Electrophysiologic Features Differentiating the Atypical AV Node
Transcription
Electrophysiologic Features Differentiating the Atypical AV Node
DOI: 10.1161/CIRCEP.113.000187 Electrophysiologic Features Differentiating the Atypical AV Node-Dependent Long RP Supraventricular Tachycardias Running title: Ho et al.; Electrophysiology of Long RP Tachycardias Downloaded from http://circep.ahajournals.org/ by guest on November 19, 2016 ad dB B.. Pa Pavr Pavri, vri, vr i, M MD D 1; Reginald T. Ho, MD, FHRS1; Daniel R. Frisch, MD1; Behzad Steven A. Levi, MD2; Arnold J. Greenspon, MD1 1 Department tme tme ment of Medi Medicine, icinee, D Division ivi vission of Cardiology, vi C rdio Ca ology gy, Thomas Thom Th omaas Jefferson om Jeffersoon U University niveerssityy Ho Hospital, osppitt Philadelphia, d lph del phia ia,, P ia PA; A 2Di A; Division Divi v ssiion vi o off Cardiology, C rd Ca rdio olo logy gy,, Our gy O r Lady Ou Lady of of Lo Lour Lourdes urde ur dess Hosp de H Hospital, o pit ital al, Camden, al Camd Ca mden md en,, NJ en N Corresponding Author: Reginald T. Ho, MD Department of Medicine, Division of Cardiology Thomas Jefferson University Hospital 925 Chestnut Street Mezzanine Level Philadelphia, PA 19107 Tel: (215) 955-7303 Fax: (215) 503-3976 E-mail: [email protected] Journal Subject Codes: [106] Electrophysiology; [5] Arrhythmias, clinical electrophysiology, drugs; [22] Ablation/ICD/surgery 1 DOI: 10.1161/CIRCEP.113.000187 Abstract: Background - Diagnosing atypical AVN – dependent long RP SVTs can be challenging. Methods and Results - Nineteen patients with 20 SVTs (atypical AVNRT without (n=11)/ with (n=3) a bystander nodo-fascicular (NF) accessory pathway (AP), orthodromic reciprocating tachycardia (ORT) using a decremental atrio-ventricular (PJRT, n=4) or nodo-fascicular (NFRT, n=2)) AP underwent electrophysiologic study. Post-pacing interval (PPI) – tachycardia cycle length (TCL), corrected PPI (cPPI)¨VA, ¨HA, ¨AH values and responses to His-refractory VPDs were studied. Compared to AVNRT, ORT patients were younger (42 + 13yrs vs. 54 + Downloaded from http://circep.ahajournals.org/ by guest on November 19, 2016 19yrs, p=0.036) and female (5/6 (83%) vs. 3/14 (21%), p=0.036); TCLs were similar ((435ms vs. s. 176ms, 1766ms 17 ms,, CI= CI= 26.3 26.3 6.3 – 89.7) 429ms, CI= - 47.5 – 35.5). PPI – TCL was shorter for ORT (118ms vs. L < 12 25m 5mss (s (sen ensi en siti si tivi ti vt but only 50% had PPI – TCL < 115ms while 5/6 (83%) had PPI – TCL 125ms (sensitivity: ificcit ity: y: 100%). 100 0 %) % . Corrected 33,PV ¨9$< 85ms, andd ¨ HA < 0ms had equi i 83%, specificity: 33,PV¨9$< ¨HA equivalent (667%) andd 100% 100 0 % specificity 00 s ec sp ecif ific if iccit ity y fo for OR RT. Co ompar a ed tto ar o PJ PJRT RT T, NFRT/AVNRT NFRT NF R /AV RT AVNR NRT NR T had h d longer ha sensitivity (67%) ORT. Compared PJRT, P YV PVYV YV mss, CI= CII= 3.033 – 35.0) 35.0)) or o AH AH(S H(N Hiss-refrracto Hi t ry to r V VPDs P s adva PD advanced vancc va ¨$+PVYVms, (SVT) (SV VT) < AH (NSR) (NSR R). His-refractory ), de ela l ye y d ((4/8 4 8 (5 4/ (50% 0%)) 0% )),, or )) or terminated d (5/ 5/88 (6 5/ (63% %)) SVT in n all AP ppatients. atie i nts. ie (4/8 (50%)), delayed (50%)), (5/8 (63%)) Conclusions n - Th ns Thi This is unusual unusu suuall SVT SVT requires requ q ires sepa separate p rate maneuvers to de deli delineate lineeat li a e its i s upper it upp pperr and pp and lower low w a dard anda an rd eentrainment ntra nt rain i me in ment ntt criteria criite teri riaa are are modestly mode mo desttly ly sensitive sen ensi siiti t vee but butt highly hiig ghl hlyy sp spec pecif iffic i for f r ORT; fo ORT OR T; and a circuit. Standard specific PPI – TCL of 125ms appears better than 115ms. The ¨$+FULWHULDRUparadoxically, AH(SVT) < AH(NSR) differentiates NFRT/AVNRT from PJRT. Bystander APs were only identified by Hisrefractory VPDs. Key words: supraventricular tachycardia, catheter ablation, atrioventricular node, accessory pathway, nodo-fascicular, nodo-ventricular, entrainment, resetting 2 DOI: 10.1161/CIRCEP.113.000187 Introduction Establishing the diagnosis of an atypical AV node-dependent long RP supraventricular tachycardia (SVT) can be difficult. Standard diagnostic criteria are lacking and often extrapolated from pacing maneuvers applied to the more common short RP SVT. Long RP SVTs involving concealed nodo-fascicular (NF) accessory pathways (AP) are particularly rare with descriptions limited to isolated case reports.1-4 Prolonged conduction over the slow pathway (SP) of the AV node or a decremental AP following entrainment from the ventricle can Downloaded from http://circep.ahajournals.org/ by guest on November 19, 2016 produce A-A-V patterns that might be mistaken for atrial tachycardia (A ((AT). T)).5 Additional Additionally, allly ly, slow AP conduction following entrainment of an atypical orthodromic reciprocating procat attin i g tachycardia ttaach hyc y arrdi diaa (ORT) can ge generate ene nera r