Noninvasive assessment of cardiac contractility by using (dP/dt)/P of carotid artery pulses during exercise

Abstract

In earlier studies we have shown that both the pressure (P) of the carotid artery pulse (CAP) and its first derivative (CAP dP/dt) could be recorded during moderate exercise. To establish that the CAP (dP/dt)/P is a noninvasive substitute for the left ventricular (LV) value, LV (dP/dt)/P, an index of cardiac contractility, we studied CAP (dP/dt)/P under various states of activity in the autonomic nervous system in 12 healthy male subjects. Increased sympathetic nerve activities yielded by passive tilting, emotional load, or cold stress increased CAP (dP/dt)/P significantly (P < 0.05). Increased parasympathetic nerve activity by ocular compression, however, did not significantly affect the value. Moderate exercise at a heart rate of approximately 150 beats.min-1 increased it significantly from 16.7 to 25.2.s-1 in a supine position (P < 0.001) and from 16.6 to 24.8.s-1 in an upright position (P < 0.001). It increased monotonically as heart rate increased, but the slope was steeper when the heart rate was greater than approximately 100 beats.min-1 than it was when the rate was less than 100 beats.min-1. In conclusion, the present study indicated that CAP (dP/dt)/P can be used as a noninvasive index of cardiac contractility even in moderate exercise.

Increased cardiovascular reactivity to the cold pressor test is not associated with increased reactivity to isometric handgrip exercise

“…The ECG was recorded from bipolar chest leads. The R-R intervals of the ECG were measured, and the instantaneous heart rate was calculated by multiplying the inverse of the R-R intervals by 60 s. (dP/dt)/P of carotid artery pulse, a non-invasive index of cardiac contractility, was calculated beat by beat according to Ifuku et al (1994) by measuring peak values of percussion wave (P) and dP/dt (Ifuku et al 1993). The heart rate and (dP/dt)/P were averaged over 30 s.…”

Assessment of cardiac contractility during a cold pressor test by using (dP/dt)/P of carotid artery pulses

“…The (dP/dt)/P of the carotid artery pulse increases during head-up tilt, cold stress, and exercise, and it reXects sympathetic nerve activity, representing a noninvasive index of cardiac contractility even during moderate exercise (Ifuku et al 1994). Using this index, the present study examined the detailed eVects of a cold stress on cardiac contractility in normal and hyperreactors.…”

“…In brief, a pulse transducer (45259, NEC San-ei) Wxed on the apparatus (originally a brace to Wx the cervical vertebrae) was held over the right carotid artery, and the subjects were allowed to swallow to relieve any discomfort from wearing the apparatus. Peak values of P and dP/dt were measured in millimeters of mercury and in millimeters of mercury per second, respectively (Ifuku et al 1993), and (dP/dt)/P (per second) was calculated beat by beat (Ifuku et al 1994) (Fig. 1).…”

“…We have reported that the ratio of the maximal rate of pressure rise (dP/dt) in carotid artery pulse to the developed pressure (P), (dP/dt)/P, is a noninvasive index of cardiac contractility even in moderate exercise, and that it reXects cardiac sympathetic nerve activity (Ifuku et al 1994). In the present study, we examined the eVects of the cold pressor test on cardiac contractility by this index.…”

Regulation of cardiac function during a cold pressor test in athletes and untrained subjects

“…This pressor response is characterized by increased cardiac output during the initial period (0-30 s) (Yamamoto et al 1992) and by enhanced muscle sympathetic nerve activity (MSNA) during the later period (30-120 s) (Victor et al 1987;Yamamoto et al 1992). By (dP/dt)/P of carotid artery pulse, a non-invasive index of cardiac contractility reflecting the state of cardiac sympathetic nerve activity (Ifuku et al 1994), cardiac contractility increases during 0-90 s of cold-water immersion, but it dose not reflect the levels of heart rate and MSNA (Moriyama and Ifuku 2007).…”