Biomedical subjects
R Gourgon
Publications and source records attributed to R Gourgon.
[Methodology of hemodynamic study of a vasodilator drug (author's transl)].
The mechanism of action of a vasodilator drug is complex and depends on its predominant site of action: arterial or venous system. it leads to a) complex alteration of ventricular load that changes cardiac output, b) alteration of myocardial energetic metabolism. To classify a vasodilator drug, it is useful to study: a) its mechanism of action on the peripheral vascular system, b) the left ventricular function, and c) the coronary blood flow and the myocardial metabolism. The peripheral action of the drug is assessed by simultaneous measurement of peripheral blood flow, arterial pressure and venous pressure. From these data, arterial resistance (AR) and venous tone (VT) are calculated. A change of AR and for VT permits to classify a vasodilator drug as arterial, venous or both arterial and venous. Changes of factors of ventricular load are appreciated by measurement of aortic pressure, left ventricular pressure and ventricular volumes. If no change of heart rate occures, modification of stroke volume and cardiac output is due to a reduction of end diastolic volume (venous vasodilator drug) or of end systolic volume (arterial vasodilator drug).
Post-extrasystolic left ventricular peak pressure with and without left ventricular failure.
18 patients without valvular pathology, coronary artery disease, or idiopathic hypertrophic subaortic stenosis were haemodynamically and angiographically investigated in order to analyse the effects of a ventricular extrasystolic beat upon the post-extrasystolic left ventricular peak pressure. In eight normal patients (group I), the post-extrasystolic peak pressure (P.ES.P.P.) was lower than that of the pre-extrasystolic beat; in 10 patients with symptoms of left ventricular failure (group II) the P.ES.P.P. significantly increased. The reasons are: 1) cardiac origin: stroke volume increased more in group II; 2) arterial origin. a) aortic compliance was lower in group II (this is probably related to the older age of patients in group II), and by decrease in end-diastolic aortic pressure was smaller in group II. Part of this arterial effect (2b) may probably be explained from the fact that post-extrasystolic compensatory pauses are equal in both groups, but the decay time of arterial pressure during diastole (assuming an exponential decay) is larger in group II. At the same age and with the identical aortic compliance only the two factors 1 and 2b play a part in the changes in P.ES.P.P.
Study of left ventricular pressure-volume relations during nitroprusside infusion in human subjects without coronary artery disease.
Studies were made on 21 patients, 8 without any symptoms of left ventricular failure, group 1, and 13 with clinical symptoms of heart failure, group 2. Cardiac output, mean aortic and left ventricular pressures (using catheter tip micromanometer), and ventricular volume (obtained from left ventricular cineangiograms) were measured before and during nitroprusside infusion. The heart rate did not change in either of the groups. Only in group 2 did cardiac index and stroke volume increase significantly. Mean aortic pressure and total systemic vascular resistance decreased significantly in both the groups. Left ventricular end-diastolic pressure decreased significantly in both the groups, but this decrease was greater in group 2 (9 mmHg compared with 3 mmHg for group 1). The decrease in the left ventricular end-diastolic volume was similar in both the groups. The decrease in left ventricular end-systolic pressure was greater in group 1, but the decrease in the left ventricular end-systolic volume was greater in group 2. These facts are explained by the differences in the active and passive left ventricular pressure-volume relations in the two groups.
[Hemodynamic changes during increasingly rapid atrial pacing].
The cardiac output (Qc), indices of left ventricular function in the isovolumic period (dp/dt/Pt), max, and during the ejection period (EF, VCF), the end diastolic and end systolic ventricular volumes, the speed of ventricular filing, the module of elasticity of the ventricular chamber (kp) and the end systolic pressure-volume relationships were measured in 20 patients (11 normal in group I and 9 with and apparently primary cardiomyopathy in group II) at rest and during progressively rapid atrial pacing. The Qc was lower and the indices of left ventricular function in the isovolumic and ejectional phases, the end systolic pressure-volume relationship and speeds of ventricular filling were decreased in group II: kp was the same in both groups of patients. At progressively higher heart rates the cardiac output slightly in both groups, the systolic volume decreased, (dp/dt/Pt) max increased, the ejection fraction and VCF were unaltered. The speeds of filling and kp were unchanged. The end systolic pressure-volume relationship increased. In group I the reduction in systolic volume seemed to be related to a greater reduction in the end diastolic volume than in the end systolic volume. In group II, the reduction of the systolic volume was related only to a reduction of the end diastolic volume.
[Multicenter epidemiological survey of primary myocardiopathies. Apropos of 380 cases].
