A new approach to the direct measurement of tension within the outer layers of the left ventricular wall of the dog heart.

Tension was measured within the outer layers of the left ventricular wall of the dog heart with the strain-gauge force transducer coupled to the wall at diastole without the distortion of its geometry. The transducer still attached to the wall or its segments was calibrated with the passive forces and with the known active force on the isolated, beating heart. The differences between the readings of the transducer and the calibrating force did not exceed 20% and in most experiments they were much smaller. The transducer was practically insensitive to the force perpendicular to the measured one. The proposed method seems to be more reliable than the formerly used by these and other authors.