[Hyperfibrinogenemia and pathological plasma viscosity. Pathogenetic factors in unstable angina pectoris?]

Plasma viscosity and erythrocyte aggregation, as the most important rheological factors in the microcirculation, and fibrinogen were measured in the blood of groups of patients in various stages of coronary-heart disease. Patients with unstable angina had viscosity and fibrinogen levels, even before any manifest infarction, that were higher than those of patients with stable angina. Plasma viscosity and hyperfibrinogenaemia (1.39 +/- 0.08 mPa.s in 48 patients and 394.4 +/- 82.7 mg/dl, respectively, in 33) were comparable to the values in patients with acute myocardial infarction (1.37 +/- 0.09 mPa.s [n = 45] and 390.2 +/- 126.9 mg/dl [n = 27], but significantly higher (P less than 0.02) than in those with stable angina (1.33 +/- 0.08 mPa.s [n = 78] and 295.3 +/- 68.6 mg/dl [n = 44], respectively). This abnormal viscosity in unstable angina plays a part in increasing myocardial ischaemia because oxygen delivery is already diminished and capillary flow slowed down. It thus contributes to progression of the angina and must be taken into account as an additional pathogenetic factor in the clinical instability.

Blood rheology and hypertension in hemodialysis patients treated with erythropoietin

Fifteen hemodialysis patients suffering from stable anemia were treated with recombinant human erythropoietin (r-HuEPO). Within 16 weeks, hematocrit values increased from 23.7 +/- 1.2 to 35.7 +/- 0.2%. Simultaneously, mean predialytic blood pressure rose significantly from 131/79 to 139/85 mm Hg. Three out of 15 patients developed frank hypertension and had to be put on antihypertensive therapy. When the hematocrit was lowered again from 36.3 +/- 1.8 to 30.5 +/- 1.2% in these 3 patients, blood pressure was attenuated and the antihypertensive medication could be reduced or abolished. With rising hematocrit values, whole blood viscosity increased at both low (+42%) and high shear rates (+33%) without reaching the values seen in healthy subjects. By contrast, plasma viscosity was already elevated in hemodialysis patients prior to r-HuEPO treatment and showed only a slight, but insignificant increase during r-HuEPO treatment. Since whole blood viscosity is one factor that determines vascular resistance, it is conceivable that the development of hypertension during correction of the renal anemia is, at least partly, due to an increment of blood viscosity.

[Significance of the thrombin-antithrombin III complex in the diagnosis of pulmonary embolism and deep venous thrombosis--comparison with fibrinopeptide A, platelet factor 4 and beta-thromboglobulin]

In 22 patients with suspected pulmonary embolism and 19 patients with suspected deep vein thrombosis, thrombin-antithrombin III complex (TAT) as an indicator of thrombin activation was measured using a newly developed ELISA. For comparison fibrinopeptide A (FPA), as a marker of an activated coagulation, as well as platelet factor 4 (PF4), and beta-thromboglobulin (beta-TG), as markers of platelet activation, were determined. In all patients in whom pulmonary embolism was confirmed by perfusion lung scan and in 15 of 16 patients in whom deep vein thrombosis was confirmed by phlebography, TAT exceeded the upper limit of normal (3.0 ng/ml). FPA was increased in 71% of the pulmonary embolism patients, PF4 in 53%, and beta-TG in 59%. The data for the patients with deep vein thrombosis were comparable. PF4 and beta-TG were increased in more than 25% of the normal controls, FPA in 17%, and TAT in 9%. TAT is very sensitive in detecting an activation of the coagulation system in patients with suspected thromboembolic events. The test, however, is not specific for thromboembolism; it only indicates an activation of the coagulation system. Acute pulmonary embolism or deep vein thrombosis would appear to be unlikely if TAT is normal. The measurement of TAT is easier and less susceptible to disturbances than that of FPA, PF4, and beta-TG.

