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

• Published in: European journal of applied physiology 2007-05, Vol.100 (2), p.185-191
• Main Authors: Moriyama, Kayo, Ifuku, Hirotoshi
• Format: Article
• Language: English
• Subjects: Adult; Blood pressure; Blood Pressure - physiology; Cardiac Output - physiology; Carotid Arteries - physiology; Carotid artery; Cold; Cold Temperature; Female; Heart; Heart rate; Heart Rate - physiology; Humans; Immersion; Male; Muscle contraction; Myocardial Contraction - physiology; Pain; Pulse; Sensation - physiology; Stroke Volume - physiology; Sympathetic nerves
• ISSN: 1439-6319; 1439-6327
• DOI: 10.1007/s00421-007-0415-x

The ratio of the first derivative (dP/dt) of a carotid artery pulse to the developed pressure (P), (dP/dt)/P, is an easily measurable, noninvasive index of cardiac contractility even in moderate exercise. We examined the effects of transient cold exposure on cardiac contractility in normal reactors (n = 12) and hyperreactors (an increase in systolic or diastolic pressure >15 mm Hg; n = 6) by using this index. Eighteen healthy participants were subjected to the cold pressor test, which required them to immerse the right hand in chilly water (4 degrees C) for 2 min. Although cold stress maximally increased mean blood pressure during the second minute, it maximally increased heart rate and cardiac contractility after 60 s of immersion in both groups of subjects. Comparing normal reactors and hyperreactors by two-way ANOVA revealed a group x time interaction for heart rate but not for cardiac contractility. These findings suggest that the increase in cardiac contractility during cold-water immersion dose not reflect the levels of heart rate and muscle sympathetic nerve activity, and that the specific responses of cardiac function to a cold pressor test in hyperreactors depends on heart rate rather than cardiac contractility.