Svt maneuvers hany abed

Hany S. Abed
B . P h a r m a c y , M B B S , P h D , I B H R E C e r t i f i e d E P a n d C a r d i a c D e v i c e s S p e c i a l i s t
C l i n i c a l C a r d i a c E l e c t r o p h y s i o l o g y F e l l o w L o y o l a U n i v e r s i t y M e d i c a l C e n t e r
Techniques for Differentiating
Supraventricular Tachycardias
Concepts and Cases
April 25th 2014

Outline
 Induction of tachycardia
 Baseline tachycardia features
 Diagnostic maneuvers during tachycardia
 Diagnostic maneuvers in sinus rhythm after
tachycardia termination

Induction of Tachycardia
 Initiation by AES or atrial pacing
 Requirement of AV conduction delay
 Warm-up
 VA interval
 Initiation by VES or ventricular pacing
 HA interval

Initiation by AES or Atrial Pacing:
Requirement of AV Conduction Delay
 SVT initiation that is reproducibly dependent on a
critical AH interval:
 Classic for typical AVNRT
 Not always obvious with atypical AVNRT
 May be present in AT but not a prerequisite
 ORT often associated with AV delay but anterograde block in
the AAVC is key

Initiation by AES or Atrial Pacing:
Requirement of AV Conduction Delay

Initiation by AES or Atrial Pacing
 Warm-up
 Characteristic but not exclusive of automatic AT
 VA linking at induction
 Compare VA interval of first tachycardia beat to the rest of SVT
 If reproducibly identical, AT is very unlikely

Initiation by VES or Ventricular Pacing
 His Bundle-Atrial interval
 Compare HA interval during during SVT with the HA interval
occurring after a VES that results in an H-H interval similar to
H-H during SVT
 AVNRT
 HASVT < HAVES
 AVRT
 HASVT > HAVES

Baseline Tachycardia Features
 Atrial activation sequence
 Eccentric vs. Concentric
 Is earliest “A” near AV rings?

Baseline Tachycardia Features:
PR/RP relationship
 AT
 PR interval usually longer than during SR
 The faster the AT, the longer the PR interval
 PR interval can be >, < or = to RP
 Watch out for PR=RR resulting in P falling within QRS
(AVNRT)
 Typical AVNRT: VA typically -40 to 75 msec
 Atypical AVNRT: long RP tach
 PR and AH intervals often shorter than during SR
 ORT: usually short RP but VA > 70 msec

AV block

AV block
 Where is the block?

Oscillation in the TCL
 SVT CL variability of ≥15 msec occurs in 73% of
PSVT
 Equally prevalent in AT, ORT, AVNRT
 Changes in atrial CL precede and predict changes in
ventricular CL
 AT or atypical AVNRT
 Changes in ventricular CL precede and predict
changes in atrial CL
 Typical AVNRT or ORT

Oscillation in the TCL

Oscillation in the TCL and P-QRS
 Variations in P-QRS relationship (AH, HA, AH/HA
ratio) especially at initiation or termination of SVT
 Should not be misdiagnosed as AT
 Often seen in atypical AVNRT
 May be seen in typical AVNRT
 Spontaneous changes in PR (AH) or RP (HA)
intervals with fixed A-A favor AT and exclude AVRT

Oscillation in the TCL and P-QRS

Effects of Bundle Branch Block
 LBBB aberrancy during SVT is suggestive of ORT
 BBB during SVT that does not prolong the VA (HA)
interval excludes ORT using ipsilateral AAVC
 May still be AVNRT, AT or ORT using contralateral
AAVC
 Prolongation of VA interval with BBB > 35 msec
indicates ORT with ipsilateral free wall AAVC
 Prolongation of VA interval < 25 msec suggests ORT
utilizing a septal AAVC

