Novel design of a regional myocardial force transducer

A novel force transducer was designed to measure the circumferential regional force developed in the ventricular myocardium in vivo. The transducer is composed of a frame, a carrier bar, and a cantilever spring. Two resistance strain gauges embedded on the spring serve as force-sensing elements. The output of a Wheatstone-bridge circuit, containing these two gauges and a temperature compensation resistor, is connected to a preamplifier. The main advantages of this prototype include the initial stretch-adjustment ability (physiologic 0) low temperature drift, high linearity (r = 0.99) with loads ranging from 0 to 100 g, and moderate sensitivity of 0.232 mV/V/g at room temperature. The transducer was validated with in-vivo canine experiments. The experimental results showed that this transducer can be used to reliably measure the myocardial force development during altered cardiac conditions, such as myocardial stunning and myocardial ischemia.