F. Jung

Retinal Capillary Blood Flow Measurement with a Scanning Laser Ophthalmoscope Preliminary Results

The scanning laser technique in combination with digital image analysis allows direct objective measurement of flow velocities in perimacular capillaries. In addition, the complete macular network of capillaries can be observed. By means of digital frame-to-frame picture analysis of digital recordings, blood flow velocities and morphologic data have been measured. The mean flow velocity in perimacular capillaries observed with the scanning laser ophthalmoscope in healthy subjects (n = 21) amounted to 3.28 +/- 0.45 mm/second. In patients (n = 13) with diabetes mellitus (no or background retinopathy), the mean flow velocity was significantly reduced (2.89 +/- 0.57 mm/seconds) compared with healthy subjects. Morphologic data of the perifoveal capillary bed showed a significant reduction of capillaries in patients with diabetes mellitus when compared with healthy subjects.

Video fluorescein angiography: method and clinical application.

Video fluorescein angiography, combined with a picture analyzing system, is a clinically applicable, objective method of evaluating the retinal blood-flow parameters. Optical density measurements were performed on videorecordings of fluorescence angiograms by means of a picture-analyzing system in order to determine the circulation parameters of the retina. These included: the arm-retina time (ART), the arteriovenous passage time (AVP), and the mean arterial dye-bolus velocity (MDV). Normal values for these parameters were derived from measurements in 75 healthy volunteers. The mean arm-retina time (ART) was 11.2 ± 3.3 s, the mean arteriovenous passage time (AVP) 1.45 ± 0.4 s and the mean arterial dye-bolus velocity (MDV) 6.39 ± 1.7 mm/s. No significant correlation could be shown between pulse or blood pressure and one of the retinal circulation parameters. A group of ten healthy volunteers was examined twice in order to obtain the intraindividual variation for the measuring parameters. The coefficient of variation for the ART was 18%, 10% for the AVP, and 26% for the MDV.

Effects of garlic coated tablets in peripheral arterial occlusive disease

SummaryFor the first time, a weak clinical efficacy of a 12-week therapy with garlic powder (daily dose, 800 mg) is demonstrated in patients with peripheral arterial occlusive disease stage II. The increase in walking distance in the verum group by 46 m (from 161.0 ± 65.1 to 207.1 ± 85.0 m) was significantly higher (P<0.05) than in the placebo group (by 31 m, from 172.0 ± 60.9 to 203.1 ± 72.8). Both groups received physical therapy twice a week. The diastolic blood pressure, spontaneous thrombocyte aggregation, plasma viscosity, and cholesterol concentration also decreased significantly. Body weight was maintained. It is quite interesting that the garlic-specific increase in walking distance did not appear to occur until the 5th week of treatment, connected with a simultaneous decrease in spontaneous thrombocyte aggregation. Therefore, garlic may be an appropriate agent especially for the long-term treatment of an incipient intermittent claudication.

[Determination of reference ranges of rheologic parameters: study of 653 randomly selected probands of the Aachen district].

To determine reference ranges for rheologic parameters (hematocrit, plasma viscosity, erythrocyte aggregation, erythrocyte rigidity) a randomized study involving 653 subjects was carried out. Conditions of sampling, transportation and storing of blood specimens were established prior to the survey. Only 283 subjects met the criteria for enrollment in the study; the others were rejected because of inconspicuous history, normal findings in physical and Doppler-sonographic examination and absence of the risk factors hypertension, diabetes mellitus, overweight, rheumatic diseases, and smoking. The reference range for hematocrit was determined by an impedance-measuring device to equal 39-52% for males and 34-50% for females. The reference range for plasma viscosity, measured by a capillary-tube-plasma viscometer, was found to vary from 1.14 mPas to 1.34 mPas. The reference values for the standardized erythrocyte aggregation index was determined with the mini erythrocyte aggregometer to range from 8 to 21. Erythrocytes measured with the selecting-erythrocyte rigidometer showed a rigidity reference range between 0.83 and 1.19. Analysis of the results revealed that the parameters were independent of age (except in young children) and sex (with the exception of hematocrit).SummaryTo determine reference ranges for rheologic parameters (hematocrit, plasma viscosity, erythrocyte aggregation, erythrocyte rigidity) a randomized study involving 653 subjects was carried out. Conditions of sampling, transportation and storing of blood specimens were established prior to the survey. Only 283 subjects met the criteria for enrollment in the study; the others were rejected because of inconspicuous history, normal findings in physical and Doppler-sonographic examination and absence of the risk factors hypertension, diabetes mellitus, overweight, rheumatic diseases, and smoking.The reference range for hematocrit was determined by an impedance-measuring device to equal 39–52% for males and 34–50% for females. The reference range for plasma viscosity, measured by a capillary-tube-plasma viscometer, was found to vary from 1.14 mPas to 1.34 mPas. The reference values for the standardized erythrocyte aggregation index was determined with the mini erythrocyte aggregometer to range from 8 to 21. Erythrocytes measured with the selecting-erythrocyte rigidometer showed a rigidity reference range between 0.83 and 1.19. Analysis of the results revealed that the parameters were independent of age (except in young children) and sex (with the exception of hematocrit).

