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Biomedical subjects

R Lerch

Publications and source records attributed to R Lerch.

At least 37 records · Page 2Linked to original sources

[Dynamic three-dimensional cardiac reconstruction by transesophageal echocardiography. A clinical experience apropos of 100 cases].

Three-Dimensional (3D) echocardiography was performed during routine transesophageal examinations in 100 patients to identify the most promising applications. The approach used was based on the integration of multiple two-dimensional images recorded with a multiplane probe to achieve 3D reconstruction. A series of 90 cardiac cycles was recorded from a fixed position during computer-controlled rotation of the transducer. The images were digitized, then reorganized according to their spatial and temporal location. The cardiac structures were then represented dynamically in three dimensions. In 100 patients referred for transesophageal echocardiography, the 3D reconstruction provided good quality images, under new angles, such as the view of the atrial aspect of the mitral valve as seen from the roof of the left atrium. This method was particularly well suited to assess mitral valve prolapse or stenosis. The spatial extent, direction and number of jets of mitral regurgitation were easily appreciated throughout systole, as were the regurgitant jets of mechanical prosthetic valves. However, the sensitivity of the 3D method was not as good as 2D echocardiography for detecting bacterial vegetations in cases of infective endocarditis. On the other hand, the determination of the precise localization of infectious, degenerative and tumoral lesions and their size were facilitated by 3D reconstruction. The authors conclude that 3D echocardiography is applicable in routine practice and the complementary information provided in certain cardiac diseases should help management of these patients.

Adult↗

[Cellular recovery after ischemia: physiopathologic aspects].

Myocytes that have survived a period of transient ischemia may present prolonged alterations of cellular function, detectable during several days. The early period of postischemic reperfusion is characterized by restoration of ion homeostasis mediated by rapid resumption of function of ion pumps (Na+/K(+)-ATPase, Ca(2+)-ATPase) and transsarcolemmal ion exchange mechanisms (H+/Na+, Na+/Ca2+ exchangers). There is experimental evidence that cellular injury may be enhanced during the initial seconds or minutes of reperfusion, depending on the conditions of reperfusion. During the late phase of reperfusion mRNA expression of a number of key proteins of myocyte function is altered. The pattern of gene expression during reperfusion exhibits features of cellular adaptation and/or dedifferentiation in addition to cell repair.

Animals↗

Superior mesenteric venous aneurysm.

The case of a 50-year-old woman with an extremely rare venous malformation of the portal venous system is reported. The patient presented with a true aneurysm of the superior mesenteric vein, which has thus far been reported in no more than eight cases worldwide. This malformation may be congenital or acquired. Secondary aneurysms are thought to be due to liver disease, portal hypertension, trauma, or inflammation. Aneurysms of the portomesenteric venous system may be asymptomatic or give rise to severe, often dramatic conditions such as crampy abdominal pain, jaundice, and upper gastrointestinal hemorrhage secondary to portal hypertension. The diagnosis is usually made by ultrasound (B-mode or color flow Doppler), CT scan, and MRI. Invasive procedures such as venous phase mesenteric arteriography or splenoportography may be helpful in confirming it. In our opinion aneurysms of the portal venous system, even if they are congenital and (still) asymptomatic, require early surgical control because the prognosis for patients with these aneurysms is unpredictable and potential complications (e.g., portal hypertension, fistula, contained perforation, or rupture) may be fatal. In the case presented the mesenteric venous aneurysm was resected and the confluent veins were reconstructed.

Aneurysm↗

Effect of nutritional state on substrate metabolism and contractile function in postischemic rat myocardium.

The pattern of substrate utilization may influence postischemic myocardial injury. To characterize the effect of nutritional state on substrate selection and contractile function during control conditions and postischemic reperfusion, hearts from fed and fasted rats were perfused retrogradely with 0.4 mM palmitate, 8 mM glucose, and 175 mU/l insulin. Under control conditions, hearts from fasted rats exhibited lower glucose oxidation (-59%) and higher palmitate oxidation (+191%) than hearts from fed rats. During reperfusion, postischemic hearts exhibited stimulation of glucose-oxidation, with no difference between hearts from fasted and fed rats. However, oxidation of palmitate remained higher after fasting (+68%). Hearts from fasted rats exhibited lower left ventricular diastolic pressure and higher left ventricular systolic pressure development during reperfusion. The results indicate that 1) substrate selection in myocardium is influenced by the nutritional state independently of substrate availability, 2) during postischemic reperfusion, inhibition of glucose oxidation is removed in hearts from fasted rats, whereas inhibition of fatty acid oxidation in hearts from fed rats is maintained, and 3) myocardial injury is lower after fasting.

