THE USE OF A MICROCOMPUTER TO AUTOMATE MEASUREMENT OF ACTION-POTENTIAL DURATION FOR BOTH TRANSMEMBRANE AND MONOPHASIC ACTION-POTENTIALS

Measurement of action potential duration is made more valuable if it c an be made simultaneously with other variables, to which it may be rel ated. We have developed a microcomputer-based system which allows meas urement of action potential duration, both for transmembrane action po tentials and for monophasic action potentials. The system allows simul taneous recording and analysis of action potentials and intraventricul ar pressures. Both end-diastolic and maximum systolic pressures have b een analysed. Action potential duration was assessed at four different levels of the repolarization curve. We have analysed the consistency of measurements made by the computer, and compared them to measurement s made manually, using results from six dog experiments. For action po tential duration, there was no systematic difference between the manua l and the computer methods, but the computer was significantly more co nsistent. In die case of the pressure measurements, the two methods we re approximately the same in their consistency, and again there was no systematic difference. We have demonstrated that potential errors in determination of the average diastolic potential did not significantly affect the results obtained by our method. The variances of action po tential duration measurements made al different levels of repolarizati on were equal. We demonstrated that there was no effect of amplitude o n the action potential duration of potentials recorded under steady-st ate conditions.