tee lo ra longg ppost-pacing ost-pacing intervals (PP (PPI) PI) th tthat at cause mi misdia misdiagnosis agnosis of atrio-ventri atrio-ventricular i 5-7 nodal reentrant tran tr nt tachycardia tachycarddia (A (AVNRT) AVN VNRT R ) de ddespite sppitte ccorrection orrrecctiionn for for ddelay elay ay in th the A AV V nod node o e (c od (cPP (cPPI). PI)).5- This study sought sough ghtt to evaluate gh evalluate t the th he electrophysiologic ellecctr trophyysi s ol olog ogic i features featu turre tu re aand res ndd cr ccriteria itteriia dif differentiating ifffe ferrenttia i ti ting the the four atypical AV V nod node–dependent de–de d pe p nddent llong ongg R RP P SV SVTs: VTs T : atypical attyp ypic i all A AVNRT, VN NRT R , at atyp atypical y icall A yp AVNRT VN NRT R w with ithh a it concealed, bystander AVNRT/NF AP), b stander tandd NF AP (atypical ((at att pi pical i l AV AVNR NRT/ T/NF NF AP) AP) OR ORT T using sing in a concealed, concealed ledd slowlyslo lo l conducting, decremental atrio-ventricular (AV) AP (also called the permanent form of junctional reciprocating tachycardia or PJRT), and ORT using a concealed NF AP (also called nodofascicular reentrant tachycardia or NFRT). Methods Nineteen patients with 20 symptomatic atypical long RP SVTs underwent diagnostic electrophysiologic study. After informed consent, femoral vein access was achieved percutaneously and multipolar catheters were positioned in the high right atrium, His bundle region, right ventricle and coronary sinus. Programmed stimulation and burst pacing were 3 DOI: 10.1161/CIRCEP.113.000187 delivered from the ventricle and atrium to evaluate retrograde and antegrade conduction, respectively and induce SVT. If SVT was non-inducible in the baseline state, isoproterenol was infused and the stimulation protocol was repeated. After tachycardia induction, scanning ventricular premature depolarizations (VPDs) were delivered during the diastolic period of tachycardia and SVT was entrained from the ventricle at a pacing cycle length (PCL) 10-50ms shorter than tachycardia cycle length (TCL). Para-Hisian pacing and/or entrainment was performed selectively to confirm diagnoses.8,9 Radiofrequency ablation was performed in all Downloaded from http://circep.ahajournals.org/ by guest on November 19, 2016 patients by targeting either the SP or AP after activation mapping or SP P usingg the standard standa daard approach during sinus rhythm.10 Definition off terms: term te r s: rm s Post-pacing g in interval nterval (PPI (PPI) I) - ti time ime between bet etween en the thee pacing pac accingg stimulus stim mul uluus to the th he 1st re return etu t rn RV electrogram eleectrroggr e ai entrai ainm nmeent off tachycardia nm tachy h carddia ffrom hy rom th thee ve vventricle nttriiclle11 following entrainment 12 Corrected t PP ted PPII (c (cPP (cPPI) PPII) = (P PP ((PPI PI – TC TCL) CL) – (A (AH H(1 ((1st st return AH followingg ent entrainment trainment from ventricle)) – AH(S ((SVT) V ) ¨9$ 9$ 9$(entrainment from ventricle) – VA(SVT)11 ¨+$ +$(entrainment from ventricle) – HA(SVT)13-15 ¨$+ $+(atrial pacing/entrainment at/near TCL) – AH(SVT)16 or AH(NSR) – AH(SVT) if paradoxically, AH(SVT) < AH(NSR)1-3 Diagnostic criteria for SVT: All tachycardias had a long RP (RP > PR) interval with earliest atrial activation near the ostium of the coronary sinus. Atrial tachycardia was excluded by the following criteria: 1) spontaneous termination with atrio-ventricular (AV) block, 2) termination of tachycardia by VPDs that failed to reach the atrium (VA block), 3) A-A-V response to entrainment from the ventricle.17 The following criteria established a diagnosis of: 4 DOI: 10.1161/CIRCEP.113.000187 Atypical AVNRT: 1) non-obligatory 1:1 AV relationship (persistence of tachycardia despite retrograde block to the atrium or antegrade block to the ventricle), 2) failure of bundle branch block (BBB) to affect tachycardia, 3) failure of His-refractory VPDs to affect tachycardia, 4) inability to entrain tachycardia from the ventricle with orthodromic capture of the His bundle, 5) PPI – TCL > 115ms (or cPPI > 110ms), 6) ¨9$> 85ms, 7) ¨HA > 0ms, 8¨$+ > 40ms (or paradoxically, AH(SVT) < AH(NSR)). PJRT: 1) obligatory 1:1 AV relationship , 2) VA/TCL prolongation with development of Downloaded from http://circep.ahajournals.org/ by guest on November 19, 2016 BBB, 3) His-refractory VPDs reset (advance or delay) the atrium or terminate rminate tachycardia tachyc y ardi diaa w di with VA block, 4) ability to entrain tachycardia from the ventricle with orthodromic hodro omic miic capture capt ptur ture of tthe His bundle, 5) PPI ¨$+ PPI – TCL TCL C < 115ms 115ms (or cPPI < 110ms), 6) ¨9$PV¨+$< ¨9$PV P ¨+$ < 0ms, 8) ¨$+ + 20ms. NFRT: R 1) RT: 1) non-obligatory non-obl b igattory 1:11 AV relationship bl rel ellat a ion ionshi io h p (persistence hi ( er (p ersi s ste si sttencee off tachycardia tachy h caard rdiia with wit ithh retrograde it rettroo block to thee atrium but b t not bu noot