ABSTRACT
Objective To analyze influences of the braiding angle and material on performance of ventricular septal defect (VSD) occluders, so as to provide theoretical basis and guidance for their design. Methods The finite element models of occluders with different braiding angles (30°, 45° and 60°) were developed respectively. The radial supporting and axial bending performances of nickel titanium (NiTi) occlude and poly-p-dioxanone (PPDO) occlude were then compared. Results Under 5 kPa radial loading, radial stiffness of the 30°, 45° and 60° NiTi occluder waists were 8.60, 1.51 and 0.99 mN/mm3,respectively, while that of 45° PPDO occluder waist was 7.35 mN/mm3. Under axial bending of 0.5 rad, the maximum radial deformation of the 30°, 45°, 60° NiTi occluder waists were 1.17, 1.24 and 0.22 mm, while that of the 45° PPDO was 0.54 mm. Conclusions Under the condition of using the same material, occluders with braiding angle of 60° show the lowest radial stiffness, indicating they have the best radial supporting ability. Furthermore, they also show the smallest maximum radial deformation, indicating they have the best axial bending ability and the compliance. On the other hand, under the condition of using the same braiding angle, NiTi occluders show lower radial stiffness, indicating they have better radial supporting ability. However, PPDO occluders show lower maximum radial deformation, indicating they have better axial bending ability and compliance.
ABSTRACT
The electromicroscopic observation of atrialbiopsy was carried out in 10 patients with ventric-ular septal defect (VSD) and middle, severe pul-monary hypertension (PH). The observation sug-gests that there are myofibrillar lysis to disappearwith various degrees, dilated rough endoplasmreticulum and the increase in lipofuscin granulesand lipid droplets; mitochondral hyperplasia, theirsize and shape being different, disorganizing of mi-tochondria, disintegration of cristae, mitochondralretrograde degenration and decreased matrix elec-tron density. The dilated intercalated discs and in-crease in myocardial fibrous tissue were found inpart of patients. These structural changes areprobably due to chronic myocardial ischemia.
ABSTRACT
We find that there is a correlation among thesize of ventricular septal defect (VSD) (X_2), PaO_2(X_3), V. /V. (X_7) and pulmonary systolic pressure(Y_1), diastolic pressure (Y_2), mean pressure (Y_3)by multivariate stepwise regression analysis, andso there are their parameters in the regression e-quations. The regression equations are Y_1 = 13. 24+ 0. 22X_2 - 0. 09X_3 + 0. 14X_7; Y_2 = 0. 65 + 0. 24X_2+ 0. 12X_7; Y_3 = 3. 54+ 0. 17X_2 + 0. 16X_7. But thecourse of the disease, ∑9 leads QRS dimension,R. /R., L. /L. are non-dominant factors, and sothere are not their parameters in the regression e-quation. The above-mentioned equations mayavoid the patients. with mild, moderate pulmonaryhypertension to have invasive examination, and re-duce its complications.