Biomedical subjects

U Solzbach

Publications and source records attributed to U Solzbach.

14 recordsLinked to original sources

PubMed1998

[Bypass perforation by stent implantation: complication management. A case report].

We describe a case-report on an perforation of an aorto-coronary venous bypass graft, a complication induced by a stent-implantation. Perforations of coronary arteries are rare, however, for interventional cardiologists well-known complications. This case report is of special interest (1) because the perforation did not occur in a coronary artery but rather in an eight year old venous bypass graft and (2) because the perforation was induced by a stent-implantation. In addition, this case report describes in great detail the management of vessel perforation: several invasive methods contributed to minimize pericardial effusion and to stabilize the patient until surgical revision could be performed.

Aged↗

PubMed1997

Vitamin C improves endothelial dysfunction of epicardial coronary arteries in hypertensive patients.

BACKGROUND: There is evidence for increased formation of free radicals in patients with hypertension, raising the possibility that NO is inactivated by free radicals, which impairs coronary endothelial function. Therefore, we tested the hypothesis that the antioxidant vitamin C could improve abnormal endothelial function of coronary arteries in patients with hypertension. METHODS AND RESULTS: In 22 hypertensive patients without relevant coronary artery stenoses, endothelium-dependent vascular responses of the left anterior descending coronary artery (LAD) to acetylcholine (0.01, 0.1, and 1.0 micromol/L) were determined before and immediately after intravenous infusion of 3 g vitamin C (17 patients) or placebo (5 patients). In a subgroup of 10 patients, papaverine-induced flow-dependent vasodilation (FDD) was measured before and after vitamin C (5 patients) or placebo (5 patients) infusion. Segmental responses of the coronary artery luminal area were analyzed with quantitative coronary angiography. Before vitamin C infusion, the mean changes of LAD luminal areas at increasing doses of acetylcholine were -6.1+/-2.2%, -15.2+/-4.9%, and -33.9+/-8.1% (negative numbers symbolize vasoconstriction) and during FDD, 5.4+/-1.0%. The vasoconstrictor response during acetylcholine was reduced and FDD was augmented by vitamin C. After vitamin C infusion, LAD luminal areas changed by -3.2+/-2.3%, -5.8+/-3.6%, and -10.2+/-5.6% (P<.05, acetylcholine) and 17.8+/-2.8% (P<.05, FDD). Doppler flow velocity (during baseline, acetylcholine, and FDD) was not significantly affected by vitamin C. CONCLUSIONS: Vitamin C improves the endothelium-dependent vasomotor capacity of coronary arteries in patients with hypertension and patent coronary arteries. These findings suggest that increased oxidative stress contributes to endothelial dysfunction in hypertensive patients.

Acetylcholine↗

PubMed1995

Digital angiographic impulse response analysis of myocardial perfusion: influence of heart rate and blood pressure changes on microcirculatory transit time measurement in the normal canine coronary circulation.

The study describes the effect of acute changes in aortic blood pressure and heart rate in the intact normal canine coronary circulation on digital angiographic measurements of the mean transit time of the microcirculation compartment and on direct flow meter measurement of resting and maximal hyperemic coronary blood flow. The mean transit time of the radiographic contrast material through the normal coronary circulation was calculated in 20 dogs by the impulse response analysis from serial digital coronary angiograms under systematically changed blood pressure and heart rate conditions. The mean aortic blood pressure (MAP) was controlled by the inflation of a balloon in the descending aorta (70-150 mmHg). The heart rate was altered by atrial pacing (90, 120, and 150/min). The mean transit times (T mu) of contrast material across the myocardial microcirculation which had been recently shown to correlate with coronary flow reserve (CFR) in stenosed arteries in the canine model were calculated under resting and hyperemic flow conditions from 428 selective coronary angiograms after a hand-injected contrast bolus, T mu was found to be heart rate independent. T mu-1 was linearly correlated with MAP (r = 0.7). There was no difference in T mu under resting and hyperemic flow conditions at comparable MAP. The corresponding distribution volume (V mu) of the microcirculation was calculated as the product of the mean transit time T mu and the measured coronary blood flow. Under resting flow conditions, V mu decreased with rising MAP. Furthermore, V mu increased with rising heart rate, V mu was constant during blood pressure or heart rate changes under hyperemic flow conditions. The data suggest that CFR whether by direct measurements of flow or by radiographic assessment of contrast material kinetics should be standardized with respect to hemodynamic conditions of heart rate and MAP.

Animals↗

PubMed1994

Optimum angiographic visualization of coronary segments using computer-aided 3D-reconstruction from biplane views.