antegrade antegr g ad de bblock lockk to the the ventri ventricle), icle), l ), 22)) VA VA/T VA/TCL TCL L pprolongation rolo l nggattio on wi w with thh development His-refractory tachycardia entt off BBB, B BBB BB 3) H His is refractor fr to VPDs VPD resett or terminate t mii te ttach h cardia rdi dia with ith ith VA block bblock, lock k 4) ability to entrain tachycardia from the ventricle with orthodromic capture of the His bundle, 5) PPI – TCL < 115ms (or cPPI < 110ms), 6) ¨9$PV, 7) ¨HA < 0ms, 8) ¨$+!PVRU paradoxically, AH(SVT) < AH(NSR)). Atypical AVNRT/NF AP: 1) non-obligatory 1:1 AV relationship (persistence of tachycardia despite retrograde block to the atrium or antegrade block to the ventricle), 2) failure of BBB to affect tachycardia, 3) His-refractory VPDs reset the atrium or terminate tachycardia with VA block, 4) ability to entrain tachycardia from the ventricle with orthodromic capture of the His bundle, 5) PPI – TCL > 115ms (or cPPI > 110ms¨9$> 85ms, 7) ¨HA > 0ms, 8) ¨$+!PVRUparadoxically, AH(SVT) < AH(NSR)). 5 DOI: 10.1161/CIRCEP.113.000187 Statistics Continuous data are expressed as mean + SD or 95% CI. Categorical data are presented as frequency and percentage. The Student t test and comparison of proportions were used to compare differences between groups. P values < 0.05 were considered significant. Results The 20 atypical long RP SVTs in 19 patients included pure atypical AVNRT (n = 11), atypical Downloaded from http://circep.ahajournals.org/ by guest on November 19, 2016 T an andd AVNRT/NF AP (n = 3), PJRT (n = 4), and NFRT (n = 2). One patientt had both NFRT ratedd an ante tegr grad ad de co ond ndu atypical AVNRT/NF AP. All APs were concealed and none demonstrated antegrade conduction. caase sess shown show sh o n are ow ar shown in Figures 1-4. Co C ompared to atypical a ypic at i al AVNRT, patientss with ic Illustrative cases Compared T/N NFRT) weree younger, youn unger, r more r, more re often oft fteen female femaalee but buut TCLs TC CLs were were similar sim mil ilar (Table (T Table 1). ORT (PJRT/NFRT) e fr ent from om vent triicle l Entrainment ventricle t terns were com om mmon and d occurred d more ffrequently requ q entl tly ly wi ith th atypical aty typi ty piical AV VNR RT th than a O A-A-V patterns common with AVNRT ORT 7% , p = 00.036). 0036) 36)) Th 36 The ere pse do d A A V patterns tt in i 9/ 9/12 12 (atypical ((at att pi pical i l AVNRT AVNR AV NRT T (n (n = 8), (79% vs. 17% They were pseudo A-A-V PJRT (n = 1)) and true A-A-V responses in the remaining 3 (atypical AVNRT with (n = 2) and without (n = 1) NF AP). Although the PPI – TCL was shorter for ORT (118ms vs. 176ms, CI = 26.3 – 89.7), half had a PPI – TCL > 115ms (sensitivity (SN): 50%, specificity (SP): 100%, positive predictive value (PPV): 100%). In contrast, PPI – TCL < 125ms occurred in 5/6 ORT and 0/14 AVNRT (SN: 83%, SP: 100%, PPV: 100%) (Figure 5). The cPPI was also shorter for ORT (115ms vs. 170ms, CI = 21.7 – 88.3), but 2/6 ORT had a value > 110ms, both associated with antidromic capture of the His bundle (SN: 67%, SP: 100%). 7KH¨9$ZDVVPDOOHUIRU ORT (101ms vs. 160ms, CI = 25.9 – 42.2) but 2/6 ORT had a value > 85ms (SN: 67%, SP: 100%). His bundle electrograms were identifiable during entrainment in 17/20 (85%) SVTs and 6 DOI: 10.1161/CIRCEP.113.000187 were captured orthodromically in ORT (n = 4) and antidromically in 13 (AVNRT (n = 11), ORT (n = 2)). 7KH¨+$was smaller for ORT (-1ms vs. 72ms, CI = 35.6 – 110) but 2/6 ORT had a value > 0ms (SN: 67%, SP: 100%). His-refractory VPDs His-refractory VPDs reset or terminated tachycardia in all 8 patients with an AP; and was the only maneuver to identify a concealed, bystander NF AP during atypical AVNRT. They advanced the atrium in 4 APs (AV AP (n = 3), NF AP (n= 1)), delayed it in 4 (NF AP (n = 3), Downloaded from http://circep.ahajournals.org/ by guest on November 19, 2016 AV AP (n = 1)), and terminated SVT with VA block in 5 (NF AP (n = 3), ), AV AP (n ( = 22)). )). ) All 4 APs exhibiting paradoxical delay was associated with PPI – TCL > 125ms. 25ms. s Other criteria e ia eria Compared tto PJRT, tKH¨$+ was longer for NFRT/atypical AVNRT (29ms oP JRT, tKH ¨$+ +w as lo onger er fo or NF FRT//attyppic i all A VNRT (29 VN 29ms m vs.. 110ms, 0m ms, CI = 3.03 – 35.0); and AVNRT/NF NFRT 1)) AH d 3 SVTs SVT VTss (atypical (attypiicall A VN VNRT NRT RT//NF AP (n = 22), ), N ), FRT FR T (n= (n= 1) )) hhad ad an nA H in iinterval tervall paradoxically shorter that Para-Hisian unhelpful a y sh ally horter than han th hat dduring uriingg sinus rhythm. rhy hythm. P hy ara-H Hisian pa ppacing ciingg was unh helpf lpf pful u in 114/19 ul (74%) patients conduction slower conduction eents ntt because bbeca e se eith either ith FP cond ndd ction ti always all a s preempted tedd sl slo l er SP SP/AP SP/A /AP P cond ndd ction ti dduring pacing (n = 12) or consistent 1:1 conduction over the SP/AP could not be achieved despite pacing at the slowest rate allowable by sinus rhythm (n = 2). Para-Hisian entrainment was successfully performed in only 2 patients and confirmed the established diagnosis. Nodal pathways The proximal insertion of all four nodal APs was the SP of the AV node. In one patient, it was the left atrio-nodal extension of the SP requiring ablation along the posteroseptal mitral annulus. The distal insertion of the nodal APs was fascicular (para-Hisian pacing (n = 1), para-Hisian entrainment (n = 1), Figure 4)), ventricular (manifest QRS fusion during entrainment (n = 1), Figure 2), and indeterminate (n = 1). 