Introduction
Inferior vena cava syndrome (IVCS) is a condition in which an individual presents with varied signs and symptoms when blood flow through the inferior vena cava (IVC) is inhibited. It could occur either due to an obstruction within the blood vessel or compression of the inferior vena cava (IVC).
What Is Inferior Vena Cava (IVC)?
The inferior vena cava is also referred to as the posterior vena cava. It is the human body's largest vein (blood vessel). It is a thin-walled blood vessel with the largest diameter in the venous system. Veins usually have valves to prevent the backflow of blood. However, the inferior vena cava (IVC), similar to a few veins of the body, does not have any valves. The pressure difference created during normal respiration drives the forward blood flow to the heart.
The inferior vena cava (IVC) originates from the junction of the right and left common iliac veins (at the level of L5 or fifth lumbar spine vertebrae) and runs on the right side of the vertebral column. In simple terms, it implies that it is located on the right side of the aorta, posterior to the abdominal wall.
What Is the Function of the Inferior Vena Cava (IVC)?
The inferior vena cava is responsible for transporting venous blood (de-oxygenated or oxygen-deficient blood) to the right atrium heart from the lower extremities (that includes the feet, legs, thighs, pelvis, and abdomen). The diaphragm (a broad-dome-shaped muscle present underneath the lungs that facilitates breathing) contracts and creates a negative pressure in the chest cavity. This negative pressure gradient helps the lung to fill up with air while drawing venous (do-oxygenated blood) from the abdominal inferior vena cava (IVC) into the thoracic inferior vena cava (IVC) and ultimately drains into the right atrium.
What Are the Causes of Inferior Vena Cava Syndrome (IVCS)?
There are several reasons for the impaired blood flow within the inferior vena cava (IVC), which is the primary cause of inferior vena cava syndrome (IVCS). Causes of obstruction of the inferior vena cava (IVC) are:
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Thrombosis of the Inferior Vena Cava (IVC): A thrombus is a blood clot that can occur within a vein or artery and can block a blood vessel entirely or partially. It occurs when the blood flow within the blood vessels is too slow, or clotting occurs when it is not needed. Thrombosis can occur due to congenital causes or can be acquired. A common type of thrombosis is a blood clot in the vein of the leg called deep vein thrombosis. When the blood flow is obstructed, the blood cannot be pumped through the vein, causing increased pressure in the deeper veins and capillaries (smaller and finer blood vessels), eventually leading to edema of the legs (red and swollen legs).
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Congenital Syndromes Such as Budd- Chiari Syndrome and May-Thurner Syndrome: These are congenital malformations (malformations present since birth) characteristic of varied presentations of blood vessels in the iliocaval region, leading to clot formation or phlebitis (inflammation of the vein).
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Iatrogenic Causes: Iatrogenic (unintentionally occurs as a result of medical treatment or diagnostic procedures) processes such as using venous catheters or filter placements within the inferior vena cava can make an individual susceptible to thrombus formation. Studies also show an association between the formation of a thrombus and the use of Broviac catheters in pediatric patients for intravenous therapy.
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Hepatic Vena Cava Syndrome (HVCS): Also known as membranous obstruction of the inferior vena cava, it is a medical condition induced by bacterial infection due to poor hygiene. It leads to thrombophlebitis of the hepatic veins, obstructing blood flow within the inferior vena cava's outflow tract.
Causes of compression of the inferior vena cava (IVC) are:
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Tumors or Malignancies: Malignancies such as renal cell carcinoma, gastric adenocarcinoma, pancreatic adenocarcinoma, and malignancies of any organ near the inferior vena cava (IVC) lead to its compression. Once the inferior vena cava (IVC) gets compressed, the blood flow is inhibited due to the obstruction in the blood flow from the periphery to the right atrium.
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Pregnancy: Occasionally, pregnant women can have a distended uterus obstructing blood flow within the inferior vena cava (IVC). Once the obstruction occurs, it leads to the pooling of deoxygenated blood or venous congestion.
What Are the Signs and Symptoms Elicited by Inferior Vena Cava Syndrome (IVCS)?
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Hypotension (decreased blood pressure).
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Tachycardia (rapid heartbeats).
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Arrhythmias (irregular heartbeats).
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Diaphoresis (unusual perspiration or sweating).
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Tachypnea (fast-shallow breathing).
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Exertional dyspnea (shortness of breath, especially on exertion or increased physical activity).
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Edema in the lower extremities (swelling in the lower limbs).
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Elevated levels of liver enzymes.
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Altered mental status.
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Nausea.
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Headache.
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Malaise (a general feeling of uneasiness or discomfort).
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Fatigue (unusual tiredness).
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Cold extremities.
How Is Inferior Vena Cava Syndrome (IVCS) Diagnosed?
A non-invasive diagnostic procedure called duplex ultrasound assesses blood flow through the arteries and veins (blood vessels). It uses high-frequency sound waves to examine the anatomy of the veins in the lower limbs and the blood flow rate. The integration of two modes of ultrasound- doppler and B-mode of ultrasonography is referred to as duplex. The transducer's doppler probe measures the blood flow direction and speed within the blood vessel. This imaging test provides information that aids in developing a suitable treatment plan.
What Is the Treatment for Inferior Vena Cava Syndrome (IVCS)?
The etiology of the lesion determines the treatment plan and is then tailored as per the patient's overall condition. If the lesion is thrombotic, treatment involves breaking down the clot immediately. A thrombotic lesion, if not treated, can propagate and lead to pulmonary embolism. The physician may also prescribe anticoagulants to facilitate the breakdown of the thrombus. Due to their high invasiveness, surgical procedures like thrombectomy, bypass, reconstruction or replacement, and ligation are only done as a last resort. If the lesions occur due to non-thrombotic lesions, such as malignancy, the treatment is tailored to manage the primary cause of compression of the inferior vena cava (IVC). Physical maneuvers can help when pregnancy causes mild compressions of the inferior vena cava (IVC).
What Complications Are Associated With Inferior Vena Cava Syndrome (IVCS)?
If not treated promptly, inferior vena cava syndrome can lead to
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Pulmonary embolism.
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Chronic venous insufficiency.
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Post thrombotic syndrome.
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Cardiac arrest.
Conclusion
The inferior vena cava syndrome (IVCS) diagnosis is one of exclusion rather than the primary diagnosis. It mimics several etiologies, and its signs and symptoms can be mistaken for those of other severe ailments. Therefore, an early diagnosis can reduce morbidity and mortality significantly. A comprehensive history, physical examination, and imaging are essential for diagnosing inferior vena cava syndrome (IVCS).
