793 - Beyond the Standard IVC: Pearls and Pitfalls for Filter Placement in Anatomic Variants

Learning Objectives: (1) Identify IVC anatomical variants and their embryological origins relevant to filter placement. (2) Understand variant-specific technical strategies for effective filter deployment. (3) Present a pictorial review of an IVC filter deployment in a duplicated IVC.

Background: The inferior vena cava (IVC) is formed at the junction of the common iliac veins in 96-97% of patients and drains into the right atrium, receiving tributaries from multiple veins {1}. A small percentage, however, exhibit anatomical deviations that significantly alter the technical approach to IVC filter placement. Many of these variants are asymptomatic and thus, failure to identify them can result in malposition, ineffective caval protection, embolization or IVC thrombosis. Recognition of IVC variants reinforces the need for careful, evidence based approach to filter placement.

Clinical Findings/Procedure Details: The most common anatomical variants of the IVC include mega-IVC, duplication, left-sided IVC, retro-aortic/circum-aortic left renal vein, and azygos/hemiazygos continuation, typically arising from persistence or regression failure of the supracardinal and subcardinal veins. The right internal jugular vein is the most common approach due to lower risk of tilt, though femoral veins are commonly used, and preferred during intravascular ultrasound-guided deployment. Deployment techniques are adjusted based on the variant: mega-IVCs may require bilateral iliac vein filters, duplicated IVC may require bilateral filters, circumaortic renal veins require positioning below the lowest renal vein, and suprarenal placement is considered when the infrarenal segment is unsuitable. Multi-detector computed tomography (MDCT) is well-suited for detecting immediate and late abnormalities. A representative case of bilateral filter deployment in a duplicated IVC will be illustrated. With careful planning, technical success is high, complications are low, and pulmonary embolism is effectively prevented.

Conclusion and/or Teaching Points: Understanding IVC anatomical variants is essential for interventionalists, allowing filter deployment to be tailored to the specific anatomy, ensuring safe and effective placement, high technical success, low complication rates, and optimal caval protection.