Accuracy of volume measurement of rabbit left ventricle by balloon method

Although the intraventricular balloon method has been commonly used to measure left ventricular volume of the isolated heart preparation of various animals, the accuracy of the method has not been examined in the ventricle of small animals such as the rabbit. To assess the accuracy of the intraventricular balloon method in measuring left ventricular volume, we measured the space between the balloon inflated in the left ventricle and the endocardial surface in eight Formalin-fixed rabbit left ventricles. The space was only 0.05-0.12 ml (1.5-3.6% of total left ventricular volume) at intraballoon pressures of 40-160 mmHg. However, it increased to 0.37 ml (14.6% of total ventricular volume) with a decrease in pressure to 5 mmHg. We conclude that the intraventricular balloon method accurately measures left ventricular volume in the rabbit, especially in the high pressure range.