Publications
Medical Device Testing
The Comprehensive Validation of a Stent Coating Durability Tester
by | RMBS 2009 | Publications, Particle Counting
Ramesh R, Conti JC, Strope ER
RMBS 2009
Keywords: stent, coating, durability, particles, counting, validation
Abstract
This study addresses the need to develop an instrument and supporting protocol to evaluate the tendency for a bare or drug coated stent to shed particles into the vasculature of a patient. The resultant experiments demonstrated that two types of instruments each properly detected, sized and counted better than 90% of the injected calibration particles within four minutes.
Comparison of Radial Expansion of Stents
by | RMBS 2008 | Publications, Compliance, High Speed Photography, Silicone Mock Arteries, Stent Testing
Ramesh R, Conti JC, Strope ER, Thompson M, Price KS, Murray D
RMBS 2008
Keywords: radial expansion, stent durability, deflection, mock vessels, coronary artery
Abstract
Coronary artery disease results in hardening of the arteries. The main reason is that cholesterol and plaque build up on the inner walls of the arteries. This results in restricting the blood flow to the heart causing injury to the heart muscle. Recently, non-surgical processes are being used to open up …
A Comprehensive Protocol and Procedural Considerations Designed to Evaluate the Shedding of Particles from Drug Eluting Stents
by | MPMD 2007 | Publications, Particle Counting
Conti JC, E. Strope, R. Ramesh, C. Conti, A. Watkins
MPMD 2007
Abstract
The American Society for Testing and Materials (ASTM) [35] and Association for the Advancement of Medical Instrumentation (AAMI)/ International Organization for Standardization (ISO) [36] committees have drafted or passed standards [38, 39] to address the release of particulates into the vasculature by drug eluting stents during deployment and implantation. A new AAMI…
Linear Elastic Mechanics of Mock Arteries: Empirical Versus …
by | RMBS 2007 | Publications, Compliance, High Speed Photography, Silicone Mock Arteries
Biomedical Science Instrumentation, 43, pp. 54-62, (2007)
Ramesh Rajesh, Conti JC, Strope ER
RMBS 2007
Keywords: linear elastic mechanics, stent durability, deflection, pulsatile, accelerated, mock artery, high speed photography, laser micrometry
Abstract
Evaluation of a medical device requires human or animal studies to be conducted. In the past decade, the use of mock arteries or mock vessels has found its place in the cardiovascular industry …
Mock Artery Distension: Comparison of Optical, Mechanical and…
by | RMBS 2007 | Publications, High Speed Photography, Silicone Mock Arteries
Biomedical Science Instrumentation, 43, pp. 46-53, (2007)
Ramesh Rajesh, Conti JC, Strope ER
RMBS 2007
Keywords: mock artery, compliance, laser, high speed photography, conversion, linear elastic mechanics, vascular stents, durability
Abstract
The relationship between the pressure inside a cylindrical mock vessel and the change in radius is called radial compliance. It has been postulated that it is the internal change in radius with pressure that has a significant effect on blood flow disturbance …
Frequency Dependent Hysteresis of Silicone and Latex Mock Arteries Used in Stent Testing
by | RMBS 2005 | Publications, Compliance, High Speed Photo, Silicone Mock Arteries
Ramesh Rajesh, Strope ER, Price KS, Conti JC
RMBS 2005
Keywords: Compliance, Latex, Silicone, Artery, Frequency, Hysteresis, Stent, Testing, Vessels
Abstract
Mock arteries also called as mock vessels are one of the best alternatives available to researchers in evaluating the mechanical characteristics and durability of intravascular medical products without having to use animal and human clinical studies. The behavior of mock arteries depends on the frequency of loading. This makes it essential to evaluate and analyze the compliance …
Mock Vascular Compliance During Intravascular Product Testing
by | 2006 | Publications, Compliance, Silicone Mock Arteries
J. C. CONTI, PH.D.
Dynatek Dalta Scientific Instruments, 105 E. Fourth Street, Galena, MO 65656
One of the most interesting topics raised at all standards, regulatory agency, and contractor meetings is related to the role that the mechanical compliance of mock arteries plays on the testing of medical products destined for intra arterial deployment or implantation.
