Angled interventricular septum on echocardiography: anatomic anomaly or technical artifact?

An acutely angled interventricular septum has been reported to constitute a distinct two-dimensional echocardiographic geometric pattern that may permit a false M-mode echocardiographic recording of asymmetric septal hypertrophy. In light of experience suggesting that the angle between the aortic root and interventricular septum varied with the intercostal space of the transducer, 45 subjects were prospectively studied by two-dimensional and M-mode echocardiography. Parasternal long- and short-axis views were obtained from two to four intercostal spaces in each subject. Two-dimensional echographic cursor-generated M-mode echocardiograms were obtained from the long-axis views; interventricular septal and left ventricular posterior wall thickness was measured from both the two-dimensional and M-mode echocardiograms. On two-dimensional echocardiography, the angle between the aortic root and septum became more acute as a progressively lower intercostal space was used (p less than 0.001). Although no change in septal thickness was apparent, the septal thickness significantly increased as a progressively lower intercostal space was used. On M-mode echocardiography, 21 subjects (47%) demonstrated asymmetric septal hypertrophy (septal/posterior wall thickness ratio greater than 1.3) from at least one intercostal space, but this was confirmed by the two-dimensional technique in only 4 subjects (9%). Thus, a two-dimensional echocardiographic recording of an angled interventricular septum can be produced by positioning the transducer in a low intercostal space, and caution must be used in the interpretation of asymmetric septal hypertrophy on M-mode echocardiograms. Two-dimensional echocardiography is a useful means of identifying subjects with apparent asymmetric septal hypertrophy that often may be the result of a technical artifact.

Aortic valve systolic flutter as a screening test for severe aortic stenosis.

Previous efforts using M-mode echocardiography or 2-dimensional (2-D) echocardiography have not consistently separated patients with and without significant aortic stenosis (AS). We postulated that an aortic valve sufficiently pliant to produce systolic flutter on M-mode echocardiography could exclude significant AS and reviewed the M-mode echocardiograms of 50 consecutive patients (mean age 59 years) catheterized for presumed AS; 2-D echocardiography was also performed in 18 of 50 patients (36%). In 40 of 50 patients (80%) the aortic valve cusps were easily identified on M-mode echocardiography: 19 of 40 (48%) had systolic flutter with a mean aortic valve gradient of 4 +/- 8 mm Hg (mean +/- standard deviation [SD]) and an aortic valve area of 2.8 +/- 0.4 cm2; 21 of 40 (52%) had no systolic flutter with a mean aortic valve gradient of 55 +/- 19 mm Hg and an aortic valve area of 0.7 +/- 0.3 cm2. In the 10 of 50 patients (20%) in whom aortic valve cusps were not clearly identified, the mean aortic valve gradient was 50 +/- 24 mm Hg and the aortic valve area 0.8 +/- 0.4 cm2. Systolic flutter was not seen with an aortic valve gradient greater than 30 mm Hg or an aortic valve area less than 1 cm2. Aortic valve systolic opening by M-mode echocardiography or 2-D echocardiography did not accurately predict the severity of AS. Thus, aortic valve systolic flutter seen on M-mode echocardiography is strong evidence against significant AS, but the absence of systolic flutter does not allow reliable prediction of the severity of AS. The finding of systolic flutter by M-mode echocardiography may be a useful screening test in patients presumed to have AS.