Respiratory changes in the length of the vena cava: implications for optimal positioning of inferior vena cava filter.

BACKGROUND

A transjugular temporary inferior vena cava (IVC) filter may change position with respiration, leading to serious complications such as filter migration to the right atrium (RA) or renal veins. We therefore evaluated respiratory changes in the length and diameter of the vena cava using MRI.

METHODS

In 20 volunteers, the length and diameter of the vascular segments from the right brachiocephalic vein (BCV) to infrarenal IVC were measured with MRI.

RESULTS

The mean lengths in mm of the BCV, superior vena cava (SVC), RA, suprarenal IVC, and infrarenal IVC during expiration vs. inspiration were 32.7±7.3 vs. 43.0±8.0, 44.6±9.6 vs. 58.5±12.7, 77.8±12.4 vs. 98.9±10.0, 104.6±19.1 vs. 85.0±14.9, and 49.0±8.7 vs. 33.8±9.7, respectively (all P<0.01). The distances in mm from the BCV to RA, upper confluence of the renal vein, and lower confluence of the renal vein during expiration vs. inspiration were 155.2±18.5 vs. 200.4±20.1, 259.7±28.5 vs. 285.4±23.5, and 308.7±31.6 vs. 319.1±24.9, respectively (all P<0.01). The diameter of the SVC decreased with inspiration, while that of the infrarenal IVC increased. The diameter of the suprarenal IVC did not change significantly with respiration.

CONCLUSIONS

The distances from the BCV to RA, upper, and lower confluences of the renal vein were 4.5, 2.6, and 1.0 cm longer on average at inspiration than at expiration, respectively. These respiratory-associated changes of the vena cava length should be taken into account when deploying an IVC filter to prevent its migration.