Single Versus Double Ended High Frequency Pressurization of Mock
by | RMBS 2006 | Publications, Compliance, High Speed Photography, Silicone Mock Arteries
Biomedical Science Instrumentation, 42, pp. 446-451, (2006)
Ramesh, R, Conti JC, Strope ER
RMBS 2006
Introduction:
Frequency response characteristics of mock arteries play a very significant role in high frequency durability testing of medical devices such as grafts and stents. In vitro durability testing of stents depends on cyclic load applied by the mock artery on the medical device.
Comparing Several Analytical Methods When Determining Dynamic Compliance of Arteries and Vascular Grafts
by | SFB 2005 | Publications, Compliance, Silicone Mock Arteries
Ramesh, R, Conti JC
SFB 2005
Introduction
Proper evaluation of mechanical characteristics of intravascular medical products often makes it necessary for researchers to conduct animal studies. Silicone mock arteries used in medical device testing have been proven to be the better alternative to animals. Radial compliance of mock arteries depends on radius and internal pressure and plays a critical role in in vitro experiments. Mock arteries are tested for radial compliance …
High Speed Photographic Verification of Intravascular Stent Strains During Accelerated Durability Testing
by | RMBS 2004 | Publications, Compliance, High Speed Photography
Biomedical Science Instrumentation, 40, pp. 219-224, (2004)
Kattelola, Brunda, Conti, JC, Strope, ER
Keywords: Stent, Durability, Vascular, Intravascular, Verification, Strain, High Speed Photographic, Mock Artery and Silicone.
RMBS 2004
Abstract
Most stent durability testing does not predict resulting clinical failures. Standards committees have taken on the task of …
Radial Compliance of Natural and Mock Arteries: How This Property Defines the Cyclic Loading of Deployed Vascular Stents
by | SFB Workshop 2002 | Publications, Compliance, Silicone Mock Arteries
SFB Workshop 2002
Slides
Radial Compliance Of Natural And Mock Arteries: How This Property Defines The Cyclic Loading Of Deployed Vascular Stents
by | RMBS 2002 | Publications, Compliance, Silicone Mock Arteries
Biomedical Science Instrumentation, 38, pp. 163-172, (2002)
J. C. CONTI, PH.D.
RMBS 2002
There has been a disturbing number of unexpected mechanical failures in deployed vascular stents and stent grafts. An analysis of the mechanical properties of mock arteries used to carry out standard durability testing on the aforementioned medical products suggests that some of the problems might be related to a frequency dependent change in the properties of these recipient vessels.
The Durability of Silicone versus Latex Mock Arteries
by | RMBS 2001 | Publications, Compliance, Silicone Mock Arteries
Biomedical Science Instrumentation, 37, pp. 305-312, (2001)
CONTI, JC, Strope, ER, Goldenberg, LM, Price, KS
RMBS 2001
Keywords: mock, arteries, stents, in-vitro, durability, accelerated, fatigue, compliance, silicone, latex.
