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B Diebold

Publications and source records attributed to B Diebold.

At least 37 records · Page 2Linked to original sources
PubMed1998

[Recommendations of the French Society of Cardiology for the training of echocardiographers and performing echocardiograms].

The considerable advances achieved in the field of echocardiography have made this investigation an essential diagnostic tool. Under the auspices of the French Society of Cardiology, the Working group on Echocardiography publishes its practical recommendations for optimising the training of echocardiographers (theoretical instruction and practical courses) and for performing echocardiography (understanding the clinical problem, referral to previous examinations, necessary recordings and measurements, and appropriate equipment). In the future, these recommendations should be updated to take into account continuing technical improvements and changes in methods of studying cardiac disease by echocardiography.

Cardiology↗
PubMed1997

Comparison of arbutamine and exercise echocardiography in diagnosing myocardial ischemia.

Arbutamine is a new catecholamine designed for use as a pharmacologic stress agent. This study compared the sensitivity of arbutamine with symptom-limited exercise to induce echocardiographic signs of ischemia. Arbutamine was administered by a computerized closed-loop delivery system that controls the infusion rate of arbutamine toward a predefined rate of heart rate increase and maximum heart rate limit. Beta blockers were stopped > or = 48 hours before both tests. Stress was stopped for intolerable symptoms, or clinical, electrocardiographic or echocardiographic signs of ischemia (new or worsening wall motion abnormality), target heart rate (> or = 85% age predicted maximum heart rate), or plateau of heart rate response. Thirty-seven patients were entered into the study (35 arbutamine and exercise, 1 arbutamine only, 1 exercise only), of which 30 had angiographic evidence of coronary artery disease (> or = 50% lumen diameter narrowing). Rate-pressure product increased significantly in response to both stress modalities (p < 0.001) and was significantly greater with exercise (11,308 +/- 2,443) than with arbutamine (9,486 +/- 2,479, p < 0.001). The time to maximum heart rate was longer during arbutamine stress echocardiography than during exercise testing (17.3 +/- 9.4 versus 9.3 +/- 4.2 minutes, respectively, p < 0.001). There were more patients with interpretable echo data for arbutamine (82%) than for exercise (67%). Sensitivity for recognition of myocardial ischemia was 94% (95% confidence interval 70% to 100%) and 88% (95% confidence interval 62% to 98%), respectively. The most frequent adverse events during arbutamine (n = 36) were dyspnea (5.6%) and tremor (5.6%). Two arbutamine stress tests were discontinued due to arrhythmias: 1 patient had premature atrial and ventricular beats, and the other had premature atrial contractions and atrial fibrillation. Arrhythmias were well tolerated and resolved without sequelae. In conclusion, the sensitivity of arbutamine to induce echocardiographic signs of ischemia was similar to that of exercise despite a lower rate-pressure product. Arbutamine was well tolerated and provides a reliable alternative to exercise echocardiography.

Adult↗
PubMed1997

Acceleration mapping by Fourier acceleration-encoding: in vitro study and initial results in the great thoracic vessels.

Acceleration mapping can be conducted by replacing the bipolar gradient pulse of a velocity mapping sequence by a tripolar pulse. However, since the acceleration encoding pulse is longer, the image quality is altered by the requirement of a long echo time. Since Fourier encoding velocity imaging has been shown to be robust, this velocity mapping method was transformed into an acceleration mapping method. Four steps of the tripolar acceleration encoding gradient pulse were applied successively; acceleration was then obtained by Fourier transform after zero-filling. The accuracy of the method was assessed with a phantom giving a pulsatile flow. Acceleration maps of the ascending aorta and pulmonary artery were obtained in 10 healthy volunteers. The acceleration values measured were in the range of known physiologic values. The feasibility of Fourier encoding acceleration imaging was also demonstrated in four patients.

Adolescent↗
PubMed1997

Genetic polymorphisms of the renin-angiotensin system and angiographic extent and severity of coronary artery disease: the CORGENE study.

