Short term oscillations in systolic time intervals

In young adults during basal conditions spectral analyses of RWPCI (R-Wave Peak to Carotid Incisura) and QT intervals identified peaks characteristic to the Traube-Hering-Mayer (THM: 0.05–0.15 Hz) and respiration (RESP: 0.2–0.4 Hz) bands. Although the position of the peaks was similar to that observed with RR intervals in both bands, there was a tendency for greater concordance of the peak positions within; the THM band. 2. The power within the THM and RESP bands was balanced in both QT and RWPCI spectra, in contrast with the THM dominance in the RR spectra. 3. QT variability accounted for under 2 percent of the RR total variance. Virtually all of the remaining RR variance was associated with tr)e TR segment representing vagai modulation. 4. The total RWPCI variability was approximately 1/3 of the total QT variability. This relationship persisted within the THM and RESP components. 5. The; neural origin of the THM power in the QT spectra suggests that neural j mechanisms may contribute to the THM power in RWPCI.