ELECTRODE FOR RECORDING DIRECTION OF ACTIVATION, CONDUCTION-VELOCITY,AND MONOPHASIC ACTION-POTENTIAL OF MYOCARDIUM

Conduction velocity and recovery of excitability are central facets of reentry arrhythmias, and yet there are no satisfactory techniques for the simultaneous measurement of both from the same area of myocardium . We have developed an electrode arrangement that allows the simultane ous recording of conduction velocity, repolarization of the myocardium together with an index of dispersion, and direction of activation of the myocardium. Three silver/silver chloride electrodes were arranged in an equilateral triangle with a reference electrode at the center. F rom this arrangement three monophasic action potentials were recorded. From the time of arrival of the wavefront of activation at each elect rode the direction of activation and conduction velocity were calculat ed in real time by a computer. There was a good correlation for the in vivo signals from the circular electrode and the new electrode both f or conduction velocity (r = 0.99, P < 0.001) and for direction of acti vation (r = 0.99, P < 0.001). This new mathematical method and electro de design allows the simultaneous measurement of conduction velocity a nd direction and monophasic action potential, and this can give a beat -by-beat indication of wavelength and dispersion of action potential d uration.