大倉 宏之¹, 吉田 清¹, 赤阪 隆史¹, 赤土 正洋¹, 穂積 健之¹, 高木 力¹, 本多 康浩¹, 山室 淳¹, 吉川 純一²

Hiroyuki OKURA¹, Kiyoshi YOSHIDA¹, Takashi AKASAKA¹, Masahiro SHAKUDO¹, Takeshi HOZUMI¹, Tsutomu TAKAGI¹, Yasuhiro HONDA¹, Atsushi YAMAMURO¹, Junichi YOSHIKAWA²

¹神戸市立中央市民病院循環器センター内科, ²大阪市立大学第1内科

¹Division of Cardiology, Kobe General Hospital , ²First Department of Internal Medicine, Osaka City University School of Medicine

キーワード : Aortic stenosis, Aortic valve resistance, Dobutamine stress echocardiography

Hemodynamic resistance has recently been proposed as a useful index of valvular stenosis. Here we attempt to clarify usefulness of aortic valve resistance in assessing severity of aortic stensis in patients with low pressure gradient. Mean pressure gradient, aortic valve area, and aortic valve resistance derived from two-dimensional and Doppler echocardiography were calculated before and after infusion of dobutamine (12/μg/kg/min) in 13 patients with valvular aortic stenosis in whom mean pressure gradient was less than 50 mmHg. Patients were divided into two groups: I, those with aortic valve area after dobutamine infusion greater than 0.75 cm²; and II, those aortic valve area after dobutamine infusion less than 0.75 cm². Mean pressure gradient was almost identical when groupss I and II were at rest, 28.9±12.9 and 35.0±11.3 mmHg, respectively, but it increased more in group II than in group I after dobutamine infusion (46.1±20.2 vs. 66.4±28.1 mmHg, p2, p2). Aortic valve resistqnce was lower at rest in patients in group I than in those in group II (215±123 vs. 452±219 dynes˟sec˟cm^-5, p-5, respectively). We conclude that aortic valve resistance is less flow-dependent than aortic valve area or Doppler-derived mean pressure gradient. Aortic valve resistance can be used to assess severity of aortic stenosis in patients with low pressure gradient.