Genetic polymorphisms of the renin-angiotensin system (RAS) have been associated with coronary artery disease (CAD) but no relation between these polymorphisms and coronary atherosclerosis has yet been systematically evaluated. The CORGENE study is a cross-sectional study involving 463 Caucasians who underwent standardized coronary angiography for established or suspected CAD [156 patients with a previous myocardial infarction (MI), 307 without MI]. Four angiographic scores assessing the extent and severity of the coronary lesions were obtained from a double visual analysis of each angiogram, arbitration being achieved by a quantitative measurement. Three different genotypes were analyzed: the angiotensin I-converting enzyme insertion/deletion (ACE I/D) polymorphism, the Met to Thr change at position 235 of the angiotensinogen gene (AGT M235T) and the A to C transition at position 1166 of the angiotensin II type-1 receptor gene (AT1R A1166C). No significant association was observed between these polymorphisms and the clinical characteristics of MI and non-MI subjects. While most classical risk factors were positively correlated with the angiographic scores, no significant relationship could be established with the three genotypes (r ranging from -0.08 to 0.05). Only one significant correlation was observed: between the presence of the AGT 235T allele and the extent of the coronary lesions (r = -0.19, P = 0.04) in patients with low-risk status. These overall results are not in favor of a role of these RAS genetic polymorphisms in the development of coronary atherosclerosis.

Angiotensinogen↗
PubMed1996

In vitro flow mapping of regurgitant jets. Systematic description of free jet with laser Doppler velocimetry.

BACKGROUND: Color Doppler and magnetic resonance imaging give pictures of abnormal jets within which the respective contribution of fluid mechanics and image artifacts are difficult to establish because of current technical limitations of these modalities. We conducted the present study to provide numerical descriptions of the velocity fields within regurgitant free jets. METHODS AND RESULTS: Laser Doppler measurements were collected in rigid models with pulsatile flow conditions, giving several series of two-dimensional flow images. The data were studied with the use of two-dimensional or M-mode flow images as well as regular plots. Numerical descriptions validated in steady flow conditions were tested at the various times of the cycle. In these free jets, the momentum was conserved throughout the cycle. The transverse velocity profiles were approximately similar. A central laminar core was found at peak ejection and during the deceleration. Its length (l = 4.08 d-0.036 mm, r = .99) and its diameter (d) were proportional to the orifice diameter. At peak ejection, the velocity decay was hyperbolic, and the transverse velocity profiles were clearly gaussian. The different relations that were tested could be combined in a single formula describing the velocity field: V(x,y,t peak) = V(O,O,t peak).4.(d/x).10(-45(y/x)2) (r = .92). CONCLUSIONS: These in vitro measurements demonstrated the presence of a central laminar core and similar transverse velocity profiles in free turbulent jets. This allowed us to validate a series of numerical relations that can be combined to describe the velocity fields at peak ejection. On the other hand, further studies are needed to describe the various singularities often encountered in pathology.

Heart Valve Diseases↗
PubMed1996

Diagnostic and therapeutic implications of transesophageal echocardiography in medical ICU patients with unexplained shock, hypoxemia, or suspected endocarditis.

OBJECTIVE: To evaluate the diagnostic and therapeutic implications of transesophageal echocardiography (TEE) in intensive care patients. DESIGN: Comparative study. SETTING: A 10-bed general intensive care unit. PATIENTS: Between 1 January 1992 and 31 May 1993, 61 patients prospectively identified with shock (n = 14), severe, unexplained hypoxemia (Partial pressure of oxygen in arterial blood/fractional inspired oxygen < 200) (n = 31), or suspected endocarditis (n = 16) underwent a TEE examination to supplement transthoracic echocardiography (TTE) examination. INTERVENTIONS: The results of each TEE examination were compared with the clinical findings and TTE data. TEE examinations were classified as follows: 0, TEE results were similar to TTE results; 00, TEE examination resulted in exclusion of suspected abnormalities; 1, TEE revealed a new but minor diagnosis compared to the TTE diagnosis; 2, TEE revealed a new major diagnosis not requiring a change of treatment; 3, TEE results revealed a new major diagnosis requiring an immediate change of treatment. RESULTS: Intraobserver reliability of the TEE classification was confirmed by a 100% concordance and interobserver reliability was evaluated as an 84% concordance. Results of the TEE classification were: class 0, n = 21 (34%); class 00, n = 13 (21%); class 1, n = 7 (12%); class 2, n = 8 (13%); class 3, n = 12 (20%). Therapeutic implications of TEE in class 3 patients were cardiac surgery in 5 patients (2 cases of acute mitral regurgitation, 2 valvular abscesses, and 1 hematoma compressing the left atrium), discontinuation of positive end-expiratory pressure in 1 ventilated patient with an atrial septal defect, weaning off mechanical ventilation in 1 patient with an atrial septal defect, prescription of antimicrobial therapy in 3 patients with endocarditis, and prescription of anticoagulant therapy in 2 patients with left atrial thrombus. No difficulty inserting the transducer was observed in any of the 61 patients studied. The only noteworthy complication was a case of spontaneously resolving atrial fibrillation. CONCLUSION: TEE is safe and well tolerated and is useful in the management of patients in the intensive care unit with shock, unexplained and severe hypoxemia, or suspected endocarditis when TTE is inconclusive.

