title: New concept of the contraction-extension property of the left ventricular myocardium.
abstract: OBJECTIVE
  Using newly developed ultrasonic technology, we attempted to disclose the characteristics of the left ventricular (LV) contraction-extension (C-E) property, which has an important relationship to LV function.
  
  
  METHODS
  Strain rate (SR) distribution within the posterior wall and interventricular septum was microscopically measured with a high accuracy of 821μm in spatial resolution by using the phase difference tracking method. The subjects were 10 healthy men (aged 30-50 years).
  
  
  RESULTS
  The time course of the SR distribution disclosed the characteristic C-E property, i.e. the contraction started from the apex and propagated toward the base on one hand, and from the epicardial side toward the endocardial side on the other hand. Therefore, the contraction of one area and the extension of another area simultaneously appeared through nearly the whole cardiac cycle, with the contracting part positively extending the latter part and vice versa. The time course of these propagations gave rise to the peristalsis and the bellows action of the LV wall, and both contributed to effective LV function. The LV contraction started coinciding in time with the P wave of the electrocardiogram, and the cardiac cycle was composed of 4 phases, including 2 types of transitional phase, as well as the ejection phase and slow filling phase. The sum of the measurement time duration of either the contraction or the extension process occupied nearly equal duration in normal conditions.
  
  
  CONCLUSIONS
  The newly developed ultrasonic technology revealed that the SR distribution was important in evaluating the C-E property of the LV myocardium. The harmonious succession of the 4 cardiac phases newly identified seemed to be helpful in understanding the mechanism to keep long-lasting pump function of the LV.
authors.affiliation: Cardiovascular Center, Tohoku Pharmaceutical University Hospital, Fukumuro 1-12-1, Miyagino-ku, Sendai 983-0005, Japan. Electronic address: m.tanaka@jata-miyagi.org.
authors.forename: Motonao
authors.initials: M
authors.lastname: Tanaka
authors.affiliation: Hanzomon Hospital, Kojimachi 1-14, Chiyoda-ku, Tokyo 102-0083, Japan.
authors.forename: Tsuguya
authors.initials: T
authors.lastname: Sakamoto
authors.affiliation: Cardiovascular Center, Tohoku Pharmaceutical University Hospital, Fukumuro 1-12-1, Miyagino-ku, Sendai 983-0005, Japan.
authors.forename: Shigeo
authors.initials: S
authors.lastname: Sugawara
authors.affiliation: Cardiovascular Center, Tohoku Pharmaceutical University Hospital, Fukumuro 1-12-1, Miyagino-ku, Sendai 983-0005, Japan.
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Katahira
authors.affiliation: Cardiovascular Center, Tohoku Pharmaceutical University Hospital, Fukumuro 1-12-1, Miyagino-ku, Sendai 983-0005, Japan.
authors.forename: Haruna
authors.initials: H
authors.lastname: Tabuchi
authors.affiliation: Cardiovascular Center, Tohoku Pharmaceutical University Hospital, Fukumuro 1-12-1, Miyagino-ku, Sendai 983-0005, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Nakajima
authors.affiliation: Cardiovascular Center, Tohoku Pharmaceutical University Hospital, Fukumuro 1-12-1, Miyagino-ku, Sendai 983-0005, Japan.
authors.forename: Takafumi
authors.initials: T
authors.lastname: Kurokawa
authors.affiliation: Department of Electrical Engineering, Tohoku University, Aramaki-Aoba 6-6-05, Aoba-ku, Sendai 980-8579, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kanai
authors.affiliation: Department of Electrical Engineering, Tohoku University, Aramaki-Aoba 6-6-05, Aoba-ku, Sendai 980-8579, Japan.
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Hasegawa
authors.affiliation: Institute of Medical Ultrasound Technology, Yokohama 2-12-15, Sagamihara 229-1122, Japan.
authors.forename: Shigeo
authors.initials: S
authors.lastname: Ohtsuki
mesh_terms: D000328:Adult; D006352:Heart Ventricles / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction / Q000502:physiology*; D014463:Ultrasonography / Q000379:methods*; D016277:Ventricular Function, Left / Q000502:physiology*
keywords: Myocardial contraction-Extension property; Non-uniformity of myocardial contraction and extension; Peristalsis and bellows action of the ventricular wall; Phase difference tracking method; Strain rate distribution