7 DOI: 10.1161/CIRCEP.113.000187 Ablation The successful ablation site for all patients with atypical AVNRT with and without a bystander NF AP was the SP of the AV node along the posteroseptum of the right atrium and includes the patient with both atypical AVNRT/NF AP and NFRT. The other patient with NFRT had an AP inserting into the left atrio-nodal extension of the SP and required ablation along the posteroseptal mitral annulus. All patients with PJRT had successful AP ablation along the posteroseptum of the tricuspid annulus near the ostium of the coronary sinus identified by Downloaded from http://circep.ahajournals.org/ by guest on November 19, 2016 activation mapping during tachycardia. Discussion n Compared ttoo atypical AVNRT, patients with atypical AVN VNRT RT, pa RT atiientss wi ithh ORT OR RT (NFRT/ (N NFR RT/ PJRT) PJRT) T) were weeree yyounger ouungeer an andd predominantly although skewed small study population. n female ntly fema fe malle alt ma l houg lt ughh the t e demographics th dem de mograp ap phic hics may hi ay bbee sk kew ewed ed d bby y th the sm mal alll stud dy popul l These long than their short g RP P tachycardias tach hyc y arrdi dias respond respo p ndd differently diffe f rently ly tha h n th heir sh hort RP counterparts couunt nterpa p rts to t pacing paci pa cii g cing maneuvers;; and tachycardia ndd the the rare tach tach h cardia di associated ciiatted d with ithh a NF A it AP P can bbee misdiagnosed isdi di d as PJRT PJR JRT T if the upper circuit is not analyzed. Therefore, separate pacing maneuvers in the atrium and ventricle are required to delineate the upper and lower circuit, particularly when a 1:1 AV relationship exists (Figure 6, Table 2). Entrainment from ventricle While A-A-V responses are generally considered diagnostic of AT, A-A-V patterns were common in our series, particularly for atypical AVNRT with its longer paced VA interval. Pseudo A-A-V patterns occur when decremental conduction over the SP or AP produced long VA intervals that exceed the PCL so that the 1st atrial electrogram after entrainment is actually driven by the penultimate pacing stimulus. True A-A-V responses were the result of dual 8 DOI: 10.1161/CIRCEP.113.000187 retrograde responses (“double fire”) with simultaneous conduction over the FP and NF AP or SP occurring only with atypical AVNRT with and without a concealed, bystander NF AP, respectively. This is different from the A-A-V response of AT which results from retrograde conduction over the AV node followed by the 1st return beat of AT after pacing. A mechanism to explain dual retrograde (“A-A-V”) responses during atypical AVNRT is the presence of a large excitable gap with collision between antidromic and orthodromic wavefronts in the SP (retrograde limb) of the circuit. The last (n) paced antidromic wavefront conducts completely Downloaded from http://circep.ahajournals.org/ by guest on November 19, 2016 over the FP to the atrium (1st A) and then collides with the previous (n n -1)) orthodromic wavefront in the SP. The last (n) paced orthodromic wavefront has noo antidromic antid idro id romi mic ic wavefront waveefr wa fron o with whichh too collide, coll co l id ll de, e, conducts con onnducts over the SP to activate activ vatee the atrium (2ndd A A)) before conductingg antegradely y ov over ver the FP to thee ven ventricle. ntr tricle. W With ith th the he mo more ccommon omm om monn sing single glee rretrograde etrogrrad et a e (“ (“A-V-A”) “A-V -V-A -V A responses, the ccollision olli ol lisi sion i ppoint oiintt between between t en antid antidromic droomi mic i andd orth orthodromic thoddro romi omi micc wavefron wavefronts nts iiss in i the the h F FP P (antegrade limb). limb) b). An b) An alternative alte al teernatiive mechanism mech haniism is i tachycardia tach hyc y ardi dia termination di termin nattion andd subsequent subs b eq que uent nt reinitiation. With pacing, occurs Wit ithh onsett off ventricular entric triic lar l pacing in retrograde ett ad d block bl k occ rs in i th the SP effectively effecti ff ti ell terminating tachycardia and conducts exclusively over the FP. When pacing stops, retrograde conduction occurs over both the FP and SP, the latter re-initiating tachycardia. Conventional SVT criteria during entrainment from the ventricle establish the lower portion of the tachycardia circuit as macroreentrant involving the His-Purkinje system/ventricle (PJRT/NFRT) or not (AVNRT).11 A PPI – TCL < 115 was specific for ORT but conduction delay over the AP caused PPI – TCL > 115ms in half ORT yielding misdiagnosis of AVNRT as has been observed in other series.7 A higher cut-off value of 125ms increased the sensitivity for ORT by 33% while maintaining 100% specificity. The cPPI correctly adjusted the long PPI during ORT when both retrograde AP and antegrade AV node decrement occurred – the latter 9 DOI: 10.1161/CIRCEP.113.000187 from antidromic capture of the His bundle and retrograde concealment into the AV node. However, when substantial delay occurred over the AP, the cPPI could not correct the long PPI and even paradoxically prolonged it because the 1st return AH became shorter than during SVT. Slow, decremental AP conduction also affected the sensitivity RIWKH¨9$DQG¨+$FULWHULDIRU ORT but maintained their high specificity. Therefore, any standard criteria positive for ORT (PPI – 7&/PVF33,PV¨9$PV¨+$PVwas diagnostic of ORT despite discordance among each other which occurred 50% of the time. Downloaded from http://circep.ahajournals.org/ by guest on November 19, 2016 His-refractory VPDs His-refractory VPDs that reset (advance or delay) or terminate tachycardia ardiaa in iindicate ndi dica di cate t th te the pr pres presence e u not ut not necessarily necces essaariily its participation in tach chyc ch y ardia. They yc y can an n reset or terminate at t of an AP but tachycardia. atypical AVNRT inn the thhe presence of a co concealed, onceealed d, by byst bystander tande deer NF A AP P in inserting nseertin ing in in into nto o the the h retrograde retro r gr ro g ad de SP SP.11,3 In e the e, h V PD cond ducts t over the the NF F AP aahead head d off th the AV AVNR NRT NR T wavefr fron fr ont andd penet on tr such a case, VPD conducts AVNRT wavefront penetrates its excitablee gap gap p in in the th he SP P after aft f er the thhe lower lower turnaround d po ppoint intt off the h ccircuit. ircu uitt. IIts ts antid antidromic id droomi mc wavefront collides llid ll id with ithh ttach it tachycardia ach h cardia di while hile hil its it orthodromic thodd mii wavefront a efront fr t encounters enco nters te eith either ith relat relative ellatt or absolute distal SP refractoriness delaying or terminating tachycardia, respectively. Hisrefractory VPDs identified an AP in all patients with ORT and was the only pacing maneuver to diagnose a concealed, bystander NF AP in 3 patients with atypical AVNRT by delaying the atrium and/or terminating tachycardia with VA block. While entrainment of atypical AVNRT/NF AP from the ventricle with orthodromic capture of the His bundle is theoretically possible, it was not observed. His-refractory VPDs also determined the degree of decremental conduction over each AP. Severe AP decrement paradoxically delayed the atrium because the degree of VPD prematurity was offset by > degree of AP conduction delay (fully compensatory).18 Mild AP decrement advanced the atrium because the degree of VPD 10 DOI: 10.1161/CIRCEP.113.000187 prematurity was offset by < degree of AP conduction delay (partially compensatory). Paradoxically delay might identify patients who have long PPIs after entrainment independent of tachycardia mechanism. Other criteria 7KH¨$+FULWHULDGLIIHUHQWLDWHVtachycardia circuits whose upper portion is partially extranodal (PJRT) or completely intranodal (NFRT/atypical AVNRT).16 During PJRT, the AH interval is a true interval reflecting sequential activation of the atrium and His bundle over the AV node and Downloaded from http://circep.ahajournals.org/ by guest on November 19, 2016 similar to the AH interval when pacing at the TCL. In contrast, duringg NFRT and atyp atypical ypic iccal a AVNRT, the AH interval is a pseudo-interval reflecting simultaneous activation activ vattio i n off the the he aatrium triiu tr iu and His bundle 7KH¨$+ ndle and nd and is, is, s, therefore, the herrefore, shorter than the AH he AH interval when wheen pacing paacing at the TCL. 7KH H was longerr for AVNRT) PJRT forr the nodal tachycardias taachhyccarddiaas (NFRT/atypical (NF N RT RT/attypiccall AV VNR NRT) ccompared omp pared ed d to PJ JRT R and andd the thhe AH interval was a par as paradoxically rad adox oxicallly sho ox shorter h rter t for forr atypical atypiccal a A AVNRT/NF VNRT VN RT T/N NF AP (nn = 2) 2) and NFRT NFR NF RT (n (n = 1) than th during sinus u rhythm. us rhy h thm. hy h $ $PDMRUOLPLWDWLRQRI¨$+FULWHULDKRZHYHULVthe P PDMR M UOL OLPLW LWDWL WLRQRI L I ¨$ $+FULLWHULLDKKRZHYHHU LV th the sensitivity sensiitiviit ity of the AV node to rapid fluctuations off AH pid id fl ctt ati ations tio iin aautonomic tonomic to mii tone to so that thatt comparison rii AH intervals iinter ntte al als l bbetween bet ett een tachycardia and pacing should be done close in time allowing for minimal change in the autonomic state of the patient. For atypical AV node – dependent long RP tachycardias, paraHisian pacing was generally not useful because 