Transducers for myocardial research

Seven miniaturized transducers to measure force, displacement, and thickness--singly and in combination--in animal experiments are described. The transducers are lightweight and during an open-chest procedure can be inserted within a heartbeat, removed, and reinserted, with minimum trauma. Six or more transducers of various kinds can be used simultaneously without artifacts. For closed-chest experiments a combination force-displacement transducer can be catheter-borne. A trifunctional transducer was used successfully to measure force-displacement thickness in a small area. A single conductor can be added for ECG measurement in the area where the transducer is implanted.