Animal Nutritional Physiological Phenomena↗

[Asymptomatic ischemia--an important part of the spectrum of coronary disease].

Angina pectoris and asymptomatic myocardial ischemia are part of the spectrum of coronary heart disease. Not the presence or absence of angina determines the future of the patient, but repeated ischemia and the progression of the coronaropathy. This progression is neither linear with time, nor is the moment of plaque rupture foreseeable. Silent myocardial infarctions increase with age and are very frequent in diabetics. In patients without neuropathy but with asymptomatic myocardial ischemia the central pain threshold is higher than in patients with angina pectoris. The best noninvasive test for the detection, localization and estimation of extension of myocardial ischemia, be it pain-free or symptomatic, is 201-thallium scintigraphy, combined with the exercise ECG. The fight against all amendable cardiovascular risk factors and pharmacotherapy are the first steps, if asymptomatic myocardial ischemia is suspected. Augmented dyspnea on effort and rhythm disturbances are indicators of advanced multivessel heart disease. Under these circumstances coronary angiography is indicated, and further treatment should follow the generally accepted rules such as for patients with angina pectoris.

Aging↗

[Reconstructive surgery of the mitral valve in the acute stage of bacterial endocarditis. Apropos of 2 cases].

Two patients in our institution underwent mitral valve reconstruction during the acute phase of Staphylococcus aureus mitral valve endocarditis. In neither case was a pre-existing valve lesion found. Echocardiographic examination revealed severe mitral insufficiency and the extent of valvular lesions. In the first patient, prolapse of the posterior commissure and paracommissural areas was due to ruptured chordae tendinae. In the second patient a perforated abscess was surrounded by vegetations in the median portion of the anterior leaflet and paramedian anterior chordae tendinae were ruptured. The surgical indication was hemodynamic, combined with suspicion of repeated emboli in one case. After a 10-day course of antibiotic therapy, both patients underwent surgical repair by Carpentier's mitral valvuloplasty. During more than 6 months' follow-up no recurrence of endocarditis was observed. Both patients were in class I of the NYHA without echocardiographic evidence of residual mitral regurgitation or stenosis. Early intervention during the acute phase of endocarditis, when mitral valve destruction is not too extensive, allows mitral valvuloplasty which preserves the native valve, eradicates infected tissues and may reduce postoperative mortality and morbidity.

Acute Disease↗

Successful term pregnancy after Mustard operation for transposition of the great arteries.

Transposition of the great arteries is a complex cardiac malformation with poor prognosis without surgical correction. Since the introduction of surgical procedures such as the intra-auricular reorientation of the venous return (Mustard procedure), an increasing number of patients may reach adulthood and experience pregnancy. Because long-term complications after the Mustard operation include systemic heart failure, arrhythmias, venous return stenosis and pulmonary edema, hemodynamic changes during pregnancy and delivery may potentially engender life-threatening complications in these patients. We report the case of a 24-year-old primigravida who underwent a Mustard procedure at the age of 2 years for transposition of the great vessels, and who carried out a full-term pregnancy. The pregnancy was uneventful until the 34th week, when the woman developed signs of moderate right ventricular failure and frequent episodes of accelerated junctional rhythm. Digitalisation improved symptoms and elicited return to normal sinus rhythm. The patient delivered at term by elective cesarean section, under close hemodynamic monitoring.

Adult↗

Standard views in cardiac multimodality tomographic imaging.

In cardiology, it is often necessary to acquire more than one type of image to investigate a given clinical problem of a single patient. Images obtained from different imaging modalities are usually recorded and displayed in different orientations, at different positions, and at different scale factors. It is then necessary for the physician to mentally integrate the image information from the different imaging modalities. This phenomenon is particularly true with tomographic imaging techniques that allow complete freedom of the acquisition plane. In particular, when comparing images obtained from ultrasound, computed tomography, magnetic resonance imaging, positron-emission tomography, and single-photon emission computed tomography. The purpose of this article is to propose a standard set of slice orientations that could be easily applied to all modalities. Such common views could greatly facilitate the user's perception of the regional abnormalities observed in the different imaging modalities. This standardization is certainly useful for clinical application but also for every research study that requires a comparative evaluation of the different imaging modalities. Although exact registration of the images from the different modalities requires sophisticated computer programs, the simple reference method in plane positioning proposed here based on plane orientation according to the cardiac geometry can certainly provide a practical and convenient method for the reasonably accurate image registration required for visual comparative studies.