Introduction
During the last century or so the ability of the human race to heal its own medical problems has experienced a growth rate that staggers the imagination. Not only have the technologies and techniques…
Evaluating the in situ Loading and Accelerated Durability of Barbs Located on Bifurcated Aorto-Iliac Stent-Grafts
by | RMBS 2000 | Publications, Barb Stent, Stent Testing
Biomedical Science Instrumentation, 36, pp. 93-98, (2000)
James C. Conti, Elaine R. Strope
RMBS 2000
Keywords: aorto-iliac, stent-graft, durability, fatigue, stent, accelerated
Abstract
A special three-part protocol has been generated for the isolated durability testing of stent barbs. This triple protocol includes an initial evaluation on a cardiovascular duplicator to determine the loading per barb that occurs during normal flow…
Cyclic Peel Testing of the Release of Silicone Products from Molds
by | 2000 | Publications, Food Analysis
J.C. Conti, E.R. Strope, D.J. Rohde
2000
Molded products fabricated from various silicones are becoming more popular. The removal of these products from their molds is essentially a peel process. Cyclic peel testing, the loading of a sample at subcritical peel levels, gives a more precise analysis of the adhesion properties of this joint than standard peel testing. A study was conducted using aluminum and silicone molds onto which two castable platinum cured silicone materials were delivered and cured. This technique allows for a simple, precise, and cost effective way of optimizing mold release agents, candidate product…
Determining the Hydrodynamic Characteristics of Unfixed Human Heart Valves: Effect of the Properties and Geometry of the Recipient Synthetic Aorta
by | SFB 2000 | Publications, Heart Valve Testing
James C. Conti,Elaine R Strope, Donald J. Rohde,Richard Carp, Steven Kulan
SFB 2000 (Not Accepted)
Introduction:
One of the main goals of engineers and scientists involved in the design of replacement internal components for human use is the replication of biological and mechanical characteristics of the original equipment. It has been shown over the last twenty years that it is not at all straightforward to determine what are the true in vivo characteristics of various …
The Durability Testing of Porous Bifurcated Stent/Grafts Without Restricting Leakage
by | SFB 2000 | Publications, Stent Testing
James C. Conti, Elaine R Strope, Donald J. Rohde, Richard Carp, Steven Kulan
SFB 2000
Introduction:
The durability or fatigue testing of porous vascular grafts or stent/grafts has, along with the standard problems associated with accelerated testing, the obvious additional disadvantage that the testing fluids are constantly leaked through the wall, thereby reducing the volume of testing fluid available. In the past the most common approach to this problem was to use a material to restrict the leakage of the fluid out of the …
The Cyclic Texture Profile Analysis of Mozzarella Cheese: Evaluating the Rate of Textural Change (RTC)
by | IFT 1999 | Publications, Food Analysis
Annual Meeting of the Institute of Food Technologists, Book of Abstracts, 80, (1999)
J.C. CONTI, E.R. Strope, F. Schmidt
IFT 1999
Justification:
The texture of mozzarella cheese is important for the development of formulations needed to fulfill increased demand. There are problems correlating sensory panels and mechanical testing. Multiple chew data better characterize textural properties.
Objective:
To develop techniques that evaluate…
The High Frequency Testing of Vascular Grafts and Vascular Stents: Influence of Sample Dimensions of Maximum Allowable Frequency
by | RMBS 1999 | Publications, Stent Testing
Biomedical Science Instrumentation, 35, pp. 339-346, (1999)
J.C. Conti, E.R. Strope, K.S. Price, L.M. Goldenberg
RMBS 1999
Keywords: Compliance, grafts, frequency, radial, testing, accelerated, durability, fatigue, stents, catheters
Abstract
There are over four dozen companies developing new products for the lucrative vascular graft and vascular stent markets. We have been studying the procedures…
Current Trends in the Durability Testing of Medical Products
by | SFB Workshop 1999 | Publications, Stent Testing
James C. Conti, Elaine R. Strope
SFB Workshop 1999
The general theory and approach to high speed testing will be reviewed. This year’s workshop will focus primarily on those testing techniques that have been developed or upgraded during the last twelve months. In particular, the latest approaches to the testing of stents, stent/grafts, septal defect closure devices, bifurcated grafts, left ventricular assist devices, adhesive bonds, and packaging will be reviewed. This workshop will give attendees a broad understanding of the issues that must be considered when designing and carrying out high speed dynamic testing …
High Frequency Testing of Grafts and Mock Arteries for Stents: Influence of Testing Frequency on Durability
by | SFB 1999 | Publications, Stent Testing
25th Annual Meeting of the Society for Biomaterials, Transaction, 403, (1999)
James C. Conti, Elaine R. Strope, Karen Price
SFB 1999
Introduction:
There is little precedent in the medical product development world for the recent introduction of new product ideas associated with the developers of stents. Product developers face the competing pressures of the need for verifiable, long term durability testing on these products and the need to minimize time to market. Although there has been some relaxation …
High Frequency Testing of Nitinol Stent Material
by | SFB 1999 | Publications, Stent Testing
James C. Conti, Elaine R. Strope, Ray Gregory
25th Annual Meeting of the Society for Biomaterials, Transactions, 398, (1999)
SFB 1999
Introduction:
The use of Nitinol in implantable medical products has been increasing at a rapid rate over the last several years. There are two reasons for this: The shape memory properties and the superelasticity which make it highly convenient for the deployment of several medical products, including stents and heart valves. Because of the need for reliable and well-designed durability/fatigue experiments on these products, frequency response determinations …
A New Adhesive Joint Test Suggest Failure Unpredicted by Standard Test Methods
by | SME 1998 | Publications, Food Analysis
Society of Manufacturing Engineers; 1999, Issue 106, pages ALL
Conti, J.C., Strope, E. R., Jones, E.
