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P Peronneau

Publications and source records attributed to P Peronneau.

At least 37 records · Page 2Linked to original sources
PubMed1989

[Clinical application of echocardiography using a transesophageal approach].

Transesophageal echocardiography is a new method of cardiac imaging with well-defined indications. In view of the absence of hindering anatomical obstacle between the probe and cardiac structures, the images obtained are of high definition, especially as regards the atria and atrial appendages, the mitral, aortic and tricuspid valves and the thoracic aorta. Being easy to perform and little traumatic, this method can be used in ambulatory patients. It is also valuable in intensive care patients and in the peri-operative period. Transesophageal echocardiography is primarily indicated to explore cardiac valve prostheses, notably those of the mitral valve, to identify vegetations and abscesses in infective endocarditis, to detect intra-atrial tumours and thrombi, to evaluate dissections of the aorta, to study the mechanism of mitral regurgitation, to investigate some congenital cardiopathies in adults, such as interatrial septal defects, and to monitor left ventricular function before and after surgery. Owing to its major contribution to the diagnosis of these potentially dangerous diseases, it should soon become a very useful and even indispensable complement of transthoracic exploration in certain cases.

Aortic Diseases↗
PubMed1989

[Electrocoagulation of the His bundle node junction in dogs by a high-frequency current delivered by suction catheter].

High-frequency currents constitute an attractive form of energy for transcutaneous myocardial destruction, but their potential for creating lesions varies with the nature of contact between electrode and skin. The adequacy of a suction catheter for electrocoagulation of the AV node-His bundle junction was assessed in 7 dogs. The high-frequency current (1.2 MHz) was delivered as bursts of 6 watts lasting 30 seconds, between the distal electrode of a bipolar catheter containing a central lumen (USCI 8F) and a wide skin electrode. During firing, an 80 kPa depression was applied to the lumen. Electrophysiological testing was performed before and immediately after firing. Continuous 24-hour Holter recording was carried out before, immediately after, then between the 2nd and 20th days post-firing. Following another electrophysiological study, the animals were killed on the 15th or 21st day for anatomical study. Complete atrioventricular block was obtained in all dogs during the first (n = 4) or second (n = 3) firing and persisted in 6 dogs up to the time of anatomical study. The atrial and right ventricular electrophysiological parameters remained unmodified after firing, and no severe ventricular arrhythmia was recorded during the study. The histological lesions were 4.7 +/- 0.7 mm in mean diameter and 3.1 +/- 0.6 mm in mean depth. It is concluded that electrocoagulation of the AV node-His bundle junction performed with high-frequency currents is a safe and selective technique. Using suction catheters makes this technique well reproducible with moderate amounts of energy. The development of preformed catheters should reduce the duration of the procedure.

Animals↗
PubMed1988

[Indirect approach of stenosis of transplanted kidneys by Doppler echography].

Pulsed Doppler ultrasound for the detection of rejection and renal artery stenoses involving transplanted kidneys was evaluated. Using mean velocity curves, the time interval between the ECG R wave and the onset of peak velocity was measured successively on the renal and ipsilateral iliac arteries and divided by the R-R interval. In 27 patients, a Doppler index defined as the ratio of the standardized renal artery and iliac artery time intervals, was determined and compared to angiographic data. The DI index failed to detect stenoses associated with rejection; conversely, in the absence of rejection, clear separation of patients without (n = 14, DI = 1.03 +/- 0.6) and with (n = 6, DI = 1.24 +/- 0.05) stenosis (t = 7.48, p less than 0.001) was achieved. Thus renal artery stenoses in transplant recipients can be detected by the comparative study of time intervals calculated for renal vessels and for the neighbouring iliac artery.

Adult↗
PubMed1987

Quantification of aortic regurgitation using Doppler imaging.

