Esophageal stenosis-especially esophageal stenosis caused by malignant tumor, although balloon dilatation can achieve certain results, tumor growth will soon lead to esophageal obstruction. If esophageal stenosis is accompanied by esophagotracheal fistula, simple balloon dilatation is contraindicated. In the early 1990s, China began to use stents to treat esophageal stenosis caused by esophageal cancer, and the short-term effect was obvious.

1. instruction

① coronary heart disease; ② Esophageal tracheal fistula or esophageal mediastinal fistula caused by malignant tumor; (3) Benign lesions with esophageal rupture and fistula, such as trauma, postoperative anastomotic leakage, chemical burn rupture, etc. , conservative treatment failure or can not tolerate surgical treatment; ④ Repeated balloon dilatation is ineffective in the treatment of benign esophageal stenosis.

2. Contraindications

① Failure to correct the disorder of coagulation mechanism; ② Severe cardiopulmonary failure; ③ Severe cachexia; ④ Stenting for severe esophageal and gastric varices may lead to bleeding.

3. Interventional therapy technology

Supporting choice is extremely important. Choosing a covered anti-skid stent for patients with esophageal cancer can delay the time of tumor growing into the stent cavity. Covered stents must be used to treat esophagotracheal fistula or esophago-mediastinal fistula. Benign stenosis is easy to shift after stent placement, so it is advisable to use anti-slip recyclable stent. At present, the commonly used diameter in clinic is 17 ~ 20 mm, and both ends of the stent should exceed the focus by about 2cm. When treating esophageal fistula, the length of stent should be appropriately increased.

After the balloon is pre-expanded, it is sent to the stent along the hard exchange guide wire for accurate positioning and then released. Immediately inject contrast agent through the catheter, observe the position, expansion degree, patency and perforation of the stent and keep the data. The selection of pre-expanded balloon diameter should comprehensively consider the nature and scope of the lesion, stent diameter, supporting force and compliance. It is not only beneficial to the smooth release and full expansion of the stent, but also beneficial to the stability of the stent after release. Generally, the diameter of the balloon is 2 ~ 3 mm smaller than that of the implanted stent, and patients with mild stenosis can also pre-expand without the balloon. 2 ~ 3 days after operation, the liquid diet gradually changed to semi-liquid, soft food and general food. Avoid swallowing thick and hard chunks of food, such as whole egg yolk and large chicken bones. Patients should be advised to sit and eat, chew fully, and drink more liquid or water after meals. Severe vomiting can lead to stent displacement.

Precautions ① Stent implantation for benign stenosis must be cautious; ② High stent may bring obvious discomfort to patients. In general, the esophageal stent should not be close to cricoid cartilage by 3cm at most. ③ The stent passing through cardia should be an anti-reflux stent. (2) Segmental occlusion of inferior vena cava (Budd-Chiari syndrome) 1, indication.

Membrane or segmental stenosis or occlusion of inferior vena cava; Restenosis occurred after inferior vena cava stenosis or occlusion balloon dilatation; Elastic retraction rate after balloon dilatation of inferior vena cava stenosis or occlusion >: 40%.

2. Contraindications

Patients with fresh inferior vena cava thrombosis.

Budd-Chiari syndrome in immature children.

