RESUMEN Introducción: Las prótesis utilizadas en los accesos vasculares para hemodiálisis presentan elevadas tasas de falla por obstrucción luminal, secundaria a hiperplasia intimal. La generación de hiperplasia intimal y falla protésica se han vinculado, entre otros factores, con las diferencias biomecánicas entre las prótesis y los vasos nativos. En busca de prótesis que superen las limitaciones de las actuales, los vasos criopreservados (crioinjertos) son una alternativa de creciente interés. Sin embargo, se desconoce si las diferencias o desacoples mecánicos entre prótesis y vasos nativos son menores con los crioinjertos. Objetivo: Caracterizar y comparar el comportamiento biomecánico de vasos nativos utilizados en accesos vasculares y crioinjertos. Para analizar posibles ventajas biomecánicas de los crioinjertos en relación con la prótesis sintética más utilizada, se estudiaron segmentos de politetrafluoroetileno expandido (ePTFE). Métodos: Segmentos de arterias humeral (n = 12), carótida (n = 12) y femoral (n = 12), y vena safena (n = 12), fueron obtenidos de 6 donantes cadavéricos. Las arterias humerales se estudiaron en estado fresco. De los restantes vasos, 6 segmentos se evaluaron en estado fresco, y 6 luego de criopreservados durante 30 días. Para la evaluación biomecánica, los segmentos vasculares y 6 prótesis de ePTFE se montaron en un simulador circulatorio, y se sometieron a condiciones hemodinámicas similares a las de in vivo. Se midió presión (Konigsberg) y diámetro (sonomicrometría) instantáneo, y se calculó: el índice viscoso y elástico, la complacencia, distensibilidad e impedancia característica. Para cada parámetro, se cuantificó el desacople mecánico entre prótesis y vaso nativo. Resultados: El ePTFE presentó mayor desacople mecánico (p < 0,05). Los crioinjertos venosos y arteriales presentaron menor desacople mecánico con venas y arterias nativas, respectivamente. La prótesis con menor desacople mecánico fue diferente, dependiendo de parámetro biomecánico, y del vaso nativo considerado. Conclusión: El desacople mecánico con vasos nativos usados en accesos vasculares podría reducirse utilizando crioprótesis.

SUMMARY Introduction: 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. Conclusion: The mechanical mismatch between the native vessel and the vascular prosthesis used in a vascular access could be reduced using cryografts.