Subjective estimates of the angiographic severity of coronary artery stenoses show variability and inaccuracy. We therefore tested the accuracy of a newly developed computerized image analysis system for quantitating vessel diameter from cineangiograms. Fourteen cylindrical phantoms of known diameter were filled with contrast medium and filmed over a wide range of clinically relevant radiograph...

Adolph Fick’s original diffusion experiments used two vessels containing water and salt to establish a steady-state concentration gradient that demonstrated the validity of what is now called Fick’s second law of diffusion. The first vessel had a cylindrical shape creating a linear gradient. The second vessel was shaped like a funnel having a correspondent variable flow area. Using Fick’s secon...

Background: Autoregulation of blood flow is a marvelous phenomenon balanc- ing blood supply and tissue demand. Although many chemically-based explanations for this phenomenon have been proposed and some of them are commonly used today, biomechanical aspects of this phenomenon was neglected. The biomechanical aspect provides insights to us to model vessel diameter changes more precisely and comp...

Highly flexible model red cells were molded of acrylamide gel and suspended in a mixture of castor oil and diiodomethane to produce a neutrally buoyant fluid suspension in which the particles behaved mechanically very much like living erythrocytes. The various suspensions were permitted to flow down long cylindrical tubes while measurements of flow rate and pressure drop were made for various c...

This paper reports a micromachined cuff that senses blood flow velocity inside a blood vessel. Utilizing two electrically isolated electrodes in the cuff, the sensor produces a voltage proportional to the flow rate in the presence of a magnetic flux, which is to be externally read out by an implanted circuit chip. The cuff structure is fabricated from planar stainless steel foil using batch-com...

Experiments are performed to assess the feasibility of cooling high flux heat sources flush mounted on the inner wall of a cylindrical vessel by a dielectric liquid flowing at high velocity parallel to the vessel wall. Fluid motion is induced by rotating a stirrer having radial blades about the axis of the vessel. The study focusses on examining critical heat flux (CHF) enhancement attributed t...

Coronary artery diseases are among the leading causes of death in the industrial countries. The high death rate leads to an increased demand of diagnosis and treatment of these diseases. Additional to the conventional coronary angiography, the CT angiography is mainly used in the extended diagnostics of coronary artery diseases. This modality allows a detailed assessment of the coronary vessels...

The rate of cooling (heating) experimental liquids is investigated separately for five thermocouples located at different heights the probe. Research carried out on an stand in system "environment I — body II", where I" water, and "body II" liquid medium a thin metal cylindrical shell under conditions free convection. studied test liquids: sunflower oil, distilled glycerin. analysis processes d...

background: autoregulation of blood flow is a marvelous phenomenon balanc- ing blood supply and tissue demand. although many chemically-based explanations for this phenomenon have been proposed and some of them are commonly used today, biomechanical aspects of this phenomenon was neglected. the biomechanical aspect provides insights to us to model vessel diameter changes more precisely and comp...