CTA of the Abdomen for Uncontrolled Hypertension
The primary purpose of CTA of the abdomen in uncontrolled hypertension is to detect renal artery stenosis (RAS), which is a potentially reversible secondary cause of hypertension that may respond to revascularization. 1
Primary Diagnostic Target: Renal Artery Stenosis
CTA provides high spatial resolution imaging to identify hemodynamically significant renal artery stenosis, with sensitivity and specificity approaching 98-99% for detecting stenoses greater than 50%. 2, 3
The prevalence of renal artery stenosis among hypertensive patients is approximately 4.3% in chronic kidney disease populations, though it can be as high as 19.2% in hypertensive patients with concurrent coronary artery disease. 1, 4
CTA is particularly indicated when there is high clinical suspicion for renovascular hypertension, such as in patients with resistant hypertension despite multiple medications, sudden onset or worsening of previously controlled hypertension, or hypertension in younger patients (especially women with fibromuscular dysplasia). 1, 5
Anatomic Detail and Pre-Intervention Planning
CTA provides detailed anatomic depiction of the renal arteries and abdominal aorta before potential percutaneous angiography or surgical intervention. 1
The volumetric acquisition enables extensive image postprocessing, including multiplanar reformatted and maximum-intensity projection images to create an arterial roadmap for treatment planning. 1
CTA can visualize collateral vessels and arteries distal to occlusions that may not appear on conventional catheter angiography. 1
Detection of Other Vascular Pathologies
CTA can identify other vascular causes of secondary hypertension, including renal artery thrombosis, arterial injury, pseudoaneurysms, and arteriovenous fistulas. 1, 6
The abdominal component allows simultaneous evaluation of the abdominal aorta and upper abdominal organs for additional pathology. 1
Important Clinical Caveats
The risk-benefit ratio must be carefully evaluated in patients with renal impairment, as contrast administration carries nephrotoxicity risk. 1, 7
When CTA is necessary despite renal impairment, use the lowest dose of contrast needed for a diagnostic study and ensure adequate volume expansion. 1, 7
Heavily calcified vessels can limit interpretation of CTA, particularly in elderly patients, diabetics, and those on dialysis, though dual-energy CTA can reduce blooming artifacts. 1
CTA is typically considered after initial ultrasound evaluation is unremarkable or indeterminate, following a stepwise diagnostic approach. 1
Arteriography remains reserved for intervention rather than initial diagnosis, with CTA serving as the primary noninvasive diagnostic tool. 1