Effect of halothane on systolic time intervals.

By simultaneous rapid-strip recordings of the electrocardiogram, phonocardiogram, and carotid pulse wave, systolic time intervals (STI) can be calculated and used to assess cardiac activity during general anesthesia. The principal advantage of this methodology over more conventional technics of determining anesthetic effects on the heart is that it is noninvasive. One anesthetic agent, halothane, was chosen to illustrate the usefulness of the technic. Results obtained by using STI supported the well-documented effect of myocardial depression produced by halothane. Becuase the equipment and technic are relatively simple, this procedure has definite clinical applications.