Aortic insufficiency induces the development of a jet within the left ventricular outflow tract. The cross sectional area of this jet at its origin is the major determinant of the severity of the regurgitation. M mode Doppler imaging reportedly allows the measurement of jet diameter. This study was designed to evaluate the quantification of aortic regurgitation using a measurement of the jet diameter by M mode Doppler imaging. The left ventricular outflow tract of 32 patients was imaged using either a multigate pulsed Doppler velocimeter of color flow mapping system (Hewlett Packard). The jet diameter was compared to a 4 grade semiquantification derived from supravalvular aortography. Adequate imaging was obtained in the 32 patients. Four of them had no regurgitation: no diastolic flow image could be found during their Doppler investigation. A clear jet image was obtained in the 28 remaining patients. We found a close relationship between the jet diameter (jd in mm) and the angiographic grade (ag): jd = 2.4 + 6.1 ag, r = 0.88, the most significant differences being found between grade 0 and grade 1, and grade 1 and grade 2. In conclusion, direct M mode measurement of the regurgitant jet of aortic insufficiency at its origin offers an additional approach of the severity of the leak.

Adult↗
PubMed1987

Limitations of ultrasound imaging and image restoration.

The definition of medical ultrasound images is strongly limited by the need for low examination frequencies which is imposed by the high attenuation of acoustic waves in tissues. The filtering effect of imaging systems is described and quantified for echography, transmission tomography and reflection tomography. Improvement of image definition is demonstrated to be the result of a numerical restoration of the received echoes implemented, in the present case, by a simplified Kalman filter. The improvement in definition obtained is emphasized on simulated data and tissue images. The comparison between the results obtained from the three techniques shows that: if only echography provides a real-time acquisition of signals, tomographic methods lead to faster processing associated with a better signal-to-noise ratio on the reconstructed images, and reflection tomography offers the best definition.

Animals↗
PubMed1987

Doppler imaging of regurgitant jet in aortic insufficiency: experimental validation and preliminary clinical evaluation.

Aortic insufficiency induces the development of a jet within the left ventricular outflow tract. The diameter of a laminar jet is a well-defined hydraulic parameter. This study was designed to evaluate, both experimentally and in patients, the accuracy of its measurement using a Doppler imaging performed with a multigate pulsed Doppler velocimeter. The experimental validation was conducted on a water tank pulsatile model including calibrated orifices. Jet images appeared clearly delineated and were not modified when changing imaging angulation (from 85 degrees to 65 degrees), pump frequency (from 60 to 100 c min-1), pump output (from 0.5 to 3.8 l min-1), wall filtering, orifice shape, or signal-to-noise ratio. The measured jet diameter (jd) correlated closely with the orifice diameter (od): jd (mm) = 1.22 + (0.79 X od), r = 0.98. A preliminary clinical evaluation was performed on jets of aortic insufficiency on a series of 26 patients. Jet cross-section was studied within the left ventricular outflow tract using a parasternal approach. A high setting of wall filters allowed good quality imaging in 24 patients. In the absence of a diastolic jet, jd was taken equal to 0. Measured jet diameters were compared to the angiographic grade (ag): jd (mm) = 2.7 + (3.9 X ag), r = 0.86. In conclusion, jet diameter measurement using M-mode Doppler imaging is experimentally accurate and potentially valuable in patients with aortic insufficiency.

Aortic Valve Insufficiency↗
PubMed1987

[Electrophysiological, hemodynamic and histological effects of fulguration on the ventricular myocardium in the dog].

The myocardial repercussions of endocavitary fulguration depend upon the interaction of different physical phenomena. We studied the influence of energy level on the one hand and of the physical properties of the catheter (Ct) on the other hand on the cardiac effects of right endoventricular fulguration in the dog. A monopolar anodal shock was delivered in 12 dogs. Two levels of energy were applied: 25 J (group A, n = 6) and 100 J (group B, n = 6), and three Ct were used which differed in resistance (R) and active surface (S): Ct 1 (R = 0.3 omega, S = 12 mm2), Ct 2 (R = 0.3 omega, S = 2 mm2) and Ct 3 R = 2 omega, S = 13 mm2). Immediately after fulguration a significant rise of the right ventricular effective refractory periods was observed in group B only (193 +/- 28 vs 174 +/- 19 ms; p less than 0.03). Compared to baseline values, the systolic and diastolic pressures fell by 12% (p less than 0.01) and 18% (p less than 0.01) respectively in group A and by 33% (p less than 0.05) and 34% (p less than 0.002) respectively in group B. In contrast, there was no significant difference between variations of these parameters with the three types of Ct. The incidence of complex ventricular arrhythmia was higher in group B (5/6) than in group A (1/6).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Intracellular and extracellular recordings of sinus node activity: comparison with estimated sinoatrial conduction times during pacemaker shifts in rabbit heart.

