With introduction of current main methods for heart fluid mechanics researches, we studied the characteristics and weakness for three primary analysis methods based on magnetic resonance imaging, color Doppler ultrasound and grayscale ultrasound image, respectively. It is pointed out that particle image velocity (PIV),speckle tracking and block match have the same nature, and three algorithms all adopt block correlation. The further analysis shows that, with the development of information technology and sensor, the research for cardiac function and fluid mechanics will focus on energy transfer process of heart fluid, characteristics of Chamber wall related to blood fluid and Fluid-structure interaction in the future heart fluid mechanics fields.
This paper aims to analyze the impact of splenic vein thrombosis (SVT) on the hemodynamic parameters in hepatic portal vein system. Based on computed tomography (CT) images of a patient with portal hypertension and commercial software MIMICS, the patient's portal venous system model was reconstructed. Color Doppler ultrasound method was used to measure the blood flow velocity in portal vein system and then the blood flow velocities were used as the inlet boundary conditions of simulation. By using the computational fluid dynamics (CFD) method, we simulated the changes of hemodynamic parameters in portal venous system with and without splenic vein thrombosis and analyzed the influence of physiological processes. The simulation results reproduced the blood flow process in portal venous system and the results showed that the splenic vein thrombosis caused serious impacts on hemodynamics. When blood flowed through the thrombosis, blood pressure reduced, flow velocity and wall shear stress increased. Flow resistance increased, blood flow velocity slowed down, the pressure gradient and wall shear stress distribution were more uniform in portal vein. The blood supply to liver decreased. Splenic vein thrombosis led to the possibility of forming new thrombosis in portal vein and surroundings.
ObjectiveTo investigate the application of high frequency color Doppler ultrasound (HFCDU) combined with wide-field imaging in the preoperative navigation of anterolateral thigh perforator flap graft.MethodsBetween January 2017 and March 2018, 28 patients with skin and soft tissue defects were treated, including 22 males and 6 females, with an average age of 33.5 years (range, 17-66 years). The causes of injury included 2 cases of scald scar, 7 cases of heavy object crushing injury, 12 cases of traffic accident injury, 4 cases of fall injury, 2 cases of machine injury, and 1 case of infection ulcer. Injury sites included 6 cases of hand and wrist, 12 cases of lower leg, 10 cases of foot. After debridement, the wound area ranged from 6.0 cm×3.5 cm to 24.0 cm×9.0 cm, and all patients were treated with free circumflex femoral artery perforator flap graft. Combo of HFCDU and wide-field imaging navigation were done preoperatively to detect the origin, quantity, course, surface location, hemodynamic characteristics, and the relationship with body area of perforator branch of lateral circumflex femoral artery. According to the perforator information displayed by wide-field imaging of source artery, the dominant perforator was determined to be a pedicle for designed flap. The flap size ranged from 7.0 cm×4.5 cm to 26.0 cm×7.0 cm. The flap donor area was sutured directly.ResultsThe dominant perforator was successfully detected by HFCDU combined with wide-field imaging in 28 patients before operation. The existence of the perforator was confirmed during operation, and the location was accurate. The course characteristics of the perforate were consistent with the results of wide-field imaging. The grafted flaps survived completely among 27 patients after operation. Necrosis at the edge of the flap was observed in 1 patient, which healed after dressing change. All patients were followed up 3-12 months, with an average of 9 months. All the flaps have good blood supply, good elasticity and shape. The donor areas healed perfectly.ConclusionUsing HFCDU and wide-field imaging navigation for designing of anterolateral thigh perforator flaps can clearly show the characteristics of perforators, hemodynamic information, and the relationship with body area, so that the surgeons can understand the perforators more accurately and intuitively, and improve the success and efficiency of flap graft surgery.
Objective To investigate the clinical application of high-frequency color Doppler ultrasound (HFCDU) in detecting perforators in the deep adipose layers for harvesting super-thin anterolateral thigh flap (ALTF). Methods Between August 2019 and January 2023, 45 patients (46 sides) with skin and soft tissue defects in the foot and ankle were treated, including 29 males and 16 females, aged from 22 to 62 years, with an average of 46.7 years. The body mass index ranged from 19.6 to 36.2 kg/m2, with an average of 23.62 kg/m2. The causes of injury included traffic accident injury in 15 cases, heavy object crush injury in 20 cases, mechanical injury in 8 cases, heat crush injury in 1 case, and chronic infection in 1 case. There were 20 cases on the left side, 24 cases on the right side, and 1 case on both sides. After thorough debridement, the wound size ranged from 5 cm×4 cm to 17 cm×11 cm. All patients underwent free super-thin ALTF transplantation repair. HFCDU was used to detect the location of the perforators piercing the deep and superficial fascia, as well as the direction and branches of the perforators within the deep adipose layers before operation. According to the preoperative HFCDU findings, the dimensions of the super-thin ALTF ranged from 6 cm×4 cm to 18 cm×12 cm. The donor sites of the flaps were directly sutured. Results A total of 55 perforators were detected by HFCDU before operation, but 1 was not found during operation. During operation, a total of 56 perforators were found, and 2 perforators were not detected by HFCDU. The positive predictive value of HFCDU for identifying perforator vessels was 98.2%, and the sensitivity was 96.4%. Among the 54 perforators accurately located by HFCDU, the orientation of the perforators in the deep adipose layers was confirmed during operation. There were 21 perforators (38.9%) traveled laterally and inferiorly, 12 (22.2%) traveled medially and inferiorly, 14 (25.9%) traveled laterally and superiorly, 5 (9.3%) traveled medially and superiorly, and 2 (3.7%) ran almost vertically to the body surface. Among the 54 perforators accurately located by HFCDU, 35 were identified as type 1 perforators and 12 as type 2 perforators (HFCDU misidentified 7 type 2 perforators as type 1 perforators). The sensitivity of HFCDU in identifying type 1 perforators was 100%, with a positive predictive value of 83.3%. For type 2 perforators, the sensitivity was 63.2%, and the positive predictive value was 100%. The surgeries were successfully completed. The super-thin ALTF had a thickness ranging from 2 to 6 mm, with an average of 3.56 mm. All super-thin ALTF survived, however, 1 flap experienced a venous crisis at 1 day after operation, but it survived after emergency exploration and re-anastomosis of the veins; 1 flap developed venous crisis at 3 days after operation but survived after bleeding with several small incisions; 3 flaps had necrosis at the distal edge of the epidermis, which healed after undergoing dressing changes. All 45 patients were followed up 6-18 months (mean, 13.6 months). Three flaps required secondary defatting procedures, while the rest had the appropriate thickness, and the overall appearance was satisfactory. Conclusion Preoperative application of HFCDU to detect the perforator in the deep adipose layers can improve the success and safety of the procedure by facilitating the harvest of super-thin ALTF.