title: Major determinants and possible mechanism of dobutamine-induced left ventricular outflow tract obstruction in patients with a sigmoid ventricular septum.
abstract: BACKGROUND
  A sigmoid ventricular septum (SVS) may be related to normal aging, but some people with an SVS develop a left ventricular outflow tract (LVOT) obstruction (defined as a gradient of >30 mmHg). Therefore, we investigated the association of LVOT obstructions with an SVS by dobutamine stress echocardiography (DSE) and assessed the possible mechanism of the latent LVOT obstruction.
  
  
  RESULTS
  DSE was performed in 64 subjects with SVS (mean age: 73.3±7.7 years; 36 women) without an LVOT obstruction. In 40 of the 64 subjects, an LVOT obstruction occurred during the DSE (defined as latent obstruction). At rest, the subjects with a latent obstruction had a shorter end-systolic mitral leaflet tethering distance ("α" distance, i.e. the distance between the tip of the posterior papillary muscle and the contralateral anterior mitral annulus) than those without one (29.9±4.2 mm versus 35.2±4.6 mm), as well as a smaller end-systolic LVOT diameter (13.4±2.7 mm versus 16.1±3.4 mm) and larger ejection fraction (72.0±5.0% versus 67.8±5.9%) (all p<0.05). They also had a higher LV outflow velocity at rest (1.23±0.24 m/s versus 1.03±0.24 m/s) and during the Valsalva maneuver (1.31±0.27 m/s versus 1.03±0.27 m/s) (both p<0.05). After adjusting for these parameters, the resting end-systolic "α" distance and LV outflow velocity at rest remained independent predictors of a latent obstruction.
  
  
  CONCLUSIONS
  A short leaflet tethering distance ("α") was the major determinant of a latent obstruction, suggesting that a mitral leaflet displacement/redundancy caused by a short "α" distance contributes to the LVOT obstruction.
authors.affiliation: Division of Cardiology, Department of Medicine, Nihon University School of Medicine, Tokyo, Japan.
authors.forename: Ayako
authors.initials: A
authors.lastname: Tano
authors.forename: Yuji
authors.initials: Y
authors.lastname: Kasamaki
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Okumura
authors.forename: Masakatsu
authors.initials: M
authors.lastname: Ohta
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Kofune
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Fujii
authors.forename: Yosihiro
authors.initials: Y
authors.lastname: Aizawa
authors.forename: Toshiko
authors.initials: T
authors.lastname: Nakai
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kunimoto
authors.forename: Takafumi
authors.initials: T
authors.lastname: Hiro
authors.forename: Ichiro
authors.initials: I
authors.lastname: Watanabe
authors.forename: Atsushi
authors.initials: A
authors.lastname: Hirayama
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000473:pathology; D004280:Dobutamine; D025401:Echocardiography, Stress; D005260:Female; D006801:Humans; D008297:Male; D014694:Ventricular Outflow Obstruction / Q000000981:diagnostic imaging* / Q000209:etiology* / Q000503:physiopathology; D054088:Ventricular Septum / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000503:physiopathology
chemical_list: D004280:Dobutamine