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Biomedical subjects

F Larrazet

Publications and source records attributed to F Larrazet.

27 records · Page 2Linked to original sources
PubMed1997

Right and left isovolumic ventricular relaxation time intervals compared in patients by means of a single-pulsed Doppler method.

Right and left isovolumic ventricular relaxation time intervals measurements were obtained as follows: from the peak R wave on the electrocardiogram to either the mitral or the tricuspid pulsed Doppler flow trace onset minus the R to end-ejection zero flow crossing of the subaortic (left side) or pulmonary (right side) D flow trace time interval. A ratio was calculated as a percent difference duration between both isovolumic ventricular relaxation time intervals. The aim was to compare isovolumic ventricular relaxation time interval values in 42 healthy controls and to study the changes induced by heart diseases in 27 patients with (1) controlled hypertension without left ventricular hypertrophy, (2) hypertrophic cardiomyopathy, and (3) Cor pulmonale. Mean values of isovolumic ventricular relaxation time intervals significantly differed at paired and unpaired studies, with right isovolumic ventricular relaxation time intervals shorter than those of the left side in all groups (p < 0.001) except for patients with Cor pulmonale. Isovolumic ventricular relaxation time intervals did not correlate with heart rate and moderately correlated with left ventricular mass and age. No significant difference was found between healthy controls and patients with controlled hypertension. Significant changes were found in patients with hypertrophic cardiomyopathy and Cor pulmonale versus healthy controls for both isovolumic ventricular relaxation time intervals. However, significant changes in the ratio were only found in patients with Cor pulmonale (p < 0.005) because of abnormal similar values for both isovolumic ventricular relaxation time intervals. This Doppler method enabled, for the first time, serial comparison of isovolumic ventricular relaxation time intervals with a homologous method. Both isovolumic ventricular relaxation time intervals significantly lengthened with age and with left ventricular indexed mass, but their ratio remained insignificantly changed except for patients with Cor pulmonale. The concomitant right and left isovolumic ventricular relaxation time intervals lengthening in patients with hypertrophic cardiomyopathy and Cor pulmonale suggests interdependence of both ventricles through the septum. This makes recommendable systematic comparison of both sides. The calculation of a ratio, free from the effect of factors intervening on isovolumic ventricular relaxation time intervals, may, in addition, be of diagnostic help.

Adolescent↗
PubMed1997

[Myocardial Doppler tissue imaging: past, present and future].

The first Doppler spectral and pulsed tissue recordings in 1992 have given way to a new generation of machines which enable cardiologists to study mechanical events of the myocardium during the cardiac cycle by Doppler tissue imaging. This technique provides valuable information about regional function with quantitative analysis of the velocities within the myocardial wall as opposed to the global qualitative or semi-quantitative character of usual echocardiographic data. The velocity mode is the most commonly used in its three different presentations: two-dimensional, M mode and, more traditionally, pulsed spectral modes. Two-dimensional imaging gives a global view of the different myocardial segments and allows a rapid approximation of the differences of velocities between these segments and of myocardial wall thickness; however, it lacks the temporal resolution of pulsed Doppler and M mode. In addition, M mode with automatic programmes of velocity analysis has the advantage of providing a continuous spatio-temporal recording of the velocities within the myocardial wall, layer by layer. There is a physiological gradient of velocities highest at the endocardium and lowest at the epicardium. Despite the present limitations related to the Doppler principle itself, the technology, and the complexity of myocardial architecture, Doppler tissue imaging is a useful complement to information already available concerning pressures, flow and cardiac structures. The future is promising and should exceed this simple complementarity to existing ultrasound methods. Progress in the fields of ultrasound physics, technology, computerisation for acquisition of two- and three-dimensional imaging should provide a new physiopathological approach to the understanding of wall motion changes during cardiac disease.

Animals↗
PubMed1996

Colour doppler valvar and subvalvar flow diameter imaging versus echo score in mitral stenosis: comparison with type of surgery.

