Engineering topics
Publications and source records attributed to Culler, V. H..
Series of transducers with seven different configurations enable measurement of forces and displacements in heart wall. New transducers small, cause minimal perturbation of heart function and attached and detached without causing excessive tissue damage. All units implanted or removed during single heartbeat, permitting rapid relocation for detail mapping.
Task of reading and recording indications of mercury dilatometer simplified by automatic system. Volume change of sample under test converted into electrical signal. Device modified by addition of resistance wire to mercury column. Height of column read indirectly by measuring resistance between terminals. Signal suitable for strip-chart recording or other processing.
Several parameters of a small region of a muscle tissue or other object, can be simultaneously measured using with minimal traumatizing or damage of the object, a trifunctional transducer which can determine the force applied by a muscle fiber, the displacement of the fiber, and the change in thickness of the fiber. The transducer has three legs with inner ends joined together and outer ends formed to piece the tissue and remain within it. Two of the legs are relatively stiff, to measure force applied by the tissue, and a third leg is relatively flexible to measure displacement of the tissue relative to one or both stiff legs, and with the three legs lying in a common plane so that the force and displacement measurements all relate to the same direction of muscle movements. A flexible loop is attached to one of the stiff legs to measure changes in muscle thickness, with the upper end of the loop fixed to the leg and the lower end of the loop bearing against the surface of the tissue and being free to slide on the leg.
Instrument consisting of compliant fingers with attached semiconductor pickups measures inside contours of narrow vessels. Instrument, originally designed to monitor human arteries, is drawn through vessel to allow finges to follow contours. Lead wires transmit electrical signals to external processing equipment.
Prototype myocardial transducer simultaneously monitors interal force, displacement, and thickness of heart muscle fiber within localized area of heart muscle. Transducer can be placed in area less than 1.5 by 4 mm.
A myocardial transducer for simultaneously measuring force and displacement within a very small area of myocardium is disclosed. The transducer comprised of an elongated body forked at one end to form an inverted Y shaped beam with each branch of the beam constituting a low compliant tine for penetrating the myocardium to a predetermined depth. Bonded to one of the low compliance tines is a small piezoresistive element for converting a force acting on the beam into an electrical signal. A third high compliant tine of the transducer, which measures displacement of the myocardium in a direction in line with the two low compliant tines, is of a length that just pierces the surface membrane. A small piezoresistive element is bonded to the third tine at its upper end where its bending is greatest. Displacement of the myocardium causes a deformation in curvature of the third tine, and the second small piezoresistive element bonded to the surface of its curved end converts its deformation into an electrical signal.
Method of implanting myocardium transducer uses special indented pins that are caught and securely held by epicardial fibers. Pins are small enough to cause minimum of trauma to myocardium during implantation or removal.
A miniature transducer for measuring changes of thickness of the myocardium is described. The device is easily implantable without traumatizing the subject, without affecting the normal muscle behavior, and is removable and implantable at a different muscle location. Operating features of the device are described.
A force transducer for measuring dynamic force activity within the heart of a subject essentially consists of a U-shaped beam of low elastic compliance material. Two lines extend from the beams's legs and a long coil spring is attached to the beam. A strain gauge is coupled to one of the beam's legs to sense deflections thereof. The beam with the tines and most of the spring are surrounded by a flexible tube, defining a catheter, which is insertable into a subject's heart through an appropriate artery. The tines are extractable from the catheter for implantation into the myocardium by pushing on the end of the spring which extends beyond the external end of the catheter.
Device consists of highly compliant circular beam attached to piezoresistive strain gage and barbed needle. Radial deflection of myocardium is measured with minimal disturbance of normal heart functions.
Sensor can be installed in left ventricle by means of procedures available for inserting catheter into an artery at body's extremities and manipulating it through vessel and past aortic valve. Metallic tines of device can be used as internal electrode for electrocardiogram.