Sinoatrial conduction times, estimated by premature atrial stimulation, were compared with direct measurement of the sinoatrial conduction time in 15 isolated rabbit sinus node preparations before and after intrasinusal pacemaker shifts induced by cooling. Transmembrane potentials and surface electrograms were recorded from the sinus node and crista terminalis. Extracellular sinus node activity was recorded in five preparations. Mapping was performed at 38 degrees C and 35 degrees C to determine the site of the dominant pacemaker. The sinus cycle was significantly longer at 35 degrees C (319.4 ms vs 258.1 ms). Intracellular measured conduction time was significantly shorter (63.8 ms vs 70.4 ms) because of caudal shift of the dominant pacemaker. Estimated sinoatrial conduction time was significantly longer (110.3 ms vs 85.4 ms) owing to the depression of automaticity by the extrastimulus. Extracellular measured conduction time did not differ significantly from intracellular measured conduction time. These results suggest that intrasinusal pacemaker shift may explain inaccuracies in indirect estimations of sinoatrial conduction time by atrial pacing techniques. Extracellular recordings appear to be a better method of evaluating sinoatrial conduction times.

Animals↗
PubMed1986

Inhomogeneity of cellular refractoriness in human atrium: factor of arrhythmia?

Spatial inhomogeneity of refractory periods, as measured during clinical electrophysiological studies, is a known predisposing factor of arrhythmia. We studied effective refractory periods (ERP) and action potential duration (ADP90) on isolated human atrium. Twelve samples of right atrium obtained during cardiac surgery from patients with (n = 6) and without (n = 6) atrial fibrillation (AF) were studied by microelectrode technique. For each preparation, ERP were measured at basic cycle lengths (BCL) of 1,600, 1,200, 800, and 400 msec in five different cells located around (0.8 mm) the stimulating electrode. Dispersion of ERP was significantly greater in the AF group (96.7 +/- 9 versus 70.9 +/- 9 msec, p = 0.01). In the non-AF group, we observed a positive linear correlation between ERP and BCL (r = 0.86) ADP90 and BCL (r = 0.93). On the contrary, in the AF group this correlation was absent between ERP and BCL (r = 0.28), poor between ADP90 and BCL (r = 0.62). These results suggest that nonhomogeneous recovery of excitability (dispersion and poor adaptation) may be an important factor of arrhythmia. This inhomogeneity is present at the cellular level as well as in the entire heart.

Action Potentials↗
PubMed1986

Effects of physical parameters of fulguration on electrophysiological and anatomical properties of canine myocardium.

In order to determine the respective roles of catheter (Ct) physical properties and of energy levels in myocardial effects of fulguration, we delivered an electrical shock between the tip electrode of a Ct placed at the apex of the right ventricle and a large cutaneous cathodal electrode in 12 dogs. Two energy levels were used: Group A = 25 J (n = 6) and group B = 100 J (n = 6), and three Cts were studied. These Cts had different resistances (R) and active surface electrodes (S): Ct 1 (R = 0.3 omega, S = 12 mm2), Ct 2 (R = 0.3 omega, S = 2 mm2), Ct 3 (R = 2 omega, S = 13 mm2). Complex ventricular arrhythmias were observed in 5/6 cases at 100 J but only in 1/6 cases at 25 J and were independent of the Ct type. Following the shock, the effective ventricular refractory period (S1 S1 = 300 msec) increased significantly only at 100 J (11%, p = 0.03). Anatomical lesions were wider (10.6 vs. 5.2 mm, p less than 0.05) and deeper (100 vs. 55%, p less than 0.05) in the 100 J group. In contrast, there was no significant difference in the electrophysiological and anatomical changes between the three Cts. In conclusion, arrhythmogenic adverse effects of ventricular Ct fulguration are related to the delivered energy; on the contrary, they seem only slightly dependent on Ct physical properties at these energy levels; a 2 J/kg shock is not only effective but also seems to be safe.

