Click on image to view larger version.
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.