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Biomedical subjects

M Constantinescu

Publications and source records attributed to M Constantinescu.

At least 19 recordsLinked to original sources
PubMed1988

Predictive changes in ventricular interdependence.

Based on the balance of forces across the interventricular septum, we developed a theoretical analysis to explain how one ventricle can directly influence the filling characteristics of the other ventricle. The analysis indicated that the pressure and volume transfer were related to the relative compliances of the interventricular septum and ventricular free walls. The present study examined whether the theoretical analysis could be used to predict changes in ventricular interdependence caused by altering regional compliance. To examine this hypothesis, hearts were removed from 18 dogs and placed in cool cardioplegic solution. Balloons were inserted into each ventricle, and the left and right pressure (delta P1, delta Pr) and volume (delta V1, delta Vr) changes caused by changing the pressure and volume of the other ventricle were recorded. After the initial measurements, acute changes in left ventricular free wall compliance (n = 6), septal compliance (n = 6), and right ventricular free wall compliance (n = 6) were induced by glutaraldehyde injections. As predicted by the theoretical analysis, decreasing left ventricular free wall compliance increased delta P1/delta Pr, delta P1/delta Vr, delta Pr/delta V1, and delta Vr/delta V1 significantly (P less than 0.05) by 89 +/- 15, 155 +/- 33, 282 +/- 65, and 112 +/- 22% (mean +/- SEM), respectively. Decreasing septal compliance decreases delta P1/delta Pr, delta V1/delta Pr, delta V1/delta Vr, delta Pr/delta P1, delta Vr/delta P1, and delta Vr/delta V1 significantly (P less than 0.05) by 48 +/- 7, 71 +/- 10, 69 +/- 14, 48 +/- 7, 62 +/- 8, and 57 +/- 13%, respectively. Decreasing right ventricular free wall compliance increased delta P1/delta Vr, delta V1/delta Vr, delta Pr/delta P1, and delta Pr/delta V1 significantly (P less than 0.05) by 97 +/- 25, 79 +/- 20, 57 +/- 18, and 59 +/- 23%, respectively. Furthermore, these alterations in ventricular coupling were predictable: The actual and predicted percentage changes in the transfer functions were in close agreement. The results of these studies show predictable alterations in the mechanical coupling between the ventricles following changes in right ventricular, septal, and left ventricular free wall compliances.

Animals↗
PubMed1988

Alterations in left ventricular compliance due to changes in right ventricular volume, pressure and compliance.

Because of ventricular interdependence, part of the measured left ventricular diastolic pressure can be attributed to the right ventricle. Therefore, we examined the hypothesis that left ventricular diastolic properties are modified by alterations in right ventricular compliance and pressure even without a change in right ventricular volume. To examine this hypothesis, the hearts were removed from six dogs, the coronary arteries perfused with cool cardioplegic solution, and the hearts submerged in cool cardioplegic solution. Balloons were inserted into each ventricle. Left ventricular pressure-volume curves were recorded and approximated by an exponential equation. With no fluid in the right ventricular balloon (control), the exponential coefficient and constant were 0.038 (SD 0.004) ml-1 and 2.38(0.75) mm Hg respectively. With right ventricular pressure held constant at 20 mm Hg, the exponential coefficient and constant were 0.035(0.002) ml-1 and 3.71(1.64) mm Hg (p less than 0.05 v control constant), respectively. With a fixed right ventricular volume, the exponential coefficient and constant were significantly different (p less than 0.05 v control values) at 0.040(0.006) ml-1 and 2.81(0.96) mm Hg, respectively. After decreasing right ventricular free wall compliance by injecting glutaraldehyde into the right coronary artery, the exponential coefficient and constant were significantly different (p less than 0.01 v control values) at 0.058(0.010) ml-1 and 1.86(0.60) mm Hg, respectively. Thus, even with a constant right ventricular pressure or volume, a significant upward shift in the left ventricular pressure-volume relation occurred. Decreasing right ventricular free wall compliance further increased left ventricular pressure. The results of these studies indicate that the diastolic properties of the left ventricle can be modified by changes in right ventricular pressure and compliance even without a change right ventricular volume. Thus indices of left ventricular diastolic properties may be altered by changes in the characteristics of the right ventricle.

Animals↗
PubMed1988

Can coronary angiography predict the site of a subsequent myocardial infarction in patients with mild-to-moderate coronary artery disease?

To help determine if coronary angiography can predict the site of a future coronary occlusion that will produce a myocardial infarction, the coronary angiograms of 42 consecutive patients who had undergone coronary angiography both before and up to a month after suffering an acute myocardial infarction were evaluated. Twenty-nine patients had a newly occluded coronary artery. Twenty-five of these 29 patients had at least one artery with a greater than 50% stenosis on the initial angiogram. However, in 19 of 29 (66%) patients, the artery that subsequently occluded had less than a 50% stenosis on the first angiogram, and in 28 of 29 (97%), the stenosis was less than 70%. In every patient, at least some irregularity of the coronary wall was present on the first angiogram at the site of the subsequent coronary obstruction. In only 10 of the 29 (34%) did the infarction occur due to occlusion of the artery that previously contained the most severe stenosis. Furthermore, no correlation existed between the severity of the initial coronary stenosis and the time from the first catheterization until the infarction (r2 = 0.0005, p = NS). These data suggest that assessment of the angiographic severity of coronary stenosis may be inadequate to accurately predict the time or location of a subsequent coronary occlusion that will produce a myocardial infarction.

Adult↗
PubMed1987

Direct assessment of right ventricular transmural pressure.

