Related Experiment Video
Updated: Jul 10, 2026
Cardiac Catheterization in Mice to Measure the Pressure Volume Relationship: Investigating the Bowditch Effect
Published on: June 14, 2015
Effects of changes in loading conditions and heart rate on the myocardial performance index in cats
Yasutomo Hori1, Masami Uechi, Atsuko Indou
1Department of Small Animal Internal Medicine, School of Veterinary Medicine, Kitasato University, 23-35-1 Higashi, Towada, Aomori 034-8628, Japan.
Objective:
To evaluate the effect of changes in hemodynamics on the myocardial performance index (MPI) in cats.
Animals:
6 mixed-breed cats.
Procedures:
Cats were anesthetized by administration of thiopental sodium; anesthesia was maintained by administration of isoflurane. Systolic arterial pressure and central venous pressure were measured by use of catheters, and heart rate was controlled by right atrial pacing. Afterload was increased by balloon occlusion of the descending aorta, and preload was increased by IV infusion of lactated Ringer's solution at a rate of 40 mL/kg/h. Echocardiography was performed for each condition.
Results:
Atrial pacing significantly increased heart rate. The MPI did not change with heart rate. Arterial pressure and MPI increased significantly during aortic occlusion. The IV infusion increased fractional shortening but did not change the MPI. Multiple regression analysis revealed that the MPI was not affected by heart rate, systolic arterial pressure, central venous pressure, fractional shortening, or velocity of the E wave.
Conclusions And Clinical Relevance:
The MPI can be used to assess cardiac function in healthy cats. The MPI is independent of heart rate and systolic arterial pressure but is sensitive to changes in afterload.
Related Concept Videos
01:29Pathophysiology of Cardiac Performance
01:19Cardiac Output I:Effect of Heart Rate on Cardiac Output
Cardiac output (CO) refers to the total amount of blood ejected by one of the ventricles in liters per minute (L/min). In a resting adult, CO ranges from 5 to 6 L/min, adjusting according to the body's metabolic requirements.
Effect of Heart Rate on Cardiac Output
Cardiac output adapts to metabolic demands during stress, physical activity, or illness. The autonomic nervous system regulates heart rate via the sinoatrial node. The parasympathetic nervous system decreases heart rate...