A retrospective study of adult congestive cardiomyopathy was carried out; the admission criteria being heart failure with cardiomegaly after the exclusion of known causes of heart failure. Coronary artery disease was excluded by forming two sub groups, one with proven normal coronary arteries at angiography or autopsy and the other with only assumedly normal coronary arteries. The results concern the study of the incidence of this disease which has been regularly seen over the last 10 years in departments with a large number of referrals of cardiomyopathy. --Professional factors are analysed to see if there is a higher incidence amongst the working classes. --Other factors are analysed by comparison with three control groups: normal, coronary and valvular disease, and diabetes which may be a predisposing factor, but not the serum cholesterol which is decreased in these patients. There is a significant association with smoking and alcoholism and the main biological sign of the latter condition, macrocytosis. This is also found in both coronary sub groups. The isolation of this alcohol factor in the genesis of congestive cardiomyopathy implies the possibility of reversing or stabilising the myocardial damage after its withdrawal, so changing the severe diagnosis associated with this disease.
[Two dimensional echocardiography in acute myocardial infarction].
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Mechanical circulatory assistance by intra-aortic balloon pumping for the treatment of cardiogenic shock.
Although the shock state due to acute myocardial infarction may be reversed by IABP in 80 per cent of patients, 55 to 65 per cent remain balloon-dependent. Therefore some attempt to correct the underlying anatomic abnormalities (reversible ischaemic areas and/or mechanical defects) appears necessary if these patients are to survive. With IABP catheterization studies performed in these critically-ill patients are well tolerated. Myocardial depression after cardiopulmonary by-pass is often related to subendocardial ischaemia. The combination of IABP and surgery has resulted in survival of approximately 50 per cent of patients in cardiogenic shock secondary either to a mechanical defect complicating myocardial infarction or to open-heart surgery.
Evaluation of the elasticity and characteristic impedance of the ascending aorta in man.
In 30 patients, simultaneous measurements of ascending aortic pressure and diameter were performed, allowing one to evaluate: (1) the influence of age, the aortic diastolic pressure, and the radius on the aortic elasticity; (2) the correlations between characteristics impedance of the aorta (Zo), systemic arterial resistance, age and diastolic aortic pressure; and (3) the importance of Zo when comparing two indices of left ventricle performance; one during isovolumic phase ([dP/dt]/Pt)max and the other during the outflow phase (maximum acceleration of aortic blood flow).
[Hemodynamic and coronary effects of atrial stimulation in normal subject and patients with coronary disease: correlation with coronary arteriography].
Thirty-two patients (group I: 7 normal subjects; group II: 25 coronary subjects) underwent coronary arteriography, and measurements were made both in normal rhythm and under atrial stimulation of the pulmonary capillary pressure and the pressure in the femoral artery, of cardiac output, of coronary sinus flow (by continuous thermodilution), of the coronary arterio-venous oxygen difference, of oxygen consumption, and in 28 of the patients of the coefficient of extraction of K lactates. During stimulation, the only differences to appear between the subjects of group I and group II were an increase in capillary pressure (p less than 0.01) and a decrease in the coefficient of extraction of lactates (p less than 0.001) in the coronary patients. Similar differences were found between coronary patients with a stenosis greater than 70% in the anterior descending or circumflex artery (group IIa) and those without it (group 11b), and between the patients with pain during atrial stimulation (n = 9) and those without it. There was a good correlation between a double score (IVA + circumflex artery, Rowe's method) and the coefficient of extraction of lactates during atrial stimulation (n = 28, p less than 0.01).
[Comparison of hemodynamic and coronary effects of 2 antianginal vasodilator drugs: nifedipine and trinitrine].
Twenty patients with coronary insufficiency had measurements taken while they were in normal rhythm (NR) and during atrial pacemaking (AP) before and after taking nifedipine (n: 12) or after intravenous perfusion of trinitrin (n: 8): measurements were taken of pulmonary capillary pressure (PCP), arterial femoral pressure (AFP), cardiac output (QC) and coronary sinus flow (QCS), coronary arterio-venous oxygen difference (DaVO2), myocardial oxygen consumption (MVO2) and the myocardial coefficient of extraction of lactates (K).--Under nifedipine in NR and AP, AFP was decreased and QC increased. QSC was increased in NR, but was not changed under AP. DaVO2 was shortened under both sets of conditions. MVO2 decreased only during AP. Nifedipine brought back to normal the lowering of K which occurred with pacemaking.--Under trinitrin, both in NR and under AP, AFP, PCP, QC, QSC and MVO2 were lowered. K and DaVO2 were unchanged.--A plethysmographic study in 13 patients showed that these haemodynamic effects could be explained by the arterial vasodilator action of nifedipine which occurred without changing the venous tone, and the mixed action of trinitrin.
