Comparisons of hemodynamics in 1-way and 2-way CABG / 生物医学工程学杂志

For the purpose of improving the hemodynamics of CABG, the authors presented a new amelioration measurement of symmetric 2-way bypass graft. The physiological blood flow in 1-way and 2-way bypass graft of coronary is simulated with finite element method, and the data on computational hemodynamics of these two cases were compared. The temporal-spatial distributions of hemodynamics during the cardiac cycle such as flow patterns and wall shear stress in the vicinity of anastomosis were analyzed. The study results showed that 2-way bypass graft was of more rational hemodynamics when compared with 1-way bypass graft, and it could improve the flow conditions and decrease the probability of restenosis.

Biomechanical properties of skin expanded by different methods in vivo / 生物医学工程学杂志

In plastic surgery, people hope the conventional expansion will be replaced by rapid expansion, which can shorten greatly the expansion period. Also people are concerned about whether the skin properties after rapid expansion approach that after conventional expansion. So we designed and made an apparatus for in vivo measurement of tension, and then measured the biomechanical properties of skin in vivo for the first time. The experimental results showed there was no significant difference between the rapid expansion method and conventional expansion method in respect to the area gain of expanded skin surface. Both the tension in vivo and the instant stretch-back ratio increased during the expansion, but fell almost to the control values after four weeks' maintaining period. So, rapid skin expansion did not produce any deleterious effect when compared with the conventional expansion. Extension of the maintaining period can improve the biomechanical properties of expanded skin and effectively reduce the stretch-back ratio. Therefore, rapid expansion with an extended maintaining period is clinically acceptable.

A new approach to detection of QRS complexes based on histogram / 生物医学工程学杂志

A brief comment on the current methods of detecting QRS complexes from ECG(electrocardiogram) including the wavelet transform method is given, and the shortcomings of those methods are discussed. A simple and effective new approach for detecting QRS complexes based on histogram is developed and presented in this paper with a description of the theory of histogram and the match principle for detecting QRS complexes. This new method is checked up on the data from the MIT/BIH ECG database and that from the Beijing Polytechnic University Hospital.

Comparison of biomechanical properties between human nasal periosteum and fascia / 生物医学工程学杂志

There has been a lot of controversies on which layer the silastic implants should be inserted in the augmentation rhinoplasty, i.e. subperiosteal or deep subfascial. This study is to investigate the biomechanical properties of human nasal periosteum and deep fascia, including tensile strength, stress-strain and stress relaxation characters under uniaxial tension system. The periosteum is stronger in tensile strength than that of the fascia, but it is less elastic. Under a sudden increase of load, the periosteum relaxes far less than the fasia. Therefore, in view of biomechanics, the periosteum is thicker, tougher, stiffer and less relaxation than facia, thus has a better fixation effect.

An alternative method of strain analysis on arterial walls / 生物医学工程学杂志

As is well known, the zero stress state of an artery is brought by cutting a ring of the artery radically and then the ring segment springs open into a sector. The zero stress state is a foundation of strain analysis of an artery. There are two methods to measure the dimensions of a blood vessel in the zero stress state. First, it is a way to measure immediately an opening angle. Second, it is a method of assuming that a cut-open, stress-free specimen forms a circular sector and there are two edge angles. In this paper, we proposed a new method to measure the dimensions of an arterial wall in the zero stress state. The new method is to measure immediately the curve length of an arterial wall in zero stress state by computer image process (CIP). We used the curve lengths to define a standard circle for the strain analysis. We compared these three methods on descending thoracic aortas, common carotid arteries, and femoral arteries of white rabbits. Conclusions are: (1) the new method, that is the strain analysis method from the curve length, is the best method among the three methods of strain analysis; (2) the lengths of a ring segment (the length between D/2 and 2D) do not affect the dimensions of the zero stress state.