Original article
Quantitative assessment of aortic sclerosis using ultrasonic backscatter

https://doi.org/10.1016/j.echo.2004.06.012Get rights and content

Abstract

Background

The development of therapeutic interventions to prevent progressive valve damage is more likely to limit the progression of structural damage to the aortic valve with normal function (aortic sclerosis [ASC]) than clinically apparent aortic stenosis. Currently, the ability to appreciate the progression of ASC is compromised by the subjective and qualitative evaluation of sclerosis severity.

Methods

We sought to reveal whether the intensity of ultrasonic backscatter could be used to quantify sclerosis severity in 26 patients with ASC and 23 healthy young adults. Images of the aortic valve were obtained in the parasternal long-axis view and saved in raw data format. Six square-shaped 11 × 11 pixel regions of interest were placed on the anterior and posterior leaflets, and calibrated backscatter values were obtained by subtracting the regions of interest in the blood pool from the averaged backscatter values obtained from the leaflets.

Results

Mean ultrasonic backscatter values for sclerotic valves exceeded the results in normal valve tissue (16.3 ± 4.4 dB vs 9.8 ± 3.3 dB, P < .0001). Backscatter values were greater (22.0 ± 3.5 dB) in a group of 6 patients with aortic stenosis. Within the sclerosis group, the magnitude of backscatter was directly correlated (P < .05) with a subjective sclerosis score, and with transvalvular pressure gradient. Mean reproducibility was 2.4 ± 1.8 dB (SD) between observers, and 2.3 ± 1.7 dB (SD) between examinations.

Conclusion

Measurement of backscatter from the valve leaflets of patients with ASC may be a feasible means of following the progression and treatment response of aortic sclerosis.

Section snippets

Patients

The study population consisted of 26 consecutive patients with ASC (14 women, mean age 76 years, range 57-91 years), 6 patients with AS (3 women, mean age 79 years, range 69-89 years) who were identified while being referred for nonemergency echocardiographic evaluation, and a control group of 23 healthy volunteers (11 women, mean age 30 years, range 21-39 years), none of whom had left ventricular (LV) dysfunction, valvular heart disease, or thickening of the aortic valves detected by

Patient characteristics

Table 1 summarizes the clinical characteristics of patients with ASC. Many of the patients with ASC had multiple coronary risk factors for ischemic heart disease (85%). Approximately 50% of patients had known symptomatic ischemic heart disease. There were 10 patients with significant renal dysfunction (serum creatinine > 0.12 mmol/L) and 4 patients with mild anemia (hemoglobin < 115 g/L). There was no significant correlation between backscatter of blood pool and hemoglobin concentrations.

Aortic valve findings

Discussion

The results of the study indicate that: (1) the mean levels of ultrasonic backscatter in patients with ASC are approximately 60% greater than in healthy young adults; (2) ultrasonic backscatter scores in patients with ASC are directly correlated with subjective scoring of sclerosis and with transvalvular pressure gradients in patients with mild-moderate AS; and, most importantly, (3) ultrasonic backscatter is a reproducible technique, with mean differences between estimates on the basis of

Acknowledgements

We gratefully acknowledge the technical assistance of Ms Linda Passfield in this publication.

References (36)

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Supported in part by a grant from the National Health and Medical Research Council of Australia. Ms Ngo was a recipient of a divisional postgraduate research scholarship from the Faculty of Health Sciences, University of Adelaide.

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