August 21, 2014

Renal Artery Variants in Patients with Normal Renal Function


3D volume rendered CT image shows a 2nd right renal artery (arrows) arising from the right common iliac artery

Facts

  • "Normal" renal arterial arrangement = single bilateral renal arteries with hilar segmental branching. This occurred in 46% of cases in a landmark angiographic report published in 1978
  • Normally, no intrarenal arterial anastomoses are present. Each artery represents an end artery -- interruption results in infarction of that segment
  • Variations include double renal arteries, triple renal arteries, pre-hilar segmental branching, fetal lobulation and exaggerated size difference (greater than 2 cm). 
  • Most common variations are multiple renal arteries followed by pre-hilar segmental branching


Knowledge of Renal Vascular Variations is Important For:

  • Renal transplantation
  • Renovascular hypertension
  • Vascular reconstruction for congenital and acquired lesions
  • Reconstructive surgery for abdominal aortic aneurysms
Our case: Double right renal artery with the smaller branch originating from the common iliac artery

Reference:
- Harrison, Jr., et al. Incidence of anatomical variants in renal vasculature in the presence of normal renal function. Ann Surg 1978;188:83-89.
- Ozkan U, et al. Renal artery origins and variations: angiographic evaluation of 855 consecutive patients. Diagn Interv Radiol 2006;12:183-6.

August 1, 2014

Vertebral Artery Hypoplasia

Curved reformat of the normal-caliber right vertebral artery showing all 4 segments of the artery. 
Curved reformat of the left vertebral artery shows diffuse, small caliber of the artery.

Facts:

  • Operational definitions are either 1) asymmetrical ratio of or greater than 1:1.7, or 2) discrepancy of greater than 2 mm diameter
  • Prevalence 2%-6% of population (from autopsy and angiographic series)
Clinical Relevance
  • Posterior circulation ischemia: hypoplasia leads to reduction of posterior circulation blood flow velocity therefore has a negative role in occlusion of major cerebral arteries
  • Migraine with aura and vestibular neuronitis: hypoplasia is believed to be associated with regional hypo perfusion and complex neurovascular consequences

Reference:
Chuang YM, Chan L, Wu HM, et al. The clinical relevance of vertebral artery hypoplasia. Acta Neurol Taiwan 2012;21:1-7.

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