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[An evaluation of right ventricular compliance (author's transl)]
Abstract:
Right ventricular "compliance" and "stiffness" in a casuistry of 51 patients were studied with varied pressure loads, using the "specific compliance" (SC) index proposed by Smith and coll. (1974) for the left ventricle and the "stiffness" constant proposed by Gaasch and coll. (1972, 1975). The pateints were subdivided according to a hemodynamic criterion, on the basis of telediastolic volume values (RVEDV) and telediastolic pressure (RVEDP) of the right ventricle. The average "specific compliance" was 0.1203 +/- 0.0283 in patients with RVEDP below or equal to 7 mmHg and 0.0517 +/- 0.0269 in those with RVEDP greater than 7 mmHg. In these two groups, the respective average values of the "stiffness" constant were 0.0136 +/- 0.0007 and 0.0210 +/- 0.0016. Comparison of the groups showed a significant statistical difference among the indices. In the subdivision into groups with telediastolic volume, the average SC values were respectively 0.0832 +/- 0.0083 in the patients with RVEDV below 150 ml/m2; 0.1131 +/- 0.0375 in the patients with RVEDV between 150 and 200 ml/m2; 0.0650 +/- 0.0132 in the patients with RVEDV above 200 ml/m2. None of the three groups demonstrated statistically significant differences. In the telediastolic volume groups, the average values of the "stiffness constant" were respectively: 0.0235 +/- 0.0020; 0.149 +/- 0.0007; 0.0117 +/- 0.0006. A comparison of the three groups showed statistically significant differences for this index. The authors consider that in pressure overloading of the right ventricle with different etiopathogenesis of "stiffness" and "compliance" indices, based on the measuring of volume and pressure, are unable to give absolute measuring of the physical characteristics of the ventricular walls. Thus, recourse to methods that can evaluate wall "stress" are necessary. However, the parametres considered are quite useful for indicating the variations of ventricular distensibility in homogenous casuistries and are therefore comparable.