Animals↗
PubMed1986

[Experimental induction of sino-auricular blocks on isolated atria. Microelectrode study of the effects of bepridil].

The effects of bepridil on sinoatrial conduction were studied by perfusing 15 isolate rabbit right atrial preparations. In a preliminary series an increase in cycle length was observed with a dose-dependent effect with concentrations of between 5 X 10(-7) M and 1 X 10(-5) M. At the latter dose, sinoatrial block was observed. Bepridil was therefore used in a series of 10 preparations to induce sinoatrial block (SAB). After 10 minutes perfusion the cycle length increased significantly (14.3%, p less than 0.02). In 4 preparations SAB occurred 18.7 +/- 2.5 minutes after the onset of the perfusion. Sinoatrial block did not occur in 6 cases and in 4 cases an intrasinus shift of the dominant pacemaker was observed. The types of SAB observed were varied and their mechanisms were complex. Different types of SAB occurred in the same preparation. The different types of block recorded were: Blumberger type I SAB, anterograde 2/1 SAB, intrasinus 2/1 block, retrograde 2/1 and advanced block, complete atrio-sinusal dissociation.

Action Potentials↗
PubMed1983

Estimation of blood-flow quality by statistical analysis or an ultrasonic Doppler signal: application to the study of perturbations caused by a vascular stenosis.

The noninvasive detection of pathological stenoses by Doppler ultrasound velocimetry is based on the appearance of modifications in velocity waveform or of a local increase in velocity. Nevertheless, these methods suffer from a lack of sensitivity. An extension of ultrasonic velocimetry including a statistical treatment of the Doppler signals affords a quantitative approach to the flow quality and seems to be able to improve the diagnosis of vascular obliterans. Accordingly a perturbation index can be computed on a microprocessor as the relative standard deviation of the zero-crossings histogram of the Doppler signal. A theoretical and experimental approach has been attempted to validate this method. Moreover, this index has been tested in vitro on calibrated flows. The in vivo experiments, performed on the abdominal aorta of the dog with artificial stenoses (0 to 50% in diameter) show a significant increase in the index value downstream from the stenosis. The relative increase of the index is greater than that of velocities for the same degree of obstruction. At the moment, it is possible to detect stenoses of 20% and above. It should be noted that changes in the perturbation index can be observed on a large part of the arterial segment, in relation with the severity of teh stenosis. Taking into account the increase in the index value and the length of the disturbed zone downstream of the stenosis, an estimation of the severity itself can be attempted. Clinical applications are in progress pointing out the diagnostic and prognostic abilities of the index method. The index perturbation method adds to velocity measurement the possibility of blood flow stability estimation. It appears useful for the localisation of stenoses, offers the possibility of quantifying their severity and could help the prognosis of their development.

Animals↗
PubMed1983

Non-invasive quantification of aortic regurgitation by Doppler echocardiography.

This study was undertaken to assess the contribution of Doppler echocardiography to the quantification of aortic valve regurgitation. Ultrasound examination was performed by recording aortic arch blood flow from the suprasternal notch. A non-invasive index of valve regurgitation was obtained by calculating the ratio between the maximal amplitude of forward flow during systole and the amplitude of retrograde flow during diastole measured at the onset of the R wave of the electrocardiogram. This index was compared with semiquantitative data derived from supravalvular aortography in 93 patients. In pure aortic regurgitation (67 patients) the results showed a high correlation coefficient between Doppler and angiographic estimates. In cases of associated aortic valve stenosis there were problems in the accurate estimation of systolic blood flow which led to global overestimation in general of the degree of regurgitation and considerable lack of precision in individual patients. But in general Doppler echocardiography appeared to be a successful technique to quantify pure aortic regurgitation.

Adolescent↗
PubMed1983

Correlation between velocity measurements from Doppler echocardiography and from M-mode contrast echocardiography.

