Non-Axisymmetrical (Life-Like) Abdominal Aortic Aneurysm Models: A Do-It-Yourself Approach

Chaudhuri, Arindam; Ansdell, Leslie E.; Richards, R.; Adiseshiah, M; Grass, Anthony J.

doi:10.1177/152660280301000612

Cited by 10 publications

(9 citation statements)

References 8 publications

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“…The latex has a Young's modulus ðEÞ of 5.151872 N/mm 2 , measured by a Hounsfield tensometer. A solution of glycerol in water (55:45 v/v, r ¼ 1172 kg=m 3 ; viscosity ¼ 15.53 cP at 25 8C) was used as a blood analogue. The increased density was calculated to generate the high-pressure setting within the limitations of the solenoid angle seat valve.…”

Section: Methodsmentioning

confidence: 99%

Aneurysmal Hypertension and its Relationship to Sac Thrombus: A Semi-qualitative Analysis by Experimental Fluid Mechanics

CHAUDHURI¹,

ANSDELL²,

GRASS³

et al. 2004

European Journal of Vascular and Endovascular Surgery

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Objectives. To ascertain the effect of aneurysm thrombus and luminal diameter on arterial blood pressure within the abdominal aortic aneurysm lumen and at the sac wall. Methods. A lifelike abdominal aortic aneurysm was incorporated in a pulsatile flow unit, using systemic blood pressure settings of 140/100 mmHg and 130/90 mmHg (denoted the high and low settings, respectively). Aneurysm sac pressure was measured in the absence of thrombus within the sac. This was repeated after a thrombus analogue (gelatine) was introduced into the aneurysm model in an asymmetric fashion. Luminal and sac wall pressures were compared to the systemic pressure, and to each other, in both blood pressure settings. Statistical analysis was performed using ANOVA in Minitab 13. Results. In the empty sac, the luminal and sac wall pressures were identical to the systemic pressures at the high and low settings. After introduction of thrombus, pressure was transmitted in a monophasic pulsatile fashion, measuring 166/142/151 mmHg (SP/DP/MP) at the sac wall, while the corresponding intraluminal pressure was 164/136/145 mmHg (p , 0.001, high setting). By contrast, in the low setting, these readings were 157/133/141 (sac wall) and 160/128/138 mmHg (lumen; p , 0.001). The sac wall pressures were significantly higher than the luminal pressures for both high and low settings (p , 0.001). Conclusions. Thrombus has a significant effect on the intraaneurysmal lumen itself and causes localised hypertension with high intraluminal pressures. The differences between the sac wall/luminal pressures may affect regional aneurysm wall biomechanics, but needs further study.

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Section: Methodsmentioning

confidence: 99%

Aneurysmal Hypertension and its Relationship to Sac Thrombus: A Semi-qualitative Analysis by Experimental Fluid Mechanics

CHAUDHURI¹,

ANSDELL²,

GRASS³

et al. 2004

European Journal of Vascular and Endovascular Surgery

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“…2 The human thrombus that is obtained during open aneurysm surgery cannot be fitted exactly in aneurysm models. Pre-stress is induced by curvature of the graft due to patient anatomy.…”

Section: Replymentioning

confidence: 99%

“…Using air that quite effectively replicates the pressures within an axially symmetric container may be an oversimplification that may not sufficiently mimic the intrasac environment. This could have been done using real or simulated thrombus within a more realistic AAA model 2,3 ; this is particularly so given that their own results previously have shown that thrombus may contribute to inconsistencies in the readings. 4 It may be that thrombus actually has a damping effect on sensor movement!…”

mentioning

confidence: 99%

Re: “Aneurysm Sac Pressure Monitoring: Effect of Pulsatile Motion of the Pressure Sensor on the Interpretation of Measurements”

Chaudhuri

2006

Journal of Endovascular Therapy

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“…Because of this, the compliance (or stiffness) of arteries has become the attribute which researchers attempt to mimic [10,16]. The manufacturing methods for creating both idealised and realistic AAA models have been previously reported [10,16–21]. O’ Brien et al [19] and Doyle et al [20] have verified a lost wax manufacturing technique and reported that the variation in wall thickness for large vessel models manufactured using this technique was between 4–11%.…”

Section: Introductionmentioning

confidence: 99%

Engineering Silicone Rubbers for In Vitro Studies: Creating AAA Models and ILT Analogues With Physiological Properties

Corbett

Doyle

Callanan

et al. 2009

Journal of Biomechanical Engineering

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Background In vitro studies of abdominal aortic aneurysm (AAA) have been widely reported. Frequently mock artery models with intraluminal thrombus (ILT) analogues are used to mimic the AAA in vivo. While the models used may be physiological, their properties are frequently either not reported or investigated. Method of Approach This study is concerned with the testing and characterisation of previously used vessel analogue materials and the development of new materials for the manufacture of AAA models. These materials were used in conjunction with a previously validated injection moulding technique to manufacture AAA models of ideal geometry. To determine the model properties (stiffness (β) and compliance) the diameter change of each AAA model was investigated under incrementally increasing internal pressures and compared to published in vivo studies to determine if the models behaved physiologically. A FEA study was implemented to determine if the pressure – diameter change behaviour of the models could be predicted numerically. ILT analogues were also manufactured and characterised. Ideal models were manufactured with ILT analogue internal to the aneurysm region and the effect of the ILT analogue on the model compliance and stiffness was investigated. Results The wall materials had similar properties to aortic tissue at physiological pressures (Einit 2.22MPa and 1.57MPa (aortic tissue: 1.8MPa)). ILT analogues had similar Young’s modulus to the medial layer of ILT (0.24 and 0.33MPa (ILT: 0.28MPa)). All models had aneurysm sac compliance in the physiological range (2.62 – 8.01×10-4/mmHg (AAA in vivo: 1.8 – 9.4×10-4/mmHg)). The necks of our AAA models had similar stiffness to healthy aortas (20.44 – 29.83 (healthy aortas in vivo: 17.5±5.5)). Good agreement was seen between the diameter changes due to pressurisation in the experimental and FEA wall models with a maximum error of 7.3% at 120mmHg. It was also determined that the inclusion of ILT analogue in the sac of our models could have an effect on the compliance of the model neck. Conclusions Ideal AAA models with physiological properties were manufactured. The behaviour of these models due to pressurisation was predicted using FEA, validating this technique for the future design of realistic, physiological AAA models. Addition of ILT analogues in the aneurysm sac was shown to affect neck behaviour. This could have implications for endovascular AAA repair due to the importance of the neck for stent-graft fixation.

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Non-Axisymmetrical (Life-Like) Abdominal Aortic Aneurysm Models: A Do-It-Yourself Approach

Abstract: Chemical metal can be manipulated quite easily to make a mould of any required size or surface character, which then allows the manufacture of a well-matched latex model for biophysical studies of non-axisymmetrical abdominal aortic aneurysms.

Cited by 10 publications

References 8 publications

Aneurysmal Hypertension and its Relationship to Sac Thrombus: A Semi-qualitative Analysis by Experimental Fluid Mechanics

Aneurysmal Hypertension and its Relationship to Sac Thrombus: A Semi-qualitative Analysis by Experimental Fluid Mechanics

Re: “Aneurysm Sac Pressure Monitoring: Effect of Pulsatile Motion of the Pressure Sensor on the Interpretation of Measurements”

Engineering Silicone Rubbers for In Vitro Studies: Creating AAA Models and ILT Analogues With Physiological Properties

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