OBJECTIVE: To compare the value of echo score with that of Doppler subvalvar flow broadening in deciding the type of mitral stenosis surgery. PATIENTS: 30 patients, mean age 47 years, with severe stenosis undergoing surgery were divided into two groups according to type of surgery: open heart commissurotomy (group 1, n = 12), or prosthesis (group 2, n = 18). A control group of 10 patients with prosthesis served as reference, representing mild stenosis without subvalvar connection. METHODS: For echo, the score proposed by Wilkins for cross sectional imaging was used. For Doppler, the flow diameters were measured in cm by an independent examiner from the long axis view in early diastole at two levels: (1) at the level of the stenosis (origin flow diameter), and (2) 1.5 cm downstream from the stenosis in the left ventricle (subvalvar flow diameter) with calculation of a Doppler ratio relating these two measurements, expressed as a percentage of broadening. Diagnostic value was compared for both procedures. RESULTS: There was no significant difference in age, mitral valve areas, or haemodynamics for the two groups. Mean values (SD) were: echo score: group 1, 9.83 (1.26) v group 2, 10.8 (8.1), NS; Doppler ratio %: group 1, 44 (24) v group 2, 12 (21) (P < 0.001); control group: 69 (15). The per cent diagnostic value for an open heart commissurotomy of respective cut off points was: Doppler ratio > 25% (range 71% to 87%); echo score < 10 (range 50% to 75%). CONCLUSIONS: The new Doppler ratio diagnostic value agreed better with surgical management, repair or prosthesis, in this study. Thus, it appears to better reflect the subvalvar involvement and changes in kinetics than the echo score alone. This easy Doppler method might become a routine examination for follow up of patients with open heart commissurotomy, to avoid performing repeated transoesophageal echocardiography.

Adolescent↗
PubMed1994

Inhibition of substance P-induced microvascular leakage by inhaled methoxamine in rat airways.

1. The effect of the inhaled alpha-adrenoceptor agonist, methoxamine (MTX), was studied on experimental airway oedema induced by injection of substance P (SP) in the rat. Sprague-Dawley rats (300-350 g) were anaesthetized with sodium thiopentone, tracheotomized and artificially ventilated. 2. MTX or its vehicle was administered by inhalation. Airway resistance and blood pressure were monitored continuously. Evans Blue dye (EB, 20 mg kg-1) was injected through a jugular catheter 1 min before SP (14.8 nmol kg-1). Airways were dissected out, weighed and placed in formamide for EB extraction and determination by spectrophotometry. 3. EB extravasation induced by SP was significantly reduced in distal intraparenchymal bronchi by inhaled MTX at doses of 50 micrograms kg-1 (58 +/- 9 vs 96 +/- 9 ng EB mg-1 tissue after vehicle, P < 0.001) and 100 micrograms kg-1 (69 +/- 11 vs 137 +/- 26 ng EB mg-1 tissue after vehicle, P < 0.01). Inhaled MTX by itself (100 micrograms kg-1) increased blood pressure: 172 +/- 6 vs 132 +/- 10 mmHg baseline (P < 0.02), but neither induced extravasation nor increased airway resistance. 4. In another set of experiments without SP, MTX was administered intravenously 1 min after EB. At 100 micrograms kg-1, i.v. MTX increased blood pressure to a similar extent as inhaled MTX (180 vs 147 mmHg baseline, P < 0.01), increased airway resistance and caused leakage of plasma proteins in distal intraparenchymal bronchi (79 +/- 7 vs 47 +/- 1 ng EB mg-1 tissue, P < 0.02). 5 Similarly, after sequential i.v. injections of doubling doses of MTX (50-800 microg kg-1), a marked EB extravasation was found in the airways. This was abrogated by pretreatment with prazosin (100 microg kg-1)but not with propranolol (2 mg kg-1).6 These results suggest that microvascular leakage and airway oedema induced by i.v. MTX may be linked to an increase in pressure in the pulmonary circulation, resulting from vasoconstriction of the pulmonary vasculature and acute cardiac dysfunction due to systemic hypertension.7 Our results with inhaled MTX show that direct deposition of MTX at the bronchial vasculature induces a reduction in SP-induced microvascular leakage in rat airways and that inhaled MTX does not share the untoward effect of i.v. MTX inducing airway oedema.

Administration, Inhalation↗
PubMed1994

[Implantation of Strecker's endocoronary prosthesis. Apropos of 21 cases].