Aged↗
PubMed1995

Relations between Doppler tracings of pulmonary regurgitation and invasive hemodynamics in acute right ventricular infarction complicating inferior wall left ventricular infarction.

To test the hypothesis that flow characteristics from pulmonary regurgitation (PR) can predict right ventricular (RV) involvement in patients with inferior wall acute myocardial infarction, we prospectively recorded continuous-wave Doppler tracings and right-sided cardiac hemodynamics in 48 consecutive patients with inferior wall acute myocardial infarction and PR. Right heart hemodynamics enabled the identification of 29 patients with (group 1) and 19 without (group 2) RV involvement. In patients with RV involvement, the pulmonary regurgitant flow pattern was characterized by a rapid rise in flow velocity to a peak level followed by an abrupt deceleration in mid-diastole, whereas in patients without RV involvement, the deceleration in mid-diastole was gradual. The pressure half-time of PR (PHTPR) and the lowest mid-diastolic to peak early diastolic velocity ratio were significantly lower in group 1 than in group 2 (91 +/- 31 vs 214 +/- 57 ms [p < 0.001], 0.35 +/- 0.08 vs 0.59 +/- 0.13 [p < 0.001], respectively). The best diagnostic accuracy (95%) was obtained with cut-off values of PHTPR < or = 150 ms and the lowest mid-diastolic to peak early diastolic velocity ratio < or = 0.5: sensitivity 100%, specificity 89%, positive predictive value 94%, and negative predictive value 100%. Using multiple logistic regression analysis, we found that PHTPR was the strongest predictor of RV involvement. Thus, these parameters, derived from pulmonary regurgitant tracings, are useful in the noninvasive bedside diagnosis of RV infarction.

Aged↗
PubMed1994

[Guidelines of the French Society of Cardiology on the training of echocardiographers and the performing of echocardiography].

The considerable advances achieved in the field of echocardiography have made this investigation an essential diagnostic tool. Under the auspices of the French Society of Cardiology, the Working group on Echocardiography publishes its practical recommendations for optimising the training of echocardiographers (theoretical instruction and practical courses) and for performing echocardiography (understanding the clinical problem, referral to previous examinations, necessary recordings and measurements, and appropriate equipment). In the future, these recommendations should be updated to take into account continuing technical improvements and changes in methods of studying cardiac disease by echocardiography.

Cardiology↗
PubMed1993

[Ultrasonography in the diagnosis of bacterial endocarditis: value and limits].

This cooperative study recensed 148 patients who had infective endocarditis (IE) with anatomopathological correlations. The infection was on native valves in 89 cases and prosthetic valves in 59 cases. Transoesophageal echocardiography diagnosed vegetations on native valves with a sensitivity, specificity, positive predictive and negative predictive values of 89%, 87%, 88% and 90% respectively, whereas for transthoracic echocardiography the results were 68%, 83%, 81% and 72% respectively. With respect to prosthetic valve vegetations, transoesophageal echocardiography had a sensitivity, specificity, positive predictive and negative predictive values of 67%, 84%, 48% and 92% respectively compared with 56%, 84%, 44% and 83% respectively for transthoracic echocardiography. These results underline the difficulties in differentiating degeneration and endocarditis of bioprostheses. Transoesophageal echocardiography diagnosed aneurysm formation and valvular perforation with a sensitivity, specificity, positive and negative predictive values of 61%, 93%, 91% and 72% respectively compared with 35%, 96%, 98% and 58% respectively for transthoracic echocardiography. The false negative results of transoesophageal echocardiography were usually observed in lesions of the posterior leaflet or commissures. In this series, the 6 aortic cusp perforations were undiagnosed by both transthoracic and transoesophageal echocardiography. With respect to aortic ring abscess, the sensitivity, specificity, positive and negative predictive values of transoesophageal echocardiography were 89%, 100%, 100% and 93% respectively, compared with 27%, 100%, 100% and 62% for transthoracic echocardiography. The false negative results of transoesophageal echocardiography were observed in cases of anterior abscesses or of calcific aortic valves. These results demonstrate the superiority of transesophageal over transthoracic echocardiography in the diagnosis of infective endocarditis and its complications. However, the limitations of the method should be recognized in the situations described.