Although the measurement of transmural pressure is important, calculation of transmural pressure is complicated by the difficulties in measuring pericardial pressure. Recently, flat balloons have been proposed to measure pericardial pressure. Over a wide range of volumes, right ventricular diastolic pressure and pericardial balloon pressure were similar in diastole, suggesting that the right ventricle is unstressed at physiologic volumes and that right atrial pressure can be used to estimate pericardial pressure. To evaluate these concepts and to assess indirectly the accuracy of measuring pericardial pressure using flat balloons, six canine hearts were examined postmortem. The pericardium was removed and the hearts were submerged in cold cardioplegic solution. Balloons were inserted into the right and left ventricles, and right and left ventricular pressure-volume curves were obtained. Right ventricular transmural pressures of 2.6 +/- 0.5, 3.9 +/- 0.9, 5.9 +/- 1.4, and 8.9 +/- 2.4 mm Hg were required to distend the right ventricle to 10, 20, 30, and 40 ml, respectively. For the left ventricle, transmural pressures of 3.4 +/- 0.7, 5.4 +/- 1.2, 8.6 +/- 2.1, and 14.1 +/- 3.8 mm Hg were recorded at volumes of 10, 20, 30, and 40 ml, respectively. Although the right ventricular transmural pressures were less than the left ventricular transmural pressures over the physiologic range, right ventricular transmural pressures were always positive and increased with increments in ventricular volume. Thus the right ventricle is not unstressed over the entire range of physiologic volumes, suggesting that pericardial balloon pressures may overestimate pericardial pressure and that right atrial pressure cannot be used to estimate pericardial pressure.

Animals↗
PubMedDate not supplied

Contribution of each ventricular wall to ventricular interdependence.

The influences of pressure and volume changes in one ventricle on the other ventricle may be determined from the relative compliances of the ventricular free walls and the interventricular septum. If this is correct, then disease states which alter regional compliances should influence the diastolic mechanical coupling between the ventricles. To examine this hypothesis, the hearts of 15 canine dogs were removed and placed in cool cardioplegic solution. Balloons were inserted into each ventricle and the right and left ventricular pressure (delta Pr, delta Pl) and volume (delta Vr, delta Vl) changes caused by changing the pressure and volume of the other ventricle were recorded. Acute changes in right ventricular free wall (N = 5), septal (N = 5), and left ventricular free wall (N = 5) compliances were induced by glutaraldehyde injections. After injecting glutaraldehyde into the right coronary artery, delta Pl/delta Vr, delta Vl/delta Vr, delta Pr/delta Pl, and delta Pr/delta Vl increased significantly (P less than 0.05). After septal artery injection, pressure and volume transfer between the ventricles was significantly depressed. After left coronary artery injection, delta Pl/delta Pr, delta Pl/delta Vr, delta Pr/delta Vl, and delta Vr/delta Vl increased significantly (P less than 0.05). Thus, selective alterations in the mechanical coupling between the ventricles occurred following changes in right ventricular, septal, and left ventricular free wall compliances. Such changes may be important in diseases which primarily affect one side of the heart.

Animals↗
PubMedDate not supplied

[Aortocoronary bypass].

Two cases are discussed, of severe myocardial ischaemia determined by coronary obstruction. The cases were solved by surgical treatment that consisted in direct myocardial revascularization with the aid of aorto-coronary by-pass with a fragment of autologous saphene vein.

Adult↗
PubMedDate not supplied

[Surgical treatment of interatrial septal defect].

On the basis of the authors' experience acquired between 1956 and 1973 (a total of 401 cases with inter-atrial communications and 234 cases of ostium secundum that have been operated by them), data are presented concerning the diagnostic means, the indications and the contra-indications of the surgical treatment, as well as the attitude to be adopted towards the associated lesions.

Adolescent↗
PubMedDate not supplied

[Personal experience with 2,500 closed heart mitral commissurotomies].

Between 1953 and 1976 a total of 2527 mitral commissurotomies have been performed in the Clinic for Cardio-Vascular Surgery of the "Fundeni" Hospital. This group included cases with pure mitral stenosis (predominantly following rheumatic disease), but also cases of mitral stenosis associated with other cardiac lesions in which the major hemodynamic element was the mitral obstruction. Criteria are discussed for surgery, the preoperative preparation of the patient, incidents, accidents and complications, as well as technical difficulties of the digital and/or instrumental mitral commissurotomies on closed heart, either carried out for the first time in the respective patient, or as iterative intervention. Comparing the results in relation with the functional stage of the disease (62.5% of the patients were classified in the III-IV evolutive degree, according to the NIHA classification), pulmonary hypertension (61.6% of the patients had medium or severe pulmonary hypertension), associated lesions (present in 17% of the cases--mitral failure predominated, together with tricuspid or aortic failures), it is appreciated that the technique of mitral commissurotomy on closed heart is an useful therapeutic method (88.6% very good and good results, a global death rate of 3.9%) that can be applied in a large category of patients, although there is a trend toward open-heart surgery, with all medico-economical major implications.

Humans↗
PubMedDate not supplied

[Observations on 35 cases of strongyloidiasis hospitalized at a clinical digestive disease unit].

After a short presentation of the etiopathogenesis of this parasitosis, the authors report their observations on 35 cases of strongyloidiasis followed in the recent years. On the basis of the epidemiologic and clinical analyses of these cases, the authors show that some data, i.e. those on the environment to which the patients belong, or their occupation, and also some clinical manifestations (clinical polymorphism) may suggest the diagnosis of strongyloidiasis in the immunosuppressed in about 30% of the cases. An associated blood eosinophilia may be a more possible for the diagnosis of strongyloidiasis. The positive diagnosis has to take into consideration, beside the repeated diet exam, the method of cultures and also jejunal biopsies, which may also verify the efficiency of the treatment recommended. The authors recommend the treatment with Mintezol and, with lower results, Vermigal and Mebendazol.

Adult↗