The slope of an individual contrast trajectory on M-mode contrast echocardiography represents a physiological variable similar to that measured by Doppler echocardiography: the projection of the intracardiac velocity vector in the direction of the sound beam. To test the hypothesis that M-mode contrast echocardiography slope measurement can yield information quantitatively similar to Doppler measurements, we performed both simultaneously in 11 normal volunteers. A pulsed Doppler unit capable of simultaneous M-mode and Doppler display was used. Contrast was obtained by intravenous injection of 5% dextrose. Two independent observers measured velocity simultaneously by both techniques at eight to 16 points per subject. One observer repeated the measurements a month later. All subjects had contrast, and 10 had sufficient quality tracings for simultaneous Doppler and contrast slope measurements. The correlation between velocity measurements by both techniques was good, though velocities by Doppler echocardiography were less than by M-mode contrast echocardiography. We conclude that the component of flow velocity towards or away from the transducer can be measured from M-mode contrast trajectory slopes as well as by Doppler echocardiography. M-mode contrast echocardiography may provide a practical method for verifying or calibrating Doppler measurements in vivo.

Adult↗
PubMed1983

Quantitative assessment of tricuspid regurgitation using pulsed Doppler echocardiography.

Tricuspid valve regurgitation was assessed quantitatively by measuring blood flow velocity in the vena cava using a pulsed Doppler velocimeter. A non-invasive index of regurgitation was obtained by calculating the ratio between the maximum amplitudes of the systolic and diastolic components of the velocity curves. The index was compared with the angiographic grading of regurgitation in 70 patients after right heart catheterisation; the results were closely correlated. Using the Doppler index the differences between the groups defined according to their angiographic grade were significant. Thus measurement of blood flow velocity in the vena cava appears to quantify accurately the severity of tricuspid regurgitation.

Adolescent↗
PubMed1982

Intra-SA-nodal pacemaker shift: indirect evaluation in the open chest dog.

Thirteen open chest dogs with normal sinus node function were studied by premature stimulations with a constant relative prematurity--50% of the preceding sinus cycle length. These premature beats were induced in the lower part of the crista terminalis of the right atrium and to the roof of the left atrium. Significant linear correlations were found between the return cycle (A2A3) and the spontaneous cycle (A1A1) lengths, with a slope of +0.75 in the right atrium, +1.36 in the left atrium. The evaluation of sinus node function is disturbed by pacemaker shifts, both spontaneous and induced. Sinus node organisation may be assessed by stimulating standardised sites, by measuring intra-atrial conduction time, and by comparing A2A3 with A1A1 at constant relative prematurity during significant variations in A1A1 obtained with changes in vago-sympathetic tone.

Animals↗
PubMed1982

[Non-invasive study of aortic insufficiency by Doppler echocardiography].

The possibilities of diagnosis and quantification of aortic regurgitation by pulsed Doppler analysis of blood flow in the aortic arch were examined in 60 patients aged between 9 and 67 years old. Aortic flow curves were recorded from the suprasternal area with the sample volume positioned at the junction of the horizontal part of the aortic arch and the descending aorta. Normal flow curves are characterised by an anterograde systolic wave with a brief proto-diastolic reflux. In aortic regurgitation holodiastolic reflux is observed. An index of regurgitation may be calculated from the ratio of the amplitude of end diastolic reflux measured on the R wave of th ECG and the maximal amplitude of anterograde systolic flow. This ratio eliminates the factor related to the incident angle between the ultrasound beam and the direction of blood flow. The values of this ratio were compared to the semi quantitative assessment of aortic regurgitation from ascending aortic angiography. The only false negatives were observed in patients with negligible regurgitation (grade I). One false positive result was obtained in a patient in whom it was difficult to obtain the recording and in whom the value of the ratio was very low (0,02). Global specificity was 91 p. 100 and sensitivity was 82 p. 100. The sensitivity for average or severe regurgitation was 100 p. 100. The correlation coefficient between the Doppler index or regurgitation and the semi quantitative angiographic estimation was 0,69. In patients with pure aortic regurgitation the correlation reached 0,85 (p less than 0,001). The differences between the different groups then became highly significant.

Adolescent↗