tachycardia circuit, the time it takes for the tachycardia to resume will be the tachycardia cycle length only, since there is no distance out side of the circuit to add time.

PPI in Concealed EntrainmentPPI in Concealed Entrainment

Entrainment MappingEntrainment Mapping

8. Olgin, et. al., 8. Olgin, et. al., Journal of Cardiovascular Electrophysiology,Journal of Cardiovascular Electrophysiology, Vol.7, No.11, Nov 96.Vol.7, No.11, Nov 96.

Double PotentialsDouble Potentials

Double potentials are indicative of a line Double potentials are indicative of a line of block of block

Lines of block are either fixed or Lines of block are either fixed or functionalfunctional– Atriotomy sites and the eustachian ridge Atriotomy sites and the eustachian ridge

are examples of are examples of fixedfixed lines of block lines of block– Evidence exists that block in region of Evidence exists that block in region of

crista terminalis during atrial flutter is a crista terminalis during atrial flutter is a form of form of functionalfunctional conduction block conduction block

Double Potentials (con’t)Double Potentials (con’t)

Double Potentials at CT during AFLDouble Potentials at CT during AFL

Ablation of Atrial TachycardiaAblation of Atrial Tachycardia

Key LocationsKey Locations– Identification of Focal Sites (if applicable) - Identification of Focal Sites (if applicable) -

FocalFocal– Identification of Anatomical Barriers (if Identification of Anatomical Barriers (if

applicable) - Macroreentrantapplicable) - Macroreentrant– Identification of Scar (if applicable) – Identification of Scar (if applicable) –

Microreentrant (Focal)Microreentrant (Focal)

Mapping and Ablation Techniques: Focal ATMapping and Ablation Techniques: Focal AT

Once a focal mechanism has been determined, the site is targeted by detailed atrial endocardial mapping during the AT or ectopic beats. A knowledge of the most common sites and the P-wave morphology can facilitate the mapping and ablation.•Leads aVL and V1 are helpful to distinguish right from left atrial foci (isoelectric or - aVL/+V1 = left; + or biphasic aVL/- or biphasic V1 = right). •Positive P waves in the inferior leads suggests a superior or anteripr focus, and biphasic or negative indicates posterior or inferior. •A negative P-wave in aVR = a right atrial focus.

Endocardial Activation Mapping: • Use HRA, His, CS catheters to regionalize the AT origin

based on the activation pattern. • Next the ablation catheter is inserted and moved to find

the site of earliest activation relative to the onset of the surface P-wave or onset of activation at the CSos or HRA which is in a known fixed relationship to the P-wave onset during AT.

Endocardial Activation Mapping:

• Fractionated or prepotentials (spikes) are also successful ablation sites, but the specificity and sensitivity is low.

• Intermittent mechanical block of the AT with catheter manipulation is also a good indicator of a successful site, but care must be taken to avoid loss of conduction for hours.

Focal AblationFocal Ablation

Focal Ablation:

•Acceleration of the tachycardia before termination is an excellent sign. •Also rapid termination of the tachycardia within 10 seconds of starting the RF delivery is also a good sign. •Successful focal ablation is verified by failure to reinduce the AT before and during an isoproterenol infusion.

Focal Ablation (Cont.)Focal Ablation (Cont.)

Focal Ablation: •Ablation at the atrial septum or Koch’s triangle can cause AV block. However, the presence of a His potential is not a contraindication for ablation. The energy needs to be titrated in such cases, by starting with 10 Watts and increase with 5-10 Watt increments to a maximum of 40 Watts with continuous AV conduction monitoring to prevent AV block.

•If the earliest site is the para-hisian area, right PV ectopy or LA origin need to be ruled out.

•If the earliest site is the superior crista, right PV ectopy also need to be ruled out. Another unusual potential site is the SVC.

Crista TerminalisSVC

Atrial TachycardiaAtrial TachycardiaCARTO SucksCARTO Sucks

RAO ViewRAO View

Left Atrial TachycardiaLeft Atrial Tachycardia

Focal Atrial Tachycardias Ablation Sites Focal Atrial Tachycardias Ablation Sites

This shows the ablation sites in a large group of AT ablation cases.This shows the ablation sites in a large group of AT ablation cases.

Mapping and Ablation Techniques: Mapping and Ablation Techniques: Macroreentrant ATMacroreentrant AT

Conventional methods include activation and entrainment mapping to identify the obstacles and boundaries of the reentrant circuits, and the critical isthmus within the reentrant circuit that becomes the target of the ablation. • The entire circuit can be mapped with the earliest and latest activations being adjacent (head meets tail). • Striking changes in signal amplitude, timing or both with very slight shifts in the catheter position indicate anatomic barriers to conduction. • A combination of diastolic potentials and concealed entrainment

pacing with the post-pacing interval within 20 msec of the TCL identifies a “protected isthmus” within the reentrant circuit.

