Contraction wave in axial direction in free wall of guinea pig left ventricle

Mechanical activation of the normal left ventricle (LV) is not simultaneous; however, the potential consequences of the ejection function of the ventricle are not entirely known. We studied contraction of the LV free wall to determine whether it reveals a contraction wave in the axial direction duri...

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Bibliographic Details
Published inAmerican journal of physiology. Heart and circulatory physiology Vol. 56; no. 2; pp. 755 - 759
Main Authors KIRN, Borut, STARC, Vito
Format Journal Article
LanguageEnglish
Published Bethesda, MD American Physiological Society 01.08.2004
Subjects
Biological and medical sciences
Blood pressure
Cardiology
Fundamental and applied biological sciences. Psychology
Heart
Rodents
Vertebrates: cardiovascular system
Wall
epicardial marker
Rodentia
latitude
Marker
Contraction
Left ventricle
apex
Wave
Vertebrata
Guinea pig
Mammalia
Circulatory system
base
triangular area
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Summary:Mechanical activation of the normal left ventricle (LV) is not simultaneous; however, the potential consequences of the ejection function of the ventricle are not entirely known. We studied contraction of the LV free wall to determine whether it reveals a contraction wave in the axial direction during ejection. Seven guinea pig hearts in situ were studied via thoracotomy. In each heart, the ventricular and aortic pressures were measured by two microtipped manometers (2-Fr, Millar). Contraction of the LV free wall was assessed with a video system (Dalsa D6-0256 camera and EPIX PIXCI D32 frame grabber; acquisition rate, 500 frames/s), and 15-18 epicardial markers were used to divide the region into 20-25 triangular areas. The area sizes were studied during contraction to locate the position of the contraction wave. For each triangular area, two variables were determined as follows: the time (tc) from the end of diastole until the size of the area reached 80% of maximum size reduction (normalized with the duration of systole) and the normalized latitude (Lax) of the area (determined at the end of diastole). A relationship between these two variables was determined by regression analysis. We found that the tc at which the contraction wave reached a triangular area was in positive correlation with the Lax value for that triangular area with a slope of 0.25 +/- 0.09 and a linear correlation coefficient of 0.41 +/- 0.08. Thus contraction in the guinea pig LV free wall occurs progressively from apex to base with successive areas reaching 80% contraction. [PUBLICATION ABSTRACT]
ISSN:0363-6135
1522-1539