Case Presentation
A 41 years old lady presented to us with drug refractory narrow QRS
tachycardia. Echocardiography revealed normal left ventricular systolic
function. 12 lead electrocardiography (ECG) showed long RP
(RP>PR) narrow QRS tachycardia. Radiofrequency catheter
ablation was performed after obtaining informed consent. Intracardiac
electrograms and 12 lead ECG were continuously monitored using Workmate
Claris system (Abbott, Plymouth, MN). Upper limb Venous angiography
showed dilated coronary sinus with left sided superior vena cava. Basal
AH and HV intervals were 85ms and 44ms respectively. Patient had
spontaneously inducible tachycardia (Fig 1B) which could be terminated
by intravenous adenosine. ECG showed narrow QRS tachycardia with
variation in both atrial and ventricular cycle length (Fig 1A).
Intracardiac electrogram during tachycardia showed variation in H-H,
A-A, V-V and HA intervals (Fig 2)
- What is the mechanism of the tachycardia onset?
- What is the substrate for re-entry?
- What could be the reason for the variation in A-A, H-H, H-A and V-V
intervals?