0:00 Hello, in this video, we're going to look at the clinical anatomy of the 0:09 superior vena 0:10 cava, as well as the zygoshemia zygosystem. 0:16 The superior vena cava is a valveless, thin-walled, low-pressure tube that 0:21 drains deoxygenated 0:22 blood from the upper half of the body, including the head arms and thoracic 0:26 wall into the right 0:28 atrium of the heart. 0:31 The right atrium also drains the inferior vena cava, which contains valves, of 0:37 course, to 0:37 prevent backflow. 0:40 The superior vena cava drains blood from the upper body, but also drains blood 0:43 from below 0:44 the diaphragm via the azygos vein here. 0:49 Taking a closer look at this area, the superior vena cava have three main t 0:55 ributaries. 0:56 The first is the right and left brachochophallic veins, which drain into and 1:03 forms the superior 1:04 vena cava. 1:06 The superior vena cava then drains into the right atrium. 1:11 There are no valves in either the superior vena cava or the brachochophallic 1:17 vein. 1:17 Halfway along its course, before it enters the pericardium, which wraps around 1:22 the heart, 1:23 the superior vena cava receives the azygos arch. 1:27 This is the second main tributary. 1:32 The third tributary of the superior vena cava is the media-stinal and pericard 1:38 io veins. 1:39 The superior vena cava passes through the pericardium as it enters the right at 1:45 rium. 1:45 The superior vena cava is a large, valveless venous channel formed by the union 1:50 of the 1:51 brachochophallic veins. 1:53 The brachochophallic veins are formed at the confluence of the subclavian and 1:58 internal 1:58 jugular vein. 2:00 The convergence of the right subclavian and internal jugular vein occur behind 2:05 the sternoclavicular 2:07 joint drawn in gray here. 2:11 The clinical anatomy to consider or surrounding the superior vena cava is the 2:17 superior vena 2:18 cava obstruction. 2:20 Sometimes with an obstructed superior vena cava means they are unable to drain 2:26 blood efficiently 2:26 from the upper limbs, neck and face into the heart. 2:30 As a result, they can present with the following signs and symptoms, such as 2:35 headache, swollen 2:36 face, cyanosis, dyspnea. 2:40 These symptoms and signs are typically due to a long mass, partially occluding 2:46 or compressing 2:47 against the superior vena cava. 2:51 When the superior vena cava is partially obstructed, obviously there is an 2:55 obstruction 2:55 in blood flow. 2:57 As a result of this disruption in blood flow, collateral circulation occurs. 3:03 The right arm can become swollen. 3:06 In serious cases, cerebral edema can result. 3:12 The superior vena cava obstruction can cause a plethora of the face and neck. 3:17 When the arms are particularly raised above the heads, this will increase the 3:22 impedance 3:22 of the superior vena cava drainage due to the mass, for example, pushing 3:27 against it. 3:28 When the superior vena cava drainage becomes more obstructed, the heart 3:32 obviously beats 3:33 faster to compensate, so you get palpitations. 3:38 The etiology of superior vena cava obstruction, as mentioned, includes lung 3:42 cancer, especially 3:44 non-small cell lung carcinomas, lymphoma, specifically, specifically, mediast 3:51 inal lymph 3:52 node enlarging, characteristic of Hodgkin's lymphoma. 3:58 Another cause is thrombosis of the superior vena cava. 4:01 The rates of thrombosis have increased, especially due to the increasing number 4:06 of 4:06 intravascular devices running through this area, including pacemakers, for 4:11 example, picklines. 4:12 The diagnosis of superior vena cava obstruction is typically clinical, 4:16 supported by imaging, 4:18 such as chest x-ray and a CT of the chest. 4:23 Here is an example of a chest x-ray of someone who presented with facial and 4:27 upper limb swelling. 4:30 Unintentional weight loss and dyspnea. 4:32 On the chest x-ray, you can make out the superior vena cava draining into the 4:37 right atrium. 