SME 1998
Abstract
Although the use of adhesives in the packaging, transportation, housing, and manufacturing markets seems to have unlimited potential, there is a problem that limits the full replacement of other fastening techniques with this bonding modality. The occurrence of unpredicted failures has plagued adhesive users for many years. One example is the use of …
Self Assurance to Quality Assurance: Knowing the Correct Things to Do
by | Article 1998 | Publications, Doppler Ultrasound
Article 1998
Introduction
In this chapter, we will address those issues that are very important to professional sonographers, namely, the ability to be sure that you are doing a good, precise, and reliable job. The ability to know that the quality of work you produce is of the highest nature not only requires training, but also an understanding of the technology and instrumentation as well as issues that pertain to overall quality assurance topics. We have taught physics to all grade levels and will use some of the simple techniques to explain the phenomenon of ultrasound. We will then expand upon this information …
Sources of Error in Monitoring High Speed Testing of Vascular Grafts
by | RMBS 1998 | Publications, Stent Testing
Biomedical Science Instrumentation, 34, pp. 240-245, (1998)
J. C. CONTI, Ph.D., E. Strope, Ph.D., and K. Price
RMBS 1998
Keywords: Compliance, tubing, grafts, mechanical, frequency, radial, testing, accelerated, durability, fatigue
Abstract
Mechanical compliance issues are increasingly important in the design, testing, and manufacture of vascular grafts. This has to do with the observed relationship between long-term patentcy of implanted grafts and…
The Dynamic Texture Analysis of Mozzarella Cheese: Evaluating the Rate of Texture Change (ROTC)
by | IFT 1998 | Publications, Food Analysis
J.C. CONTI, E.R. Strope
IFT 1998 (Not Accepted)
A dynamic approach to texture profile analysis has been used to address poor sensory panel/instrument correlations. It has been demonstrated that a multiple chewing test using appropriately shaped mock teeth and synthetic cheek material is effective in generating data that shows expected changes in the hardness, cohesiveness, and other textural parameters that one might expect from mozzarella cheese. We have used the dynamic texture analyzer to evaluate…
Current Trends in the Durability Testing of Medical Products
by | SFB Workshop 1998 | Publications, Compliance
WORKSHOP
J.C. Conti, E.R. Strope
SFB Workshop 1998
Last year’s workshop covered the history and more recent approaches used to evaluate the durability of a variety of medical products in vitro. The general theory and approach to high speed testing was reviewed. This year’s workshop will focus primarily on those testing techniques that have been developed or upgraded during the last twelve months. In particular, the latest approaches to the testing of stents, stent/grafts, septal defect closure devices, bifurcated grafts, left ventricular assist devices, adhesive bonds,…
Mock Arterial Compliance: Influence of Hydration, Temperature, Mandril Location, Age and Lot
by | SFB 1998 | Publications, Compliance
J.C. Conti, E.R. Strope and K. Price
SFB 1998
Introduction
The use of latex or other synthetic arterial conduits is vital to the testing programs of intravascular devices that must be flexed for various periods of time. Not only are fairly precise morphological characteristics important but the three-dimensional pressure/volume or compliance characteristics are extremely important when using these mock vessels to evaluate intravascular stents, intra-aortic balloons, stent grafts, etc.
