title: Relationships of left ventricular strain and strain rate to wall stress and their afterload dependency.
abstract: Whether and how left ventricular (LV) strain and strain rate correlate with wall stress is not known. Furthermore, it is not determined whether strain or strain rate is less dependent on the afterload. In 41 healthy young adults, LV global peak strain and systolic peak strain rate in the longitudinal direction (LS and LSR, respectively) and circumferential direction (CS and CSR, respectively) were measured layer-specifically using speckle tracking echocardiography (STE) before and during a handgrip exercise. Among all the points before and during the exercise, all the STE parameters significantly correlated linearly with wall stress (LS: r = -0.53, p < 0.01, LSR: r = -0.28, p < 0.05, CS in the inner layer: r = -0.72, p < 0.01, CSR in the inner layer: r = -0.47, p < 0.01). Strain more strongly correlated with wall stress than strain rate (r = -0.53 for LS vs. r = -0.28 for LSR, p < 0.05; r = -0.72 for CS vs. r = -0.47 for CSR in the inner layer, p < 0.05), whereas the interobserver variability was similar between strain and strain rate (longitudinal 6.2 vs. 5.2 %, inner circumferential 4.8 vs. 4.7 %, mid-circumferential 7.9 vs. 6.9 %, outer circumferential 10.4 vs. 9.7 %), indicating that the differences in correlation coefficients reflect those in afterload dependency. It was thus concluded that LV strain and strain rate linearly and inversely correlated with wall stress in the longitudinal and circumferential directions, and strain more strongly depended on afterload than did strain rate. Myocardial shortening should be evaluated based on the relationships between these parameters and wall stress.
authors.affiliation: Department of Cardiovascular Medicine, Hokkaido University Graduate School of Medicine, Kita-15, Nishi-7, Kita-ku, Sapporo, 060-8638, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Murai
authors.affiliation: Department of Cardiovascular Medicine, Hokkaido University Graduate School of Medicine, Kita-15, Nishi-7, Kita-ku, Sapporo, 060-8638, Japan. syamada@med.hokudai.ac.jp.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Yamada
authors.affiliation: Department of Cardiovascular Medicine, Hokkaido University Graduate School of Medicine, Kita-15, Nishi-7, Kita-ku, Sapporo, 060-8638, Japan.
authors.forename: Taichi
authors.initials: T
authors.lastname: Hayashi
authors.affiliation: Faculty of Health Sciences, Hokkaido University, Sapporo, Japan.
authors.forename: Kazunori
authors.initials: K
authors.lastname: Okada
authors.affiliation: Division of Laboratory and Transfusion Medicine, Hokkaido University Hospital, Sapporo, Japan.
authors.forename: Hisao
authors.initials: H
authors.lastname: Nishino
authors.affiliation: Division of Laboratory and Transfusion Medicine, Hokkaido University Hospital, Sapporo, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Nakabachi
authors.affiliation: Division of Laboratory and Transfusion Medicine, Hokkaido University Hospital, Sapporo, Japan.
authors.forename: Shinobu
authors.initials: S
authors.lastname: Yokoyama
authors.affiliation: Division of Laboratory and Transfusion Medicine, Hokkaido University Hospital, Sapporo, Japan.
authors.forename: Ayumu
authors.initials: A
authors.lastname: Abe
authors.affiliation: Division of Laboratory and Transfusion Medicine, Hokkaido University Hospital, Sapporo, Japan.
authors.forename: Ayako
authors.initials: A
authors.lastname: Ichikawa
authors.affiliation: Clinical Research and Medical Innovation Center, Hokkaido University Hospital, Sapporo, Japan.
authors.forename: Kota
authors.initials: K
authors.lastname: Ono
authors.affiliation: Faculty of Health Sciences, Hokkaido University, Sapporo, Japan.
authors.forename: Sanae
authors.initials: S
authors.lastname: Kaga
authors.affiliation: Department of Cardiovascular Medicine, Hokkaido University Graduate School of Medicine, Kita-15, Nishi-7, Kita-ku, Sapporo, 060-8638, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Iwano
authors.affiliation: Faculty of Health Sciences, Hokkaido University, Sapporo, Japan.
authors.forename: Taisei
authors.initials: T
authors.lastname: Mikami
authors.affiliation: Department of Cardiovascular Medicine, Hokkaido University Graduate School of Medicine, Kita-15, Nishi-7, Kita-ku, Sapporo, 060-8638, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Tsutsui
mesh_terms: D000328:Adult; D004452:Echocardiography; D005260:Female; D064368:Healthy Volunteers; D006352:Heart Ventricles / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006801:Humans; D008297:Male; D009200:Myocardial Contraction / Q000502:physiology*; D013599:Systole; D018487:Ventricular Dysfunction, Left / Q000503:physiopathology*; D016277:Ventricular Function, Left / Q000502:physiology*; D055815:Young Adult
keywords: Afterload; Speckle tracking echocardiography; Strain; Strain rate; Wall stress