1) retrograde FP conduction consistently preempted SP/AP conduction, 2) SP/AP often exhibited retrograde Wenckebach conduction despite ventricular pacing at the slowest cycle length allowable by the sinus rate and 3) an “AV nodal” response is not diagnostic of pure AV nodal conduction but can also be observed with a nodo-fascicular AP.4 Nodal pathways The proximal insertion of all four nodal APs was determined to be the SP of the AV node by the 11 DOI: 10.1161/CIRCEP.113.000187 ability of His-refractory VPDs to perturb the retrograde limb of the circuit during atypical AVNRT and NFRT. A SP insertion can also be identified by the ability of His-refractory VPDs to reset or terminate typical AVNRT in the antegrade limb.19 Various maneuvers can determine the distal insertion site of concealed nodal APs. An “accessory pathway” response to paraHisian pacing/ entrainment identifies a nodo-ventricular AP because retrograde conduction is dependent upon myocardial capture. An “AV nodal” response indicates a nodo-fascicular AP because retrograde conduction is dependent upon His-RB capture.4 Limited data suggest that Downloaded from http://circep.ahajournals.org/ by guest on November 19, 2016 manifest fusion during RV entrainment of ORT using a nodal AP is specific p cific to a nodope ventricular fiber.20 Because the circuit for NFRT is contained within the specialized spe peciializ alliz i ed d cconduction onndu du n ri ntri ricu cula cu laar fusion fusi fu s onn cannot occur with paced d ccomplexes omplexes tha at penetrate peenetrate the excitable gap g system, ventricular that and entrain n ta tac tachycardia chycardia ((analogous annalo ogouss tto o AV AVNR AVNRT). NRT)). Whi While hile this thi hiss iss true trrue rue when whhen ccollision ollisiion n between betweeen rttho rtho hodromiic wavefro ont nts occu occurs cu urs iin n th tthee AV nnode odee orr H od His i bbundle, is undl dlee, iitt is nnot dl ott when whhen the antidromic andd oorthodromic wavefronts collision point oint is in in the th he right riigh ght bundle bundl dle distal distall to the h bif bifurcation i urcation off th if the he Hi His bu bundle nddle andd proximal pro roxi ximal to xi the take-off ff off th the nodo nodo-fascicular do ffascic a ic lar l AP A AP. P In In this thi case, case th the His Hi bbundlendle ndl dle left left ft bundleb ndle dl ventricular entric nttrii llar a axis is orthodromically activated and can fuse with paced complexes from the right ventricle. Limitations The number of patients in our collection is relatively small and our data should be evaluated in more patients. Furthermore, one patient contributed two SVTs which violates the requirement for independent observations. However, it is to our knowledge the only series comparing both bystander NF tachycardias and NFRT providing useful information about these rarely-described tachycardias. Accurate diagnosis requires evaluating all available clues from the EP study (e.g. effect of BBB) as differentiating NFRT from atypical AVNRT/ NF AP using entrainment alone can be difficult and potentially misleading in certain situations. If the refractory period of a 12 DOI: 10.1161/CIRCEP.113.000187 bystander NF AP is sufficiently short to support 1:1 conduction during entrainment and conduction over the NF AP is faster than over the His-Purkinje system, the pathway for entrainment of atypical AVNRT/NF AP and NFRT are the same and the PPI can be short. Conversely, severe decremental conduction over a NF AP might generate long PPIs during entrainment of NFRT that resemble atypical AVNRT. Entrainment results therefore, should be corroborated with the other important findings of the study. Entrainment is not possible for patients with only non-sustained tachycardia or whose tachycardia repeatedly terminates with Downloaded from http://circep.ahajournals.org/ by guest on November 19, 2016 pacing. In such situations, evaluating the response of tachycardia at the beginning ventricular he begi g nningg of ven entr en ti tr overdrive pacing can help differentiate ORT from AVNRT but does not distinguish ot di isttin ingu guiis ish NFRT NFRT from 21 22 PJRT or AVNRT/NF AP VNR VNR NRT/ T NF T/ N A P fr ffrom om ORT.21,22 Atrial ext extrastimulation xtra xt r stimulation and ra a d ov an ooverdrive erdrive pacing weree not systematically a y performed ally al d dduring urrin ng ta tachycardia achyccarddiaa to eexclude xclludde jjunctional unnctionnal nal tachycardia tacchyccarrdia (JT) (JT J ) or or assess asssess VA 2 25 linking. 