The Design, Fabrication and Characterization of Mock Latex Aorto-Iliac Bifurcations
by | SFB 1998 | Publications, Silicone Mock Arteries
J.C. Conti, E.R. Strope, D. Rohde, K. Price, and S. Kulan
SFB 1998
Introduction
Mock arteries made of latex or other materials greatly aids the development of medical products in that certain durability and performance characteristics can be determined in vitro. It is critically important, however, that the dimensions and three-dimensional mechanical properties of these devices be precisely known. Up until now, we have been unable to design aorto-iliac bifurcations to be used …
The Design and Laser Evaluation of a Pulsatile Flow Standard
by | SBEC 1998 | Publications, Doppler Ultrasound
Seventeenth Southern Biomedical Engineering Conference, Proceedings, 150, (1997)
Conti, J.C., Strope, E.R., Rohde, D.J.
SBEC 1998
In our laboratory we repeatedly have a need to be able to calibrate a variety of flow and velocity instruments that are used in various hydro-dynamic testing. There are many other laboratory applications including a clinical ultrasound laboratories and laser doppler velocimetry facilities that could utilize a device that would increase their reliability in their flow measurements.
Dynamic Peel Analysis Demonstrates Package Seal Failure Not Predicted By Standard Peel Tests
by | Adhesion Society 1997 | Publications, Food Analysis
21st Annual Meeting of the Adhesion Society, Proceedings, 150, (1997)
J. C. Conti, Ph.D., E. Jones, E. Strope, Ph.D., and D. Rohde
Adhesion Society 1997
Introduction
The packaging industry experiences many unpredictable seal failures before, during, and after the development and manufacturing procedures associated with new packaging. Many of these failures are similar to unpredictable failures found in adhesive joint applications. The magnitude …
Accelerated Mechanical Testing
by Dynatek Labs | SFB Workshop 1997 | Publications, Compliance
SFB Workshop 1997
Slides
Cardiovascular Considerations
by | FDA 1997| Publications, Compliance
Presentation to the FDA 1997
Slides
State-of-the-Art Stent Testing: A Review of Protocols, Concerns, and Considerations for the End User
by | Society for Cardiac Angiography and Interventions 1997 | Publications, Compliance
J.C. Conti, E.R. Strope, L.D. Spence
Dynatek Dalta Scientific Instruments, PO Box 254, Galena, MO 65656
Society for Cardiac Angiography and Interventions 1997 (Not Accepted)
Currently there are at least eighteen different stent designs used clinically worldwide. In addition, it is projected that there are as many as three dozen more under evaluation in non-clinical laboratory settings throughout the world. Although the primary concern for the cardiologist is long-term clinical efficacy, the plethora of stents presents a design …
Evaluation of the Dynamic Mechanical Properties and Fatigue Resistance of Vascular Grafts Dynamic
by | FIICMSSM-Washington, DC 1997 | Publications, Compliance
FIICMSSM-Washington, DC 1997
The first step in any In Vitro testing program must include a careful analysis of the mechanical and chemical environments that the device being tested will experience once implanted. Once this is done, the next step in the process is to determine the three dimensional properties of the experimental vascular grafts at biologically relevant pressures. These properties should be determined at In Vivo frequencies (ca. 70bpm) and then again at higher frequencies. The evaluation of mechanical property vs. frequency is critically important to allow an investigator …
The Dynamic Texture Analysis of Mozzarella Cheese: Effect of Chewing Rate and Dwell Time
by | IFT 1997 | Publications, Food Analysis
IFT 1997
Slides
High Speed Vascular Graft Testing: The Influence of Varying Structural Characteristics of Polyurethane and Natural Rubber Arterial Substitutes
by | SFB 1997 | Publications, Stent Testing
Conti, J.C., Strope, E.R., Rohde, D.J., and Spence, L.D.
