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Published on: June 21, 2016
Echocardiographic and radiographic aortic remodeling in cats with confirmed systemic hypertension
Merrilee Holland1, Erik H Hofmeister1, Caitlin Kupiec2
1Auburn University College of Veterinary Medicine, Auburn University, Auburn, Alabama, USA.
Insights
Systemic hypertension in cats can cause aortic changes, including larger aortic diameters and cusp lengths. Radiographic analysis revealed that aortic knob formation is a potential indicator of this target organ damage in felines.
Area of Science:
- Veterinary Cardiology
- Feline Medicine
- Diagnostic Imaging
Background:
- Systemic hypertension (SH) in cats is often secondary to other conditions like renal disease or hyperthyroidism.
- Target organ damage (TOD) from SH, such as aortic dilation, is well-documented in humans but not extensively in cats.
- Previous studies have not reported aortic knob formation as a sign of SH in feline patients.
Purpose of the Study:
- To compare echocardiographic aortic changes between cats with systemic hypertension (SH) and cats with normal blood pressure (NBP).
- To assess heart size and aortic shape/size using thoracic radiographs in cats with SH and NBP.
- To identify potential radiographic indicators of TOD in feline SH.
Main Methods:
- Retrospective case-controlled study involving 76 cats with SH and 76 cats with NBP.
- Echocardiographic measurements of aortic diameter and cusp length were compared between groups.
- Blinded reviewers evaluated thoracic radiographs for heart size (Vertebral Heart Score - VHS) and aortic knob formation.
- Statistical analysis included a two-way unpaired t-test with significance set at alpha = 0.01.
Main Results:
- Cats with SH exhibited significantly larger mean aortic diameter and cusp length compared to NBP cats.
- Aortic cusp size alterations were noted in 62 of 76 cats with SH (50/62 ≥ 1.0 mm).
- Radiographic analysis showed an Area Under the Curve (AUC) of 0.74 for aortic knob formation as an indicator of SH, with a sensitivity of 81% and specificity of 69%.
Conclusions:
- Systemic hypertension in cats is associated with significant echocardiographic changes in the aorta, including dilation.
- Aortic knob formation on radiographs may serve as a useful, non-invasive indicator of target organ damage in feline systemic hypertension.
- Further research is warranted to fully elucidate the diagnostic and prognostic implications of these aortic changes in cats.
Abstract:
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%.
