This study was designed to develop a two-dimensional echocardiographic method of measuring the mass of the left ventricle. The general formula for an ellipse was used to derive an algorithm that described the shell volume of concentric truncated ellipsoids. In 10 canine left ventricular two-dimensional echocardiograms, this algorithm accurately predicted postmortem left ventricular mass (r = .98, SEE ± 6 g) and was independent of cardiac cycle phase (systole vs diastole, r = .92). Circulation 68, No. 1, 210-216, 1983. LEFT VENTRICULAR MASS is an important descriptor of cardiac functional status. Pathologically or physiologically increased mass results from the hypertrophic process that frequently, but not always, is accompanied by increased wall thickness. Invasive and noninvasive imaging techniques such as M mode echocardiography and angiography allow quantitation of left ventricular mass by methods that rely on limited measurements of wall thickness taken from one or two loci at the cardiac base in combination with ventricular volume estimates of varying accuracy. 17Although M mode methods have been shown to have useful clinical and investigative applications,7 9 they require technically excellent septal and posterior wall imaging and are proscribed in regional myocardial disease.6 Two-dimensional echocardiography has been shown to provide noninvasive cardiac images from which left ventricular volumes can be reliably measured. IO-2 These methods are superior to M mode I A geometrically rational method of measuring mass from two-dimensional echocardiograms is desirable because it should be less vulnerable to errors arising from the extrapolation of three-dimensional information from linear measurements and from segmental disease.Our purpose was to develop and validate a twodimensional echocardiographic technique for estimating left ventricular mass in which a geometrically representative algorithm, a representative measure of wall thickness, and easily obtained internal left ventricular dimensions are used. MethodsThe study consisted of two phases. In the first phase an algorithm was derived that was both anatomiically logical and solvable with easily obtained echocardiographic dimensions; in the second phase this algorithm was tested in an animal model. Derivation of a mass algorithm. A truncated ellipsoid of revolution was used as a model for developing the algorithm because its shape closely resembles that of the left ventricle.Geiser and Bove'5 found that a similar model provided accurate left ventricular mass predictions from direct measurements of postmortem ventricular wall thickness. Figure 1 is a schematic representation of the long-and short-axis sections of the left ventricle as a truncated ellipsoid. This figure shows the locations of some of the minor-axis radii (semiminor axis) and the major-or long-axis segments (semimajor axis and truncated semimajor axis).Wall thickness was approximated from the short axis at the level of the papillary muscle tips by directly tracing and measuring t...

IntroductionThe purpose of the present study was to determine whether the abatacept autoinjector can be used by the intended population without patterns of preventable use errors, and is acceptable when assessed against key user needs.MethodsTwo independently conducted simulated-use studies, with no active drug administered, quantified use errors and evaluated the abatacept autoinjector and competitor devices on key attributes (comfort, control, ease of use, confidence of dose) and overall acceptability. Autoinjector preference was also assessed. Participants were patients with rheumatoid arthritis, caregivers, and healthcare professionals (HCPs). Participants were informed that a new rheumatoid arthritis autoinjector was being tested but were blinded to the intended drug and sponsor identity.ResultsIn the formative (pre-validation) study (n = 54), two high-priority use errors occurred, both of which resulted from protocol non-compliance rather than mental confusion or physical limitations. In the summative (validation) study (n = 99), one high-priority use error occurred; this was deemed a simulated-use study artifact as participant behavior was guided by actual experience associated with the feel of drug delivery into the skin rather than by protocol, so no mitigation steps were considered necessary. Across user groups, average scores were consistently high for the pre-defined key attributes. Overall acceptability scores (7-point scale) were significantly higher for the abatacept versus competitor autoinjectors—formative study: patients 6.7 vs 5.2 (P = 0.0001), caregivers 7.0 vs 4.6 (P = 0.0093), HCPs 6.8 vs 5.1 (P = 0.0020); summative study: patients 6.5 vs 5.9 (P = 0.0404), caregivers 6.8 vs 5.8 (P = 0.0047), HCPs 6.8 vs 5.1 (P = 0.0002). The abatacept autoinjector was preferred to competitor devices: patients 85.7% vs 14.3% (P = 0.00002), caregivers 84.2% vs 15.8% (P = 0.00443), HCPs 95.0% vs 5.0% (P = 0.00004). Positive experiences with the abatacept autoinjector were attributed to the rubberized grip, device size, visualization of dose progression, button ergonomics, and ease of use.ConclusionThe abatacept autoinjector demonstrated usability without patterns of preventable use errors, and with high acceptability ratings across all key attributes assessed. Preference over competitor autoinjectors was due to device ergonomics, visualization of dose progression, confidence of dose delivery, and overall ease of use.FundingBristol-Myers Squibb.Electronic supplementary materialThe online version of this article (doi:10.1007/s12325-016-0286-9) contains supplementary material, which is available to authorized users.

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