of the carotid artery is significantly more rare, since attempts to access the nearby jugular vein are increasingly done with ultrasound guidance. the incidence of catheter fracture is 2.3%. the fracture can be due to "pinch-off syndrome" when the vein and the catheter is compressed when passes between the clavicle and first rib before turning 90 degrees into the superior vena cava. fractured catheter component can dislodge most commonly into pulmonary arteries (35%), right atrium (27%), right ventricle (22%), and superior vena cava and peripheral veins (15.4%). malpositioning of the catheter happens in 0.1 to 5.6% of the time. this can be due to malposition within or outside the superior vena cava. causes includes: unexpected branches of the veins, vessel angulations, vein stenosis or venous tortousity. thrombosis or the formation of a blood clot in the catheter may block the device irrevocably. it happens in 0.3 to 28.3% of the cases. administering cancer drugs through the port, frequent injury to the vessel during usage, or simply prolonged usage of the port can contribute to clot formation within the catheter. to prevent risk of thrombosis, right internal jugular vein is usually selected, as it has the lowest risk of thrombus formation than subclavian vein. once thrombosis happens, the port either anticoagulant therapy is given or the port is totally removed. age: if the device is put into a child, the child's growth means that the catheter becomes relatively shorter and will move towards the head. it may become necessary to remove or replace it. pneumothorax: attempts to gain access to the subclavian vein or jugular vein can injure the lung, potentially causing a pneumothorax. if the pneumothorax is large enough, a chest tube might need to be placed. in experienced hands, the incidence of this complication is about 1% when accessing the subclavian vein. when accessing the jugular vein the pneumothorax rate is virtually nonexistent. vascular occlusion: formation of a blood clot between the catheter and the vascular wall leading to partial or complete occlusion of the vein. the occlusion is cleared by removal of the port if possible. if not, then heparin therapy may clear the occlusion. intravenous drug use: if an intravenous drug user is discharged to be treated with a port in place to be treated on an outpatient basis, they may be likely to use the port improperly to inject illicit drugs. this use poses a serious risk of injury or severe infection, including of the heart lining. maintenance to reduce damage or coring of the septum (cutting out small pieces of membrane with the needle, plugging it up), low or non coring needles are to be used. after every cycle of chemotherapy, the port should be flushed with 1:10 diluted heparin (5000 iu/ml) to prevent clot formation within the port. if the port is not used for a long time, it should be flushed with diluted heparin every two months. alternatives sometimes, the physical condition of the patient, especially the structure of their veins, does not allow for the insertion of a port. an alternative is the picc line, despite drawbacks such as external entry point and limited lifespan of the device. in popular culture in the 1984 cyberpunk novel neuromancer, a minor character, peter riviera, has a kind of medical port placed in his arm to facilitate his recreational drug use. history niederhuber et al. first reported the use of totally implantable central venous port system (ticvps) in 1982.