23-25 However, Howe Ho wever, we e bbecause ecause focal al JT ass associated soc o ia iatedd wi with ith retrograde ret e ro roggrad adee co ad conduction ndducti tion ti on over th tthee SP SP is extremely rare r aand ndd nonee of our tachycardias tachy hycarddias exh hy exhibited hibbiitedd nonreentrant nt behavior beh havior (e.g. (e.gg. wa (e warm warm-up/ rm-upp rm cool-down ph phenomena, confident phenomena h iinitiation niti itiati tio after aft fte a spontaneous spontaneo ta s jjunctional nctional ti all complex), comple pll ) wee are confiden nfid fid of our diagnoses. Additionally, the value of VA linking in long RP tachycardias is unclear because VA intervals can vary significantly during atypical ORT and AVNRT due to decremental conduction over the AP and SP, respectively. Rather, AT was excluded by classical electrophysiologic criteria. Conclusion Diagnosing the atypical AV node – dependent long RP SVT requires separate pacing maneuvers to delineate the upper and lower limbs of the circuit. Long PPIs are common and a PPI – TCL < 125ms appears better than 115ms for differentiating ORT (PJRT/NFRT) from atypical AVNRT. 13 DOI: 10.1161/CIRCEP.113.000187 2WKHUHQWUDLQPHQWFULWHULDF33,PV¨9$PV¨+$PVDUHonly modestly sensitive but 100% specific for ORT. Differentiating nodal tachycardias (NFRT/atypical AVNRT) from PJRT can be established by ¨$+criteria or the paradoxical finding of AH(SVT) < AH(NSR). His-refractory VPDs was the only maneuver to identify a bystander, concealed NF AP during atypical AVNRT. Conflict of Interest Disclosures: None Downloaded from http://circep.ahajournals.org/ by guest on November 19, 2016 References: chycar ardi ar dia: di a: W hatt is the ha th 1. Ho RT, Fischman DL. Entrainment versus resetting of a long RP tachycardia: What diagnosis? Hear Heart artt Rh ar Rhyt Rhythm. Rhythm y hm m. 2012;9:312-314. 2012;9:312 314 Luebbert J. An A U n su nu sual al L onng RP R T achhyccarrdiaa: Wh W att iss th he m ech chan ch nissm? Heart Hear He art ar 2. Ho RT, Luebbert Unusual Long Tachycardia: What the mechanism? Rhythm. 2012;9:1898-1901. 012 012 12;9 ; :1898-19901. 3. Ho RT, Levi L iS SA. A. An Aty Atypical typi ypi pical Long Lo o g RP Tach Tachycardia: hyc ycar a di ar d a: Wha What h t is the m mechanism? echani n sm m? Heart Rhy Rhythm. y 2012. 4. Ho RT, Pa Pavri avr v i BB. BB B. A lo llong ngg R RP P interval i te in t rvvall tachycardia: tac achy hycard hy caarddia ia: Wh What att iiss th thee me mechanism? ech han a is i m?? Heart Heear H a t Rh Rhythm. 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Differentiation of atypical atrioventricular node reentrant tachycardia from orthodromic reciprocating tachycardia using a septal accessory pathway by the response to ventricular pacing. J Am Coll Cardiol. 2001;38:1163-1167. Downloaded from http://circep.ahajournals.org/ by guest on November 19, 2016 12. Gonzalez-Torrecilla E, Arenal A, Atienza F, Osca J, Garcia-Fernandez nde dezz J, Puchol Puch Pu chol ch ol A, A, Sanchez San San A, Almendra J. First postpacing interval after tachycardia entrainment with h ccorrection orre or rect cti tion ion fo forr atrioventricular node delay: A simple maneuver for differential diagnosis osis off atrioventricular atr trio iove io vent ve ntri nt ricu ri c la cu l nodal reentrant Rhythm. t nt ta tran ttachycardias ch hyc y ardi diias versus orthodromic reciprocating reeci cipprocating tachycardias. tach chycar ardias. Heart Rhythm ar m 2006;3:674-679. 4-6 4-6 - 79. 13. 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Sarkozyy A, Richter Brugada L, Buyl e S, er S, Chierchia Ch hieerchi hiaa G, D hi Dee A Asmundis smu mundiis C, Seferlis Seferliss C, C, Br Bruugad ada ad P,, Kaufman Kau ufman an L R, Dorian P, manoeuvre Europace. P Mangat Man anga gat ga at I. A novell pacing paciing manoe oeuvvre ttoo diagnose oe d ag di agnnose se atrial atr tria tr i l tachycardia. ia tach hycar ardi ar dia. Eu di E ropacee 2008;10:459-466. 5 4666. 59-46 16 DOI: 10.1161/CIRCEP.113.000187 Table 1. Electrophysiologic criteria differentiating the four atypical AV node – dependent long RP SVTs Downloaded from http://circep.ahajournals.org/ by guest on November 19, 2016 Age (yrs) Female TCL A-A-V pattern PPI – TCL PPI – TCL< 115 PPI – TCL< 125 cPPI cPPI< 110 ¨9$ ¨9$ ¨+$ ¨+$ ¨$+ Atypical AVNRT (w/wo NF AP) (n = 14) PJRT/ NFRT (n = 6) p value /95% CI 54 + 19 3/14 (21%) 429ms 11/14 (79%) 176ms 0/14 (0%) 0/14 (0%) 170 + 34ms 0/13 (0%)* 160 + 34ms 0/14 0/ /14 1 (0%) (0% 0%)) 72 + 40ms m 0/11 0/ 1 (0%) 11 (0% %) NFRT/ N NF RT// RT Atypical A At ypiicall AVNRT yp AVN NRT R 29 2 + 19 19ms 9ms m 42 + 13 5/6 (83%) 435ms 1/6 (17%) 118ms 3/6 (50%) 5/6 (83%) 115 + 69 4/6 (67%) 101 + 76ms 4/6 4/6 (67%) (67% (6 7% 7%) % -11 + 58 58ms 8ms 4/6 4//6 (67%) (667% 7%)) PJRT PJRT p= 0.036 p= 0.036 CI= - 47.5 – 35.5 p= 0.036 CI= 26.3 – 89.7 p= 0.029 p= p 00.001 .001 .0 01 CI= CI = 21 21.7 .77 – 88 88.3 p= 0.007 0.0 .007 07 CI= 25.9 – 42 42.2 2 p= 00.005 .0005 0 CI= C I= 35 35.6 – 11 110 1 p= 00.012 .0012 1 p value/ vaalu ue/ 95% CI 95% CI= CI = 3.03 – 35 35.0 5 100 + 17 17ms ms * cPPI could not be calculated in 1 patient because a His bundle deflection was not observed following entrainment Table 2. Differential diagnosis of a long RP tachycardia reset (advanced or delayed) or terminated (with VA block) by His-refractory VPDs. Atypical AVNRT + bystander NF NFRT PJRT PPI – TCL >125ms <125ms <125ms ¨$+ >40ms or >40ms or <20ms