Mapping of ventricular tachycardia induced by thoracic neural stimulation in dogs

To investigate ventricular tachycardias produced in healthy canine myocardium by stimulation of sympathetic ganglia or cardiac nerves, we simultaneously recorded a surface ECG and 63 ventricular electrograms in anesthetized open-chest dogs. Isochronal and isopotential maps were generated off-line by computer. Ventricular tachycardia with uniform beat-to-beat morphology was induced in 13 or 22 dogs by electrical stimulation of the left stellate ganglion (five experiments), the left middle cervical ganglion (four experiments), the left caudal pole cardiopulmonary nerve (two experiments), or the ventrolateral cardiac nerve (eight experiments). It was not inducible by stimulation of the right-sided major cardiopulmonary nerves or ganglia. In most instances the earliest measured electrical excitation occurred on the posterior aspect of the ventricles. Isochronal maps demonstrated a radial spread of the impulse away from the area of earliest excitation. Changes in the region of earliest excitation and (or) activation pattern were accompanied by changes in QRS morphology. The potential gradients measured between areas displaying positive and negative T waves on the anterior and left lateral aspects of the ventricles were significantly increased by ventrolateral cardiac nerve stimulation. However, the ventricular regions where these potential gradients existed differed from the regions of earliest excitation during ventricular tachycardia. These results demonstrate that the thoracic autonomic nervous system can induce repetitive ventricular excitation originating from consistent loci.