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Biomedical subjects

I Azancot

Publications and source records attributed to I Azancot.

At least 19 recordsLinked to original sources
PubMed1992

Improvement of digital coronary angiography: high resolution processing coupled with a real time functional synchronization procedure.

The use of Digital Subtraction Angiography in coronary applications is restricted by the difficulty in: 1. Obtaining a good resolution of the distal branches. 2. Avoiding, for the purpose of subtraction, the motion artifacts induced by artery and background displacement during the cardiac and respiratory cycles. 3. Preserving the dynamic vascular motion. 4. And storing the digital dynamic information on a permanent support. We used for this study an angiography system, based upon a high resolution 45 MIPS-32 Mbyte image processor, interfaced with a 2.75 Gbyte Winchester drive allowing the real time storage of either 30 frames/s in the 512*512*8 bits matrix or of 7.5 f/s in the 1024*1024*8 bits matrix. To preserve the most important dynamic informations on the basis of the 7.5 f/s maximal storage rate, we developed a synchronization device able to recognize in real time, from chronologic delays derived by using both ECG and Aortic Pressure curves, the functional End-Diastolic (ED) and the End-Systolic (ES) positions, even in the case of heart rates varying during the procedure. The ED and the ES images are stored together with the Mid-Systolic (MS), the 1/3-Diastolic (1/3D) and 2/3-Diastolic (2/3D) images. To establish the validity of this sampling method, which uses a reduced number of frames per cardiac cycle, 7200 coronary injections performed during 450 routine coronary angiographies were compared by two independent observers (A and B), using: first a Digital (D) 5 frames/cycle sequence, and secondly a cine Film (F) 50 frames/s sequence acquired immediately after the corresponding D injection. The D technique resulted in the best image and diagnostic quality, particularly when the F quality was estimated 'fair' or 'poor' by both observers, and in an important reduction on X-Ray doses. The visualisation of the sequential ED, MS, ES, 1/3D and 2/3D frames gives the possibility: 1. of saving the dynamic information, as a regular sample of functional images can be displayed with a cine loop technique. 2. of facilitating cardiac synchronized subtractions. 3. of reducing the amount of frames per cycle, thus allowing an important reduction of X-ray doses and the digital and permanent storage of the most important cardiac cycles.

Angiography, Digital Subtraction↗
PubMed1992

Left ventricular regional dysfunction induced by intracoronary papaverine in patients with isolated stenosis of the left anterior descending coronary artery.

Intracoronary papaverine was administered to eight subjects with normal coronary arteries and to nine patients with single-vessel disease of the left anterior descending coronary artery. All patients had normal left ventricular function at baseline. After papaverine, global and regional ventricular function were unchanged in the normal group. In patients with left anterior descending coronary artery stenosis, intracoronary papaverine resulted in significant wall motion abnormalities and decrease of ejection fraction (from 65 +/- 6% to 54 +/- 9%, p less than 0.01). A full spectrum of responses was observed, however, in these patients, some having almost no change of regional wall motion while others had large anterior dyskinesis. No relationship was found between the severity of the stenosis and the amount of regional dysfunction induced by intracoronary papaverine. These data demonstrate the lack of relationship between the angiographic severity of a stenosis and its impact on left ventricular segmental contraction. This suggests that techniques aimed at producing wall motion abnormalities by means of coronary anterior vasodilation may not be recommended as first-line strategy for the detection of patients with coronary artery disease.

Constriction, Pathologic↗
PubMed1988

[Quantitative analysis of ventricular volumes by digital two-dimensional echocardiography].

The purpose of this study was to assess the usefulness of digital enhancement of two-dimensional echocardiographic images by cardiac cycle-synchronized summation and digital manipulation of the resulting images. We developed a system which provides for: (1) real-time storage of end-diastolic and end-systolic cardiac cycle images irrespective of rhythm variations; (2) exclusion from summation of end-diastolic and end-systolic images altered by respiratory movements or transducer displacements; (3) performance on the resulting images of various mathematical operations (3*3 convolutions, colour scale-guided manipulation of grey shades); (4) performance of complex mathematical calculations from the extracted edges including, in particular, reconstruction of ventricular volumes by Simpson's crossed method from a transverse and an apical section or from two apical sections. This method was used to collect echocardiographic images from 32 patients who had undergone left ventricular quantitative angiography during the same week. Qualitatively, digital enhancement of two-dimensional echocardiographic images undoubtedly facilitated the identification of endocardial edges and reduced image noise, notably in patients whose ventricular edges were virtually unrecognizable by any other method. Moreover, summation improved correlations with angiography and reduced the variability of quantitative ventricular volume assessment. Finally, the ease and rapidity with which this "real-time" system can be used enables quantitative analysis of left ventricular function to be routinely carried out.