Role of Rheologic Factors in Patients with Acute Central Retinal Vein Occlusion

PURPOSE To assess the rheologic findings in acute central retinal vein occlusion (CRVO) with respect to associated risk factors, the clinical appearance of ischemic or nonischemic CRVO, and to elucidate the etiology of possible changes. METHODS The authors enrolled 173 patients with acute CRVO (ischemic, 33%; nonischemic, 67%) in this prospective study. One hundred seventy-three patients who were matched for age, sex, and cardiovascular risk factors served as control subjects. All patients underwent testing to determine hematocrit values, plasma viscosity (PV), erythrocyte aggregation (SEA), and erythrocyte rigidity (SER). RESULTS Hemocrit values and PV were increased significantly (P<0.01) in patients with ischemic and nonischemic CRVO compared with control subjects but did not differ significantly between the two groups. No significant differences were found in SEA and SER values between the clinical subsets of patients with CRVO and when the patients were compared with matched control subjects. Analysis revealed that hemocrit and PV values were (P<0.001) increased significantly independent of associated cardiovascular risk factors. CONCLUSION These results suggest that increased hemocrit and PV values may be contributing factors in the pathogenesis of CRVO.

Quantification of characteristic blood-flow parameters in the vessels of the retina with a picture analysis system for video-fluorescence angiograms: initial findings

Fluorescence angiograms of the retina were performed on 12 healthy, adult subjects between the ages of 20 and 52 years with a 30° fundus camera (C. Zeiss), a low-light TV camera and a video recorder. Characteristic blood-flow parameters for the retina were obtained from the video recording using the picture-analysis system (Mikrovideomat 3, C. Zeiss). These included: the arm-retina time (ART), the arteriovenous passage time (AVP) and the arterial contrast-medium velocity (ACMV). Normal values for these parameters were derived for the four retinal quadrants and then discussed. In addition, the filling characteristics of venules were measured and discussed.

Factors affecting the restenosis rate after percutaneous transluminal coronary angioplasty

In an open study follow-up angiographies were performed independently from the clinical course on altogether 131 consecutive patients (99 men, 32 women) six months after percutaneous transluminal coronary angioplasty (PTCA). During this period patients received at least 320 mg of aspirin daily. Possible factors affecting the restenosis rate included age, sex, diabetes mellitus, arterial hypertension, abnormal lipid metabolism, smoking, dosage of aspirin administered, degree of stenosis shown by affected vessels before dilatation, number of vascular segments dilated and platelet reactivity. Restenosis was defined as a renewed narrowing of the dilated segment by 50% or more, with an increase in stenosis by at least 20%. In the present study the following restenosis rates were found six month after a primarily successful PTCA: 30% for the entire sample (39 out of 131 patients); 25% in patients with normal platelet function, 50% in those with mildly abnormal platelet function, and 60% in those with frankly abnormal platelet function; 24% in non-diabetic patients and 45% in diabetics. Analysis of the findings showed that abnormal platelet function and the presence of diabetes mellitus were the most important factors in the subsequent development of restenosis after angioplasty. The same also applied in a more restricted manner to the degree of stenosis present before angioplasty.

Primary and secondary microcirculatory disorders in essential hypertension

SummaryIn this prospective cross-sectional study blood fluidity and peripheral microcirculation were measured in patients suffering from essential hypertension with and without macroangiopathy. The cutaneous microcirculation was evaluated by intravital microscopy and the intramuscular by pO2 needle electrode. Disorders in the microcirculation without macroangiopathy in the system of the feeding arteries are defined as primary microangiopathy. Disturbed microcirculation with macroangiopathy in the feeding arteries in one area but no detectable microcirculatory disorder in another region is defined as a secondary microcirculatory disorder. Of the 57 patients in this study 27 had a primary microcirculatory disorder. It was remarkable that all 27 hypertension patients had a microcirculatory disorder in the area of the skin. Intramuscular microcirculatory disorder on its own without affection of the skin was not detected in any case. An exclusively secondary microcirculatory disorder occurred in 16 patients. This study shows that 93% of the patients with long-term essential arterial hypertension have microcirculatory disorders. It is most interesting that about one-half of these hypertension patients had a primary microcirculatory disorder, i.e., no indication of a hemodynamically active stenosis was found in the large vessels.

Haemorheology in patients with branch retinal vein occlusion with and without risk factors

Abstract• Purpose: The study was carried out to ascertain the role of blood viscosity in patients with branch retinal vein occlusion (BR-VO) with and without risk factors. • Methods: In 292 patients with acute BRVO (mean age 65 ± 10 years) and 292 controls matched for gender, age, and cardiovascular risk factors, haematocrit, plasma viscosity, erythrocyte aggregation and erythrocyte rigidity were measured. A subgroup analysis in patients with and without risk factors was performed. • Results: Haematocrit and plasma viscosity values were significantly higher in BRVO patients than in controls, but erythrocyte rigidity and erythrocyte aggregaton did not differ. Subgroup analysis revealed no differences in haematocrit and plasma viscosity values between patients with and those without cardioavascular risk factors. • Conclusions: This study shows increased plasma viscosity and haematocrit values in patients with BRVO which are not associated with the presence of other cardiovascular risk factors. Thus, changes in blood fluidity appear to be important factors in the pathogenesis of BRVO.

Ein Gerät zur elektrischen Messung der Verformbarkeit von Erythrozyten - A Device for the Electrical Measurement of the Deformability of Red Blood Cells

Schlüsselwörter: Verformbarkeit von Erythrozyten, Einzelloch-Membran, elektrische Meßwertorf assung Es wird ein Gerät zur Messung der Verformbarkeit einzelner Erythrozyten vorgestellt. Als Maß für die Verformbarkeit gilt dabei die Zeit, die einzelne Erythrozyten benötigen, um eine Einzelloch-Membran zu passieren. Bei der Passage des Erythrozyten durch die Pore ändert sich der Gesamtwiderstand der Meßkammer; dies wird elektrisch registriert und ist ein direktes Maß für die Passagezeit. Das Meßsignal der elektrischen Messung wird verglichen mit dem Signal der bisher verwendeten optoelektrischen Meßwerterfassung.