Effects of Bundle Branch Block

Diagnostic Maneuvers During Tachycardia
 AES during tachycardia
 Resetting
 Termination
 Atrial pacing during tachycardia
 Entrainment
 Δ AH
 Acceleration
 Overdrive suppression
 Termination
 Differential site atrial pacing
 VA interval in return cycle following cessation of pacing

Atrial Extrastimulation During SVT:
Resetting
 AES can reset AT, AVNRT and ORT
 Resetting with manifest atrial fusion
 May be seen in ORT and macroreentrant AT
 Not seen in AVNRT or focal AT

Atrial Pacing During SVT:
Entrainment
 Overdrive atrial pacing can entrain macroreentrant
AT, AVNRT and ORT
 Automatic or triggered AT cannot be entrained
 Entrainment with manifest fusion in ORT or
macroreentrant AT (similar to AES concept)
 VA linking
 Compare postpacing VA interval to SVT VA interval

Entrainment

Overdrive Suppression
 Return CL following the pacing train prolongs with
increasing duration and/or rate of pacing train
 Suggests automatic AT
 Entrained reentrant circuits have constant return
cycles regardless of the length of pacing drive
 Warm up may be seen in automatic AT after
cessation of atrial pacing

Differential-Site Atrial Pacing

Δ VA < 14 msec = ORT/AVNRT

Δ VA > 14 msec = AT

Diagnostic Maneuvers During Tachycardia
 VES during tachycardia
 Resetting (His refractory VES, Preexcitation index)
 Termination
 Ventricular pacing during SVT
 Atrial activation sequence
 Entrainment
 AV vs AAV response
 Termination

VES During SVT:
His Refractory VES
 VES delivered during SVT when the His potential is
already manifest or within 35 to 55 msec before the
time of the expected His potential
 Advancing the next A +/- termination of SVT
 Confirms presence of retrogradely conducting AAVC
 Excludes AVNRT but not AT with bystander AAVC
 Advancing the next A with activation sequence
identical to SVT favors ORT over AT with bystander

VES During SVT:
His Refractory VES

VES During SVT:
His Refractory VES
 Delay of the next A = ORT
 Decremental conduction over AAVC
 An innocent bystander AAVC cannot delay A during AT
 Termination of SVT without an A = ORT
 VA block in the AAVC
 Note, even a well timed His refractory VES may not
affect the next atrial activation if the stim is far from
the site of the AAVC

VES During SVT:
Preexcitation Index
 Preexcitation index: VES usually reset ORT
 Distance between stim and ventricular insertion of AAVC
 VES coupling interval (Preexcitation index)
 PI > 75 msec suggests left free wall AAVC
 PI < 45 msec suggests septal AAVC
 The inability of single or double VESs to reset SVT
despite advancement of all ventricular EGMs
(including local V in EGM with earliest A) by > 30
msec excludes ORT

VES During SVT:
Preexcitation Index

 AVNRT or ORT
 Ventricular pacing during AVNRT and ORT reaches the atrium
over the tachycardia retrograde limb
 Atrial activation sequence during SVT = Retrograde atrial
activation with V pacing during SVT
 AT
 Atrial activation during AT ≠ retrograde atrial activation with
V pacing
 Pitfall: AT originating close to AVJ
 Beware bystander AAVC with retrograde conduction
resulting in retrograde atrial activation during
V pacing ≠ SVT even if due to AVNRT or ORT
Ventricular Pacing During SVT:
Atrial Activation Sequence

Entrainment
 PPI – TCL and SA – VA
 Original paper evaluated 30 patients with atypical
AVNRT and 44 patients with ORT using a septal
AAVC
 Same criteria apply to typical AVNRT
 For borderline values pace RV base instead of apex
 PPI-TCL will be exaggerated in AVNRT (farther from circuit)
 No significant change in ORT (still in the circuit for septal
AAVCs)

PPI - TCL and SA - VA
AVNRT
PPI - TCL = 150 msec SA – VA = 120 msec
*S-A measured from last pacing stimulus to HRA