Adult↗
PubMed1985

Relationships between single-vessel coronary artery obstructions and wall motion dysfunction analyzed by four computer-based methods.

We analyzed regional wall motion in 238 patients by using cineangiograms recorded in the 30 degrees right anterior oblique projection. The sample was divided into three groups: a normal group (n = 71), a group with isolated obstruction of the left anterior descending coronary artery and previous anterior myocardial infarction (n = 85), and a group with isolated obstruction of the right coronary artery and previous inferior myocardial infarction (n = 82). Both anterior and inferior groups also had motion abnormality within the corresponding anterior or inferior wall as judged by the qualitative analysis of cineangiograms. Four quantitative methods were compared: a long axis method and a center of mass method using internal reference systems, a method derived from the Stanford model and an area-based method using external reference systems. Normal regional values were determined from the normal group to evaluate the specificity and sensitivity of the methods. The area-based method was the most sensitive in the anterior infarction group, whereas the center of mass method was the most sensitive in the inferior infarction group. We conclude that there is no evidence that any method, among those tested, is superior to others for every expected location of wall motion abnormality.

Adult↗
PubMed1985

Changes in left ventricular performance during chronic pressure or volume overload: importance of physical properties of the arterial system.

The present study was aimed at evaluation of changes in systolic and diastolic left ventricular function during chronic pressure of volume overload, in comparison with normal subjects. Sixty-two patients were included: group 1 was composed of 25 normal subjects, group 2 was composed of 20 subjects with essential hypertension, and group 3 was composed of 17 subjects with aortic regurgitation without congestive heart failure. Cardiac output, aortic and left ventricular pressures (micromanometers), ventricular volume and ascending aortic radius (cineangiography), ejection fraction (EF), mean velocity of fiber shortening (VCF), ventricular mass (m), and the ratio m/EDV (EDV, end diastolic volume) were determined. Also measured were maxima for end systolic pressure (ESP), end systolic stress (ESS), and end systolic volume (ESV) and radius (ESR), as well as the modulus of left ventricular chamber and muscle stiffness (method of Gaash et al.) (1) and characteristic impedance of the ascending aorta (Zc). In hypertensive patients, m and m/EDV were increased, as was the ESP/ESV ratio, whereas EF and VCF were not modified and the ESS/ESR was normal or sometimes decreased. The systolic "pump" function thus appeared to be increased, whereas the muscle function appeared normal or decreased. The moduli of left ventricular chamber stiffness and muscle stiffness were increased. Zc was increased because of a greater pulse wave velocity, although aortic radius was larger. A close relationship was found between Zc and the ratio m/EDV. In patients with aortic regurgitation, the increased left ventricular mass was closely related to the regurgitant fraction (RF). The m/EDV ratio was normal. EF was unmodified and VCF and the ESP/ESV ratio were decreased.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Ventricular function and arterial compliance in patients with congestive cardiomyopathy.

In order to study the interrelationship between left ventricular afterload, estimated from the mean left ventricular wall stress, and the mechanical properties of the aorta, we have simultaneously measured systemic arterial compliance and left ventricular wall stress in 19 patients with congestive cardiomyopathy. The strong linear relationship between the ejection fraction of the left ventricle and systemic arterial compliance, and between left ventricular wall stress and systemic arterial compliance, suggests that systemic arterial compliance is an important determinant of left ventricular afterload and thus of left ventricular function.

Adult↗
PubMed1984

Comparison of geometrical models for evaluating left ventricular wall motion from cineangiograms.

Regional wall motion of the left ventricle (LV) has been analyzed from contrast ventriculograms by using 4 methods based on different geometrical frameworks. Two of them utilize moving internal reference systems, the center of mass (CMM) and the long axis (LAM) methods; the two other ones use fixed external reference systems, the area-based (ABM) and the Palo Alto (PAM) methods. The techniques were applied on a set of 81 patients: 42 were normal and composed the group I; 22 had a single vessel obstruction greater than 75% of the left anterior descending coronary artery (group II) with old necrosis or active ischemia of the LV anterior wall; 17 had a single vessel obstruction greater than 75% of the right coronary artery (group III) with old necrosis or active ischemia of the LV inferior wall. ABM and PAM showed the highest specificities and sensitivities on the studied sample. Therefore, we believe these two methods, of the techniques tested, are the best to quantitate wall motion from cineangiograms.

Cineangiography↗
PubMed1983

Subcostal M-mode computerised echocardiography. An alternative or complementary approach to parasternal echocardiography?

