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Biomedical subjects

H Rijsterborgh

Publications and source records attributed to H Rijsterborgh.

26 records · Page 2Linked to original sources
PubMed1987

A simplified mitral valve method for two-dimensional echo Doppler blood flow calculation: validation in an open-chest canine model and initial clinical studies.

Quantitative two-dimensional Doppler echocardiography is increasingly used for the calculation of cardiac blood volumes. This study evaluates a simplified method for measuring volume flow at the mitral valve orifice. In four open-chest dogs the simplified mitral valve method was compared to a previously described mitral orifice method for Doppler volume flow calculation and to data obtained by electromagnetic flow measurement. Cardiac output varied from 1.4 to 7.7 L/min. Correlation for both the Doppler method and the electromagnetic meter volume flows was r = 0.98 to 0.99, and there was no significant difference between the two methods. In a clinical pilot study, 10 children were studied in the catheterization laboratory, and the simplified Doppler flow method was compared to thermodilution cardiac output measurements with good results. The study indicates that the simplified mitral valve method provides acceptable accuracy for Doppler cardiac output measurement.

Animals↗
PubMed1987

Doppler assessment of aortic stenosis: Bernoulli revisited.

The application of Bernoulli's law allows the non-invasive estimation of pressure drops across stenotic valves from Doppler velocity measurements. However, several assumptions are to be made, which influence the accuracy of the pressure drop estimation. Energy losses, non-uniform velocity profiles, pressure recovery, unsteady flow and omission of the upstream velocity affect accuracy and are critically reviewed. In vitro experiments, published in the literature, show good correlations between estimated and actual pressure drop. In only one of these studies does the data allow a comparison between theory and practice and to study the relationship between the pressure drop at the inlet of the obstruction and the Doppler velocity measurement. It appears that this relationship is not completely described by the simplified Bernoulli equation. In vivo verifications of Bernoulli's law show favourable correlations. However, the expected differences between peak pressure drops measured by cardiac catheterization and the pressure drops estimated by Doppler echocardiography may be as high as 25 mmHg.

Aorta↗
PubMed1984

Reference ranges of echocardiographic measurements in the Dutch population.

Reference ranges for echocardiographic measurements were determined in 609 healthy Dutch subjects, using height, weight, age, sex, RR-interval and blood pressure (in adults only) as determinants. End-systolic as well as end-diastolic measurements of the aortic root as well as left ventricular inner diameter, posterior and septal thickness were taken, as was the left atrial end-systolic diameter. Multiple linear regression was performed of the form: M = A.(age)B.(height)C.(weight)D.(RR-interval)E.(sex)F. The residuals were calculated in order to determine the percentile limits by means of linear interpolation. Sex and weight were significant determinants in all the echocardiographic parameters studied. The results were presented twofold, with a simple version for males and females separately, using only weight as a determinant and allowing graphical presentation, and secondly a complex version taking into account all determinants, which can only be solved with help of a calculator.

Adolescent↗
PubMedDate not supplied

On the aliasing problem in pulsed Doppler cardiac studies.

In pulsed Doppler echocardiography the maximum measurable velocity is limited due to the aliasing phenomenon. Particularly in cardiac echo studies in adults, aliasing may occur frequently. The principle of and the parameters that influence aliasing will be explained. The importance of aliasing is demonstrated in examples of tricuspid, mitral, and aortic Doppler echocardiographic studies in adults. Ways to reduce or avoid aliasing are presented.

Adult↗
PubMedDate not supplied

Histopathologic validation of intracoronary ultrasound imaging.

The purpose of this study was to validate intracoronary ultrasound imaging by correlation with histologic examination. In this in-vitro study of pressure-perfused human coronary arteries, 104 matching intracoronary ultrasound imaging images and histologic cross-sections from 12 hearts were compared to determine the diagnostic accuracy of 30 MHz commercially available intracoronary ultrasound imaging. For lipid deposits, sensitivity was 46% and specificity 97%. The smallest lipid deposit that was visualized measured 0.25 mm in axial diameter on histologic study. For calcific deposits, sensitivity was 77% and specificity 100%. The smallest calcific deposit that was visualized measured 0.25 mm in axial diameter on histologic examination. Atherosclerotic intimal thickening could not be distinguished qualitatively or quantitatively from nonatherosclerotic intimal thickening unless there were localized deposits of lipids or calcium. Intracoronary ultrasound imaging is accurate in detecting lipid and calcium deposits. Intimal thickening in intracoronary ultrasound imaging images does not prove the presence of atherosclerosis.

Adult↗
PubMedDate not supplied

Reference ranges of left ventricular cross-sectional echocardiographic measurements in adult men.

Reference ranges for left ventricle cross-sectional echocardiographic measurements were determined in 67 healthy Dutch men. Age, weight, height, and heart rate were used as the determinants. The images were made with the apical long-axis view, and the calculations were done with the area-length method. The end-diastolic volume, end-systolic volume, stroke volume, and ejection fraction were measured for six consecutive cardiac cycles in every subject and were averaged. Data were analyzed by means of both simple linear regression and multiple linear regression after logarithmic transformation of all measurements. Weight proved to be the best predictor of the echocardiographic end-diastolic volume, end-systolic volume, and stroke volume. The left ventricular ejection fraction could be regarded as independent of the determinants studied. Nomograms of the 5th, 50th and 95th percentile limits were made of the echocardiographic parameters versus weight.

Adult↗
PubMedDate not supplied

Can we assess the changes of ventricular filling resulting from acute allograft rejection with Doppler echocardiography?

We investigated the value of several Doppler echocardiographic measurements for the diagnosis of acute allograft rejection after orthotopic heart transplantation. In all, 144 transmitral flow velocity curves and 159 internal jugular venous flow velocity curves were recorded by continuous wave Doppler echocardiography, and the results were compared with the histologic findings. The recordings were evaluated with a computer-aided analysis system. The Doppler measurements did not show any significant correlation with the biopsy results. Only one recording obtained during a moderate acute rejection episode supported the hypothesis about the relation between jugular venous flow and cardiac rejection. We conclude that these Doppler echocardiographic measurements are not suitable to detect acute allograft rejection noninvasively.

Adult↗