Superior vena cava (SVC) is one of the most important veins in the body. It is short but large in diameter and located in the superior mediastinum (anterior right). The name derived from the Latin word cadaver, which means hollow, due to the superior vena cava’s large pipe-like appearance.
The vein serves a very important function in the body, performing a central role in the cardiovascular system. It largely controls the input of blood towards the right atrium. The inferior and the superior vena cava retrogradely affected by hypertensive processes in the right section of the heart, including the pulmonary circulation.
The veins not built to withstand high pressures and can result in aneurysms, or even rupturing the wall of the superior vena cava.
Anatomy
The left and right brachiocephalic veins form the superior vena cava embryologically. The brachiocephalic veins are also known as the innominate veins which receive blood from certain parts of the head and the upper limbs.
The superior vena cava not divided by any valve to the right atrium. The right atrium conducts blood from the right atrial, while the ventricular contractions send blood into the internal jugular vein. The blood also conducted into the sternocleidomastoid muscle.
The superior vena cava begins from the lower area of the 1st right costal cartilage and descends vertically on the backside of 2nd and 3rd intercostal spaces. Then draining into the right atrium at the level of the 3rd costal cartilage. The fibrous pericardium covers the lower half, and the SVC pierces it at the 2nd costal cartilage.
The superior vena cava is one among the 2 large veins through which the blood is returned to the heart from the body.
The blood is circulated through the body systematically and deoxygenated blood is returned to the right atrium of the heart. This is done through either the superior vena cava, which takes blood from the upper body or the inferior vena cava, responsible for draining blood below.
Superior Vena Cava Function
The superior vena cava bears the responsibility of collecting the deoxygenated blood from the upper portion of the body and delivering it to the heart, from where it is sent to the lungs to be reoxygenated. It transfers blood to the heart from the head, neck, arms, organs within the chest cavity.
Tributaries of Superior Vena Cava
The tributaries of superior vena cava from the head and neck, the arms, and part of the chest join together to form its complete structure. Two layers of the dura mater hold the venous channels called venous sinuses.
These communicating vessels affect the venous drainage of the brain. Downward through the neck, the internal jugular vein forms the innominate veins at the level of the collarbone, as these continuations unite with the subclavian vein.
Through the union of its tributaries at the lower jaw or mandible, the external jugular vein formed. Its job is to conduct blood and other contents from the head and neck into the innominate vein of the same side.
Veins of the same arm tributaries from the subclavian which found in both deep and superficial locations. The majority of the deep veins in cross-connections and arranged in pairs.
Venous drainage of the hand completed by small interconnecting veins that come together to build the cephalic vein. This vein travels up the radial side of the forearm, while the basilic vein, courses up and receives blood from the forearm, hand, and arm.
Radial veins, the deep veins of the forearm, and their continuations are deep anastomosing veins of the hand and wrist.
A convergence of radial and ulnar veins at the elbow to form a branchial vein. It is then united with the basilic vein at the shoulder’s level to build the axillary vein. The axillary vein turns into the subclavian vein at the outer border of the first rib.
Superior Vena Cava Syndromes and Diseases
Superior Vena Cava Obstruction (SVCO)
Superior vena cava obstruction refers to semi or full obstruction of superior vena cava, often found in cancer cases. This usually includes metastatic cancer, lung cancer, or lymphoma. Clinically, an obstruction such as SVCO can lead to several medical complications such as enlarged veins of head and neck, chest pain, shortness of breath, cough, and difficulty swallowing.
This condition identified through a clinical test known as Pemberton’s sign. The test works through the sign, as the patient elevates both arms until they are in contact with the sides of the face. This determined after one minute of the activity and facial congestion and cyanosis show positive Pemberton’s sign. The SVCS usually a result of mass in the mediastinum.
Superior Vena Cava Syndrome (SVCS)
SVCS is commonly the result of obstruction of the superior vena cava. It manifests in patients with a malignant disease process, such as cancer within the thorax. It is a medical emergency and the patient requires immediate diagnostic evaluation and therapy.
Without a doubt, 90% of the SVCS cases caused by Cancer. Do you know?. The most common type of cancer that leads to SVCS is bronchogenic carcinoma. This includes lung carcinoma occurs of small cell and non-small cell. Others include lymphoblastic lymphomas, Burkitt’s lymphoma, pre-T-cell lineage acute lymphoblastic, and other different acute leukemias found in patients.
In brief, Edema of the arms and face, shortness of breath, cough, swollen collateral veins on the chest wall, stridor, and difficulty swallowing are among the characteristic symptoms. Neurological symptoms include reduced alertness. To identify SVCO, Pemberton’s sign used.
Various factors that come into play when treating the blockage of superior vena cava. They include the severity of the condition, the general health of the patient, preferential form of treatment, etc. These treatments include, but not limited to surgical intervention, stent placement, radiation therapy, thrombolysis, and chemotherapy.
A thorough medical analysis necessary for deriving an accurate diagnosis which will help decide the best form of treatment. Failure to do so can result in misunderstanding the patients’ condition and opting for the wrong treatment, which can be potentially fatal.
Superior Vena Cava Thrombosis
In general, Cancer patients with permanent indwelling CVCs usually have thrombosis. It occurs from a thrombus, after a long-term CVC. In adults, CVC related thrombus found overwhelmingly at 30%. Removal of the catheter, thrombolytics, or anticoagulants used to treat thrombosis patients.
A common side effect of permanent infusion catheter is thrombosis, which typically occurs in the SVC and subclavian vein. The formation of blood clots in Thrombosis results in Edema (swelling of affected areas).
These blood clots drastically increase the risk of pulmonary embolism and characterized by obstruction in the lungs. It must be noted that there is no proven correlation between systematic embolization into the cerebral circulation and Edema.
Superior Vena Cava Aneurysm
The majority of aneurysms arise from the SVC, which fusiform (“spindle-shaped”) aneurysms. Aneurysms that come from the mediastinal systemic veins are rare. That called a Venous aneurysm.
Such cases of aneurysms extremely rare: only 27 proven cases registered so far. Most of them traced back to SVC.
SVC aneurysms often discovered when looking into idiopathic, iatrogenic, and congenital causes of medical complications. The primary objectives of treatments are to eliminate the chances of thrombus formation and rupture. The treatment relies on surgical excision, monitored observation, prescribing injections of thrombin, and various medical management strategies.
Persistent Left Superior Vena Cava (PLSVC)
PLSCV usually starts during embryologic development, as a result of failure to involute in this stage. It is an embryonic remnant and a known variation of the thoracic venous system.
At this time, The complication is present in 0.3% of the entire population. It traced back to the embryonic remnant that did not succeed to involute.
The variation is classified as benign when in isolation. However, it forms a strong correlation with cardiac issues, e.g. atrioventricular and ventricular sept defects. It has high mortality as well as morbidity rate. The condition commonly diagnosed in patients suffering from congenital heart disorders.
The anomaly identified during an ultrasound procedure. A fetal echocardiogram is done to accurately identify whether the fetus has that condition or not. Excluding that, the condition most often goes unnoticed unless further checkup is needed for other reasons, which is usually after a lot of time has passed.
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