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By John Gorcsan III, William A. Mandarino, Lee G. Deneault, Shigeki Morita, Akihiko Kawai, Bartley P. Griffith, Robert L. Kormos. The International Journal of Cardiac Imaging 10, 103–111, June 1994. Publisher title, full byline, author affiliations and abstract verified at link.springer.com/article/10.1007/BF01137705 . Abstract: six excised dog hearts were perfused ex vivo; an intraventricular balloon supplied volume and a micromanometer catheter supplied pressure. Automated echocardiographic borders measured mid-ventricular short-axis area. Three volume runs in 1 mL increments per heart yielded 1,080 simultaneous observations. The experiment compared pressure-area with pressure-volume relationships; it did not establish clinical validation. Full article not inspected.

Shigeki Morita is a coauthor of the 1994 isolated-heart study comparing automated echocardiography with a pressure-volume reference for ventricular compliance. The exact full name appears in the publisher byline. The experiment combined intraventricular balloon volumes, micromanometer pressure and image-derived short-axis area.^[ref]

The study's replication has two levels: three runs of changing volume were performed in each of six hearts. Repeated observations help describe a curve within a preparation, while different hearts supply biological replication. The reported 1,080 simultaneous measurements are not 1,080 independent hearts.^[ref]

An original error model shows why that distinction matters. Let $Y_{ij}=\mu +u_i+{ϵ}_{ij}$, with independent heart-level effects $u_i$ of variance ${\sigma }_b^2$ and independent within-heart errors of variance ${\sigma }_e^2$. For $H$ hearts and $m$ observations per heart,Adding more measurements to the same heart reduces the second term but not the first. This stipulated model is not a reanalysis of the study's observations; it illustrates how the apparatus and replication structure shape the scientific question.

Morita's verified contribution is coauthorship of that measurement experiment. Its evidence supports the tested preparation and does not establish universal interchangeability of imaging area and chamber volume.