Aortic insufficiency (AI) induces backflow of blood in the arterial system that is most pronounced in the major arteries close to the heart. Assuming that the intensity of the arterial backflow of blood may reflect the severity of AI, the systolic and diastolic flow profiles of the subclavian artery were studied in 40 patients with and 10 patients without AI that was angiographically proved by use of continuous wave Doppler ultrasound (8 MHz transducer, supraclavicular approach). Patients with angiographically determined severe AI (n = 17) had significantly higher diastolic regurgitant flow velocities (V-max) than patients with only mild (n = 9) or moderate (n = 14) degrees of AI (Severe AI = 35.0 +/- 12.0 cm/sec, moderate AI = 16.8 +/- 3.9 cm/sec, mild AI = 7.4 +/- 2.6 cm/sec; p < 0.01) and also showed significantly higher values with regard to the time velocity integral of the regurgitant jet (severe AI = 13.8 +/- 5.6 cm; moderate AI = 5.7 +/- 2.4 cm, mild AI = 1.4 +/- 0.9 cm; p < 0.01). After classification by jacknife discrimination analysis, the Doppler ultrasound grading was compared with a corresponding three-point scale (mild, moderate, severe) from aortic root angiography. A correct estimation of the severity of AI was possible in 44 of 50 patients (88%; overestimation in one, underestimation in five) and in 41 of 50 patients (83%; overestimation in one, underestimation in eight) with regard to V-max and the time velocity integral of the regurgitant jet, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)