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Biomedical subjects

T Bartel

Publications and source records attributed to T Bartel.

47 records · Page 3Linked to original sources
PubMed1996

Detachment of defective septum primum. A potential source of embolism?

Cardiac sources of embolic stroke include various abnormalities of the atrial septum. An atypical detachment of the septum primum was detected in two patients by dynamic three-dimensional echocardiography (DTDE). Between the septum primum and septum secundum a cavity with interatrial communication was detected. Within the cavity a turbulent color Doppler signal and an entry of the contrast agent EchovistR were detected. One of the patients suffered from repeated cerebrovascular events. This unusual defect of the atrial septum may be a potential source of embolism. Transesophageal echocardiography is considered the most sensitive method for the examination of the atrial septum. However, clear anatomic details could only be shown by DTDE.

Adult↗
PubMed1996

Doppler-derived diastolic indices in dilated cardiomyopathy: a hemodynamic evaluation relating pre- and afterload parameters to flow velocity.

OBJECTIVE: To explain the well known finding of a normal early diastolic filling velocity in advanced grade heart failure due to dilated cardiomyopathy (DCM) exclusively by hemodynamics and to relate Doppler-flow velocity parameters to indices representing pre- and afterload. DESIGN: DCM was hypothesized to be a disorder in which pre- and afterload contribute in equal proportion to cardiac insufficiency independently from ischemic impairment of relaxation. PATIENTS: Twenty patients with DCM were enroled in the study after definitive exclusion of coronary and valvular heart disease. METHODS: Diastolic transmitral and transtricuspid Doppler readings and hemodynamic measurements were done simultaneously by two blinded observers. A Swan-Ganz catheter was employed. MAIN RESULTS: Simple and multiple regression analyses revealed early diastolic filling velocity to depend on hemodynamic parameters representing afterload. Pulmonary capillary wedge pressure (PCWP) was found to be directly related to early diastolic filling velocity. An inverse relation between early diastolic filling velocity and parameters representing afterload (systemic vascular resistance and mean arterial pressure) was demonstrated; however the most significant correlation using multiple regression analysis was shown between mitral early diastolic peak-flow velocity (dependent) and PCWP as well as systemic vascular resistance index (independents) (r = 0.75; P < 0.001). Correspondingly, the transtricuspid early diastolic peak-flow velocity was shown to be related to the equilibrium of right atrial pressure and pulmonary vascular resistance index. The atrial diastolic flow velocity parameters were found not to be related to hemodynamic indices. CONCLUSION: A definitive but not one-to-one relationship between early diastolic Doppler-flow indices and hemodynamic parameters was defined. A functional coupling of pre- and afterload can be considered the main determinant of early diastolic filling velocity in DCM.

Adult↗
PubMed1995

Dynamic three-dimensional transesophageal echocardiography using a computed tomographic imaging probe--clinical potential and limitation.

Dynamic three-dimensional echocardiography is a new diagnostic tool for spatial visualisation of cardiac anatomy and volumetric assessment. A computer-controlled probe acquires parallel tomographic slices, from which dynamic three-dimensional images of the heart can be reconstructed. Thirty adult patients with valvular heart diseases, congenital heart diseases, intracardiac masses, heart failure and other cardiac lesions, underwent conventional two-dimensional (n = 30), three-dimensional echocardiography (n = 30) and thermodilution (n = 17). The feasibility, usefulness and possibility of simulating a surgical view of intracardiac anatomy and exact volumetry were determined. The two different morphologic images were compared qualitatively. For quantitative analysis volumetry was performed using standard thermodilution technique and dynamic three-dimensional echocardiography. In more than 80% of the patients additional morphologic information was gained and a strong correlation (r = 0.75-0.95) between two volumetry assessments was found. Based on this findings, dynamic three-dimensional echocardiography is an additional and valuable approach in the perioperative and intensive care management in this group of patients.

Adult↗
PubMed1995

Corrected transposition of the great arteries: dynamic three-dimensional echocardiography and volumetry. A new diagnostic tool in intensive care management.

Today, an increasing incidence of severe complications of cardiac malformations in adult patients must be expected since the life expectancy of such individuals is prolonged due to improved management. A 32-year-old woman with corrected transposition of the great arteries (CTGA) was admitted to the intensive care unit because of cardiac decompensation. Information provided by multiplane two-dimensional transesophageal echocardiography was not sufficient for an unequivocal explanation of the cardiac decompensation. In CTGA uncommon complications may cause pulmonary edema. Using dynamic three-dimensional echocardiography to reveal function, volume parameters and the morphology of both ventricles and to exclude additional complications may be considered an adequate diagnostic tool for responding to this challenge.

Adult↗
PubMed1994

Left and right heart Doppler stress echo in congestive heart failure.

Doppler echocardiographic assessment of the left and right ventricular function at rest, during and 6 minutes after submaximal exercise was performed in 60 patients with a mean age of 43 +/- 11 years suffering from heart failure classified stage I-III according to the NYHA-criteria and 10 volunteers with a mean age of 36 +/- 9 years who served as a control group. At mitral (m) and tricuspid (t) valve early diastolic peak-flow velocity (VEm, VEt), atrial peak-flow velocity (VAm, VAt), speed-time integrals (Em, Et, Am, At) and the ratios (VE/VAm, VE/VAt, E/Am, E/At) were determined. The left ventricular end-diastolic diameter (LVEDD) and the right ventricular outflow tract (RVOT) were measured in addition. The left ventricular ejection fraction (LVEF) was decreased to < 36% in 9 patients (group 1). In 51 individuals LVEF was found to be > 35% but < 50% or LVEF was shown to be > 50% but VE/VAm-ratio was found to be < 1 (group 2). Out of all the determined parameters, VE/VAt, VEt and VAm during exercise were found to be the most sensitive parameters for the detection of early to advanced grade left heart failure.