4:38 You also notice an irregular lesion in the upper right lobe compressing against 4:43 the superior 4:44 vena cava, which explains this person's symptoms. 4:47 With the CT chest, you are able to outline the superior vena cava and the 4:52 irregular mass 4:53 in more detail. 4:55 This person likely has lung cancer causing superior vena cava obstruction. 5:01 The management of superior vena cava obstruction can be divided into the acute 5:05 management, 5:06 which is where patients may be symptomatic, and then you have the definitive 5:10 management, 5:11 which typically involves some sort of procedure. 5:14 The acute management is sitting the person up and giving them oxygen. 5:18 Next, a methosone to reduce edema and swelling in the area also helps. 5:23 The definitive management is a stent inserted to open up the superior vena cava 5:28 vessel, allowing 5:29 better return to the right atrium. 5:33 Radiotherapy is used to reduce the size of a tuber or mass, if there is any, 5:39 and this 5:39 is for symptomatic relief. 5:42 If it is a suspected malignancy that is causing the superior vena cava 5:46 obstruction, a biopsy 5:47 will be taken to confirm the type of cancer, and this is obviously followed by 5:51 chemotherapy. 5:52 One of the main tributaries of the superior vena cava is the azigos vein I 5:56 mentioned earlier. 5:58 The azigos vein forms the azigos hemizygosystem. 6:02 This system has two main functions. 6:04 The first, the azigos hemizygosystem provides an important collateral pathway 6:10 in cases of 6:12 inferior vena cava or superior vena cava obstruction. 6:16 The second main function is that it drains venous blood from the thoracic wall 6:20 and the 6:21 upper lumbar regions. 6:24 Here is the 12 thoracic vertebrae's, the heart. 6:28 The sternal angle is an imaginary line that crosses the T4 to tell T5 vertebral 6:35 level. 6:36 Here is the superior vena cava which enters the right atrium, the azigos vein 6:41 drains into 6:42 the superior vena cava. 6:48 The azigos vein is a connection between the superior vena cava and the inferior 6:53 vena cava 6:54 / right renal vein. 6:59 The high limb of the kidney is situated at another imaginary line called the 7:04 transpyloric 7:05 plane which is the lumbar 1 vertebral level. 7:09 The azigos vein starts at the T12 to L2 vertebral level typically and then 7:17 drains up 7:18 The azigos vein ascends on the right side up to the level of T4, then passes 7:27 anterior 7:28 to form an arc joining the superior vena cava. 7:34 This is the azigos arc. 7:37 The azigos vein drains the right second to 11th right intercostal veins. 7:45 The azigos vein is the continuation of the right ascending lumbar vein. 7:56 The azigos hemizygosystem forms a H-shaped network in the posterior mediastinum 8:03 , anterior 8:04 to the body of the thoracic vertebrae. 8:07 The azigos vein gives the entire right arm of the H. The hemizygos gives the 8:12 left lower 8:13 and there's also this little accessory hemizygos vein which gives the left 8:19 upper segment 8:20 of the H. 8:22 The accessory hemizygos vein has more variations than the azigos and hemizygos 8:28 veins. 8:29 Usually it drains the second to seventh intercostal veins. 8:33 The accessory hemizygos vein joins and drains into the azigos vein at about the 8:38 T8 vertebral 8:40 level. 8:41 The hemizygos vein starts similar to the azigos vein but on the left side of 8:46 the vertebral 8:47 column at T12 to L2 vertebral level. 8:52 The hemizygos crosses over and joins with the azigos at about the T8 vertebral 8:58 level. 8:59 Major tributaries of the hemizygos are the left posterior 8th to 11th intercost 9:06 al veins. 9:07 It can also connect to the left renal vein and is the continuation of the left 9:14 ascending 9:14 lumbovane from the iliac vein. 9:18 I hope you enjoyed this video on superior vena cava and azigos hemizygos vein, 9:25 clinical 9:26 anatomy. 9:27 Thank you for watching.