3, interventional therapy technology

1. Femoral vein and/or jugular vein approach can be selected. 2. The pigtail catheter was sent to the proximal and distal ends of the occluded segment of the inferior vena cava through the femoral vein and the right internal jugular vein, respectively. Angiography of the upper and lower ends of the occluded segment can clearly show the position, scope and shape of the occluded segment. 3. In case of complete occlusion, replace the femoral vein sheath of 10~ 12F, and send the J-shaped trocar cannula through this sheath to the distal end of the occluded segment of inferior vena cava along the guide wire. Withdraw the guide wire, insert the metal needle into the jacket and fix it. The pigtail catheter sent to the proximal end of the occluded segment of inferior vena cava through jugular vein was reserved as a positioning sign for bottom-up puncture. The position and angle of the trocar tip are adjusted by referring to the images taken by two-way end-to-end photography under the supervision of the front two-way perspective. After confirmation, push the trocar slowly into the occluded lesion, inject a small amount of contrast agent every 5~ 10mm, observe the position of the needle tip, and pay attention to whether there are signs of blood vessel puncture. When the tip of the trocar reaches the curved part of the inferior vena cava, adjust the direction and angle of the tip again to keep it on the same axis with the positioning marker catheter near the heart. Continue to push the trocar towards the right atrium until it passes through the occluded part. After angiography confirmed that the outer cannula had entered the right atrium, the metal needle was pulled out and the exchange guide wire was entered. After the exchange guide wire was sent into the superior vena cava, the trocar cannula was removed and the exchange balloon catheter was used to reach the lesion. 4. Fully dilate the lesion with a balloon and mark the lesion on the body surface at the same time. 5. Exchange the following vena cava stent delivery systems. After the stent is delivered to the lesion, the inner tube of the stent delivery system is fixed, and the outer sheath is gradually pulled out to release the stent. 6. If the inferior vena cava is narrow or the diaphragm is perforated, there is no need to penetrate the lesion. As long as the guide wire passes through the lesion, balloon dilatation and stent implantation can be directly performed. 7. Pull out the catheter and vascular sheath, press the puncture point to stop bleeding, and press the puncture point.

Matters needing attention

1. Generally, on the lateral position, the inferior vena cava of the posterior segment of the liver usually enters the right atrium forward and upward, and its curvature is usually 135 ~ 160. The angle of the puncture needle should be adjusted according to the direction of the blood vessel. It is best to observe the lesion alternately in the frontal position and the lateral position, so that the direction of the puncture needle is always aimed at the positioning catheter near the occluded heart. 2. Immediately tell the patient to hold their breath when placing the stent, because the inferior vena cava can move up and down with breathing, which affects the positioning of the stent. 3. heparin anticoagulation is needed during and after operation.

In vitro stent implantation based on 3D printing and microfluidic technology

In medicine, cardiac stent implantation has become one of the important means to treat cardiovascular diseases. However, about one year after operation, restenosis will occur at the stent implantation site (figure 1), especially when the stent implantation site is wrong, the evolution of restenosis will accelerate and become a major problem in the treatment of coronary heart disease. In the past, simple Y-shaped channels with smooth walls were often used in numerical simulation to calculate the effect of wall shear stress (WSS) in the bifurcation region of arteries after stent placement. This simple simulation result can not provide reliable information for actual clinical cases.

In order to solve this problem for real cases, the Biophysics Laboratory of the Institute of Physics of Chinese Academy of Sciences, together with the Microfluidic Research Group of LNM Room of the Institute of Mechanics of Chinese Academy of Sciences, the Department of Cardiology of anzhen hospital, and the Chinese University of Science and Technology, carried out a cooperative study combining clinical, experimental and simulation (Figure 2). First, the hospital provided clinical cases and scanned the lesion site by angiography. Then, 3D printing and microfluidic technology are introduced to "copy" the real vascular lesion site model onto the 3D microfluidic chip. The microfluidic research group of LNM Laboratory of Institute of Mechanics undertook the fabrication of microfluidic chip and the measurement of flow field. Through the MicroPIV and * * focusing experimental system, the flow field near the actual lesion site is measured and the wall shear stress is calculated. The critical wall shear stress is about 0.4-0.5Pa, and it is found that the blockage will occur when the wall shear stress is less than the critical value, which provides reference data for clinical diagnosis.

For the first time, this study provides a laboratory research method for replicating real cases for stent implantation in vitro, and makes a preliminary exploration for future in vitro experiments to optimize stent implantation position closely combined with clinical cases to reduce the risk of re-occlusion after stent implantation. The related results were published in Scientific Reports (Vol.5:10945, May 20 15), with Zheng Xu as the first author and Li Zhanhua as the * * * correspondent. The research was supported by the National "973" Project (20 13CB837200) and the National Natural Science Foundation (1 1474345, 1 1272322,1/.