[Estimate of the systolic parietal stress of the left ventricle by magnetic resonance imaging. A new approach to the study of the overload].
OBJECTIVE
To determine the systolic parietal stress of the left ventricle by image of magnetic resonance in healthy subjects.


METHODS
21 healthy subjects studied: 11 male and 10 female: the ages among 26 and 31 years (29.33). A magnetic resonance of heart was made using the short axis at the level of the papillary muscles, from where the epicardic and endocardic areas of the left ventricular cavity were obtained in diastolic as in systolic by means of the layout with an electronic pencil, later the radius of each drawn up area was calculated, with the value of the radius, the diastolic and systolic thickness was calculated; to obtain the relation between thickness/radio. Once the relation was obtained between thickness/radio in diastole as systole the degree of change between both values and the percentage of this change was calculated. Finally, the systolic parietal stress developed by the left ventricle was calculate with the following formula: S = PVI x A4/A3-A4 x 1.35.PVI: systolic pressure of the left ventricle (the average of 5 synchronized systolic arterial pressures, obtained by an esphingomanometer). A4: endocardic area in systole; A3: epicardial area in systole. The value obtained in this equation was multiplied per 1.35 to turn mmHg gm/cm2.


RESULTS
The average of the arterial systolic pressure was of 103.24 +/- 10.27 mmHg; A3 (average 27.58 +/- 2.29); A4 (average 6.84 +/- 0.71); being the systolic stress of the left ventricle of 46.12 +/- 4.9 gm/cm2, not existing significant differences between sexes.


CONCLUSIONS
With this new method it is possible to determine with greater exactitude in a noninvasive way, through the best definition of its epicardic and endocardic edges, the areas and the radio of the left ventricular cavity in systole as in diastole, to determine the thickness of the wall and its relation with the radius, for one better valuation of the ventricular function, specially in those subjects with overloads of volume or pressure that depress the ventricular function.
Cué Carpio
José Ramón
JR
Instituto Nacional de Cardiologia "Ignacio Chávez" (INCICH, Juan Badiano No. 1 Col. Sección XVI, Tlalpan 14080, México, DF.
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Aloha
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Guadalajara Boo
José Fernando
JF
D000328:Adult; D055592:Biophysical Phenomena; D001703:Biophysics; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D013314:Stress, Mechanical; D013599:Systole; D016277:Ventricular Function, Left