AH(SVT) < AH(NSR) AH(SVT) < AH(NSR) 17 DOI: 10.1161/CIRCEP.113.000187 Figure Legends: Figure 1. ORT using a decremental atrio-ventricular AP (PJRT). Top: A His-refractory VPD paradoxically delays tachycardia by 19ms (fully compsensatory). Bottom: Entrainment from the ventricle with antidromic capture of the His bundle showing a pseudo A-A-V pattern. All criteria (PPI (253ms), cPPI (251ms)¨9$ (233ms)¨+$ (124ms)) yield a false diagnosis of atypical AVNRT. Downloaded from http://circep.ahajournals.org/ by guest on November 19, 2016 Figure 2. ORT using a concealed nodo-ventricular AP (NVRT). Top: A sspontaneous Hisp nt po ntan taneo eous us Hi His srefractory VPD block. Paradoxically, VPD te tterminates rm min inattes tachycardia with VA bloc ock. oc k Paradoxica c llyy, AH(SVT) < AH(NSR) w which excludes PJRT JRT . Bottom Bottom: m: En Entrainment ntrrainm mentt fr ffrom om m thee vventricle en ntrricle le w with ith orthodromic ortthoddroomic capture cappture ooff tthe he H His bundle showing wingg an A-V-A A-V V-A A response, e, P PPI PI – TCL TCL = PV¨9$ PV ¨9$ PVDQG¨HA P VDQG QG ¨HA A = -1 -11ms. 11mss Figure 3. At Atypical concealed, nodo-fascicular AP. Hispical icall AVNRT AVN VNRT RT with ith ith a concealed ledd bbystander stander tandd nodo do ffascic a ic llar A AP P T Top: o A His Hi refractory VPD paradoxically delays tachycardia by 41ms (fully compensatory). The AH(SVT) is very short (38ms) (AH(NSR) = 54ms). Bottom: Entrainment from the ventricle with antidromic capture of the His bundle showing a true A-A-V response (retrograde FP and SP/NF AP) and long PPI – TCL = PV¨9$ PVDQG¨+$ PV Figure 4. Atypical AVNRT with a concealed, bystander nodo-fascicular AP. Top: A Hisrefractory VPD terminates tachycardia with VA block. Paradoxically, AH(SVT) < AH(NSR) which excludes PJRT. Middle: Entrainment from the ventricle yields a true A-A-V response and a long PPI – TCL = 232ms. Note that the atrium is not advanced until the 3rd complex despite 18 DOI: 10.1161/CIRCEP.113.000187 retrograde capture of the His bundle indicating that the His bundle is not part of the circuit further excluding ORT. Bottom: Para-Hisian entrainment. Loss of His bundle capture (last paced complex) causes a 55ms increase in the VA at the anteroseptum (indicating FP conduction) which then exposes conduction over a slowly-conducting NF AP caused by the penultimate pacing stimulus (arrows). Note the change in the proximal CS electrogram and equivalent increase in the VA at the posteroseptum that is only possible with a NF (not NV or AV) AP. Downloaded from http://circep.ahajournals.org/ by guest on November 19, 2016 Figure 5. PPI –TCL values for atypical AVNRT (with/without a concealed, cealeed, d bystander bys ysttand nder der NF NF AP) and ORT (PJRT/NFRT). P RT/ PJR T NF FRT RT).. Figure 6. Diagram D gra Diag ram m iillustrating llustrati t ti t ng the the reentrant ree e ntrant ee nt ccircuits ircuitts for ir irc for th the fo four aatypical t piicall AV ty V nnode ode – de ddependent penn SVTs. The upper require maneuvers upppe p r andd lower lowe lo w r po pportions rtiions of each each h circuit ciircuit i differ diff f er and d req eq quire sseparate e arate pa ep ppacing cing ng m anee for diagnosis. sis si i * A concealed ledd NF AP AP bbypasses passes tthe he His His bundle b ndle dl andd allows allo all llo s access to to the the AVNRT A AVN VN circuit from the ventricle. HPS = His-Purkinje system 19 Downloaded from http://circep.ahajournals.org/ by guest on November 19, 2016 Downloaded from http://circep.ahajournals.org/ by guest on November 19, 2016 Downloaded from http://circep.ahajournals.org/ by guest on November 19, 2016 Downloaded from http://circep.ahajournals.org/ by guest on November 19, 2016 Downloaded from http://circep.ahajournals.org/ by guest on November 19, 2016 Downloaded from http://circep.ahajournals.org/ by guest on November 19, 2016 Electrophysiologic Features Differentiating the Atypical AV Node-Dependent Long RP Supraventricular Tachycardias Reginald T. Ho, Daniel R. Frisch, Behzad B. Pavri, Steven A. Levi and Arnold J. Greenspon Downloaded from http://circep.ahajournals.org/ by guest on November 19, 2016 Circ Arrhythm Electrophysiol. published online April 29, 2013; Circulation: Arrhythmia and Electrophysiology is published by the American Heart Association, 7272 Greenville Avenue, Dallas, TX 75231 Copyright © 2013 American Heart Association, Inc. All rights reserved. Print ISSN: 1941-3149. Online ISSN: 1941-3084 The online version of this article, along with updated information and services, is located on the World Wide Web at: http://circep.ahajournals.org/content/early/2013/04/27/CIRCEP.113.000187 Permissions: Requests for permissions to reproduce figures, tables, or portions of articles originally published in Circulation: Arrhythmia and Electrophysiology can be obtained via RightsLink, a service of the Copyright Clearance Center, not the Editorial Office. 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