Abscess↗
PubMed1992

[Non-invasive methods in the study of the elastic properties of the thoracic aorta. Effect of isosorbide dinitrate].

The role of the great arteries is to distribute and stock blood. Pulsatile discontinuous flow is transformed to a continuous flow system. The elastic properties of the aorta play a major role in these functions. It is generally agreed that changes in these elastic properties may lead to the development of left ventricular hypertrophy. The evaluation of the aorta has, until recently, depended on invasive hemodynamic and angiographic techniques. In addition, the measurement of pulse wave velocity, though useful, is a global and only an approximate method. Transoesophageal echocardiography (TEE) enables accurate measurement of the aortic diameter and its systolo-diastolic variations. The accuracy of these measurements has been validated in vitro and the reproducibility is much better than with previously used techniques. Previous studies have shown an improvement of the elastic properties of the great arteries with nitrate derivatives. In recent studies using TEE, isosorbide dinitrate caused dilatation of the descending thoracic aorta and thereby improved its elastic properties. The development of tonometry techniques in our department has resulted in the finding of excellent correlations between carotid and aortic pulse pressures measured non-invasively. The association of TEE and tonometry thereby provides a direct approach to the evaluation of aortic compliance. It has then become possible to study the effects of nitrate derivatives on the aortic compliance of elderly patients in whom it is the most reduced.

Aorta, Thoracic↗
PubMed1992

[Left coronaro-ventricular fistula after septal myectomy].

The authors report the case of a 17 year old patient operated for valvular aortic stenosis associated with severe hypertrophy of the interventricular septum. The operation consisted of aortic valve replacement and septal myectomy. Color-flow imaging in the postoperative period showed a coronary artery--left ventricular fistula in the region of the septal myectomy. In view of the small size of the fistula on echocardiographic examination and the absence of a codified strategy of management of acquired coronary left ventricular fistula after surgery, a simple Doppler echocardiographic follow-up was proposed in this case.

Adolescent↗
PubMed1991

Intra-operative transoesophageal echocardiography after mitral repair--specific conditions and pitfalls.

The aim of this study was to determine the specific conditions and pitfalls of immediate assessment of the reconstructed mitral valve in open chest patients. Sixty-two patients had a mitral reconstruction controlled by transoesophageal echocardiography and colour Doppler (TEE) from the moment when cardiac activity restarted under extracorporeal circulation (ECC), until complete rewarming of the patient and weaning off the by-pass. The following conditions altered the imaging quality: (1) dried probe in the oesophagus or air bubbles, (2) non-aspirated air from the stomach, (3) small or empty left atria, (4) invagination of the left atrial appendage, (5) trapped air in the posterior pericardium, (6) spontaneous contrast. Transient mitral regurgitation disappeared completely in 12/62 patients: five had temporary impairment of LV function, two had reduced filling of the heart, one had left ventricular outflow obstruction exacerbated by isoproterenol and nitroglycerin, two had ventricular ectopic rhythms, and two epicardial pacing. Only one of the 62 patients had persistent significant MR which required a second run of ECC. We conclude that mitral regurgitation after mitral valve repair is closely related to the quality of LV function. A decision to reoperate should eliminate the possible pitfalls, and take into consideration the specific conditions of immediate postoperative cardiac function.

Echocardiography, Doppler↗
PubMed1991

Diagnosis and hemodynamic assessment of valvular heart disease.

This paper will discuss the contribution of nonultrasonic methods to the diagnosis and the hemodynamic assessment of valvular heart disease as it has been discussed in the literature since the end of 1989. From recently published papers, several topics can be developed: the continuing importance of evaluating symptoms, the possible end of the epidemic of mitral valve prolapse, the persisting value of invasive assessment in case of inadequate Doppler echocardiographic examination, the need for coronary angiogram before surgery, the assessment of the left ventricular function, and the relation between fluid mechanics and new diagnostic modalities.

Coronary Angiography↗
PubMed1991

Influence of pulsatility on the development of intracardiac jets: an in vitro laser Doppler study.