Using a biplane multidirectional isocentric X-ray system, a computer-aided simulation procedure was developed to calculate the 3D structure of the coronary arteries. The algorithm uses the geometry of the biplane X-ray system and the alignments of corresponding points of the coronary arteries in two X-ray images acquired under different viewing angles. The identification of the corresponding points is greatly simplified by the calculation and display of the intersection lines of the confocal plane with the image intensifier entrances on the computer monitor. To minimize the total number of necessary corresponding points we used Bézier curves to match the courses of the coronary segments between neighboring corresponding points. The projection of the calculated 3D structure was found to be in very good agreement with the 2D course of the coronary arteries in the angiograms. The 3D structure can be viewed on the computer screen under any desired simulated projection angle within the geometrical limitation of the X-ray gantries. The user can select views on the computer monitor with orthogonal projection angles and minimal overlapping problems caused by under- and overlying structures. The method was applied in 10 cases of elective angioplasty. Previously taken diagnostic angiograms were used to reconstruct the arterial structure and to select favorable views for the forthcoming intervention.

Cineangiography↗

PubMed1993

Comparing wall motion quantification methods by numerical classification.

Quantitative left ventriculography has been studied for many years as a method for assessing left ventricular function. All currently used quantitative left ventriculography methods evaluate functional status based on different assumptions concerning the time course of contraction, shape of the ventricular silhouette, and/or fixed points of reference. Commonly, analyses are performed using only end-diastolic (ED) and end-systolic (ES) frames. However, myocardial infarction manifests itself not only in spatial parameters, e.g., area of affected myocardium, but also in temporal parameters, e.g., deviation from a synchronous contraction during systole. ED/ES comparisons omit information contained in other frames of the cardiac cycle. Therefore, each single method has a limited reliability or usefulness. The present study used several quantitative methods, fitted curvatures, correlation coefficients of the percentage of radial shortening from end diastole to end systole, and Fourier coefficients of the polar coordinates of the endocardial contour points. Features were derived from a sequence of ventriculograms of a whole cardiac cycle from patients with anterior myocardial infarction (AMI group) and without (NV group) to address three major goals: (1) Determine features derived from LV-grams that discriminate between the two patient groups and do so with the highest accuracy, "recognition rate," or lowest error rates; (2) compare the accuracy of features generated by different quantitative methods; and (3) group features generated by the different quantitative methods to achieve higher accuracy. The discriminant capabilities of several feature sets were tested on a patient sample containing 102 patients (63 patients with AMI, 39 patients with no infarction) using numerical classification. The numerical classification had a Supervised Learning design with two cardiologists assigning the patients to the two patient groups. Each quantification method showed a characteristic pattern for detecting pathologic or normal wall motion. Combining features generated by different extraction methods into one feature set improved the correct classification rates.

Algorithms↗

PubMed1989

[ACPA reaction in atypical Wegener's disease. Diagnostic test].

Clinical and biopsy findings in six patients (aged 29-64 years), suspected of having Wegener's granulomatosis, were not diagnostic. Cardinal signs were skin necroses, isolated deficits of cranial nerves, sudden amaurosis, renal failure with shunt sepsis and lung opacities suspicious of tumour. Only positive tests for anti-cytoplasmatic antibodies (ACPA) in serum made the diagnosis and led to appropriate treatment. This simple yet highly specific immunofluorescence test should be performed in every case of vasculitis of uncertain cause, even if typical clinical signs of Wegener's granulomatosis are at first absent.

Adult↗

PubMed1989

[Status of the technic of angiography procedures].

Angiocardiography continues to expand inspite of competitive non-invasive imaging techniques (echocardiography, CT, nuclear magnetic resonance). Only angiography yields images of sufficient spatial and temporal resolution as they are needed for coronary diagnostic work and interventional catheter therapy. Angiographic systems are mono- or biplane with high degree of mobility and flexibility for oblique and angulated projections. Currently available systems do not fulfill the requirements. Image resolution and contrast are today satisfactory, however, still not sufficient for interventional techniques. Only digital image processing will allow further improvement, thereby enhancing contrast and detail while reducing radiation dose (pulsed, high-contrast fluoroscopy, on-line image processing). Cine-filming seems not needed in all cases. In the future, angiocardiography will hardly be needed for study of cardiac chambers, valves or great vessels. Instead, specialized systems of extreme mobility and flexibility with high resolution and digital image processing for image improvement and documentation, radiation reduction for coronary and general arterial diagnostic and therapeutic interventions will be developed.

Angiocardiography↗

PubMed1989