ABSTRACT
INTRODUCTION: In-vivo implanted vascular grafts fail due to the mechanical mismatch between the native vessel and the implant. The biomechanical characterization of native vessels provides valuable information towards the development of synthetic grafts. MATERIALS AND METHODS: Five samples of electrospun nanofibrous poly(L-lactic acid)(PLLA) tubular structures were subjected to physiological pulsating pressure using an experimental setup. Four ovine femoral arteries were also tested in the experimental setup under the same conditions. Instantaneous diameter and pressure signals were obtained using gold standard techniques, in order to estimate the dynamic pressure-strain elastic modulus (E(Pε)) of both native vessels and grafts. RESULTS: Synthetic grafts showed a significant increase of E(Pε) (10.57±0.97 to 17.63±2.61 10(6) dyn/cm(2)) when pressure was increased from a range of 50-90 mmHg (elastin-response range) to a range of 100-130 mmHg (collagen-response range). Furthermore, femoral arteries also exhibited a significant increase of EPε (1.66±0.30 to 15.76±4.78 10(6) dyn/cm(2)) with the same pressure variation, showing that both native vessels and synthetic grafts have a similar behavior in the collagen-acting range. CONCLUSION: The mechanical behavior of PLLA vascular grafts was characterized In vitro. However, the procedure can be easily extrapolated to In vivo experiences in conscious and chronically instrumented animals.
Subject(s)
Arteries/metabolism , Collagen/chemistry , Femoral Artery/pathology , Lactic Acid/chemistry , Polymers/chemistry , Animals , Arteries/pathology , Biomechanical Phenomena , Bioprosthesis , Blood Vessel Prosthesis , Elastic Modulus , Elasticity , Elastin/chemistry , Male , Polyesters , Pressure , Sheep , Sheep, Domestic , Vascular GraftingABSTRACT
Simultaneous measurement of pressure and diameter in blood vessels or vascular prosthesis is of great importance in cardiovascular research. Knowledge of diameter changes as response to intravascular pressure is the basis to estimate the biomechanical properties of blood vessel. In this work a new method to quantify arterial diameter based in high resolution ultrasonography is proposed. Measurements on an arterial phantom placed on a cardiovascular simulator were performed. The results were compared to sonomicrometry measurements considered as gold standard technique. The obtained results indicate that the new method ensure an optimal diameter quantification. This method presents two main advantages respect to sonomicrometry: is noninvasive and the vessel wall strain can be measured directly.
