Table 1.
Summary of clinical and electrophysiological findings
| Case 1 | Case 2 | Case 3 | |
|---|---|---|---|
| Age | 35 | 40 | 48 |
| Sex | Female | Female | Female |
| Rate of SVT (bpm) | 250 | 250 | 260 |
| Initiating beat | |||
| Coupling interval (ms) | 310 | 230 | 220 |
| Axis | Superior | Superior | RBBB, superior |
| QRS duration (ms) | 110 | 100 | 100 |
| PMVT | |||
| Duration (s) | 13.2 | 12.5 | 8.5 |
| Postreversion PVCs | Yes | No | No |
| Axis | Left superior | N/A | N/A |
| Electrophysiology study | |||
| Sedation | Nil | Yes | Nil |
| Method of induction | Atrial extrastimuli (on isoprenaline) | Atrial extrastimuli (no isoprenaline) | Atrial burst pacing (on isoprenaline) |
| Rate of induced SVT (bpm) | 240 | 250 | 250 |
| Septal VA interval (ms) | 12 | 15 | 0 |
| Effect of His-synchronous PVC | Nil | Nil | Nil |
| Duration of induced SVT | 10 minutes | 5 minutes | 6 minutes |
| Termination | Pace-terminated | Spontaneous AV block | Pace-terminated |
| VT induction | |||
| Minimum pacing CL (ms) | 280 | 250 | 300 |
| Extrastimuli, S1,2,3,4 (ms) | 400,220,210 | 400,220,210,200 | 400,260,240 |
| VT induction result | No VT | No VT | No VT |
| Exercise testing | |||
| Peak rate (% age-pred max) | 183 (97%) | 179 (99%) | 143 (80%) |
| PVC/VT | No PVC/VT | No PVC/VT | 1 PVC in recovery (RBBB morphology, superior axis) |
AV = atrioventricular; bpm = beats per minute; CL = cycle length; N/A = not applicable; PMVT = polymorphic ventricular tachycardia; Pred max = predicted maximum; PVC = premature ventricular contraction; RBBB = right bundle branch block; SVT = supraventricular tachycardia; VA = ventriculoatrial; VT = ventricular tachycardia.