Chronobiology of rate pressure product in young adults

Cardiac events are known to precipitate at specific hours of the day implying that a circadian rhythm of myocardial oxygen demand may exist. Rate - pressure product (RPP) is regarded as a surrogate measure of myocardial oxygen demand and can be obtained without any invasive procedure. Hence the project was designed to study the circadian rhythmic pattern of RPP in healthy individuals and its gender variability in Indian population. Blood pressure was monitored at 2 hourly intervals for 24 hours in 55 male and 70 female healthy subjects between 18 to 25 years of age without any acute or chronic illness. Independent samplet test were performed for descriptive analysis. Repeated measures post hoc Tukey ANOVA test was performed for comparison of RPP within the groups. RPP values were seen to be minimum at 2 am in males (5332 924) and at 4 am in females (6567 1092) and maximum at 2 pm in males (8206 1296) and at 8 pm in females (9928 1709). At all the observed time intervals RPP values were higher in females. There exist a definite pattern of circadian rhythm in RPP with peak values attained during daytime and least values during early morning hours. Also the rhythm and amplitude of RPP is different in both genders