Abstract: An ultrasonic transducer includes a transducer element having a backing element bonded thereto. The thickness of the backing element is selected to be less than or equal to half the length of an ultrasonic pulse, expressed in wavelengths of the center frequency of the pulse, so that the first reflection from the back side of the backing element is received by the transducer element before the primary pulse rings down. A method for mounting the transducer that reduces the formation of air bubbles includes the steps of forming a peaked mound and continually lowering the transducer to flatten the mound against the underside of the transducer.

Abstract: The present invention provides an improved drive shaft for use in a catheter system having a rotating imaging or interventional work element. A drive shaft according to the present invention is formed at least in part of a material having super elastic properties. This material provides an advantageous combination of column strength and torsional rigidity with the ability to sustain substantial bending without permanent deformation. Preferred embodiments are formed as hollow tubes to allow electrical conducting wires to be disposed within the body of the drive shaft. Some embodiments combine relatively rigid proximal segments with relatively flexible distal segments to allow for entry of the work element into narrow and twisting regions of a patient's vascular system.

Abstract: The present invention provides improvement usable with an intravascular catheter having a single common distal lumen with a reduced profile connected to two or more proximal lumens. The catheter will be loadable over a guidewire into a region of interest within a patient's vascular system. According to one aspect of the present invention, means are provided to ensure that the guidewire enters into a desired one of the proximal lumens. In a preferred embodiment, a special tool is provided to achieve this. According to a second aspect of the present invention, the catheter is provided with a proximal housing and an axially expandable member to shield the rotating parts at the proximal end of the catheter and to allow for convenient movement of a work element within the catheter body.

Abstract: A flow control apparatus is disclosed which is particularly useful in liquid flow systems for blood pressure monitoring in humans and other animals. A resiliently biased valve plunger is provided with a marine bore capillary passage extending from one side of the plunger seating area to the other, thus establishing a first, low flow path. When the plunger is moved from its seat, a second, high flow path is established which flushes the apparatus. In one embodiment, the apparatus is combined with a pressure transmitting diaphragm assembly used to transmit pressure to instrumentation, the flush flow then serving to sweep air from the plenum above the diaphragm.