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Biomedical subjects

M Chevigné

Publications and source records attributed to M Chevigné.

13 recordsLinked to original sources
PubMed1987

Quantification of valvular regurgitation using radioisotopes.

Mitral and aortic regurgitations impose an abnormal volume overload on the left ventricle. Recent advances in radionuclide angiographic measurements of all cardiac volumes have made this a practical technique for the detection, quantification and functional assessment of valvular regurgitations and shunts. The method is based on the comparative evaluation of total and effective left ventricular stroke volume. In the radionuclide technique, the right ventricular stroke volume is most frequently used to represent the effective left ventricular stroke volume although techniques have been presented which used as reference the left ventricular stroke volume calculated from measurements of heart rate and cardiac output (Fick method or dye dilution or scintigraphic techniques). The technique can be performed either during first-pass or at equilibrium. Equilibrium measurements are performed in the left anterior oblique position. The stroke volume ratio and the regurgitant fraction are calculated. This technique has been shown to provide adequate quantitative measurements of mitral and aortic regurgitations. Its specificity is adequate with careful positioning and if regions of interest are determined and care is taken to exclude inadequate studies (as these can be prospectively recognized). The technique can separate moderate from severe regurgitation, provide follow-up values for both left ventricular volume and regurgitant fraction, and assess the effect of interventions on the amount of regurgitation. The technique is, however, not adequate to detect mild or minimal regurgitation. In conclusion, equilibrium scintigraphic measurement of valvular regurgitation is an attractive new technique for measuring valvular regurgitation. Its clinical value lies in its simplicity, its reproducibility and its wide applicability. Its accuracy will be improved by performance of gated tomographic acquisitions.

Adaptation, Physiological↗
PubMed1987

Value, sensitivity and specificity of stroke volume ratio in routine equilibrium gated scintigraphy.

The stroke volume ratio (SVR) is a new, non invasive method to quantify ventricular volume overload (VVO). We have analyzed its value, sensitivity and specificity in routine clinical practice. The results of 238 consecutive patients (pts) were analysed prospectively within a 3 months period. The SVR was expressed as the ratio of left ventricular (LV) stroke counts over the right ventricular (RV) stroke counts measured on the time-activity curves. One region of interest was drawn per ventricle on the phase and amplitude images. Values above 1.6 were considered as LVVO and below 0.9 as RVVO. Fifty-one patients had VVO due to valvular regurgitation or left-to-right shunt; 187 patients had no evidence of VVO. Mean value obtained for 23 normal subjects with adequate positioning was 1.27 +/- 0.14 (MV +/- SD), ranging from 0.9 to 1.47. Among patients with adequate positioning, no difference was observed in subgroups with dilated cardiopathy (DC) or anteroseptal aneurysm (AA) despite a low EF. MV for patients with LV or RV hypertrophy (H) were statistically different. Sensitivity was 82% for the 51 patients with VVO. False negatives were due to biventricular overload or mild VVO. Specificity evaluated in the 187 patients without VVO was 76%. The 45 false positives were due to poor separation of the right cardiac chambers and/or of the 2 ventricles. They were observed in 4 patients with AA, 3 patients with DC, 7 patients with LVH, 4 patients with RVH and 24 patients with inadequate positioning. No explanation was found in 3 patients. We conclude that cardiac equilibrium blood pool scintigraphy has an adequate sensitivity and specificity to evaluate patients with VVO.

Cardiomegaly↗
PubMed1985

Evaluation of the effects of molsidomine by cardiac equilibrium blood pool scintigraphy.

We have used equilibrium gated blood pool scintigraphy to evaluate the hemodynamic effects and duration of action of molsidomine, a new peripheral vasodilator antianginal drug, after sublingual administration (4 mg) in five patients with heart failure. The following parameters were studied at rest and 10, 60, and 240 minutes after drug administration: left and right ventricular ejection fractions, end-diastolic and end-systolic volumes, stroke volume, heart rate, and cardiac index. Systolic and diastolic blood pressures were determined by cuff measurement. Statistically significant (p less than 0.05) changes were observed after 10 minutes for left ventricular ejection fraction (+26.2%), left and right end-diastolic volume (-12.4% and -15.2%), left ventricular end-systolic volume (-15%), and cardiac index (+7.9%); after 60 minutes for left ventricular ejection fraction (+49%), left ventricular systolic volume (+30.5%), cardiac index (+29.7%), systolic blood pressure (-7.9%), and right ventricular end-diastolic volume (-14.3%); and after 240 minutes for cardiac index (+23.9%), systolic blood pressure (-6.3%), and right ventricular ejection fraction (+23.1%). No changes in heart rate were observed. No patient experienced any side effect. We conclude that the hemodynamic improvement observed with molsidomine can be prolonged and results both from preload and afterload reduction.

Adult↗
PubMed1984

Effect of ticlopidine on saphenous vein bypass patency rates: a double-blind study.