So far, it has been hypothesized that numerical data obtained in steady flow conditions apply to pulsatile flows. In order to study the modifications of the velocity fields due to pulsatility, jets were produced by 8 orifices (with a diameter "D" of 4.4 to 11.3 mm) included in a chamber of 50 mm. The velocity was measured using laser Doppler anemometry with a pulsatile flow ("pf") and compared to the values obtained in steady ("sf"): at maximum velocity, the longitudinal velocity profile is qualitatively similar to this observed in steady flow: it is made of a plateau followed by an hyperbolic velocity decay in the turbulent area. The length of the core ("Lpf") is strongly related to "D" (Lpf = 3.72 D + 5.49, r = .99) and the velocity decay depends on the ratio between the distance "x" from the orifice and "D" (V/Vo = 2.83D/x + 3.46, r = .85, where V is the velocity at "x" and Vo the initial velocity). During the acceleration and the deceleration, the laminar core is disturbed by turbulences. The comparison of "pf" data with "sf" data demonstrated similar diameters at the origin of the jets (Dpf = 0.96 Dsf + .12, r = .99), but significant (p less than .0001) differences both for "L" and "V/Vo": Lpf = .91Lsf + 6.58, r = .97, V/Vopf = .63 V/Vosf + .34, r = .76. Thus, pulsatility modifies velocity fields and the results obtained in steady flow conditions do not apply to pulsatile jets.

Animals↗
PubMed1991

Velocity profiles and streamlines of a revolution post-stenotic flow.

Velocity fields have been measured in models simulating arterial stenoses for continuous and revolution flows. A pulsed Doppler velocimeter allows for velocity readings in the entire tube and in the wall area. Streamlines are determined by numerical solving of the system of equations defining the current function. Velocity profiles and streamlines are presented and discussed either for steady or for unsteady flows, with different Reynolds numbers and variable degrees of stenosis. There is, in the wall area, a recirculating zone made of a well-defined rouleau. Its length varies increasingly according to the increasing severity of the stenosis. The stability of axial flow depends on the input profile, the degree of stenosis and the Reynolds number. Plotting streamlines allows to describe accurately the flow; its quantitative aspect offers advantages with respect to conventional visualization mode.

Blood Flow Velocity↗
PubMed1991

[Thrombosis of atrioventricular prosthesis. Contribution of transesophageal echocardiography].

The aim of this study was to assess the diagnostic value of transesophageal echocardiography for the detection of thrombosis of a mechanical mitral or tricuspid valve prosthesis. Twelve patients (mean age 54 +/- 12 years) out of a series of 39 patients operated between April 1988 and June 1989 for prosthetic valve dysfunction had valve thrombosis at operation (11 mitral and 1 tricuspid valve prosthesis). Transesophageal echocardiography was routinely performed preoperatively in addition to transthoracic Doppler echocardiography to search for an abdominal mass on the prosthetic valves. The largest diameter of the diastolic jet at the level of the prosthetic valve annulus was measured using transesophageal color flow Doppler in the 8 Starr-Edwards mitral valve prostheses and compared with 5 control valves. The results of transthoracic Doppler echocardiography and transesophageal echocardiography were compared with the operative findings. The specificity of transthoracic echocardiography for the positive diagnosis of prosthetic valve thrombosis was 18%. A thrombosis could be suspected in 10 of the 12 cases by transthoracic echocardiography giving a sensitivity of 83%. Eleven of the 12 abnormal masses on the prostheses were visualised by transesophageal echocardiography, a sensitivity of 91%. Detection of the masses on the arterial side was possible in all cases (10/10) but 5 of the 6 extensions of the thrombus into the ventricle could not be visualised. The diameter of the transprosthetic jet was less than 12 mm in 7 of the 8 thrombosed valves compared with greater than 15 mm in the 5 normal control prostheses.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

[Quantitative analysis of systolic function of the right ventricule by Doppler echocardiography].

The recording of the velocity of tricuspid valve regurgitation by continuous wave Doppler enables the calculation of the instantaneous systolic pressure gradient between the right ventricle and right atrium. As right atrial pressure is relatively constant, the rate of acceleration of the regurgitant jet reflects the quality of the rise in pressure in the right ventricle in early diastole, and therefore right ventricular contractility. The authors studied 3 Doppler parameters of the rate of velocity increase of the tricuspid regurgitation; the maximum rate of acceleration (dV/dt max), the maximum derivative of the pressure (dP/dt max) and the mean rate of increase in pressure (T). The interobserver variability of these indices is low (r greater than 0.96); reproducibility is good in patients with sinus rhythm but mediocre in atrial fibrillation. The comparison of the Doppler indices with the right ventricular isotopic fraction in 26 patients with tricuspid regurgitation showed a good correlation (dV/dt max, r = 0.79, p less than 0.0001; dP/dt max, r = 0.69, p less than 0.0001; T, r = 0.60, p = 0.0012). These results show that right ventricular systolic function can be evaluated by continuous wave cardiac Doppler by recording the spectral envelope of tricuspid regurgitation.

Aged↗