title: A novel method to estimate blood flow velocity in the left atrial appendage using enhanced computed tomography: role of Hounsfield unit density ratio at two distinct points within the left atrial appendage.
abstract: Low blood flow velocity in the left atrial appendage (LAA) indicates a high risk of thromboembolism. Although transesophageal echocardiography (TEE) has been the standard method with which to evaluate the LAA blood flow velocity, a clinically noninvasive method is desired. We hypothesized that the ratio of the Hounsfield unit (HU) density at two distinct points within the LAA represents the blood flow velocity in the LAA. We retrospectively investigated 60 consecutive patients with atrial fibrillation (paroxysmal type, n = 29) who underwent enhanced computed tomography (CT) and TEE. The peak emptying flow velocity in the LAA (LAAPV) was evaluated using TEE. HU density was measured at proximal and distal sites of the LAA (LAAp and LAAd) on CT images. The LAAd/LAAp ratio was correlated with the LAAPV (P < 0.01, r = 0.69). Among several indices, the HU ratio was the most significant parameter associated with the LAAPV (β = 0.469, CI 28.602-68.286, P < 0.001). Receiver-operating characteristic analysis (area under the curve, 0.91) demonstrated that an HU density ratio cutoff of 0.32 discriminated a low LAAPV (<25 cm/s) with sensitivity of 90% and specificity of 84%. Flow velocity of the LAA can be estimated by the HU density ratio at distal and proximal sites within the LAA. Our method might be a feasible substitution for TEE to discriminate patients with a reduced LAAPV.
authors.affiliation: Division of Cardiology, Department of Medicine, Faculty of Medicine, Kindai University, 377-2 Onohigashi, Osaka-Sayama, Osaka, 589-8511, Japan.
authors.forename: Ryobun
authors.initials: R
authors.lastname: Yasuoka
authors.affiliation: Division of Cardiology, Department of Medicine, Faculty of Medicine, Kindai University, 377-2 Onohigashi, Osaka-Sayama, Osaka, 589-8511, Japan. kuritat@med.kindai.ac.jp.
authors.forename: Takashi
authors.initials: T
authors.lastname: Kurita
authors.affiliation: Division of Cardiology, Department of Medicine, Faculty of Medicine, Kindai University, 377-2 Onohigashi, Osaka-Sayama, Osaka, 589-8511, Japan.
authors.forename: Yasuhito
authors.initials: Y
authors.lastname: Kotake
authors.affiliation: Division of Cardiology, Department of Medicine, Faculty of Medicine, Kindai University, 377-2 Onohigashi, Osaka-Sayama, Osaka, 589-8511, Japan.
authors.forename: Yuzuru
authors.initials: Y
authors.lastname: Akaiwa
authors.affiliation: Division of Cardiology, Department of Medicine, Faculty of Medicine, Kindai University, 377-2 Onohigashi, Osaka-Sayama, Osaka, 589-8511, Japan.
authors.forename: Naotaka
authors.initials: N
authors.lastname: Hashiguchi
authors.affiliation: Division of Cardiology, Department of Medicine, Faculty of Medicine, Kindai University, 377-2 Onohigashi, Osaka-Sayama, Osaka, 589-8511, Japan.
authors.forename: Koichiro
authors.initials: K
authors.lastname: Motoki
authors.affiliation: Division of Cardiology, Department of Medicine, Faculty of Medicine, Kindai University, 377-2 Onohigashi, Osaka-Sayama, Osaka, 589-8511, Japan.
authors.forename: Hiromi
authors.initials: H
authors.lastname: Yamamoto
authors.affiliation: Division of Cardiology, Department of Medicine, Faculty of Medicine, Kindai University, 377-2 Onohigashi, Osaka-Sayama, Osaka, 589-8511, Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Kobuke
authors.affiliation: Division of Cardiology, Department of Medicine, Faculty of Medicine, Kindai University, 377-2 Onohigashi, Osaka-Sayama, Osaka, 589-8511, Japan.
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Iwanaga
authors.affiliation: Division of Cardiology, Department of Medicine, Faculty of Medicine, Kindai University, 377-2 Onohigashi, Osaka-Sayama, Osaka, 589-8511, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Hirano
authors.affiliation: Division of Cardiology, Department of Medicine, Faculty of Medicine, Kindai University, 377-2 Onohigashi, Osaka-Sayama, Osaka, 589-8511, Japan.
authors.forename: Shunichi
authors.initials: S
authors.lastname: Miyazaki
mesh_terms: D000368:Aged; D020517:Atrial Appendage / Q000503:physiopathology*; D001281:Atrial Fibrillation / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D001783:Blood Flow Velocity; D017548:Echocardiography, Transesophageal; D005260:Female; D006801:Humans; D007564:Japan; D016014:Linear Models; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed
keywords: Atrial fibrillation; Flow velocity; Left atrial appendage; Multi-detector computed tomography; Transesophageal echocardiography