Subcostal M-mode echocardiography has been suggested as a method for assessment of left ventricular size and function. Parasternal and subcostal measurements (direct and derived) of left ventricular function were compared in 30 healthy young subjects. We calculated instantaneous left ventricular diameter and wall thickness every 10 ms for both the subcostal and parasternal approaches using a computer program for echocardiographic digitisation and compensation. All variables were filtered to calculate instantaneous first derivative (velocity) and logarithmic derivative (normalised velocity). The program provided normal values for computerised variables of left ventricular function from the subcostal approach. It was found that there was no identity and no correlation or a poor one between subcostal and parasternal left ventricular internal diameters and volumes. The parietal wall thickness was significantly greater using the subcostal approach, and the comparative velocities study showed striking variations between the two approaches, especially in diastole, where the peak lateral wall thinning rate was 20% lower than the posterior thinning rate. We conclude that for a normal and young population, the subcostal and standard parasternal data cannot be used interchangeably for precise studies of left ventricular function. The subcostal approach, however, provides useful complementary information about lateral wall motion.

Adult↗
PubMed1983

[Adiastole caused by a secondary cardiac hemochromatosis. Successful treatment with an iron chelating agent].

Severe congestive cardiac failure developed in a few weeks in a 44 year old man who had undergone porto-caval anastamosis for post-hepatitis cirrhosis one year previously and then treated for anaemia by repeated blood transfusion and chronic daily oral iron therapy. Infiltrative, congestive and restrictive cardiomyopathy was diagnosed in the presence of global cardiomegaly, electrocardiographic changes (microvoltage, diffuse ST-T wave changes), echocardiographic appearances (dilatation of the left ventricle, with hypertrophic and hypokinetic walls), and hemodynamic signs of adiastole with equalisation of filling pressures at 15 mmHg and a cardiac index of 1,88 l/min/m2. Cardiac haemochromatosis was confirmed by the laboratory (serum iron: 35 mumol/l; siderophilin saturation: 100 p. 100; serum ferritin: 1854 ng/ml; induced siderouria: 51 mg/24 hours) and histological findings (endomyocardial biopsy showing pigment overload). The absence of a family history, of homozygote A3 antigen, of diabetes, of iron overload on hepatic biopsy one year previously, excluded the diagnosis of familial idiopathic haemochromatosis. A secondary form of the disease was diagnosed on a possible genetic predisposition (heterozygote A3 antigen) and on environmental factors (blood transfusions, iron therapy, cirrhosis, alcoholism and perhaps the porto-caval anastamosis. Cardiac haemochromatosis was cured in this case by iron chelating therapy comprising daily subcutaneous infusions of 2 g of desferrioxamine for 2 months. The cure was confirmed by regression of the signs of clinical cardiac failure and of cardiomegaly, the increase in QRS voltages and the near normalisation of the hemodynamic and laboratory findings.

Adult↗
PubMed1982

Effects of acebutolol on myocardial infarct extension: a randomized electrocardiographic, enzymatic and angiographic study.

The effect of acebutolol (1 mg/kg i.v. during the first 2 days followed by a daily oral dose of 600 mg for 3 weeks) was studied in a randomized trial involving 26 patients seen within 24 hours after the onset of uncomplicated anterior transmural myocardial infarction (TMI). Myocardial ischemia and necrosis were evaluated by precordial maps recorded daily for 9 days. Left ventricular pump function and dyssynergy were quantitatively measured on 30 degrees right anterior oblique cineangiograms. Angiography was performed, using the postextrasystolic potentiation technique, within the first 24 hours after TMI and was repeated 1 month later. The basal and postextrasystolic beats from the initial angiography were computerized and compared with those from the final angiogram. MB-CK serum level was measured from blood samples drawn every 3 hours for the first 72 hours. Fourteen patients selected at random received acebutolol within the first 24 hours; 12 subjects were untreated and served as controls. During the 1-month study, no other drugs were administered. Treated patients showed a significant reduction in capillary wedge pressure, extent of hypokinesis and ST-segment elevation; no significant differences were observed in the control group. However, the predictability based on the angiographic data was the same in both groups, and beta blockade did not alter this predictability significantly. Furthermore, no significant difference was found during the final evaluation for treated compared with control patients for any single variable or set of variables. The incidence of infarct extension was not decreased, but only significantly delayed in treated patients. The high variability of the measurements, probably related to the high variability of the pathophysiologic factors, may account for the failure to demonstrate the efficacy of acebutolol.

Acebutolol↗
PubMed1982

[Effect of nitroglycerin and N-ethoxycarbonyl-3-morpholinosydnonomine on the walls of large arteries].

