1-ATYPICAL AVNRT WITH BYSTANDER NODOFASCICULAR AP (aAVNRT/NF AP) 2-ATYPICAL AVNRT (aAVNRT) 3-ORTHODROMIC RECIPROCATING TACHYCARDIA USING A DECREMENTAL AV PATHWAY (PJRT) 4-ORT USING A CONCEALED NODOFASCICULAR AP (NFRT)
All these tachycardias have a long RP interval with earliest A near the CS Os. AT was excluded by -Spontaneous termination with AVB -Termination with PVCs that failed to reach the A -A-A-V response to entrainment from the ventricle
PPI-TCL Corrected PPI (cPPI)=(PPI–TCL)–(AHfirst return AH after entrainment from ventricle–AHSVT) ΔVA=VAentrainment from ventricle–VASVT ΔHA=HAentrainment from ventricle–HASVT ΔAH=AHatrial pacing/entrainment at/near TCL–AHSVT, or AHNSR–AHSVT if paradoxically, AHSVT<AHNSR HRPVC
ATYPICAL AVNRT 1-Non obligatory 1:1 AV relationship (persistence of tachycardia despite retrograde block to the A or antegrade block to the V) 2-Failure of antegrade BBB to affect tachycardia 3-Failure of HRPVC to affect tachycardia 4-Failure to entrain tachycardia from the V with orthodromic capture of the His bundle 5-PPI -TCL > 115 ms (or cPPI > 110 ms) 6-ΔHA > 0 ms 7-ΔAH> 40 ms (or paradoxically AHSVT<AHNSR)
PJRT 1-Obligatory 1:1 AV relationship 2-VA/TCL prolongation with the development of BBB 3-HRPVC reset the atrium (advance or delay A) or terminate tachycardia with VA block 4-Ability to entrain the tachycardia from the ventricle with orthodromic capture of the His bundle 5-PPI - TCL < 115 ms (or cPPI < 110 ms) 6-ΔVA < 85 ms 7-ΔHA < 0 ms 8-ΔAH < 20 ms
NFRT 1-Nonobligatory 1:1 AV relationship (persistence of tachycardia with retrograde block to the atrium but not antegrade block to the ventricle) 2-VA/TCL prolongation with the development of BBB 3-HRPVC reset or terminate tachycardia with VA block 4-Ability to entrain tachycardia from the ventricle with orthodromic capture of the His bundle 5-PPI–TCL<115 ms (or cPPI<110 ms) 6-ΔVA<85 ms 7-ΔHA<0 ms 8-ΔAH>40 ms (or paradoxically, AHSVT<AHNSR)
Atypical AVNRT/NF AP 1-Nonobligatory 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-HRPVC 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 ≥ 115 ms (or cPPI≥110 ms) 6-ΔVA≥85 ms 7-ΔHA>0 ms 8-ΔAH>40 ms (or paradoxically, AHSVT<AHNSR)
Compared to AVNRT ORT were younger (42±13 years vs. 54±19 years) ORT were women (83% vs. 21%) ORT had same TCL as AVNRT (435 vs. 429 ms) ORT had shorter PPI-TCL (118 ms vs 176 ms) ORT had PPI-TCL < 125 ms (83%, only 50% had PPI-TCL < 115 ms) ORT cPPI < 110 ms ORT ΔVA < 85 ms ORT ΔHA < 0 ms (100% specificity, 67% sensitivity)
When compared to permanent form of JR, NFRT / AVNRT had Longer ΔAH (29 vs. 10 ms) AH(SVT)<AH(NSR)
PJT should give a short PPI-TCL and a very long RP interval. Shouldn't look anythink like AVNRT
-Bystander accessory pathways were only identified by HRPVC which advanced (50%), delayed (50%), or terminated (63%) SVT in all accessory pathway patients.
Standard diagnostic criteria are lacking regarding atypical long RP SVT and are often extrapolated to from pacing maneuvers applied to the more common short RP SVT Long RP SVTs involving concealed NF AP are rare.
-Prolonged conduction over the SP of the AVN or decremental AP after entrainment from the ventricle can produce A-A-V patterns that might be mistaken for AT. -Slow AP conduction after entrainment of an atypical ORT can generate long PPI that causes misdiagnosis of AVNRT despite cPPI
ENTRAINMENT FROM THE VENTRICLE A-A-V patterns are common, mostly with aAVNRT than ORT (79% vs 17%) PPI-TCL was shorter for ORT than aAVNRT (118 ms vs. 176 ms) PPI-TCL< 125 ms occurred in 5/6 ORT and 0/14 aAVNRT cPPI was shorter for ORT (115 ms vs 170 ms) Although A-A-V responses are generally considered diagnostic of AT, A-A-V patterns were common in this series with aAVNRT 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 pacing cycle length so that the first atrial EGM after entrainment is actually driven by the previously paced stimulus. True A-A-V responses were the result of dual 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. 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 over the FP to the atrium (first A) and then collides with the previous (n−1) orthodromic wavefront in the SP. The last (n) paced orthodromic wavefront has no antidromic wavefront with which to collide, conducts over the SP to activate the atrium (second A) before conducting antegradely over the FP to the ventricle.
HRPVC HRPVC reset or terminated the tachycardia in all patient with AP It was the only maneuver to identify a concealed, bystander NF AP during aAVNRT (advanced, delayed, or terminated with VA block) The VPD conducts over the NF AP ahead of the AVNRT wavefront and penetrates its excitable gap in the SP after the lower turnaround point of the circuit. Its antidromic wavefront collides with tachycardia, whereas its orthodromic wavefront encounters either relative or absolute distal SP refractoriness delaying or terminating tachycardia, respectively. -Severe AP decrement paradoxically delayed the A because the degree of PVC prematurity was offset by a greater than or equal to degree of AP conduction over each AP. -Mild AP advanced the A because the degree of PVC prematurity was offset by a lesser degree of AP conduction delay (partially compensatory)
ABLATION The successful ablation site of all aAVNRT with and without a bystander NF AP was the SP of the AVN along the posteroseptum of the RA This included patients with NFRT where the AP would insert on the SP of the AVN except for one patient who had an AP inserting into the left atrionodal 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 CS identified by activation mapping during tachycardia.