Key result
In vivo dog papillary muscle demonstrates ~23% mean shortening, contradicting isolated muscle studies.
Why the study?
There is a contradiction between the degree of papillary muscle shortening observed in vivo and the reduced shortening seen in isolated papillary muscle studies under load.
Population
6 intact, tranquilized dogs with implanted metal markers in anterior left ventricular papillary muscle
Comparison
Papillary muscle shortening and lengthening velocities measured in two orthogonal positions
Design
Cineradiographic observational study
Follow-up
3-50 months (marker implantation duration)
Authors
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Challenges isolated papillary muscle data; leaves open in vivo mechanics translation in large-animal models.
In vivo dog papillary muscle exhibits surprisingly large shortening (22.8%), contrasting with reduced shortening observed in isolated muscle studies under tension.
Grimm et al. (1975) studied this question. Cineradiographic observation was evaluated on Mean percent shortening of the anterior papillary muscle. In vivo dog papillary muscle demonstrated a surprisingly large mean percent shortening of 22.8 ± 6.5%, contradicting findings from isolated papillary muscle studies.