The aim of this study was to assess the safety and efficacy of implantation of Strecker coronary stents. The implantation was performed in 21 patients during elective angioplasty (N = 18) or in emergency situations (N = 3). The indications were acute occlusion after angioplasty (N = 3), restenosis (N = 12), incomplete balloon angioplasty results (N = 4) and implantation of first intent (N = 2). The site of implantation was a venous bypass graft in 9 cases, the left anterior descending artery in 5 cases, the right coronary artery in 4 cases and the left circumflex in 3 cases. The average length of the lesions was 8.4 +/- 4.1 mm, including 15 short (< 10 mm) and 6 long (> 10 mm) lesions. Four lesions were located at an acute angle (> 45 degrees) and 4 at the site of origin of a side branch. The diameter of the normal segment of the treated artery was < 3 mm in 12 cases and > 3 mm in 9 cases. Seven 3 mm, five 3.5 mm, six 4 mm and three 4.5 mm diameter stents were implanted. There were no failures to position or implant the stents. After the implantation, the minimal lernen diameter of the artery at the angioplasty site was greater than that obtained with balloon (2.87 +/- 0.67 mm versus 1.83 +/- 1.11 mm, p < 0.001). There was no early restenosis at control angiography at 24 hours (2.78 +/- 0.20 mm versus 2.87 +/- 0.67 mm NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

[Evaluation of coronary vasomotricity by intracoronary ultrasonography].

Coronary vasomotion dependent on the endothelium and on the smooth muscle has been intensively studied by quantitative angiography and intracoronary Doppler. Intracoronary ultrasound is a new imaging technique which allows precise measurement of the section of the coronary artery. This study was undertaken to assess the value of intracoronary ultrasound in the investigation of epicardial coronary artery vasomotion. Twenty hypercholesterolaemic patients with irregularity of the arterial lumen on angiography and 6 normo-cholesterolaemic subjects with normal coronary angiogram (control group) were included. An intracoronary ultrasonic catheter with a rotating mirror (4.3 French, CVIS) emitting at 30 MHz was positioned in the proximal segment of a coronary artery. Endothelial function was studied during sympathetic stimulation by a cold pressor test and during increased coronary flow by local injection of papaverine. The intima of the coronary arteries of the patient group was significantly thicker than that of the control group. The cold test induced significant paradoxical vasoconstriction of the atheromatous coronary arteries and a significant vasodilatation of the coronary arteries of the control group. The increased coronary flow tended to constrict the ateromatous arteries but significantly dilated the normal arteries. Administration of Linsidomine (SIN-1) induced vasodilatation by direct relaxation of the smooth muscle in both groups. No correlation was observed between the thickness of the intima measured by intracoronary ultrasound and the abnormal vasomotor response to the vasomotion different stimuli. The results of this study concord with those of studies of coronary by quantitative angiography. Intracoronary ultrasound provides an accurate method of studying coronary endothelial function and the vasomotor tone of the epicardial coronary arteries.

Aged↗
PubMedDate not supplied

Feasibility, safety, cost-effectiveness and 1 year follow-up of coronary stenting without predilation: a matched comparison with the standard approach.

BACKGROUND: We evaluated the feasibility, safety, procedural cost-effectiveness, radiation dose and time and 1-year target vessel revascularization rate of direct unprotected mounted stenting without previous balloon dilatation (DS) in native coronary artery lesions. METHODS: DS was attempted in 119 patients; 39 had a recent myocardial infarction, 62 had unstable angina, and 18 had stable angina. The clinical follow-up was obtained at 14+/-5 months (range 6 to 24 months). These results were compared with those for a consecutive group of 160 patients matched for type and length of lesions and who had a stent only if the post-balloon residual stenosis was >30%. RESULTS: The feasibility of DS was 112/119 (94%). The number of inflations, the length of the stent/length of the lesion ratio, the time and the dose of radiation were dramatically lower in the DS group (P<0.001). DS conferred a slight reduction in procedure-related cost [$820+/-157 for DS vs. 894+/-427 for standard dilatation (SD) per patient]. The 1-year target vessel revascularization rate was similar in both groups [nine (8%) for DS vs. 17 (11%) patients for SD, ns]. CONCLUSIONS: DS is feasible and safe in selected coronary lesions. This method provides a low rate of repeat revascularization and reduces the time and the dose of radiation compared with the standard approach.

Aged↗