Left Ventricular Dimensions Recorded by Sonocardiometry

Abstract

A new technic for continuously recording the dimensions of internal organs in intact unanesthetized animals has been developed as a modification of sonar technics. A sound is emitted by a small barium titanate crystal mounted on one side of the left ventricle, and the time required for the sound waves to pass through the chamber to another crystal on the opposite side is monitored 1,000 to 2,500 times/sec. Such crystals have continued to function reliably for more than 3 months after installation in the animal. Changes in left ventricular diameter have been recorded during spontaneous cardiac responses to various conditions including physical exertion on a treadmill.