title: Modification of human left ventricular relaxation by small-amplitude, phase-controlled mechanical vibration on the chest wall.
abstract: BACKGROUND
  Direct clinical manipulation to improve an impairment of left ventricular (LV) relaxation has not been reported. We investigated whether the LV relaxation rate in humans could be modulated by phase-controlled mechanical vibration applied to the patient's anterior chest wall and whether there are some quantitative differences in the responses of normal (N), hypertrophied (H), and failing (F) ventricle.
  
  
  RESULTS
  In 46 patients (N, 10; H, 18 [hypertrophic cardiomyopathy]; F, 18 [heart failure]), the vibrator was attached to the precordium and a 50-Hz, 2-mm sinusoidal mechanical vibration was applied, with the timing restricted from the onset of isovolumic relaxation to end-diastole during cardiac catheterization. Heart rate and peak LV pressure showed no difference with vibration. However, in all patients, precordial vibration caused an acceleration of the LV pressure fall. The magnitude of the induced reduction of the time constant of LV pressure decay (delta T) was larger (P < .01) in H and F than in N (4.6 +/- 2.3, 4.0 +/- 1.6, and 0.6 +/- 1.5 ms for H, F, and N, respectively). Delta T correlated strongly with the magnitude of impaired relaxation and the magnitude of transmitted vibration to the ventricle.
  
  
  CONCLUSIONS
  Phase-controlled, small-amplitude vibration on the chest wall can directly modulate LV relaxation rate, especially in those with hypertrophy or failing ventricle.
authors.affiliation: First Department of Internal Medicine, Tohoku University School of Medicine, Sendai, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Koiwa
authors.forename: H
authors.initials: H
authors.lastname: Honda
authors.forename: T
authors.initials: T
authors.lastname: Takagi
authors.forename: J
authors.initials: J
authors.lastname: Kikuchi
authors.forename: N
authors.initials: N
authors.lastname: Hoshi
authors.forename: T
authors.initials: T
authors.lastname: Takishima
mesh_terms: D000328:Adult; D002312:Cardiomyopathy, Hypertrophic / Q000503:physiopathology* / Q000628:therapy; D003971:Diastole; D006333:Heart Failure / Q000503:physiopathology* / Q000628:therapy; D006352:Heart Ventricles / Q000503:physiopathology; D006439:Hemodynamics; D006801:Humans; D008433:Mathematics; D008875:Middle Aged; D012044:Regression Analysis; D018487:Ventricular Dysfunction, Left / Q000503:physiopathology / Q000628:therapy*; D017725:Ventricular Pressure; D014732:Vibration / Q000627:therapeutic use*