Diagnostic Imaging↗

[Remodeling of the left ventricle following myocardial infarction: physiopathology and prevention].

The degree of left ventricular dilatation occurring after myocardial infarction is a major prognostic factor. Left ventricular remodeling is characterized by early expansion of the infarcted region and predominantly excentric hypertrophy of the noninfarcted myocardium, resulting in left ventricular cavity dilatation. Remodeling is most pronounced in large anterior infarctions. Recent evidence indicates that remodeling is amenable to treatment. Several randomized studies have demonstrated that long-term administration of converting enzyme inhibitors not only reduces left ventricular enlargement but also lowers morbidity and mortality after myocardial infarction.

Angiotensin-Converting Enzyme Inhibitors↗

Antigenic heterogeneity of the attachment protein of bovine respiratory syncytial virus.

A panel of 23 monoclonal antibodies (MAbs) specific for the attachment (G) glycoprotein of bovine respiratory syncytial virus (BRS virus), recognizing seven antigenic areas on the G protein, was used to determine the antigenic heterogeneity among 19 BRS viruses isolated over a 20 year period from various parts of the world. The pattern of reactivity of the isolates, as determined by ELISA, identified two major subgroups of BRSV. This finding was confirmed by radioimmunoprecipitation of the G protein by the MAbs and was also demonstrated using polyclonal sera obtained from calves hyperimmunized with BRS virus strains from each subgroup. The subgroups could also be differentiated by differences in the apparent M(r) of the fusion (F) glycoprotein and its cleavage products. The apparent M(r)s of the F0, F1 and F2 polypeptides were 73K, 46K and 17K for subgroup A strains and 77K, 46K and 23K for subgroup B strains. These studies provide evidence for two major lineages of BRS virus, similar to the situation with human RS virus.

Animals↗

Substrate competition in postischemic myocardium. Effect of substrate availability during reperfusion on metabolic and contractile recovery in isolated rat hearts.

Normal myocardium can derive energy for contraction and relaxation from oxidative metabolism of a variety of substrates. This investigation examined the influence of substrate availability early during reperfusion on the substrate pattern of oxidative metabolism and recovery of contractile function. For this purpose, isovolumically beating isolated rat hearts, perfused retrogradely with erythrocyte-supplemented buffer containing 0.4 mmol/L palmitate and 11 mmol/L glucose, were subjected to 40 minutes of no-flow ischemia. Hearts were reperfused with medium containing selected concentrations of palmitate and glucose. The substrate pattern for oxidative metabolism was determined on the basis of myocardial release of 14CO2 after equilibration of the hearts during the initial 15 minutes of reperfusion with either [1-14C]palmitate or [U-14C]glucose. In continuously perfused control hearts, glucose oxidation was largely inhibited by palmitate. During postischemic reperfusion, oxidation of glucose was increased by 59% (P < .05) and 467% (P <.01) in hearts reperfused after the ischemic period with 11 mmol/L glucose plus 0.4 or 1.2 mmol/L palmitate, respectively. Oxidation of palmitate was concomitantly reduced during reperfusion at low (0.4 mmol/L) but not at high (1.2 mmol/L) palmitate concentration. Compared with hearts reperfused with medium containing 0.4 mmol/L palmitate as sole substrate, hearts reperfused with medium containing 11 mmol/L glucose with 0.4 mmol/L palmitate exhibited lower left ventricular diastolic pressure (69 +/- 5 versus 90 +/- 3 mm Hg [mean +/- SEM], P < .05), less release of creatine kinase (31 +/- 5 versus 59 +/- 7 U/g wet wt, P < .05), and better recovery of left ventricular pressure development (26 +/- 9 versus 6 +/- 4 mm Hg, P < .05). Omission of palmitate or increasing the palmitate concentration to 1.2 mmol/L did not significantly alter postischemic myocardial contracture and enzyme release. The findings support the view that glucose oxidation early during reperfusion may be crucial for functional recovery. The results further indicate that interaction of substrates of oxidative metabolism is altered in severely injured postischemic myocardium. Inhibition of glucose oxidation by fatty acids was partially reversed during reperfusion.

