Biomechanical properties of relevant blood vessels in the heterogeneic heart transplantation from swine to human

Yifei ZHANG; Minghua YU; Jie TANG; Tiezhu HUANG

ABSTRACT

BACKGROUND:

The source of conspecific heart transplantation organ is very limited and deficiency becomes more and more obvious.

OBJECTIVE:

To observe the mechanical properties of ascending aorta at one-dimensional loading between healthy persons and swine of different months, so as to provide necessary biomechanical experimental basis for anastomosing blood vessel in heterogeneic heart transplantation from swine to human.

DESIGN:

Open design

SETTING:

Staff Room of Anatomy, Yunyang Medical College MATERIALS This experiment was carried out at the Laboratory of Biomechanics, Yunyang Medical College from April 2002 to July 2003.Ascending aortas of human were obtained from the 6 adult male corpses without cardiovascular diseases, aged 18 to 30 years, who died for accident and donated by Yunyang Medical College. Totally 42 conspecific swine of 1 month old, with certification number of QN0202, were provided by Animal Experimental Center of Yunyang Medical College. They were raised with common foodstuff. The 42 swine were butchered respectively at 1,2,3,4,5,6 and 7 months, 6 swine once. After anatomical isolation and in situ measurement of respective in vivo length, ascending aorta from aorta valve ring base plane to initiation part of innominate artery was taken out (Artherosclerosis was not presented in all the samples) and divided into five equal segments, and the second and fourth segments were used for mechanical test of one-dimensional loading.

METHODS:

Six adult male corpses and ascending aorta of 42 swine of 1 to 7 months were performed mechanical test of one-dimensional loading.All the blood segments were pre-treated ten times with the same strain rate at room temperature 32 ℃(loading range from 0 to 0.5 N). Hysteresis disappeared after blood vessel was given periodic permanent loading and unloading, and repeated force-deformed data were obtained. Blood vessel was given loading and unloading once with the same loading range and strain rate. The recorded force-deformed data were used for computer analysis. Force and displacement were scaled with standard weight and percentage scale at the end of each time. Constant α and elastic modulus Dt/dλ were fitted from experimental data.MAIN OUTCOME

MEASURES:

① Comparison of the mechanical characteristic constant of ascending aorta at one-dimensional loading be tween human and swine of different months. ② Comparison of elastic mod ulus of ascending aorta at one -dimensional loading between human and swine of different months .

RESULTS:

① Comparison of the mechanical characteristic constant of ascending aorta at one-dimensional loading between human and swine of different months With the increase of month, although the material con stant of blood vessel of swine had a little increase, there was no significant difference (P ＞ 0.05). The mechanical material constant of ascending aorta at one-dimensional loading of human was basically familiar to that of swine of 1 to 7 months (P ＞ 0.05). ② Comparison of elastic modulus of ascend ing aorta at one -dimensional loading between human and swine of differ ent months With the increase of months, elastic modulus of ascending aorta was significantly increased in swine of 7 months old in comparison with that in other months old (P ＜ 0.05); there was no significant difference of elastic modulus of corresponding blood vessel between human and swine of different months (P ＞ 0.05).

CONCLUSION:

There is no significant difference in mechanical characteristic constant and elastic modulus of ascending aorta between human and swine of 1 to 7 months. Mechanical characteristics of corresponding blood vessel were similar in some segments at least. From the mechanical angle, anastomosis of corresponding ascending aorta in the process of heterogeneic heart transplantation from swine to human has certain feasibility.