title: Noninvasive evaluation of left ventricular force-frequency relationships by measuring carotid arterial wave intensity during exercise stress.
abstract: OBJECTIVE
  Estimation of the contractility of the left ventricle during exercise is important in drawing up a protocol of cardiac rehabilitation. It has been demonstrated that color Doppler- and echo tracking-derived carotid arterial wave intensity is a sensitive index of global left ventricular (LV) contractility. We assessed the feasibility of measuring carotid arterial wave intensity and determining force-frequency (contractility-heart rate) relations (FFRs) during exercise totally noninvasively.
  
  
  METHODS
  We measured carotid arterial wave intensity with a combined color Doppler and echo tracking system in 25 healthy young male volunteers (age 20.8 ± 1.2 years) at rest and during exercise. FFRs were constructed by plotting the maximum value of wave intensity (WD1) against heart rate (HR).
  
  
  RESULTS
  We first confirmed that HR increased linearly with an increase in work load in each subject (r (2) = 0.95 ± 0.04). WD1 increased linearly with an increase in HR. The goodness-of-fit of the regression line of WD1 on HR in each subject was very high (r (2) = 0.48-0.94, p < 0.0001, respectively). The slope of the WD1-HR relation ranged 0.30-2.20 [m/s(3) (beat/min)].
  
  
  CONCLUSIONS
  Global LV FFRs can be generated in healthy young volunteers with an entirely noninvasive combination of exercise and wave intensity. These data should show the potential usefulness of the FFR in the context of cardiac rehabilitation.
authors.affiliation: Faculty of Health Care Sciences, Himeji Dokkyo University, 7-2-1 Kamiohno, Himeji, Hyogo 670-8524 Japan.
authors.forename: Midori
authors.initials: M
authors.lastname: Tanaka
authors.affiliation: Faculty of Health Care Sciences, Himeji Dokkyo University, 7-2-1 Kamiohno, Himeji, Hyogo 670-8524 Japan.
authors.forename: Motoaki
authors.initials: M
authors.lastname: Sugawara
authors.affiliation: Department of Medical Engineering, Kawasaki University of Medical Welfare, Kurashiki, Japan.
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Ogasawara
authors.affiliation: Clinical Laboratory, Japanese Red Cross Society, Himeji Hospital, Himeji, Japan.
authors.forename: Isao
authors.initials: I
authors.lastname: Suminoe
authors.affiliation: Department of Physical Therapy, Health Sciences University of Hokkaido, Ishikari, Japan.
authors.forename: Tadafumi
authors.initials: T
authors.lastname: Izumi
authors.affiliation: Biomedical Engineering Department, Tokyo City University, Tokyo, Japan.
authors.forename: Kiyomi
authors.initials: K
authors.lastname: Niki
authors.affiliation: Department of Medical Engineering, Kawasaki University of Medical Welfare, Kurashiki, Japan.
authors.forename: Fumihiko
authors.initials: F
authors.lastname: Kajiya
mesh_terms: D002339:Carotid Arteries / Q000000981:diagnostic imaging*; D005080:Exercise Test; D005240:Feasibility Studies; D006352:Heart Ventricles / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D018615:Ultrasonography, Doppler, Color; D016277:Ventricular Function, Left; D055815:Young Adult
keywords: Echocardiography; Exercise; Force−frequency relation; Wave intensity