Pacing-induced palmar sweating evaluated by unique hygrometer: possible implications of sympathetic activation during tachycardia

Although reflex sympathetic activation is a major determinant of the haemod ynamic tolerability of ventricular tachycardia (VT), the methods for evalua ting this aspect during on-going VT remain invasive and complicated. Palmar sweating as an indirect but non-invasive measure of sympathetic activity w as estimated by means of a unique hygrometer under right ventricular (RV) r apid pacing (up to 150 beats min(-1)) replicating VT, and concurrent monito ring of aortic blood pressure in five patients with various kinds of cardia c arrhythmias in our electrophysiological laboratory. The peak palmar sweat ing rate in arbitrary units was augmented as the RV pacing rate increased a nd was proportional to the pacing-induced fall in systolic blood pressure ( SBP), with a correlation coefficient of more than 0.903 (P < 0.006). The sl ope of linearity between the sweating rate and the fall in SBP varied among individual patients, with greater sweating amplitude in the younger patien ts even with the same extent of fall in SBP. This preliminary study suggest s sympathetic acceleration caused by haemodynamic deterioration under simul ated VT, and therefore this protocol may be able to predict the haemodynami c tolerability of sustained monomorphic VT.