Use of retrievable filters in alternative common iliac vein location in high-risk surgical patients

Developmental or Procedural Vena Cava Interruption and Venous Thromboembolism: A Review

The inferior vena cava (IVC) and superior vena cava are the main conduits of the systemic venous circulation into the right atrium. Developmental or procedural interruptions of vena cava might predispose to stasis and deep vein thrombosis (DVT) distal to the anomaly and may impact the subsequent rate of pulmonary embolism (PE). This study aimed to review the various etiologies of developmental or procedural vena cava interruption and their impact on venous thromboembolism. A systematic search was performed in PubMed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines per each clinical question. For management questions with no high-quality evidence and no mutual agreements between authors, Delphi methods were used. IVC agenesis is the most common form of congenital vena cava interruption, is associated with an increased risk of DVT, and should be suspected in young patients with unexpected extensive bilateral DVT. Surgical techniques for vena cava interruption (ligation, clipping, and plication) to prevent PE have been largely abandoned due to short-term procedural risks and long-term complications, although survivors of prior procedures are occasionally encountered. Vena cava filters are now the most commonly used method of procedural interruption, frequently placed in the infrarenal IVC. The most agreed-upon indication for vena cava filters is for patients with acute venous thromboembolism and coexisting contraindications to anticoagulation. Familiarity with different forms of vena cava interruption and their local and systemic adverse effects is important to minimize complications and thrombotic events.

Placement and retrieval of bilateral iliac vein filters in patients with mega cava

Temporary interruption of the inferior vena cava is the recommended treatment to prevent pulmonary embolism in patients with venous thromboembolism (VTE) and active contraindications for therapeutic anticoagulation. In patients with mega cava (diameter >30 mm), temporary inferior vena cava filters are contraindicated. In the present report, we have described the successful placement and retrieval of bilateral iliac vein filters in two patients with VTE, mega cava, and active contraindications for therapeutic anticoagulation. At the last follow-up, both patients had recovered without recurrent VTE and had had all filters successfully retrieved without complications.

Cavographic vs. cross-sectional measurement of the inferior vena cava diameter before filter placement: are we routinely oversizing?

OBJECTIVE

A megacava (vena cava with a diameter of 28 mm or greater) requires a particular filter to avoid migration. However, caval morphologies are variable. As the inferior vena cava (IVC) usually adopts a circular geometry after a filter is inserted, this study aims (a) to classify caval geometry and orientation; (b) to compare discrepancy between anterioposterior projective diameter (PD) and circumference-based calculated diameter (CD) measurements on cross-sectional computed tomography (CT) images; (c) if a discrepancy exists, determine how often it can affect IVC filter selection.

METHODS

A total of 1503 patients were retrospectively reviewed. Caval morphology was classified. PD and CD were measured at infrarenal IVC. Differences between the PD and CD were assessed by the Wilcoxon signed-rank test or paired t test (if appropriate). The scatterplot of PD vs. CD was used to show whether one is consistently larger than the other.

RESULTS

The PD was significantly larger than the CD (22.3 ± 3.5 vs. 20.4 ± 2.8, p < 0.001). The caval morphologies were divided into five types. Type 1 was oval IVC oriented left-anterior-oblique to the horizontal line with an angle (n = 999, 66.5%), type 2 was round IVC (n = 49, 3.3%), type 3 was oval IVC with a vertical long axis (n = 8, 0.5%), type 4 was oval IVC with a horizontal long axis (n = 75, 5.0%), and type 5 was irregularly shaped IVC (n = 372, 24.7%).

CONCLUSION

Patients with round IVC are rare. Measurement of CD may be better to assess maximum IVC diameter compared with PD for the purpose of IVC filter placement.

KEY POINTS

• Five types of IVC orientation are described in this paper: type 1 (n = 999, 66.5%), type 2 (n = 49, 3.3%), type 3 (n = 8, 0.5%), type 4 (n = 75, 5.0%), and type 5 (n = 372, 24.7%). • The incidence of megacava (vena cava with a diameter of 28 mm or greater) measured on anterioposterior projective imaging may be overestimated. • As an IVC will adopt a circular geometry following filter placement, circumference-based calculated diameter may be an appropriate approach for caval size determination.

Surgical removal of venous filter and snare complex in a patient with solitary left pelvic kidney

Anticoagulation is used to prevent thromboembolism; inferior vena cava filters are an alternative in patients with contraindications to anticoagulation. Although it is safe and effective, there are recognized complications related to inferior vena cava filter placement. We describe the case of a young man with congenital solitary left pelvic kidney who required unique filter placement to suit the anatomy and surgical removal after entrapment of the filter-snare complex in the left internal iliac vein. Patients may also acquire solitary pelvic kidneys after renal transplantation. This anatomy poses unique challenges to venous filter placement and requires tailored management.

Influence of breathing movements and Valsalva maneuver on vena caval dynamics

AIM: To study changes produced within the inferior vena cava (IVC) during respiratory movements and identify their possible clinical implications.

METHODS: This study included 100 patients (46 women; 54 men) over 18 years of age who required an abdominal computed tomography (CT) and central venous access. IVC cross-sectional areas were measured on CT scans at three levels, suprarenal (SR), juxtarenal (JR) and infrarenal (IR), during neutral breathing and again during the Valsalva maneuver. All patients were instructed on how to perform a correct Valsalva maneuver. In order to reduce the total radiation dose in our patients, low-dose CT protocols were used in all patients. The venous blood pressure (systolic, diastolic and mean) was invasively measured at the same three levels with neutral breathing and the Valsalva maneuver during venous port implantation. From CT scans, three-dimensional models of the IVC were constructed and a collapsibility index was calculated for each patient. These data were then correlated with venous pressures and cross-sectional areas.

RESULTS: The mean patient age was 51.64 ± 12.01 years. The areas of the ellipse in neutral breathing were 394.49 ± 85.83 (SR), 380.10 ± 74.55 (JR), and 342.72 ± 49.77 mm² (IR), and 87.46 ± 18.35 (SR), 92.64 ± 15.36 (JR) and 70.05 ± 9.64 mm² (IR) during the Valsalva (Ps < 0.001). There was a correlation between areas in neutral breathing and in the Valsalva maneuver (P < 0.05 in all areas). Large areas decreased more than smaller areas. The collapsibility indices were 0.49 ± 0.06 (SR), 0.50 ± 0.04 (JR) and 0.50 ± 0.04 (IR), with no significant differences in any region. Reconstructed three-dimensional models showed a flattening of the IVC during Valsalva, adopting an ellipsoid cross-sectional shape. The mean pressures with neutral breathing were 9.44 ± 1.78 (SR), 9.40 ± 1.44 (JR) and 8.84 ± 1.03 mmHg (IR), and 81.08 ± 21.82 (SR), 79.88 ± 19.01 (JR) and 74.04 ± 16.56 mmHg (IR) during Valsalva (Ps < 0.001). There was a negative correlation between cross-sectional caval area and venous blood pressure, but this was not statistically significant in any of the cases. There was a significant correlation between diastolic and mean pressures measured during neutral breathing and in Valsalva.

CONCLUSION: Respiratory movements have a major influence on IVC dynamics. The increase in intracaval pressure during Valsalva results in a significant decrease in the IVC cross-sectional area.