[Vascular access for haemodyalisis. Comparative analysis of the mechanical behaviour of native vessels and prosthesis].
BACKGROUND
The prosthesis nowadays used in the vascular access for haemodialysis have low patency rates, mainly due to the luminal obstruction, determined by the intimal hyperplasia. Several factors have been related to de development of intimal hyperplasia and graft failure. Among them are the differences in the biomechanical properties between the prosthesis and the native vessels. In the searching for vascular prosthesis that overcomes the limitations of the currently used, the cryopreserved vessels (cryografts) appear as an alternative of growing interest. However, it is unknown if the mechanical differences or mismatch between prosthesis and native vessels are lesser when using cryografts.


OBJECTIVE
To characterize and compare the biomechanical behaviour of native vessels used in vascular access and cryografts. Additionally, segments of expanded polytetrafluoroethylene (ePTFE) were also evaluated, so as to evaluate the potential biomechanical advantages of the cryografts respect to synthetic prosthesis used in vascular access.


METHODS
Segments from human humeral (n = 12), carotid (n = 12) and femoral (n = 12) arteries, and saphenous vein (n = 12), were obtained from 6 multiorgan donors. The humeral arteries were studied in fresh state. The other segments were divided into two groups, and 6 segments from each vessel were studied in fresh state, while the remaining 6 segments were evaluated after 30 days of criopreservation. For the mechanical evaluation the vascular segments and 6 segments of ePTFE were mounted in a circulation mock and submitted to haemodynamic conditions similar to those of the in vivo. Instantaneous pressure (Konigsberg) and diameter (Sonomicrometry) were measured and used to calculate the viscous and elastic indexes, the compliance, distensibility and characteristic impedance. For each mechanical parameter studied, the mismatch between the prosthesis and the native vessel was evaluated.


RESULTS
The ePTFE was the prosthesis with the higher mechanical mismatch (p < 0.05). The venous and arterial cryografts showed the least mismatch with native veins and arteries, respectively. The prosthesis with the least mechanical mismatch was different, depending on the native vessel evaluated, and for a native vessel, on the parameter considered.


CONCLUSIONS
The mechanical mismatch between the native vessel and the vascular prosthesis used in a vascular access could be reduced using cryografts.
Bia
D
D
Departamento de Fisiologia, Facultad de Medicina, Universidad de la Republica, Montevideo, Uruguay.dbia@fmed.edu.uy
Zócalo
Y
Y
Armentano
R
R
Pérez
H
H
Cabrera
E
E
Saldías
M
M
Galli
C
C
Alvarez
I
I
D000328:Adult; D001166:Arteriovenous Shunt, Surgical; D001696:Biomechanical Phenomena; D001808:Blood Vessels; D002408:Catheters, Indwelling; D006801:Humans; D011138:Polytetrafluoroethylene; D006435:Renal Dialysis
D011138:Polytetrafluoroethylene