In vitro investigation of blood compatibility of Ti with oxide layers of rutile structure

Structure characteristics of titanium oxide layer on titanium matrix were investigated by Rutherford Backscattering Spectroscopy (RBS), Auger Electron Spectroscopy (AES) and X-ray diffraction. It has been identified that the titanium oxide layers had rutile structure. The blood compatibility of the titanium oxide layers of different thickness was studied by blood clotting time measurement. It was shown that as the thickness of the titanium oxide layers increased, blood compatibility of these layers was obviously improved.

[Research on thixotropic parameters of whole blood from Chinese adult subjects]

This study measured the thixotropic parameters of whole blood from 314 healthy subjects (154 women, 160 men) with our modified method by Low Shear-30 Rheometer according to Huang's equation. We suggested the range of normal values of thixotropic parameters from man and woman group. The results demonstrated that no significant differences existed in the plasma viscosity (eta p) and fibrinogen between man and woman group. Man group had significantly higher values than those in woman group in hematocrit (HCT), yield stress (tau 0), Newtonian contribution of viscosity (mu), non-Newtonion contribution of viscosity (eta s-mu), apparent viscosity at 2.37s-1 (eta s), the equilibrium value of the structural parameter (A) and apparent kinetic rate constant of rouleaux breakdown (ARC). The man and woman groups could be separately divided into five subgroups on the basis of age. All parameters were compared with one another and treated statistically. We found that the levels of fibrinogen and eta p had an increasing trend with aging. In the old subgroup (greater than or equal to 60 years) of man and woman, HCT, tau 0, mu, eta s, (eta s-mu) and A had significantly lower values than those in young and middle age subgroups. However, it was very interesting that there were differences of ARC versus age between the man and woman groups, i.e., ARC in the man subgroup 3, 4 had lower values and in the woman subgroup 2, 3, 4 had higher values than their respective older subgroups did.

[Observation and measurement of coronary arteries of goat]

The coronary arteries of 50 goats were studied by means of angiography and dissection. The results were as follows: The right coronary artery (RCA) and left coronary artery (LCA) arose from the right and left aortic sinuses respectively. At the beginning, the average external diameter of RCA (2.98 +/- 1.02 mm) was smaller than that of LCA (3.42 +/- 0.74 mm). An independent inter ventricular septal artery (in 94%) supplied the upper two-thirds of the inter ventricular septum. The arterial distributive types were divided into three: The LCA was dominant in 96%, symmetrical in 4%, RCA dominant in 0%. Sixty two percent of the S-A node arteries arose from the RCA, 28% from LCA, 10% from both RCA and LCA. All the A-V node arteries originated from the LCA.

[Intraoperative hemodynamics of pyrolytic carbon cambered bileaflet valve replacement in animals]

Pyrolytic carbon cambered bileaflet valve developed by Chengdu University of Technology and Sciences was evaluated for its hemodynamics. The curved surface of the valve leaflet is cylindrical. Under anaesthesia, cardiopulmonary bypass and chemical cardioplegia, a cambered bileaflet valve (i.d. = 16 mm) was replaced at mitral position in each of 12 goats. Before valve replacement, mitral flow rate (MFR) was 74.9 +/- 12.3 ml.sec-1, average valvular pressure drop delta P) 0.56 +/- 0.17 kPa (4.2 +/- 1.3 mmHg) and effective opening area (EOA) of the valve 1.20 +/- 0.18 cm2. After valve replacement, corresponding hemodynamic parameters were 49.3 +/- 12.7 ml.sec-1, 0.46 +/- 0.17 kPa (3.8 +/- 1.3 mmHg) and 0.81 +/- 0.12 cm2 respectively. In our previous report on yak pericardiac heart valve (i.d. = 20 mm) in goats, corresponding hemodynamic parameters after valve replacement were 45.6 +/- 11.8 ml.sec-1, 0.86 +/- 0.32 kpa (6.4 +/- 2.4 mmHg) and 0.65 +/- 0.26 cm2. With comparable mitral flow rate and heart rate (113.6 +/- 19.6 min-1 vs 119.1 +/- 17.1 min-1), the average valvular pressure drop of pyrolytic carbon cambered bileaflet valve is significantly smaller than that of the yak pericardiac valve (P less than 0.001), and the effective opening area is marginally larger than that of the yak pericardiac valve (0.05 less than P less than 0.1). If the same-sized valves of this two kinds are used, the hemodynamic parameter of cambered bileaflet valve would be better than those of yak pericardiac valve. Since the latter valve has been successfully used in patients, the present valve might be applicable in clinical situation.