[The prevention of recurrent pulmonary emboli using a Mobin-Uddin filter (author's transl)].
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[Cardiac output in acromegaly. Effects of hypophysectomy and somatostatin].
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Clinical and hemodynamic results of intraortic balloon counterpulsation and surgery for cardiogenic shock.
Forty-two patients with cardiogenic shock (CS) secondary to myocardial infarction were treated with intra-aortic balloon pumping (I.A.B.P.). In 14 patients C.S. was associated with ventricular septal defect (V.S.D.) and in four with mitral regurgitation (M.R.) secondary to rupture of the posterior papillary muscle. All patients were resistant to conventional medical therapy. Shock was reversed in 20 of the 24 patients in C.S. without mechanical complications. After 24 to 48 hours of I.A.B.P., cardiax index (C.I.) increased from 1.38 to 2.00 L./min./M2, systolic arterial pressure (S.A.P.) from 83 to 96 mm. Hg, urinary output (U.O.) from 10 to 56 ml. per hour, and pulmonary wedge pressure (P.W.P.) decreased from 22 to 16 mm. Hg. Three patients treated with I.A.B.P. alone survived more than 1 year; of the 13 patients who were balloon dependent, four have undergone emergency surgical procedures and two were long-term survivors. In all patients with mechanical complications, I.A.B.P. resulted in significant clinical and hemodynamic improvement. P.W.P. decreased from 19 to 15 mm. Hg, and U.O. increased from 13 to 38 ml. per hour while S.A.P. remained unchanged. In patients with V.S.D. the pulmonary/systemic flow ratio (P/S) declined from 3.5 to 2.8; in patients with M.R., "V" wave amplitude decreased by 8 mm. Hg. Emergency surgery was performed in 10 patients with V.S.D. and in three patients with M.R. and there were eight long-term survivors (13 to 27 months). It is concluded that I.A.B.P. is an effective means of supporting the circulation in C.S. Of the 42 patients with C.S. treated by combining I.A.B.P. and emergency surgery, 13(31%) were long-term survivors (20 +/- 6 months).
[Role of the characteristic impedance of the ascending aorta in the evolution of indices of left ventricular performance during the ejection stage].
In this study of 61 patients (group I: 37 patients with no signs of cardiac failure, group II: 24 patients with signs of cardiac failure), a comparison is made between the indices of left ventricular performance obtained during the isovolumic phase dp/dt/Pt max of the left ventricle (5F Millar micromanometer) and in the ejection phase (ejection fraction, mean speed of fibre contraction, corrected mean systolic ejection speed (left ventricular cineanigiography) and maximal acceleration of the aortic blood flow (electromagnetic velocimeter). Calculations were also made of the modulus of elasticity (Ep) and the characteristic impedance of the ascending aorta (Zo) in every patient. The results show that, for group I patients the correlation between the indices in the isovolumic and ejection phases is improved by taking Zo into account. This result is not true for group II cases except with respect to the acceleration of aortic blood flow. An analysis has been made of the hypotheses and the discrepancies.
[The relationship between left ventricular end-systolic pressure and volume. Comparative study of changes in load and inotropism].
This work consists of a comparison of the indices of left ventricular performance measured during the isovolumic nad/or ejection period under changes in load and inotropism, and of the findings on measuring the pressure/volume ratio of the left ventricle. The indices of performance of the left ventricle. The indices of performance of the left ventricle during the ejection phase (ejection fraction, mean speed of fibre shortening, mean standardised speed of systolic ejection) and the ratio pressure/volume were listed for 36 patients, 21 of them before and after perfusion with nitroprussiate, in 6 before and after perfusion of angiotensine, and in 9 from the group before and after post-extra-systolic potentialisation. The indices of left ventricular performance during the isovolumic (formula see text) were measured in 24 of these patients, 15 of them before and after nitroprussiate, and 9 before and after post-extra-systolic potentialisation. These results show that the level of the pressure/volume ratio at the moment of end-systole is independent of the conditions of load--to a greater extent than any other index measured during the isovolumic period or ejectional period--and appears to be thoroughly related to the changes of inotropism.
[Vasodilator treatments in left ventricular insufficiency. Physiopathogical bases and indications].
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[Interruption of the inferior vena cava by the Mobin-Uddin filter: indications and results in 37 cases].
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