The nutcracker phenomenon of the left renal vein (NCP) – improved understanding as “midline congestion syndrome“ by dynamic color-Doppler sonographic tissue perfusion measurement

Objective: To describe quantitatively hemodynamic sequelae of the nutcracker phenomenon of the left renal vein and to observe the change of symptoms after therapeutic relief of perfusion decline.

Patients and methods: 16 patients (4–18 years; mean 12,8 years) with a nutcracker phenomenon of the left renal vein and a variety of long lasting complaints including migraine, flank pain, dysuria, pollakisuria, micturition disturbances, dyspareunia, back pain and abdominal pain were included.

Renal cortical tissue perfusion was measured by means of the PixelFlux-technique (www.chameleon-software.de). This method quantifies sonographically perfusion signals of color Doppler sonographic videos from a standardized region of interest in a heartbeat-triggered manner.

Results: All patients demonstrated engorgement of midline pelvic or vertebral collaterals. Left renal vein compression resulted in a significant drop of cortical perfusion in the left kidney before therapy (left/right ratio: 0,79). After a treatment with acetylsalicylic acid a complete relief of so far long lasting therapy-resistant symptoms was achieved. Simultaneously the left/right renal perfusion ratio increased significantly to 1,24 (p=0,021).

Conclusion: NCP is a clinically relevant entity. Complaints may be associated with the congestion of collateral veins in midline organs. Thereby so far unrelated symptoms may be linked by a novel pathophysiologic concept of “midline congestion“. The effects of this left renal congestion and its alleviation by medical therapy can be measured now with the PixelFlux-technique.

An improvement of left renal perfusion was associated with disappearance of pain and functional derangement in the affected midline organs.