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  • 1
    Online Resource
    Online Resource
    Chronic right ventricular pressure overload results in a hyperplastic rather than a hypertrophic myocardial response
    Wiley ; 2008
    In:  Journal of Anatomy Vol. 212, No. 3 ( 2008-03), p. 286-294
    Details
    In: Journal of Anatomy, Wiley, Vol. 212, No. 3 ( 2008-03), p. 286-294
    Abstract: Myocardial hyperplasia is generally considered to occur only during fetal development. However, recent evidence suggests that this type of response may also be triggered by cardiac overload after birth. In congenital heart disease, loading conditions are frequently abnormal, thereby affecting ventricular function. We hypothesized that chronic right ventricular pressure overload imposed on neonatal hearts initiates a hyperplastic response in the right ventricular myocardium. To test this, young lambs (aged 2–3 weeks) underwent adjustable pulmonary artery banding to obtain peak right ventricular pressures equal to left ventricular pressures for 8 weeks. Transmural cardiac tissue samples from the right and left ventricles of five banded and five age‐matched control animals were studied. We found that chronic right ventricular pressure overload resulted in a twofold increase in right‐to‐left ventricle wall thickness ratio. Morphometric right ventricular myocardial tissue analysis revealed no changes in tissue composition between the two groups; nor were right ventricular myocyte dimensions, relative number of binucleated myocytes, or myocardial DNA concentration significantly different from control values. In chronic pressure overloaded right ventricular myocardium, significantly ( P   〈  0.01) more myocyte nuclei were positive for the proliferation marker proliferating cellular nuclear antigen than in control right ventricular myocardium. Chronic right ventricular pressure overload applied in neonatal sheep hearts results in a significant increase in right ventricular free wall thickness which is primarily the result of a hyperplastic myocardial response.
    Type of Medium: Online Resource
    ISSN: 0021-8782 , 1469-7580
    URL: Issue
    URL: Article
    DOI: 10.1111/joa.2008.212.issue-3
    DOI: 10.1111/j.1469-7580.2008.00853.x
    Language: English
    Publisher: Wiley
    Publication Date: 2008
    detail.hit.zdb_id: 1474856-3
    SSG: 12
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  • 2
    Online Resource
    Online Resource
    Indexes of diastolic RV function: load dependence and changes after chronic RV pressure overload in lambs
    American Physiological Society ; 2002
    In:  American Journal of Physiology-Heart and Circulatory Physiology Vol. 282, No. 4 ( 2002-04-01), p. H1350-H1358
    Details
    In: American Journal of Physiology-Heart and Circulatory Physiology, American Physiological Society, Vol. 282, No. 4 ( 2002-04-01), p. H1350-H1358
    Abstract: Diastolic function is a major determinant of ventricular performance, especially when loading conditions are altered. We evaluated biventricular diastolic function in lambs and studied possible load dependence of diastolic parameters [minimum first derivative of pressure vs. time (dP/d t min ) and time constant of isovolumic relaxation (τ)] in normal ( n = 5) and chronic right ventricular (RV) pressure-overloaded ( n = 5) hearts by using an adjustable band on the pulmonary artery (PAB). Pressure-volume relations were measured during preload reduction to obtain the end-diastolic pressure-volume relationship (EDPVR). In normal lambs, absolute dP/d t min and τ were lower in the RV than in the left ventricle whereas the chamber stiffness constant ( b) was roughly the same. After PAB, RV τ and dP/d t min were significantly higher compared with control. The RV EDPVR indicated impaired diastolic function. During acute pressure reduction, both dP/d t min and τ showed a relationship with end-systolic pressure. These relationships could explain the increased dP/d t min but not the increased τ-value after banding. Therefore, the increased τ after banding reflects intrinsic myocardial changes. We conclude that after chronic RV pressure overload, RV early relaxation is prolonged and diastolic stiffness is increased, both indicative of impaired diastolic function.
    Type of Medium: Online Resource
    ISSN: 0363-6135 , 1522-1539
    URL: Article
    DOI: 10.1152/ajpheart.00782.2001
    RVK:
    WA 15000
    Language: English
    Publisher: American Physiological Society
    Publication Date: 2002
    detail.hit.zdb_id: 1477308-9
    SSG: 12
    Location Call Number Limitation Availability
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  • 3
    Online Resource
    Online Resource
    Biventricular systolic function in young lambs subject to chronic systemic right ventricular pressure overload
    American Physiological Society ; 2001
    In:  American Journal of Physiology-Heart and Circulatory Physiology Vol. 281, No. 6 ( 2001-12-01), p. H2697-H2704
    Details
    In: American Journal of Physiology-Heart and Circulatory Physiology, American Physiological Society, Vol. 281, No. 6 ( 2001-12-01), p. H2697-H2704
    Abstract: In various clinical situations of congenital heart disease, the right ventricle (RV) is subject to a chronic systemic pressure overload which affects biventricular function and may progress to the development of RV failure. Young lambs (2–3 wk old) underwent adjustable pulmonary artery banding (PAB) at systemic (aortic) level for 8 wk. Biventricular function was determined by using load-independent indexes of global ventricular contractile performance by the end-systolic pressure-volume relationship (ESPVR) using the conductance catheter at baseline and during dobutamine infusion. PAB resulted in a significant fivefold increase in RV end-systolic pressure (12–64 mmHg) and a doubling of the RV-to-left ventricular (LV) wall thickness ratio ( P 〈 0.01). RV global contractile performance increased significantly, as indicated by an increased slope of the ESPVR. Compared with age-matched control lambs, cardiac output decreased from 2.6 to 1.6 l/min ( P 〈 0.05) whereas heart rates were equal. In contrast with RV volume, LV volume decreased significantly after PAB ( P 〈 0.01), whereas the LV-ESPVR slope was unchanged. In the PAB group, the RV, but not the LV, showed a reduced response to dobutamine. We concluded that chronic RV pressure overload for 8 wk results in diminished pump function despite compensatory increased RV global contractile performance.
    Type of Medium: Online Resource
    ISSN: 0363-6135 , 1522-1539
    URL: Article
    DOI: 10.1152/ajpheart.2001.281.6.H2697
    RVK:
    WA 15000
    Language: English
    Publisher: American Physiological Society
    Publication Date: 2001
    detail.hit.zdb_id: 1477308-9
    SSG: 12
    Location Call Number Limitation Availability
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  • 4
    Online Resource
    Online Resource
    Differential Response of the Right and Left Ventricle to β-Adrenergic Stimulation: An Echo Planar MR Study in Intact Animals
    Ovid Technologies (Wolters Kluwer Health) ; 1998
    In:  Journal of Computer Assisted Tomography Vol. 22, No. 4 ( 1998-07), p. 569-576
    Details
    In: Journal of Computer Assisted Tomography, Ovid Technologies (Wolters Kluwer Health), Vol. 22, No. 4 ( 1998-07), p. 569-576
    Type of Medium: Online Resource
    ISSN: 0363-8715
    URL: Article
    DOI: 10.1097/00004728-199807000-00012
    RVK:
    XA 10000
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 1998
    detail.hit.zdb_id: 2039772-0
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