Single Versus Double Ended High Frequency Pressurization of Mock …

Mock Artery Compliance

by Dynatek Labs | RMBS 2006 | Publications, Compliance, High Speed Photography,  Silicone Mock Arteries

Single Versus Double Ended High Frequency Pressurization of Mock Arteries: Symmetry of Expansion

Biomedical Science Instrumentation, 42, pp. 446-451, (2006)

Ramesh, R1, Conti JC2, Strope ER1

1 Dynatek dalta Scientific Instruments, 105 E Fourth St, Galena, MO 65656

2 Department of Physics, Astronomy and Material Sciences, Southwest Missouri State University, Springfield, MO, 65803

RMBS 2006


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.

Silicone Mock Arteries

• This study analyzes distension of mock arteries at different locations with single and double ended mode of pressurization at various frequencies.

• Single Ended Pressurization: Pressurizing mock arteries by forcing fluid from one end.

• Double Ended Pressurization: Pressurizing mock arteries by forcing fluid from both ends.


• Six 10cm long silicone mock arteries with internal diameter 27.75 ±0.2mm.

• Length chosen represents the most common length used for testing stents.

• Radial compliance of 6.55 % per 100mm Hg @ 72bpm between 80 and 120mm Hg.

• Large Vascular Prosthesis (LVP) tester was used to test mock arteries between frequencies of 0 to 100 Hz.

• LVP is equipped with Ling Dynamic Shaker (V408 –PA 100 E) with peak force of 22 lbf and maximum peak to peak displacement of 14mm.

• Dynamic Shaker in turn compresses the bellow drive system.

• High speed photography (Fast Cam PCI 1280 with Photron Motion Tools 1.0.5 software) was used to measure the distension of mock arteries.

Silicone Mock Arteries

Figure 1: Large Vascular Prosthesis with Ling Dynamic Shaker.

Technique used for measurement:

a. High Speed camera will track the markings on the outer diameter of mock arteries.
b. Relative distance between the markings changes during expansion.
c. Percentage change in chord length = percentage in diameter and circumference of arteries.
d. Assume section of mock artery to be a circle with the radius (ri )and center O.

Silicone Mock Arteries

e. Select two points Ai and Bi on the circle such that the arc AiBi subtends an angle Θ at the center of the circle.
f. Let AiBi = ci; Therefore ci = 2 sin (Θ/2) ri     (Eqn. 1)
g. As the mock arteriesare pulsed from lower pressure to higher pressure, let Af and Bf be the final positions of points Ai and Bi respectively, rf be the final radius.
h. Let Af Bf = cf;
% strain in the chord length = % Є = ((cf-ci)100)/ci
      (Eqn. 2)
    But cf = 2 sin (Θ/2) rf      (Eqn. 3)
Therefore, % Є =(rf – ri)/ ri      (Eqn. 4)


• All six mock arteries were connected to proximal and distal manifolds of the LVP tester.

• Manifolds contains a reservoir connecting all mock arteries in common.

• Mock arteries filled with distilled water and a pressure transducer fixed to the distal manifold.

• Two points on the uppermost mock artery were marked 16mm apart at three different locations.

• High speed photographic camera was fixed vertically above such that all three points are monitored simultaneously.

Silicone Mock Arteries

Figure 3: Schematic representation of experimental setup.

Silicone Mock Arteries

Figure 4: Schematic representation of silicone mock artery.

 Single ended pressurization:

• Fluid is forced into mock arteries from proximal end by the bellows.

• Experiment was conducted at different frequencies between 5 to 100 Hz.

• Pressure measured at distal manifold cycled between 160 and 80mm Hg.

• At each testing frequency, respective movements of the markings were recorded with sinusoidal pressure variation.

• After each recording, the position changes of each of the markings were tracked by an automated tracking function.

• Strain in the chord length was determined at all three locations.

Double ended pressurization:

• A rigid hollow central tube of 1.5 inches diameter was attached between the manifolds.

Silicone Mock Arteries

Figure 5: Schematic representation of distal manifolds.

• Central tube had higher rigidity, hence its compliance is negligible compared to mock arteries.

• During forward stroke of bellows, fluid passes through the central tube and enters mock arteries from both distal and proximal end.

• Experiment was conducted at different frequencies between 5 to 100 Hz.


• Markings were tracked by automated tracking function of Photron Motion Tools 1.0.5 software.
• Strain of chord lenght was measured.
• % Є per 100mm Hg =Є104/δ P     (Eqn. 5)
δ P represents change in pressure measured in mm Hg.

Silicone Mock Arteries

Figure 6: Graphical representation of % strain versus frequency for single ended pressurization.

Silicone Mock Arteries

Figure 7: Graphical representation of % strain versus frequency for double ended pressurization.


• Complexity of relation between distension (% E) and frequency at different locations is partially understandable.

• Experimental considerations such as harmonics and asymmetric pressurization are possible sources of frequency dependent variations.

• Frequency dependent compliance of mock arteries and experimental apparatus explain some of the changes.

• End effects could have a possible influence on the data.

• Further experiments in longer tubes are ongoing.



Special thanks to all employees of Dynatek dalta Scientific Instruments.


1) Conti, J.C. and Strope, E.R., Radial Compliance of Natural and Mock Arteries: How this Property Defines the Cyclic Loading of Deployed Vascular Stents. Biomedical Sciences Instrumentation, 38, 163-171, (2002)

2) Conti, J.C., Strope, E.R., Rohde, D.J. and Spence, L.D., Frequency Dependent Radial Compliance of Latex Tubing. Biomedical
Sciences Instrumentation, 33, 524-529 (1997)

3) Conti, J.C., Strope, E.R., Price K.S, Sources of Error in Monitoring High Speed Testing of Vascular Grafts, Biomedical Sciences Instrumentation, 34, 240-245, (1998)

4) Gonza, E.R., Mason, W.F., Marble, A.E., and others, Necessity for Elastic Properties in Synthetic Arterial Grafts. Can. J. Surg., 17,176-179 (1974)

5) AAMI/ISO standard ISO/CD- V-1 25539-01:2003 and ANSI/AAMI VP-20, (1994)

6) Ramesh R., Strope E.R., Price K.S., Conti J.C., Frequency Dependent Hysteresis of Silicone and Latex Mock Arteries Used in Stent Testing.
Biomedical Sciences Instrumentation, 41, 163-168, (2005)

7) Kattekola, B., Conti J.C., Strope E.R., High Speed Photographic Verification of Intravascular Stent Strains During Accelerated Durability Testing, Biomedical  Sciences Instrumentation, 40 (2004)

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