Structural Basis of Cardiac Valvar Function

Cooper, Theodore; Napolitano, Leonard; Fitzgerald, M. J. T.; Moore, K. E.; Daggett, Willard M.; Willman, Vallee L.; Sonnenblick, Edmund H.; Hanlon, Christopher

doi:10.1001/archsurg.1966.01330050071010

Cited by 53 publications

(25 citation statements)

References 4 publications

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“…The atrialis layer of the anterior MV leaflet contains cardiac muscle cells and well-defined cell bundles, several myofibrils thick, arranged end-to-end and side-to-side, in continuity with LA muscle, surrounded by connective tissue, accompanied by blood vessels and efferent nerves, and tapering in thickness, number, and orientational regularity from annular base to central leaflet, with only slips of muscle near the occlusive margin (2,6,11,12,18,30,39,47,48). As shown in Fig.…”

Section: Discussionmentioning

confidence: 99%

“…Black springs, collagen; red arrows, valvular interstitial cells; red interdigitating symbols, leaflet atrial muscle. (29)], annulus, leaflet, chordae, and papillary muscles (1,6,8,10,12,18,26,(43)(44)(45) to carry this stimulus from the aorticmitral continuity into the anterior leaflet. Within the anterior leaflet, however, no myoneural junctions are observed (18,39), the neuromuscular distance being Ͼ50 nm and filled with connective tissue (8,18); thus contractile myofibers in the leaflet are not directly innervated, and paracrine action is most consistent with our findings.…”

Section: Ivc (A) Ivr (B) Ivc (C) Ivr (D) Ivc (E) Ivr (F) Ivc (G) Ivr (H)mentioning

confidence: 99%

“…Medical and surgical therapies for this disease have traditionally assumed that the valve leaflets, the key components of the valve, are passive flaps (46). However, muscle fibers (2, 6, 11, 12, 18, 25, 30 -32, 34, 39, 41, 47, 48), blood vessels (6,8,11,24,26,37,39), and nerves (1, 6 -13, 18 -20, 26, 29, 35, 36, 39, 43-45) have been recognized in the MV leaflets of animals and humans since the 19th century, and the physiological function of these entities, along with other contractile elements in the leaflets, such as smooth muscle (8,18,26,47) and valvular interstitial cells (VICs) (4,13,18,23,26,28,38,40), is not understood.…”

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confidence: 99%

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Active stiffening of mitral valve leaflets in the beating heart

Itoh

Krishnamurthy²,

Swanson³

et al. 2009

American Journal of Physiology-Heart and Circulatory Physiology

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The anterior leaflet of the mitral valve (MV), viewed traditionally as a passive membrane, is shown to be a highly active structure in the beating heart. Two types of leaflet contractile activity are demonstrated: 1) a brief twitch at the beginning of each beat (reflecting contraction of myocytes in the leaflet in communication with and excited by left atrial muscle) that is relaxed by midsystole and whose contractile activity is eliminated with β-receptor blockade and 2) sustained tone during isovolumic relaxation, insensitive to β-blockade, but doubled by stimulation of the neurally rich region of aortic-mitral continuity. These findings raise the possibility that these leaflets are neurally controlled tissues, with potentially adaptive capabilities to meet the changing physiological demands on the heart. They also provide a basis for a permanent paradigm shift from one viewing the leaflets as passive flaps to one viewing them as active tissues whose complex function and dysfunction must be taken into account when considering not only therapeutic approaches to MV disease, but even the definitions of MV disease itself.

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Section: Discussionmentioning

confidence: 99%

Section: Ivc (A) Ivr (B) Ivc (C) Ivr (D) Ivc (E) Ivr (F) Ivc (G) Ivr (H)mentioning

confidence: 99%

mentioning

confidence: 99%

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Active stiffening of mitral valve leaflets in the beating heart

Itoh

Krishnamurthy²,

Swanson³

et al. 2009

American Journal of Physiology-Heart and Circulatory Physiology

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“…The average 16% increase in MAA observed in the EXP group at all 3 time points was created by treating a little known muscular band that runs along the anterior mitral annulus with phenol. Originally described by Cooper et al 23 in dogs, subsequent work by that group showed that the radially and circumferentially oriented muscle fibers in that structure act on both the mitral annulus and anterior leaflet to modulate shape and forces that might dynamically determine MAA. Recently, Marron et al 24 performed pathology studies in humans and described this muscle in some detail.…”

Section: Discussionmentioning

confidence: 99%

Mitral Annular Dilatation and Papillary Muscle Dislocation Without Mitral Regurgitation in Sheep

Green

Dagum²,

Glasson³

et al. 1999

Circulation

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Background-Asymmetrical mitral annular (MA) dilatation and papillary muscle dislocation are implicated in the pathogenesis of functional mitral regurgitation (MR). Methods and Results-To determine the mechanism by which annular and papillary muscle geometric alterations result in MR, we implanted radiopaque markers in the left ventricle, mitral annulus, anterior and posterior mitral leaflets, and papillary muscle tips and bases in 2 groups of sheep. One group served as controls (CTL, nϭ7); an experimental group (EXP, nϭ9) underwent topical phenol application to obliterate anterior annular and leaflet muscle (confirmed histologically ex vivo). After 1 week of recovery, markers were imaged with biplane videofluoroscopy, and hemodynamic data were recorded. MA area (computed from 3-dimensional marker coordinates) was 11% to 13% larger in the EXP group than in the CTL group (PϽ0.05 by ANOVA). This area increase resulted exclusively from intercommissural axis increase except in 1 heart with large (Ͼ1 cm) increases in both the intercommissural and septolateral annular axes. The anterior papillary muscle tip in EXP was displaced from CTL by 2.9Ϯ0.23 mm toward the anterolateral left ventricle and 2.5Ϯ0.12 mm toward the mitral annulus at end systole; the posterior papillary muscle geometry was unchanged. Transthoracic echocardiography revealed MR only in the heart exhibiting biaxial annular enlargement.

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“…Similar physiological role of cardiac fibers in the dog mitral valves (COOPER et al, 1966;SONNENBLICK et al, 1967) and in the rabbit proximal vena cava has been already conceived.…”

Section: Discussionmentioning

confidence: 56%