Mapping and Ablation Techniques: Mapping and Ablation Techniques: Macroreentrant AT (Cont.)Macroreentrant AT (Cont.)

• Macroreentrant AT can arise from upper loop reentry in the right atrium due to a conduction gap in the crista terminalis (CT). Lower turn-around points are located at the conduction gaps in the CT. RF linear ablation of the conduction gap (narrowest part of the reentrant circuit) effectively abolishes the right free wall AT.

• Left atrial reentrant substrates are mostly at the posterior wall, the PV ostium or base of the appendage. Left atrial marcroreentrant AT is highly variable of 1-3 loops rotating around the mitral annulus, PVs and zone of block or a silent area.

• 3D mapping is usually needed in LA macroreentrant AT.

Case 1Case 1 A 58 year old lady was referred to us due to frequent

episodes of palpitation refractory to Propafenone and Amiodarone.

An EP study had been performed 6 month prior to referral in another center and ablation was not tried because of presumed para-hisian atrial tachycardia .

Another EP study was performed. The diagnostic catheters were placed in High RA, His, RV apex, Coronary Sinus and Tricuspid Ring (halo).

The arrhythmia was induced by isopreterenol infusion.

Earliest A at para-hisian site in initial tracingEarliest A at para-hisian site in initial tracing

Before ablation at the parahisian sites, other Before ablation at the parahisian sites, other potential sites should be considered because potential sites should be considered because of the risk of AV block.of the risk of AV block.

Entrainment mapping at TV-IVC isthmus Entrainment mapping at TV-IVC isthmus rule out typical AFL.rule out typical AFL.

Although CS showed concentric, LA Although CS showed concentric, LA mapping was still performed. LA mapping, mapping was still performed. LA mapping, including the right PVs, did not reveal earlier including the right PVs, did not reveal earlier site than the His area.site than the His area.

A at NCC even earlier than HisA at NCC even earlier than His

DiscussionDiscussion Due to the close contact of the right and left

aortic cusps with ventricles, arrhythmias originating from these cusps present with PVC's or VT.

Non- coronary cusp of the aorta with its posterior orientation is in the vicinity of the right atrium and ectopic pulses from here conduct to atrial chambers resulting in PAC's or AT.

Case 2Case 2

•A 34 y/o woman presented with intermittent palpitation for 3 A 34 y/o woman presented with intermittent palpitation for 3 weeks.weeks.•UCG revealed no structural heart.UCG revealed no structural heart.•ECG revealed intermittent atrial tachycardia or paroxysmal ECG revealed intermittent atrial tachycardia or paroxysmal atrial fibrillationatrial fibrillation

Earliest A at the upper crista terminalis (SVC not earliest)Earliest A at the upper crista terminalis (SVC not earliest)

Intermittent atrial fibrillation upon RF energy applicationIntermittent atrial fibrillation upon RF energy application

Case 3Case 3 A 28 y/o woman had suffered from A 28 y/o woman had suffered from

palpitation and shortness of breath for one palpitation and shortness of breath for one week.week.

She went to ER where ECG showed PSVT.She went to ER where ECG showed PSVT. IV verapamil was administered; however, IV verapamil was administered; however,

ECG showed PSVT turned to cardiac ECG showed PSVT turned to cardiac standstill.standstill.

Prolonged CPR did not result in ROSC, and Prolonged CPR did not result in ROSC, and ECMO was instituted.ECMO was instituted.

She was then transferred to NTUH.She was then transferred to NTUH. SVT recurred immediately at arrival at SVT recurred immediately at arrival at

NTUH ER.NTUH ER. Variable AV conduction was noted. AT was Variable AV conduction was noted. AT was

confirmed.confirmed. HRA AT was favored since the A sequence HRA AT was favored since the A sequence

mimicked sinus tachycardia in 12-lead EKG.mimicked sinus tachycardia in 12-lead EKG. UCG revealed LVEF 26%.UCG revealed LVEF 26%.

EPS revealed mid cirsta terminalis AT.EPS revealed mid cirsta terminalis AT. After ablation, no more tachycardia was After ablation, no more tachycardia was

inducible (patient was in ECMO with high inducible (patient was in ECMO with high dose dopamine; no isoproterenol was dose dopamine; no isoproterenol was administer to induce tachycardia).administer to induce tachycardia).

Two weeks later before discharge, UCG Two weeks later before discharge, UCG revealed LVEF 53%.revealed LVEF 53%.

Atrial tachycardia

ecg differential

simple electrocardiographic

tachycardia

av node reentry

inappropriate

focal atrial

sinus node

va interval

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