Variation of P-QRS relation during atrioventricular node reentry tachycardia
Yasuhiro Taniguchi, MDa,1,
San-Jou Yeh, MDa,
Ming-Shien Wen, MDa,
Chun-Chieh Wang, MDa,
Fun-Chung Lin, MDa and
Delon Wu, MD, FACCa
a Second Section of Cardiology, Department of Medicine, Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Taipei, Taiwan
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Figure 3 Continuous recordings from case 8 showing entrainment of the tachycardia by overdrive ventricular pacing. The tachycardia displayed a cycle length of 435 to 445 ms. The ventricular pacing was conducted from the right ventricular apex at a cycle length of 400 ms. The last three paced beats entrained the tachycardia. Note the atrial activation sequences of the entrained beats are similar to that during tachycardia.
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Figure 4 Continuous recordings from case 12 showing induction of nonsustained fast-slow form atrioventricular node reentry tachycardia with variation of P-QRS relation. The tachycardia was induced by a ventricular extrastimulus, which was coupled to a ventricular driven cycle length of 500 ms at a coupling interval of 230 ms. Note there were trivial changes in AH, HA and AH/HA ratio at the beginning of the tachycardia. It was followed by a progressive lengthening of AH interval (from 105 to 310 ms) and a progressive shortening of HA interval (from 210 to 50 ms) concomitant with a progressive lengthening of the tachycardia cycle length (from 300 to 360 ms). The AH/HA ratio was reversed before termination of the tachycardia. S1 = artifact of the basic driven beat.
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Figure 5 Recordings from case 24 showing induction of a nonsustained atypical atrioventricular node reentry tachycardia. The tachycardia was induced by a ventricular extrastimulus, which was coupled to a ventricular driven cycle length of 480 ms at a coupling interval of 240 ms. At the beginning, the tachycardia appeared to be of the fast-intermediate form with an AH of 150 ms and HA of 150 ms. A progressive shortening of the HA interval (from 150 to –10 ms) and a progressive lengthening of the AH interval (from 150 to 350 ms) concomitant with a lengthening of the tachycardia cycle length (from 300 to 340 ms) were observed. The AH/HA ratio was reversed before termination of the tachycardia. Note that the atrial activation of the last beat was registered before the His bundle potential.
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Figure 6 Recordings from case 19 showing induction of sustained fast-slow atrioventricular node reentry tachycardia and variation of P-QRS relation with block proximal to the His bundle recording site following intravenous bolus of 3.5 mg adenosine triphosphate. (A) A sustained fast-slow atrioventricular node reentry tachycardia was induced following rapid ventricular pacing at a cycle length of 300 ms. Note the tachycardia was induced after the fourth ventricular paced beat during an atypical retrograde Wenckebach periodicity when conduction shifted from the fast to the slow pathway. The cycle length of the tachycardia varied between 290 to 310 ms, AH 70 to 90 ms and HA 220 ms. (B) After adenosine triphosphate, a prolongation of AH between 90 to 130 ms, a variation of the tachycardia cycle length between 310 to 320 ms and a shortening of HA between 230 to 190 ms were noted before a blocked beat (indicated by a star) occurred. This was then followed by an episode of 3:2 block proximal to the His bundle recording site (indicated by stars) with progressive lengthening of the tachycardia cycle length and, then, termination of the tachycardia. s = stimulus artifact.
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Figure 7 Ladder diagram showing the hypothetical model of variation P-QRS relation during atrioventricular node reentry tachycardia. In this diagram, the atypical form of tachycardia using a fast pathway for anterograde and an intermediate pathway for retrograde conduction is presented. The first beat represents a beat during stable tachycardia. The second beat represents a beat with changes in AH, HA and AH/HA ratio due to decremental conduction in the distal common pathway; the conduction time in anterograde limb and the retrograde limb and, therefore, the cycle length of the tachycardia remain unchanged. The third beat represents a beat with block proximal to the His bundle recording site due to block in the distal common pathway. The fourth beat represents a beat with variation of P-QRS relation due to simultaneous prolongation of the conduction time in the distal common pathway and the retrograde limb. The fifth beat represents a beat with variation of P-QRS relation due to prolongation of the conduction time in the distal common pathway as well as the distal anterograde and retrograde limb. The cycle length of the tachycardia is increased in the fourth and the fifth beats. Note that in the fifth beat the AH/HA ratio is that of the slow-fast form. A = atria; N = compact atrioventricular node; NH = nodo-Hisian zone; H = His bundle. Solid line represents stable conduction; interrupted lines represent decremental conduction.
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Figure 1 Recordings from case 8 showing variation of P-QRS relation with changes in AH, HA and AH/HA ratio at the initiation of slow-fast atrioventricular node reentry tachycardia following delivery of two atrial extrastimuli during sinus rhythm. The sinus cycle length was 655 ms and the coupling interval of the first extrastimulus was 320 ms. (A) The coupling interval of the second extrastimulus was 280 ms, and was 260 ms in (B). Note that the HA interval of the first echo beat was the longest and a progressive shortening of HA interval associated with changes in AH interval, AH/HA ratio and the cycle length of the tachycardia was observed after initiation of the tachycardia. The atrial activation sequence was unchanged, and the earliest atrial activation was registered from the orifice of the coronary sinus. Note also that the HA interval of the first echo beat was longer in (A) when the tachycardia was induced at a longer coupling interval (A2A3) with a shorter AH interval (A3H3) as compared to that in (B). I, aVF and V1 = ECG leads I, aVF and V1; HRA, CSd, CSp and HBE = bipolar electrograms recorded from the high right atrium, the distal two electrodes of coronary sinus catheter, the proximal two electrodes of the coronary sinus catheter, and the His bundle recording catheter; CL = cycle length; S2 and S3 = stimulus artifact of the first and the second extrastimulus; A1, A2 and A3 = atrial responses to the basic sinus or driven beat, the first extrastimulus and the second extrastimulus; H1, H2 and H3 = His bundle responses to the basic sinus or driven beat, the first extrastimulus and the second extrastimulus; Ae and He = atrial and His bundle responses during atrioventricular node reentry echoes or tachycardia. The cycle lengths of the tachycardia, AeHe and HeAe intervals are listed.
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Figure 2 Continuous recording from case 8 showing variation of P-QRS relation with block proximal to the His bundle recording site (beat with a star) without interruption of the tachycardia after intravenous bolus of 4 mg adenosine triphosphate (see text for discussion).
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