Relationship between the Initial Systolic Time Interval and RR-interval during an exercise stimulus measured with Impedance Cardiography

Femke Hoekstra*, Esther Habers, Thomas W.J. Janssen, Rudolf M. Verdaasdonk, Jan H. Meijer

*Corresponding author for this work

Research output: Contribution to journalConference articleAcademicpeer-review

3 Citations (Scopus)

Abstract

The Initial Systolic Time Interval (ISTI), obtained from the electrocardiogram and impedance cardiogram, is considered to be a measure for the time delay between the electrical and mechanical activity of the heart and reflects an active period of the heart cycle. The relationship between ISTI and the total heart cycle (RR-interval) was studied in three groups of young, healthy volunteers: low, moderately and highly trained subjects. The three groups were exposed to an exercise stimulus on a cycle ergometer with an increasing work load to increase the heart rate. ISTI was decreased with decreasing RR-interval. However, the relative proportion of ISTI, ISTI/RR, was found to increase with decreasing RR-interval. This relationship was found to be inversely proportional. The rate of this increase in ISTI/RR was significantly higher in highly trained subjects. Also, over the whole range of heart rates ISTI was longer in these subjects. It is concluded that ISTI can be used to evaluate cardiac performance during physical exercise non-invasively and in an extramural setting.

Original languageEnglish
Article number012117
JournalJournal of physics: Conference series
Volume224
Issue number1
DOIs
Publication statusPublished - 1 Jan 2010
Externally publishedYes
Event14th International Conference on Electrical Bioimpedance 2010 - Gainesville, United States
Duration: 4 Apr 20108 Apr 2010
Conference number: 14

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