SFB 1997
As the arrival of an efficacious arterial substitute (vascular graft) and vascular stent becomes more imminent, a thorough understanding of how their properties influence how they must be tested is critical. A challenging yet critically important issue is the ability to evaluate the long term durability characteristics of a device in a reasonable period of time. The obvious solution is to test at an accelerated rate or frequency.
Barbs on Vascular Stents: A Three-Part Protocol to Evaluate Durability
by | SFB 1997 | Publications, Barb Stent, Stent Testing
Conti, J.C., Strope, E.R., Rohde, D.R.
SFB 1997
Dozens of new stent designs are under evaluation to address the problems of occlusion, reocclusion, and aneurysm formation. A common design element utilizes small barbs or projections from the stent that pierce the adjacent vessel wall and anchor the stent or graft/stent combination.
Recently, a barb-containing stent that had supposedly passed durability testing when evaluated using currently accepted accelerated protocols failed in vivo due to barb breakage. These failures have resulted in the need for protocols to specifically…
Frequency Dependent Radial Compliance of Latex Tubing
by | RMBS 1997| Publications, Compliance
Biomedical Science Instrumentation, 33, pp. 524-529, (1997)
J.C. CONTI, E.R. Strope, D.J. Rohde, L.D. Spence
RMBS 1997
Keywords: Compliance, latex, tubing, mechanical, grafts, stent, artery, frequency, radial, testing
Abstract
Custom latex tubing is often used in medical device evaluation. Examples include thin-walled devices used to reduce leakage of porous vascular grafts, and thicker-walled prototypes used as mechanically equivalent synthetic arteries. Medical devices such as stents and balloons are introduced…
Cyclic Versus Single-Pull Peel Testing: Influence on the First Yield Point of a Pressure-Sensitive Adhesive
by | Adhesion Society 1997 | Publications, Food Analysis
20th Annual Meeting of the Adhesion Society, Proceedings, pp. 425-427, (1997)
J. C. Conti, Ph.D., and E. R. Strope, Ph.D., E. Jones
Presented by: Eran Jones
Adhesion Society 1997
Introduction
Many properly designed adhesive joints fail via a peel mechanism. It is important to understand the influence of loading versus time on the peel process. Peel adhesion of tapes with elastomeric adhesives is strongly dependent on viscoelastic properties of the adhesive [1-3]. Mode of peeling failure is…
Use of a Precise and Portable Flow Standard to Improve the Accuracy of Medical and Scientific Laboratory Flow Measurements
by | SBEC 1997 | Publications, Doppler Ultrasound
Sixteenth Southern Biomedical Engineering Conference, Proceedings, 10, (1997)
J.C. CONTI, E.R. Strope, L.D. Spence
SBEC 1997
There is an ever increasing need in both medical imaging, industrial, and research laboratories for the use of any number of new and modern flow probes. Some of these probes are designed to measure flow rate and others, for instance, using laser or ultrasound, utilize Doppler analysis to measure velocity directly and flow…
Dynamic Texture Analyzer Addresses Poor Sensory Panel / Instrument Correlation
by | IFT 1996 | Publications, Food Analysis
Annual Meeting of the Institute of Food Technologists, Book of Abstracts, 44, (1996)
J.C. CONTI, E.R. Strope, D.J. Rohde, L.D. Spence
IFT 1996
Texture is an important property of foods that is sometimes difficult to quantitate. Although sensory panels can be trained to evaluate the various textural properties of a new or modified food, they also suffer from a degree of unsurity associated with the aboption of parameters that are presented during training. It would be beneficial to food scientists and technologists to be able to…
Relating the Frequency Dependent Radial Compliance to the Tensile Modulus of Polyurethane Vascular Grafts
by | SFB 1996 | Publications, Compliance
5th World Biomaterials Congress, Transactions Volume 2, 434, (1996)
Bozzi, R, Conti JC, Rohde D, Soldani G, Spence L, Strope E, and Withrow D
SFB 1996
Introduction
Since first introduced as a biomaterial in 1967, (1) polyurethanes have been utilized as candidate materials for vascular grafts. They show a high degree of toughness combined with a tendency to be blood compatible. It has been suggested that compliance matching of vascular grafts to …
EchoCal Presentation: GOUS 1995
by | GOUS 1995 | Publications, Doppler Ultrasound
Presentation Slides
GOUS 1995
Benefits of Accurate Doppler Ultrasound
by | AR 1993 | Publications, Doppler Ultrasound
James C. Conti, Ph.D. and Elaine R. Strope, Ph.D.