Systemic arterial compliance was measured in 20 patients with left ventricular failure due to congestive cardiomyopathy. The method consisted in evaluating arterial compliance by analysing the exponential fall of the arterial pressure curve on a simple visco-elastic model. In the patient group, significant correlations were found between arterial compliance and age (r = 0,64 ; p less than 0,01) and arterial compliance and systolic blood pressure (r = -0,58 ; p less than 0,001). These relationships suggest that arterial compliance depends on the height of the systolic blood pressure and/or the elasticity of the arterial walls. Two groups of patients were defined : Group I (10 patients) given a single oral dose of 7,5 mg of nitroglycerine (Lenitral), and Group II (10 patients) giben a single oral dose of 4 mg N ethoxycarbonyl-3-morpholinosydnonomine (Molsidomine). There was no significant difference in the hemodynamic parameters or arterial compliance between the two groups before administration of these drugs. However, systolic blood pressure was significantly lower (p less than 0,01) and compliance significantly higher (p less than 0,05) after treatment in Group II. In Group I, nitroglycerine caused a significant increase in compliance (p less than 0,01), a significant decrease in systolic (p less than 0,02) and mean blood pressure (p less than 0,05) whilst heart rate, cardiac output and total systemic resistance remained unchanged. In Group II, Molsidomine caused a significant increase in arterial compliance (p less than 0,01), a decrease in systolic (p less than 0,001), diastolic (p less than 0,01) and mean blood pressure (p less than 0,01) and in cardiac output (p less than 0,01), whilst heart rate and total systemic resistance remained unchanged. This study shows that both drugs studied had significant effects on the walls of the large arteries.

Adult↗
PubMed1982

[Changes in the physical properties of the arterial system and left ventricular performance with age and in permanent arterial hypertension: their interrelation].

The purpose of this work was to study interactions between physical properties of the arterial system and left ventricular performance during aging in normal and in hypertensive patients. 50 patients were studied; 28 normal patients (age range 22 to 68 years) and 22 patients with essential hypertension (age range 23 to 63 years). In hypertensive patients, the end systolic pressure-volume ratio (ESP/ESV), modulus of chamber stiffness (kp), left ventricular wall thickness (h), mass (m), m/LVEDV ratio (LVEDV: left ventricular end diastolic volume), systemic arterial resistance (SAR), pulse wave velocity (C) and characteristic impedance of the ascending aorta (Zc) were increased compared to normal subjects of similar age. The ejection fraction (EF), the mean velocity of fiber shortening (VCF) and dp/dt max were unchanged. In normal patients: the ESP/ESV ratio, kp, h, m, m/LVEDV ratio, SAR, C and Zc increased with age; there were no age related changes in EF, VCF or dp/dt max. In both groups, there was a close relationship between the m/LVEDV ratio and Zc, the characteristic impedance of the ascending aorta. These results suggest that: 1. aging and arterial hypertension lead to similar changes in the physical properties of the arterial system and in left ventricular performance; 2. in both cases, the development of concentric cardiac hypertrophy is closely related to the physical properties of the arterial system.

Adult↗
PubMed1981

Detection of residual myocardial function in acute transmural infarction using postextrasystolic potentiation. A computerized angiographic study.

Twelve subjects without clinical or hemodynamic heart failure, admitted for a first untreated anterior transmural myocardial infarction, were evaluated within the first 24 hours after the onset of symptoms. Pulmonary angiography was performed while a right ventricular extrastimulus was delivered every fourth beat at 50% of the RR interval to systematically analyze the basal and the postextrasystolic left ventricular frames. Left ventriculograms were quantitatively processed to determine the ejection fraction (EF) and the percentage of the end-diastolic circumference showing hypokinetic (%HK) or akinetic (%AK) areas. Left ventricular angiography was performed 1 month later in all cases at the same paced atrial heart rate to compare this final angiogram to the basal and the electrically induced postextrasystolic initial beats. During the 1-month period of the study none of these subjects had complications such as recurrent chest pain, heart failure or rhythm disturbances, and no drug administration was necessary. Comparing the basal cycle of the initial angiogram and the final cycle, a poor correlation was found between the corresponding values of EF (r = 0.34), %HK (r = 0.38) and %AK (r = 0.48). The correlations were much better when a comparison was made between the postextrasystolic cycle of the initial angiogram and the final cycle (EF, r = 0.84; %HK, r = 0.96; %AK, r = 0.95). These results indicate that, from the first day after a TMI, the analysis of the postextrasystolic frame allows accurate estimation of the final left ventricular function and regional wall motion abnormalities. Postextrasystolic potentiation may be useful in the acute state of transmural infarction to discriminate potentially reversible ischemic from definitely jeopardized areas.

Acute Disease↗