Related Experiment Video
Updated: Aug 9, 2026
Exercise Test for Evaluation of the Functional Efficacy of the Pig Cardiovascular System
Published on: May 12, 2023
Vectorcardiographic ST deviations related to increased heart rate in the absence of ischemia in an experimental pig
Sören Häggmark1, Michael F Haney, Göran Johansson
1Cardiothoracic Surgery, Heart Centre, University Hospital, Umeå, SE-901 85 Umeå, Sweden. soren.haggmark@vll.se
Abstract:
The electrocardiographic ST segment may change when heart rate (HR) increases. We aimed to analyze vectorcardiographic ST relation and myocardial conditions during controlled HR increases in anesthetized pigs. The relative parameters ST change vector magnitude and ST change vector angle were calculated at paced HRs ranging from 85 to 175 beats per minute. ST change vector magnitude increased from baseline 6.3 +/- 1.3 to 26.0 +/- 3.1 microV (P < .01; range, 4-50 microV) at HR 175 beats per minute with similar changes in ST change vector angle, whereas the absolute parameter ST vector magnitude demonstrated a heterogeneous pattern without any systematic relation to HR changes. Microdialysis results from left ventricular wall, with analysis of glucose, lactate, and pyruvate, showed no sign of ischemia during pacing. Potassium concentrations did not change during pacing. We conclude that significant HR-related ST vector changes can occur in the absence of myocardial ischemia.