Adult↗
PubMed1994

Preoperative assessment of cor triatriatum in an adult by dynamic three dimensional echocardiography was more informative than transoesophageal echocardiography or magnetic resonance imaging.

Classic cor triatriatum is rarely found in adults. Preoperative assessment of classic cor triatriatum in a 22 year old man without symptoms by three dimensional echocardiography was more informative than transoesophageal echocardiography or magnetic resonance imaging, which both showed only a small hole in the membrane separating the accessory atrium from the true left atrium. The size of the hole indicated a strong likelihood that symptoms would develop in this patient. Dynamic three dimensional echocardiography, however, showed a long wide hole in the separating membrane. This finding was consistent with the absence of symptoms in this patient. Symptom free patients with moderate obstruction do not need early surgical correction.

Adult↗
PubMed1993

Doppler stress echocardiography of the left and right ventricle: a new echo device to quantify left ventricular backward failure.

OBJECTIVES: A novel non-invasive procedure which evaluates left-right ventricular interaction is introduced. This procedure is suitable for the classification of congestive heart failure. METHODS: In 48 patients showing mild, moderate or advanced stage congestive heart failure (NYHA I-III) Doppler echocardiography was performed at rest, during and after submaximal bicycle exercise. Mitral (m) and tricuspid (t) filling parameters were determined: early diastolic (VEm, VEt) and atrial maximal velocities (VAm, VAt), the velocity integrals (Em, Et, Am, At) and the corresponding ratios (VE/VAm, VE/VAt, E/Am, E/At). Group 1 (n = 29) was composed of those patients presenting with a VE/VAm < 1 at rest. Four individuals (group 2) were found to have a VE/VAm ratio < 1 during exercise only. Six other patients showing a dilated left ventricle or an ejection fraction of less than 40% produced false negative results in left ventricular Doppler examination (VE/VAm > 1) at rest and during exercise (group 3). In 9 cases (group 4) systolic function, size and Doppler echocardiographic parameters of the left ventricle were proven to be normal. RESULTS: The VE/VAt-ratio decreased notably during exercise (p < 0.05) but increased again after exercise in group 3. In the groups 1 and 2 similar changes occurred as well, however not to a significant degree. In group 4, exercise VE/VAt ratio did not differ from values seen at rest or during recovery (variability 4%). CONCLUSION: The results of this study indicate, that high sensitivity towards left ventricular backward failure can be achieved for Doppler stress echocardiography by extending the examination to right-sided diastolic parameters.

Adolescent↗
PubMed1990

Mathematical modelling of the purine metabolism of the rat liver.

The regulation of the purine metabolism of the rat liver is studied on the basis of a mathematical model which comprises rate laws and kinetic constants of all physiologically relevant reactions. The computed stationary and time-dependent concentrations are in good accordance with experimental data obtained in the ischaemic rat liver and in isolated hepatocytes. In particular, model-based simulations of the adenine nucleotide metabolism have been performed for situations where ATP-deficient states of the cell (hypoxia, anoxia or ischaemia) of various length are followed by onset of ATP production (reoxygenation). These simulations confirm the experimentally observed incomplete recovery of ATP and of the total pool of adenine nucleotides within a few hours of reoxygenation after long-term ATP depletion. Therefore, it can be concluded that this phenomenon is an intrinsic regulatory property of the purine metabolism and not necessarily due to some irreversible changes in the activity of the enzymes involved.

Animals↗
PubMed1990

[The possible significance of coronary vascular resistance in chronic ischemic heart disease].

From a pool of patients, treated because of cardiac diseases on ward for 4 years, 8 subjects, the mean age of which amounted to 46 (SD 12) years, showing stable angina pectoris in usual physical activity, were chosen. In these patients widespread examinations including invasive procedures had not been evident for one of the well defined heart diseases. In two patients dysrhythmias appeared during standardized exercise test while in four other subjects acute cardiac findings consisted of chest pain, significant depression of ST segments or inversion of T waves were observed. One patient had a normal result of the exercise test. A myocardial thallium-201 imaging was performed in four subjects. In three patients imaging showed questionable or mild signs of ischemia. The result suggest the existence of unknown shapes in coronary heart disease, the origin of which is possibly connected with a disorder of microvascular smooth muscle reactivity.

Adult↗
PubMedDate not supplied

Preliminary report: evaluation of three-dimensional echocardiographic volumetry by simultaneous thermal dilution in coronary heart disease.

In 12 patients with coronary heart disease, the end-systolic and end-diastolic left-ventricular volumes were measured employing three-dimensional echocardiography. Cardiac output (COe) and stroke volume (SVe) were calculated and correlation with simultaneous thermal dilution measurements (COth, SVth) was performed. In 9 subjects the variability between the mean heart rate and the heart rate at any given time was found to be < 10% (observer 1:SVe vs. SVth r = 0.78, p < 0.01, COe vs. COth r = 0.86, p < 0.01 and in 9 cases with steady heart rate SVe vs. SVth r = 0.95, p < 0.01; observer 2:SVe vs. SVth r = 0.78, p < 0.01, COe vs. COth r = 0.77, p < 0.01 and in 9 cases with steady heart rate SVe vs. SVth r = 0.93, p < 0.01). Using the new bedside approach three-dimensional imaging and volumetry becomes possible by means of one examination.

Cardiac Output↗