[Heparin-induced thrombopenia]

Cutaneous necroses, acute renal failure and an adrenocortical insufficiency appeared during heparin therapy in a 47 year old patient with myocardial infarction. The thrombocytes fell to 73,000/microliter and displayed intensified spontaneous aggregation. In histological investigation of the cutaneous necroses, intensive thromboses of the cutaneous and subcutaneous blood vessels were found. The findings indicate a thromboembolic etiology of the acute renal failure and the adrenocortical insufficiency. This case involves a complex example of a heparin-induced thrombopenia with thromboembolic complications.

Recent progress in improving data processing in filtration measurements

Nucleopore filter membranes currently utilized to assess RBC "deformability" do not meet the strict metrological requirements of a measuring gauge. They present different kinds of inhomogeneities introducing an useless information (a background noise) into measurement results and expressed as poor reproducibility. Variance reduction can only be achieved by eliminating aberrant results from a series of parallel measurements made with different membranes. To this end a procedure is proposed to identify aberrant values by an iterative statistical regression analysis of data from filter calibration and measurements on RBC suspensions and to express results as "reduced" initial flow rates for a standard filter resistance.

[Serum levels and urine excretion of L-carnitine in patients with normal and impaired kidney function]

The influence of age, sex, and renal function on serum levels and urinary excretion of free carnitine was studied in 187 subjects. Sixty-one subjects with normal renal function (creatinine clearance greater than 100 ml/min) showed a serum carnitine level of 72.2 +/- 23.2 mumol/l. The carnitine values of males (76.8 +/- 23.3 mumol/l, n = 39) were higher (p less than 0.05) than those of females (64.0 +/- 21.0 mumol/l, n = 22). Carnitine levels did not correlate with age. Values in patients with normal renal function did not differ from serum carnitine levels in healthy controls (74.7 +/- 17.5 mumol/l, n = 49). The mean urinary carnitine excretion per day was 163.5 mumol (range 63.7-419.6 mumol) in patients with intact renal function. Extreme impairment of glomerular filtration rate (creatinine clearance less than 20 ml/min) resulted in higher carnitine concentrations in serum (108.9 +/- 39.4 mumol/l, n = 18, p less than 0.05), lower carnitine elimination per day (78.5 mumol, range 14.5 - 424.3 mumol, n = 18, p less than 0.05) and a decreased carnitine clearance (0.8 ml/min, range 0.2 - 3.8 ml/min). These data together with earlier results obtained in dialysis patients suggest that carnitine metabolism in renal failure is altered by reduction of both endogenous carnitine biosynthesis and renal carnitine clearance.

Quantitative assessment of carnitine loss during hemodialysis and hemofiltration

Carnitine deficiency has been claimed to be responsible for the myo- and cardio-myopathy observed in dialysis patients and has been attributed to the loss of carnitine during dialysis. To quantitate carnitine loss, we determined the carnitine concentrations in 29 patients on chronic hemodialysis, 10 patients on chronic hemofiltration, and 8 patients on CAPD. Mean plasma carnitine levels in hemodialysis and hemofiltration patients (39.8 +/- 2.7 mumoles/liter; N = 39) were significantly lower (P less than 0.01) than in controls (49.8 +/- 2.0 mumoles/liter; N = 43). Hemodialysis or hemofiltration led to a further reduction (33.2 +/- 3.5 mumoles/liter; P less than 0.001). There was no significant difference in the mean plasma carnitine level between CAPD patients (40.0 +/- 5.7 mumoles/liter) and controls. Hemofiltration treatment resulted in a weekly loss of 795 +/- 84 mumoles of carnitine. This was significantly lower (P less than 0.0001) than the urinary carnitine excretion in healthy controls (1534 +/- 134 mumoles per week; N = 27) and the carnitine elimination in the dialysate of CAPD patients (1905 +/- 236.6 mumoles per week; N = 8). It is concluded that carnitine deficiency in dialysis patients cannot be explained by loss into dialysate or filtrate. Because intestinal reabsorption of carnitine does not seem to be impaired, decreased endogenous carnitine synthesis is considered as the most plausible explanation for the moderate degree of carnitine deficiency observed in dialysis patients.