AR 1993
A crisis is clearly developing in the American health care system. On the one hand, those of us involved in health care delivery want the highest quality system the world can offer. On the other hand, as administrators we must address the ever spiraling costs that threaten to bankrupt not only hospitals and clinics, but also the country. But there is good news for hospital, radiology, and imaging center administrators. There are ways to reduce health care costs, and at the same time maintain quality of service and improve patient safety. Can this be true?
Accuracy of Measurements of Flow Velocity by Pulsed and Continuous Wave Doppler Echocardiography: An In-Vitro Study
by | ACC 1993 | Publications, Doppler Ultrasound
Presented by: Takahiro Shiota
ACC 1993
Flow velocity (VEL) estimation by Doppler echocardiography has been widely accepted clinically. To determine the accuracy of Doppler measurement of flow VELs compared to those from a precisely calibrated pulsatile Doppler phantom (EchoCal CD 10 Dynatek Laboratories Inc.) designed as a “Gold Standard”, we evaluated a total of 6 commercially available echo-Doppler systems with 9 pulsed (PW) and 4 continuous wave (CW) Doppler transducers. Actual flow VELs ranged from 30 cm/sec …
Doppler Ultrasound Calibration: Instrumentation and Protocols for Quality Assurance
by Dynatek Labs | Euroson 1993 | Publications, Doppler Ultrasound
James C. Conti
Euroson 1993 (Not Accepted)
Just as ultrasound imaging modalities became quantitative with the use of appropriate phantoms and protocols, Doppler ultrasound studies can now be implemented as quantitative tools by the use of a reliable flow phantom and appropriate procedures. The need for equipment to calibrate Doppler ultrasound instrumentation has been properly noted in scientific literature and textbooks.1-2 In addition, the design characteristics of an ideal flow phantom have been defined.1 A device and simple protocol have been evaluated that allows a Doppler…
Flow Acceleration Towards and Into a Long Segmental Stenosis: Spatial Movement of the Vena Contracta: An In Vitro Study Using Digital Color Doppler
by | AHA 1992 | Publications, Doppler Ultrasound
Presented by: Takahiro Shiota (David Sahn)
AHA 1992
We used color Doppler (CD) to estimate changes in flow velocity (VEL) when fluid accelerates towards and into a long segment stenosis in a modified pulsatile flow phantom (EchoCal CD 10) with calibrated VELs. Fluid enters the system through a 2.6 cm (diameter) cylinder to accelerate through a tapering segment ending in an abrupt orifice (OR) into a 0.8 cm diameter tube. We used a Ving-Med 750 scanner with on-line transfer of digital CD VEL data to a Macintosh IIci computer.
