Cardiac output measurements using sonomicrometer crystals on the left ventricle at rest and exercise.

This research investigates the effectiveness of using sonomicrometer crystals for measuring cardiac output in horses, both at rest and during exercise. The results suggest that using sonomicrometer crystals generally delivers an accurate estimate of ventricular dimensions and could potentially be useful for assessing various cardiac factors, including diastolic flow.

Methodology:

• This research involved surgically fitting eight sonomicrometer crystals each onto the pericardium of the left ventricle of eight horses. Each horse was also fitted with a left atrial catheter.
• The horses were then allowed to return to regular treadmill exercise.
• Their cardiac output – or the volume of blood pumped by the heart per unit of time – was analyzed at rest and during exercise to evaluate how precisely the sonomicrometer crystals were able to estimate this value.

Results:

• Of the initial cohort, three horses were able to return to their usual activity with a maximum oxygen consumption rate that was comparable to their pre-surgery levels. These horses were taken into consideration in the final analysis.
• The research compared the results obtained through using the sonomicrometer crystals against those calculated using the Fick principle, a different traditional steady-state technique of measuring cardiac output.
• The variance between the two methods was discovered to be approximately 12.5%, which mirrors the coefficient of variation for the Fick estimates – this implies that the two measurement techniques have roughly the same margin of error.

Conclusion:

• Based on the research findings, it was concluded that left ventricular sonomicrometer measurements in horses furnish a reasonable estimate of ventricular dimensions.
• This technique could potentially be utilized to appraise various other cardiac variables, including the blood flow during the relaxation phase of the heartbeat (diastolic flow).