The effects of ticlopidine, a new antiplatelet agent, on graft patency rate was investigated in a group of 150 consecutive patients undergoing aortocoronary bypass graft procedures. In a double-blind study, two groups of 75 patients each received ticlopidine (250 mg twice daily) or a placebo during a three-month period. Graft patency was evaluated by repeat angiography in 38 patients and by rest and stress myocardial scintigraphy in 93. Combined angiographic and scintigraphic analysis was performed in 36 patients. The biological effects of ticlopidine on platelet activity were assessed by bleeding time and appropriate ex vivo tests. Graft patency was evaluated in 131 patients (87%). Evaluation was performed at the end of the three-month therapy period in 77 patients (Groups T1 [ticlopidine] and P1 [placebo]) and five months later in 54 patients. The total graft attrition rate was 10.1% in Group T1 compared with 20.3% in Group P1 (p less than 0.1). Excluding patients with discordant biological data, the attrition rate was 7.1% for Group T1 compared with 21.8% for Group P1 (p less than 0.02). There was no difference between the subgroups evaluated five months after the end of therapy. Ticlopidine appears to be an effective means of protecting graft patency as long as the biological effects of the drug are present. This protective effect disappears when the drug is discontinued, which suggests that ticlopidine should be prescribed for a longer period, at least for the first year after operation.

Coronary Artery Bypass↗
PubMed1983

Radiocardiographic evaluation of left ventricular function after inhalation of C15O2.

Inhalation of C15O2 delivers a bolus of labelled water into the pulmonary veins and the left atrium; analysis of the left ventricular curve provides an easy method for the evaluation of left ventricular function. the patient was seated before six collimated probes positioned toward the lungs. An additional probe was directed toward the heart in a modified 15 to 20 degrees left anterior oblique projection. One to two mCi C15O2 was administered per study. The left ventricular curve was analysed and the ejection fraction was calculated using a new method. The background was first calculated for the cycle with the largest diastolic counts using characteristic points of the curve before and after transit of the indicator through the left ventricle. For the other cycles, the background was considered to be a constant fraction of the end-diastolic counts. The left ventricular ejection fraction was obtained for each cycle after corresponding background subtraction as the ratio of diastolic activity minus systolic activity over diastolic activity. The ejection fraction thus determined in 20 patients was highly reproducible from beat to beat and from study to study in the same patient (r = 0.97 and 0.96). It corresponded closely to the ejection fraction determined using a camera-computer system (r = 0.92). We conclude that C15O2 inhalation is an easy, rapid, reproducible and attractive method to assess left ventricular function.

Adult↗
PubMed1983

Radioisotopic studies during exercise testing: how valuable?

Myocardial imaging and exercise radionuclide angiography have proven useful in the detection of exercise-induced regional dysfunction. EF monitoring is, however, inadequate to detect deterioration of cardiac performances with complex changes in the ventricular loading conditions. Measurement of absolute volumes and especially of end-systolic volume by a count-derived technique will further enhance the value of this method when attenuation correction can be consistently performed. Non-invasive estimates of end-systolic indices could then be obtained. Concomitant evaluation of right ventricular ejection and function provides data on ventricular interdependence and allows quantification of regurgitant lesions and of their changes with exercise. Combined evaluation of these parameters will allow a better definition of the changes occurring in valvular heart disease. Radioisotopic studies also permit evaluation of stress-induced changes in pulmonary blood volume and in the pulmonary distribution of thallium. These parameters, although incompletely studied, could provide further evidence of transient LV dysfunction and deserve further study.

Aortic Valve Insufficiency↗
PubMed1982

Hemodynamic response to glyceryl trinitrate in a spray at rest and during exercise in a sitting position.

Glyceryl trinitrate (GNT, 0.8 mg) was administered in a spray to 15 coronary patients of whom 7 had a pulmonary wedge pressure (PWP) greater than 16 mm Hg on exercise (subgroup I) and the others (subgroup II) had a normal PWP at rest and during exercise. At rest, GNT increased heart rate and decreased cardiac output, systolic index, stroke work index, right atrial pressure, pulmonary wedge and mean systemic pressures in all patients. Peripheral resistances did not change. During exercise, GNT lowered PWP, systemic arterial pressure and peripheral resistances in all cases. It increased cardiac output as well as systolic and stroke work indices only in patients of subgroup I. In subjects with coronary disease, no overt cardiac failure but elevated PWP on exercise, GNT in a spray can quickly improve exercise capacity and hemodynamic reserves and increase anginal threshold.

Administration, Oral↗
PubMed1982

Measurement of left-to-right shunts by gated radionuclide angiography: concise communication.

Gated cardiac blood-pool scans allow comparison of left- and right-ventricular stroke volume. We have applied these measurements to the quantification of left-to-right shunts (QP/QS) in nine patients with atrial septal defects, one patients with partial anomalous pulmonary venous return, four patients with ventricular septal defects, and two patients with patent ductus arteriosus. None of these patients had combined lesions. QP/QS was measured as the right-ventricular (RV) stroke counts divided by the left-ventricular (LV) stroke counts and as the LV stroke counts divided by the RV stroke counts in patients with RV and LV diastolic volume overload respectively. All patients had also QP/QS measurements by oximetry and first-pass radionuclide angiography. The stroke-count measurements indicated the overloaded ventricle in all patients. QP/QS determined by equilibrium gated studies correlated well with those obtained by oximetry (r = 0.79). Reproducibility of the equilibrium measurements was good. We conclude that gated cardiac blood-pool scans can measure left-to-right shunts and can distinguish between shunts with RV and LV volume overload.

Adolescent↗
PubMed1981

Prognostic value of thallium-201 stress myocardial scintigraphy with exercise ECG after myocardial infarction.

The prognostic value of stress electrocardiogram and thallium-201 stress myocardial scintigraphy was analyzed in 224 patients 3 months after a myocardial infarction; both techniques allowed an adequate stratification based on the presence of ST depression or multivessel disease. Combining stress electrocardiogram and stress myocardial scintigraphy data improved the prognostic ability, particularly in patients who associated multivessel disease and ST depression.

Aged↗