PPI - TCL and SA - VA
ORT
PPI - TCL= 80 msec SA – VA = 40 msec
*S-A measured from last pacing stimulus to HRA

Traditional vs. Corrected PPI - TCL

Manifest Ventricular Fusion During
Entrainment

Analysis of Transition Zone During
Entrainment
 Not dependent on tachycardia continuation after
RVP
 His bundle recording is unnecessary
 AVNRT was identified with PPV and NPV of 100%
using criteria of > 1 QRS of fixed morphology to
accelerate TCL to PCL
 A cut-off of ≤ 1 QRS of fixed morphology resulting in
acceleration of TCL to PCL had a PPV and NPV of
100% for identifying ORT

“Transition Zone”
concepts:
• AVRT circuit is large
• AVNRT circuit is small
• It is easier to get into the AVRT
circuit when pacing from the
RV apex
• You will fuse and manifest into
the QRS quickly as you entrain
the atrium in AVRT
• You will require more
progressive fusion of the QRS
(less quickly) as you entrain the
atrium in AVNRT
• Advantage is it is independent
of SVT termination after VOP
• Need to look at all 12 ECG
leads

Fixed
morphology
RVP beats
required to
accelerate
TCL to PCL
Analysis of Transition Zone During
Entrainment

A-V vs. A-A-V Response
 A-V = AVNRT or ORT
 Antegrade limb not refractory so able to conduct to V
 A-A-V = AT
 Antegrade limb (AVN) refractory since just used retrograde
 Must confirm entrrainment before applying
 Pseudo A-V and Pseudo A-A-V

Diagnostic Maneuvers in NSR After SVT
Termination
 Atrial pacing at TCL
 ΔAH interval
 AV block
 Ventricular pacing at TCL
 ΔHA interval
 VA block
 Atrial activation sequence
 Differential RV pacing
 Parahisian pacing

Atrial Pacing at TCL: ΔAH Interval
 AT/ORT
 AH during SVT comparable to during A pacing at TCL due to
similar activation
 AVNRT
 AH during SVT shorter than during A pacing at TCL due to
different activation (parallel vs. series)
 Δ AH (AHatrial pacing at TCL - AHSVT)
 > 40 msec suggests AVNRT
 < 20 msec suggests AT or ORT

Atrial Pacing in Sinus Rhythm at TCL:
ΔAH interval

Atrial Pacing in Sinus Rhythm at TCL:
AV block
 AT/ORT
 Atrial pacing at the TCL should result in 1:1 AV conduction
 Should test shortly after SVT termination to maintain similar
autonomic tone
 The development of AV block with atrial pacing at
TCL is consistent with AVNRT
 Upper common pathway block

 AVNRT
 HA activated in parallel during SVT and in series during
ventricular pacing
 HA during SVT shorter than during ventricular pacing at TCL
 ORT
 HA activated in series during SVT and in parallel during
ventricular pacing
 HA during SVT is longer than during ventricular pacing at TCL
 Δ HA (HAV pacing at TCL – HASVT) more negative (<)
than -10 msec = ORT
 Δ HA > -10 msec = AVNRT
Ventricular Pacing in Sinus Rhythm at TCL:
ΔHA interval

ΔHA interval

ΔHA interval
Greg Michaud et al

VA Block
 VA block during ventricular pacing makes ORT with
a fast retrograde AAVC unlikely
 More likely in setting of VA block
 AT
 AVNRT with lower common pathway block
 PJRT

Retrograde Atrial Activation Sequence
 AVNRT
 Atrial activation sequence usually similar during AVNRT and
ventricular pacing in NSR
 ORT
 Retrograde VA conduction during ventricular pacing may proceed
over the AVN, the AAVC, or both
 Atrial activation sequence may be similar or different during
ORT and ventricular pacing in NSR
 AT
 Atrial activation during AT ≠ retrograde atrial activation with
V pacing
 Pitfall: AT originating close to AVJ

