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S Anicic

Publications and source records attributed to S Anicic.

5 recordsLinked to original sources
PubMed2006

Mathematical explanation of the buckling of the vessels after twisting of the microanastomosis.

BACKGROUND: To obtain free flap success, microvascular anastomosis must be perfectly constructed. External compression, twisting (torsion) of the anastomosis site, tension on the anastomosis site, and kinking of the pedicle must be avoided. Few experimental studies report the patency rates of rat vessels after twisting (torsion) of the microanastomosis: these results recently opened a discussion for the maximal angle of torsion, which can be impressed to a vessel in order to have the best patency rates. MATERIALS AND METHODS: To describe specifically the changing of shape of the vessels after the twisting of the microanastomosis, we extrapolate, to our experimental model (constituted by the femoral vessels of Wistar rats), the mathematical formula that engineers use to calculate the torsion of a beam when a torsion force is applied. The mathematical model used is the shell theory. Then, with a computer program using MATLAB, we could obtain the representation of these shapes at any degree of torsion. RESULTS: If a small load is applied to the vessels, it maintains its straight geometry. However, as soon as the load exceeds a critical value, which is a function of the vessel geometry and its mechanical characteristics, it snaps suddenly to a different equilibrium configuration. This phenomenon is called "buckling." When buckling occurs, wave-like deformations appear on the wall of the vessels. We calculate, in our experimental rat model, the critical twisting angle that induces buckling: maintaining a constant length of dissection of 25 mm, a minimum twisting angle of 360 degrees + 161 degrees, or 105 degrees, is required, respectively, for the femoral artery or vein, to have the buckling phenomenon and the appearance of two waves and decreased section area. CONCLUSIONS: In surgical practice, with the parameters of our experimental Wistar rats model (vessel diameter, length of dissection), it is fundamental to be below 105 degrees of torsion angle for the vein microanastomosis, in order to decrease its risk of failure.

Anastomosis, Surgical↗
PubMed1990

Use of continuous-wave Doppler echocardiography to evaluate the hemodynamic importance of atrial systole in patients with mitral stenosis.

Continuous-wave Doppler echocardiography was used to assess the hemodynamic role of left atrial systole and its effect on left ventricular performance in 31 patients with pure mitral stenosis. Seventeen (group I) had severe stenosis, and 14 (group II) had mild-to-moderate stenosis. The contribution of atrial systole to cardiac output was 15% in group I and 24% in group II (p < 0.01). This study shows the effectiveness of using continuous-wave Doppler echocardiography to assess the influence of atrial systole on left ventricular performance in patients with mitral stenosis.

Journal Article↗
PubMed1989

Doppler echocardiographic analysis of the transmitral flow velocity profile in patients with ventricular septal defects.

Using continuous-wave Doppler echocardiography, we evaluated the mitral flow velocity pattern in 30 ventricular septal defect patients, 11 of whom had severe pulmonary vascular obstructive disease (Group I); 10 of whom had severe pulmonary hypertension without pulmonary vascular obstructive disease (Group II); and 9 of whom had no pulmonary hypertension and hemodynamically unimportant left-to-right shunts (Group III). In addition, 25 healthy subjects (Group IV) were studied for comparative purposes. The peak velocity of early left ventricular filling (E) was significantly lower in Group I than in all the other groups (p < 0.01). The peak velocity of late left ventricular filling (A) was significantly higher (p < 0.01) in Group I than in Group III, or than in normal individuals (Group IV) (p < 0.01). The ratio A/E was the most prominent difference between Group I patients and the other groups, with Group I having a significantly higher ratio (p < 0.01), which was 1 or greater in 9 of 11 patients. In contrast, none of the remaining ventricular septal defect patients or normal subjects had an A/E ratio of 1 or greater. Group II had increased mitral flow velocities, while Group III had normal mitral flow velocity profiles. A positive correlation between the magnitude of the left-to-right shunt and early mitral flow velocity peak (r = 0.86) and late peak (r = 0.81) was found, regardless of the degree of pulmonary hypertension. These results indicate that significant alterations of the mitral flow velocity pattern, which mimic the abnormalities associated with impaired left ventricular diastolic function (A/E ratio of 1 or greater), occur in ventricular septal defect patients who have severe pulmonary vascular obstructive disease. The transmitral velocity profiles in the ventricular septal defect patients without severe pulmonary vascular obstructive disease were similar to those of the normal patients, although the values relative to the degree of left-to-right shunting were higher in the ventricular septal defect patients.

Journal Article↗