Standardization of Doppler Echocardiographic Signals
by | ASE 1990 | Publications, Doppler Ultrasound
James C. Conti, Ph.D. and Elaine R. Strope, Ph.D., D. J. Rohde, C. L. Hanawalt, R.D.M.S., K. Scott, R.D.M.S
ASE 1990
A flow standard or phantom has been developed that allows the cardiologist, or other medical professional to assure that the flow velocity values they are obtaining are indeed reliable. Proven technologies have been utilized to fabricate a device that generates highly reproducible and reliable pulsatile flow up to 6 meters per second. Internationally recognized experts in the area of cardiovascular flow dynamics have contributed to this project. It is expected that this standard will be reproducible …
AAMI 24th Annual Meeting Presentation by James C. Conti, Ph.D.
by | AAMI 1990 | Publications, Heart Valve Testing
AAMI 1990
Presentation:
Thank you Dr. Gabbay, Dr. Mueller, and thank you for inviting me to this gathering. I am excited and hope that this opens up a new wave of interest in in-vitro durability testing.
The usefulness of experimental data is of course dependent upon the reliability of that information, and any scientist or engineer who would be queried concerning this fact would be quick to agree, I am sure. Nonetheless, I am continually confronted with attitudes from my colleagues concerning the value of in-vitro heart valve durability testing, this from individuals in laboratories …
Experimental Considerations that Determine the Utility of Accelerated Durability Testing for Prosthetic Heart Valves
by | FDA 1990 | Publications, Heart Valve Testing
James C. Conti, Ph.D., Elaine R. Strope, Ph.D., Donald Rohde
Presented By: James C. Conti, Ph.D.
FDA 1990
The reliability and usefulness of experimentally generated data is dependent upon, among other things, the generation of an experimental protocol that recognizes the importance of pertinent variables. Any experiment that fails to control or at least recognize those variables is probably better off not being performed. This experimental sloppiness is rampant throughout many of the world’s prosthetic heart valve…
Measuring the Dynamic Compliance of Vascular Grafts
by | FDA 1990 | Publications, Compliance
FDA 1990
Slides
Current Progress Toward Stentless Heart Valve Testing
by | FDA 1990 | Publications, Heart Valves Testing
FDA 1990
The True Flow Calibration of Ultrasound Diagnostic Instruments
by | AAMI 1990 | Publications, Doppler Ultrasound
25th Annual Meeting of the Association for the Advancement of Medical Instrumentation, Proceedings, 22, (1990)
J. C. Conti, Ph.D., E. R. Strope, Ph.D., D. J. Rohde
AAMI 1990
The Effective Measurement of Dynamic Internal Compliance of Vascular Grafts
by | AAMI 1990 | Publications, Compliance
25th Annual Meeting of the Association for the Advancement of Medical Instrumentation, Proceedings, 22, (1990)
J. C. Conti, Ph.D., E. R. Strope, Ph.D., D. J. Rohde
AAMI 1990
Introduction
The clinical importance of matching the compliance of a vascular graft to the host vessel has been a point of contention for many years (ref.). One possible explanation for this unsettled controversy could be that the compliance determinations used to evaluate compliance/patency correlations …
A New Technique to Determine Vascular Compliance In Vivo
by | NHLBI 1989 | Publications, Compliance
James C. Conti, Ph.D., Elaine R. Strope, Ph.D., Donald Rohde, Howard P. Greisler, MD
Presented By: James C. Conti, Ph.D.
NHLBI 1989
There currently is a need for a simple, accurate and reproducible technique to determine the in vivo compliance of arteries and veins.1 The injected volume technique monitors the pressure-volume relationship of an artery, vein or vascular graft and thereby allows an investigator to evaluate the three-dimensional physical properties of these objects.
Design Considerations for the In Vitro Testing of Cardiovascular Prosthesis
by | ISAO 1986 | Publications, Heart Valve Testing, Stent Testing
Elaine R. Strope, Ph.D.
ISAO 1986
Abstract:
Prosthetic cardiovascular devices are unique in that, in addition to the requirement of functioning for nearly a billion cycles or more, failure can result in death of the user. As a result, in vitro testing becomes critically important. The special considerations in design of instrumentation to test these devices will be reviewed and examples of data generated will be given.
Introduction:
For nearly a decade, personnel now associated with Dynatek …
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