title: Recurrent syncope in two patients with a sigmoid-shaped interventricular septum and no left ventricular hypertrophy.
abstract: Sigmoid-shaped interventricular septum (SIS) is not uncommon in elderly patients and is considered a normal part of the aging process. However, several patients have been reported to have clinical symptoms due to the narrowing of the left ventricular outflow tract (LVOT). Two patients with SIS presented with recurrent episodes of syncope after drinking or taking sublingual nitroglycerin (NG). In both patients, a head-up tilt test involving provocation with alcohol, NG, or isoproterenol induced the vasovagal reflex along with an increase in the pressure gradient between the apex and LVOT. The patients experienced no further episodes of syncope after initiating bisoprolol treatment. In patients with SIS, induction of the vasovagal reflex via an increase in left ventricular (LV) pressure due to LVOT obstruction concomitant with increased LV construction is a potentially important cause of syncope, which may be effectively prevented by beta-blockers.
authors.affiliation: Second Department of Internal Medicine, Graduate School of Medicine, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan.
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Yamaguchi
authors.affiliation: Clinical Research and Ethics Center, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan.
authors.forename: Koichi
authors.initials: K
authors.lastname: Mizumaki
authors.affiliation: Second Department of Internal Medicine, Graduate School of Medicine, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan.
authors.forename: Jotaro
authors.initials: J
authors.lastname: Iwamoto
authors.affiliation: Second Department of Internal Medicine, Graduate School of Medicine, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan.
authors.forename: Kunihiro
authors.initials: K
authors.lastname: Nishida
authors.affiliation: Second Department of Internal Medicine, Graduate School of Medicine, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan.
authors.forename: Tamotsu
authors.initials: T
authors.lastname: Sakamoto
authors.affiliation: Second Department of Internal Medicine, Graduate School of Medicine, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan.
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Nakatani
authors.affiliation: Second Department of Internal Medicine, Graduate School of Medicine, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan.
authors.forename: Naoya
authors.initials: N
authors.lastname: Kataoka
authors.affiliation: Second Department of Internal Medicine, Graduate School of Medicine, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Inoue
keywords: Left ventricular outflow tract obstruction; Sigmoid septum; Vasovagal reflex