Biomaterial Database

Compilation of regression equations employing the RR interval for the correction of systolic time interval measurements for heart rate in sheep. 1989

W J du Plooy, and P J Schutte

Department of Physiology, Medical University of Southern Africa.

The aim of this study was to determine the validity of regression equations relating RR interval and heart rate to systolic time intervals in sheep. Regression equations were compiled employing the RR interval to correct systolic time intervals for heart rate in six Merino ewes. A range of heart rates was obtained by means of pharmacological intervention as well as electrical pacing. Heart rate did not affect the pre-ejection period, isovolumetric contraction time, the pre-ejection period to left ventricular ejection time ratio, the ratio QS2/QT, electrical delay (Q1), or the PR interval. Heart rate did, however, affect the duration of electromechanical systole (QS2), left ventricular ejection time and mechanical systole (S1S2). The study showed that it was preferable to correct the systolic time intervals using the RR interval rather than the heart rate. Bazett's equation to correct electrical systole (QT) for heart rate in humans was also validated in sheep.

UI	MeSH Term	Description	Entries
D012044	Regression Analysis	Procedures for finding the mathematical function which best describes the relationship between a dependent variable and one or more independent variables. In linear regression (see LINEAR MODELS) the relationship is constrained to be a straight line and LEAST-SQUARES ANALYSIS is used to determine the best fit. In logistic regression (see LOGISTIC MODELS) the dependent variable is qualitative rather than continuously variable and LIKELIHOOD FUNCTIONS are used to find the best relationship. In multiple regression, the dependent variable is considered to depend on more than a single independent variable.	Regression Diagnostics,Statistical Regression,Analysis, Regression,Analyses, Regression,Diagnostics, Regression,Regression Analyses,Regression, Statistical,Regressions, Statistical,Statistical Regressions
D006339	Heart Rate	The number of times the HEART VENTRICLES contract per unit of time, usually per minute.	Cardiac Rate,Chronotropism, Cardiac,Heart Rate Control,Heartbeat,Pulse Rate,Cardiac Chronotropy,Cardiac Chronotropism,Cardiac Rates,Chronotropy, Cardiac,Control, Heart Rate,Heart Rates,Heartbeats,Pulse Rates,Rate Control, Heart,Rate, Cardiac,Rate, Heart,Rate, Pulse
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D012756	Sheep	Any of the ruminant mammals with curved horns in the genus Ovis, family Bovidae. They possess lachrymal grooves and interdigital glands, which are absent in GOATS.	Ovis,Sheep, Dall,Dall Sheep,Ovis dalli
D013599	Systole	Period of contraction of the HEART, especially of the HEART VENTRICLES.	Systolic Time Interval,Interval, Systolic Time,Intervals, Systolic Time,Systoles,Systolic Time Intervals,Time Interval, Systolic,Time Intervals, Systolic
D013997	Time Factors	Elements of limited time intervals, contributing to particular results or situations.	Time Series,Factor, Time,Time Factor