Superior vena cava syndrome pathophysiology
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Maria Fernanda Villarreal, M.D. [2]
Overview
Superior vena cava syndrome arises from the obstruction of venous blood drainage of the superior vena cava, which is normally involved in the major blood flow return from head, neck, upper extremities, and upper thorax to the heart. Superior vena cava syndrome is a complication of a partial or complete obstruction due to malignant causes (60%) or benign causes (20%). This syndrome consists on the invasion of the venous wall associated with intravascular thrombosis, enlarged nodes, enlarged ascending aorta or by extrinsic pressure of a tumor mass against the thin-walled superior vena cava which leads to the development of superior vena cava syndrome. Superior vena cava syndrome is associated with a number of conditions that include malignant tumors, tuberculosis, histoplasmosis, and syphilis.[1]
Pathogenesis
The superior vena cava is the major blood vessel for the drainage of the upper body (head, neck, upper extremities, and upper thorax). Extrinsic compression of the superior vena cava by a mediastinal tumor is possible because it has a low intravascular pressure. In addition, the superior vena cava is also surrounded by rigid structures, so it is relatively easy to compress. Moreover, the superior vena cava is thin-walled, and the blood flowing therein is under low pressure. Therefore, when the nodes or ascending aorta enlarge, the superior vena cava is compressed, blood flow slows, and complete occlusion may occur.[2]
Knowledge of the anatomy of the superior vena cava and its relationship to the surrounding lymph nodes is essential to understanding the development of the syndrome. The superior vena cava is formed by the junction of the left and right brachiocephalic veins in the mid third of the mediastinum. It extends caudally for 6 to 8 cm, coursing anterior to the right mainstem bronchus and terminating in the superior right atrium, and extends anteriorly to the right mainstem bronchus. The superior vena cava is joined posteriorly by the azygos vein as it loops over the right mainstem bronchus and lies posterior to and to the right of the ascending aorta. The mediastinal parietal pleura is lateral to the superior vena cava, creating a confined space, and the superior vena cava is adjacent to the right paratracheal, azygous, right hilar, and subcarinal lymph node groups.[3]
Associated Conditions
- Superior vena cava syndrome is associated with a number of conditions that include:
- Malignancy[4]
- Lymph node metastasis
- Non–small cell lung cancer
- Small cell lung cancer
- Lymphoma
- Metastatic lesions (most commonly from breast and testicular cancers)
- Infections
- Iatrogenic intravascular devices
- Thyroid goiter
- Thrombosis
- Pericardial constriction
- Idiopathic sclerosing mediastinitis
- Aortic aneurysm
- Malignancy[4]
Gross Pathology
On gross pathology, there are no characteristic findings of superior vena syndrome.
Microscopic Pathology
On microscopic pathology, there are no characteristic findings of superior vena syndrome.
References
- ↑ Menon A, Gupta A (2015). "Superior vena cava syndrome". Indian J. Med. Res. 142 (3): 350. doi:10.4103/0971-5916.166606. PMC 4669875. PMID 26458355.
- ↑ Wilson LD, Detterbeck FC, Yahalom J (2007). "Clinical practice. Superior vena cava syndrome with malignant causes". N. Engl. J. Med. 356 (18): 1862–9. doi:10.1056/NEJMcp067190. PMID 17476012.
- ↑ Uberoi R (2006). "Quality assurance guidelines for superior vena cava stenting in malignant disease". Cardiovasc Intervent Radiol. 29 (3): 319–22. doi:10.1007/s00270-005-0284-9. PMID 16502166.
- ↑ National Cancer Institute. http://www.cancer.gov/about-cancer/treatment/side-effects/cardiopulmonary-hp-pdq#link/_102_toc Accessed on January,11 2016