Maneuvers in NSR After SVT Termination:
Differential RV Pacing
 Compare VA interval and atrial activation sequence
with pacing from RV base vs. RV apex
 (-) Retrogradely conducting septal AAVC
 Shorter VA interval when pacing from the apex
 Same atrial activation sequence
 (+) Retrogradely conducting septal AAVC
 Shorter VA interval when pacing from base
 Atrial activation sequence can be same or different depending
on degree of contribution of AVN and AAVC
 Pitfalls
 Doesn’t exclude free wall AAVC or slowly conducting AAVC

2

Parahisian Pacing
 Ventricle and HB capture
 Relatively narrow QRS
 S-A interval = HA interval (direct His capture)
 Only ventricular capture
 Wide QRS, LBBB
 S-A = S-H interval + HA interval

Parahisian Pacing

Case 1: Which arrhythmia mechanism can be excluded?

Case 2: What arrhythmia mechanism can be confirmed?

Cases 1 and 2: Coumel and Reverse Coumel
BCT LBBB and NCT, VA association, eccentric CS activation, no change in CL or VA time with
change from LBBB to NCT

Case 3: What is the diagnosis and why?

Case 3: Tachycardia termination
• NCT with A>V. Short VA time
• Cannot be AVRT
• AT or AVNRT (“atypical”)
• His refractory PVC terminates the
tachycardia without affecting the
atrium
• Can only be AVNRT with block below
the final common pathway

Case 4: Describe the following?

Case 5: Describe the following?

Case 4 and 5: Para-His bundle pacing?
• No pathway: High output captures His and
myocardium via HPS
• No pathway: Low output captures septum
myocardium, travels to distal HPS to invade
retrograde
• Pathway present:
High output captures
His and pathway
(short-cut to atrium)
• Pathway present:
Low output captures
pathway and septum
myocardium (short-
cut to atrium)

Case 4 and 5: Para-His bundle pacing elaborated

Case 6: Which tachycardia mechanism is ruled out?

Case 6: Tachycardia termination
Eccentric activation of the coronary sinus catheter suggests left lateral AP
However AVNRT utilising a leftward nodal extension cannot be excluded
• PVC terminated the
tachycardia without an early
(“pulling in”) atrial
electrogram
• Indicates the SVT is AVN
dependent – thus ruling out
FAT
• Note subtle delay in atrial
electrogram – suggests
decremental retrograde
conduction

Case 7: Which tachycardia mechanism does the following
maneuver “rule-in”?

Case 7: Which tachycardia mechanism does the following
maneuver “rule-in”?
• Note the PAC is delivered away from the septum. Being able to perturb the circuit far away
from the septum suggests a wide excitable gap.
• Compare that to AVNRT or Nodoventricular/Nodofascicular accessory pathway, which
have a narrow excitable gap
• If AVNRT with bystander accessory pathway: A His refractory PAC will advance next V,
BUT not “pull-in” the subsequent A.
• This is an antidromic AVRT using an AV
accessory pathway
• Delivering a PAC during His bundle
refractoriness advances the ventricle
• QRS morphology remains identical

Case 8: What is the most likely tachycardia mechanism?

Case 8: What is the most likely tachycardia mechanism?
• Pacing during sinus rhythm from
the His bundle region does not
conduct in the retrograde direction
to the atrium.
• This makes AVRT very unlikely,
AVNRT unlikely. AT is most likely

The End
Hany S. Abed
B . P h a r m a c y , M B B S , P h D , I B H R E C e r t i f i e d E P a n d C a r d i a c D e v i c e s S p e c i a l i s t
C l i n i c a l C a r d i a c E l e c t r o p h y s i o l o g y F e l l o w
L o y o l a U n i v e r s i t y M e d i c a l C e n t e r
A p r i l 2 0 1 4

Svt maneuvers hany abed

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