Systemic hypertension (SH) in cats may occur secondary to renal disease, hyperthyroidism, or idiopathic causes. Asymmetric dilation of the sinuses of Valsalva has been recognized in people with systemic hypertension as target organ damage (TOD). Aortic knob formation (lateral bowing of the aortic arch to proximal descending aorta on the posteroanterior/anteroposterior radiographic projection) is recognized as TOD in people due to SH. None of these changes have been reported in feline patients. The first objective of this retrospective case-controlled study was to compare echocardiographic changes in the aorta of 76 cats with systemic hypertension (SH) to those seen in 76 cats with normal blood pressure (NBP). Our second objective was to have blinded reviewers assess heart size and aortic shape and size from available thoracic radiographs of 49/76 cats with SH and 46/76 cats with NBP. A two-way unpaired t-test with significance set at alpha = 0.01 was used to evaluate aortic echocardiographic parameters. The mean of the aortic diameter and length of each aortic cusp was significantly larger in cats with SH than in cats with NBP. The aortic cusps were considered altered in size in 62 of 76 cats with SH, 12/62 ≥ with 0.5 mm, and 50/62 ≥ 1.0 mm. No significant difference in the vertebral heart score (VHS) was noted between groups. The aortic knob to lateral margin of the trachea in cats with SH had an area under the curve (AUC) of 0.74 (95% CI:0.61-0.87) with best cutoff of 1.12 cm with sensitivity of 81% and specificity of 69%.
Keywords: aortic dilatation; aortic knob; target organ damage.
© 2022 American College of Veterinary Radiology.