A cross-sectional imaging study to identify organs at risk of thermal injury during renal artery sympathetic denervation

BACKGROUND: The technology used to perform catheter-based renal artery sympathetic denervation has evolved: catheters can now access arteries as small as 3mm in diameter and create ablation zones of up to 10mm in depth. Recent evidence suggests that the procedure may be more effective if a more thorough ablation strategy is employed. Limited data are available regarding inadvertent soft tissue thermal injury during such procedures.  We used computed tomography (CT) to identify structures lying within the expected thermal ablation field or the 'at risk zone' (ARZ). METHODS: 63 consecutive CT aortograms were reviewed, yielding 100 renal arteries anatomically eligible for treatment. Structures lying within a predefined ARZ (within 10mm of the renal artery wall) were recorded. RESULTS: The 63 subjects had a mean age of 74.6years, 48% were males and 88% had hypertension.  The inferior vena cava and renal veins were in the ARZ in all cases.  Psoas muscles and small bowel were within the ARZ in at least a fifth of the kidneys. Other structures found in the ARZ included the liver, pancreas, adrenal glands and diaphragm. CONCLUSIONS: This study describes the variable anatomical relationship between renal arteries and important abdominal structures that may be exposed to thermal energy during modern denervation procedures.  The consequence of delivering such thermal energy to these structures is unknown but clinicians should be alert to the presenting symptoms if these structures are damaged. CT may have a pre-procedure role in assessing this risk.