Adenosine Triphosphate↗

[Role of transesophageal echocardiography in the diagnosis of cardiac disorders].

Transesophageal echocardiography provides a new window for ultrasound examination of the heart. The approach allows ultrasonic access to the heart in patients with transthoracic images of inadequate quality. Furthermore, transesophageal examination may provide information additional to that from the conventional transthoracic approach in the search for lesions including complications of endocarditis, mitral prosthesis dysfunction, aortic dissection, embolism of cardiac origin and selected cardiac malformations.

Echocardiography, Transesophageal↗

[Role of echocardiography in the diagnosis of aortic dissection].

Since the introduction of transesophageal transducers, Doppler echocardiography allows to detect aortic dissection with high sensitivity. The extent of the dissection can be determined accurately and the possibility of conducting the examination at bedside is particularly advantageous. Caution is advisable in interpreting doubtful observations in the distal part of the ascending aorta, which often ist incompletely visualized.

Aortic Dissection↗

Effect of altered loading conditions during haemodialysis on left ventricular filling pattern.

Changes in the circulating volume associated with haemodialysis result in modification of left ventricular loading conditions. To determine the influence of haemodialysis on Doppler indices of left ventricular filling, 12 patients (mean age 40.8 +/- 2.7 (SEM) years) with renal insufficiency but without overt heart disease were studied by Doppler-echocardiography immediately before and after haemodialysis. Haemodialysis resulted in a decrease in body weight from 68.0 +/- 3.8 kg to 65.0 +/- 3.7 kg (P < 0.01). Heart rate and blood pressure did not change significantly during haemodialysis. Left ventricular diastolic dimension (M-mode) decreased from 53.5 +/- 1.1 mm to 49.5 +/- 1.9 mm (P < 0.05), whereas the shortening fraction did not change. Haemodialysis elicited marked changes in the early diastolic rapid filling wave (E wave) recorded by pulsed Doppler at the level of the mitral annulus. Peak velocity of the early rapid filling phase (peak E) decreased significantly from 95.3 +/- 8.2 cm.s-1 to 63.0 +/- 5.7 cm.s-1 (P < 0.001) and mid-diastolic deceleration of transmitral velocity decreased from 437.3 +/- 54.2 cm.s-2 to 239.7 +/- 54.4 cm.s-2 (P < 0.01). The peak filling velocity during atrial contraction (peak A) did not change (79.7 +/- 6.3 cm.s-1 vs 74.1 +/- 4.7 cm.s-1; P = NS). The ratio peak E/peak A decreased from 1.19 +/- 0.06 to 0.85 +/- 0.04 (P < 0.01) during haemodialysis. The results provide further evidence for the pronounced preload-dependence of Doppler indices of left ventricular diastolic function.

Adult↗

Effects of dialysate composition during hemodialysis on left ventricular function.

To determine the effects of dialysate composition during hemodialysis on left ventricular systolic and diastolic function, 12 patients treated by chronic hemodialysis (mean age 40.8 +/- 2.7 years), without overt heart disease, were studied by Doppler-echocardiography successively before and after acetate hemodialysis (AHD), bicarbonate hemodialysis (BHD), and acetate-free biofiltration (AFB). The three types of hemodialysis resulted in a comparable decrease of the body weight. Mean arterial blood pressure decreased by 5 mm Hg (NS), 8 mm Hg (NS) and 10 mm Hg (P < 0.05) during AHD, BHD and AFB, respectively. There was a significant increase of the heart rate and the shortening fraction of the left ventricular diameter after AHD, but not after BHD and AFB. Mean total systemic resistance increased by 20% after AHD, 18% after BHD and by 7% after AFB (all changes NS). During each type of hemodialysis there was a significant reduction of the peak velocity of the early diastolic rapid filling wave (peak E) without change of the peak filling velocity during atrial contraction (peak A). During AHD and BHD the pressure half-time of the early filling phase (TP/2) increased, and the velocity-integral of the early diastolic filling phase (E-area) decreased. However, TP/2 and E-area did not change significantly after AFB.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetates↗