Formation, Consistency and Degradation of Artificial Thrombi in Severe Renal Failure

Abstract

SummaryA novel study of dynamic blood coagulation in uraemic patients was based on the application of the variable-frequency thromboviscometer, VFTV, an advanced form of the thrombelastograph. Clotting times, rates of formation, consistencies, and rates of degradation of artificial thrombi cast at 60 and 180 cycles/min (equal to mean shear rates of 26.8 and 80 sec–1) were investigated in 35 patients and in normal controls.The study shows that there exists a profound difference in VFTV parameters between normals and patients with severe renal failure. The most significant are the rate of degradation of thrombi formed at 60 cycles/min (p < 0.001), the consistency of thrombi formed at 180 cycles/min (p < 0.005), and the total thrombus formation time at 180 cycles/min (p < 0.001). Thrombi formed at 60 cycles/min adhered to brass rather than Teflon in many patients with renal failure, in contrast to the findings in normals and in all types of patients previously tested.A division of patients into clinical subgroups (acute renal failure, non-oliguric or oliguric chronic renal failure, and long-term dialysis) shows that all these groups are quite homogeneous from the dynamic coagulation viewpoint, although the thrombus degradation rate (when coagulation proceeds at 60 cycles/min) differs significantly (p = 0.025) between the long-term dialysis group and the non-oliguric chronic renal failure group. These same groups also show a difference in their platelet count. The VFTV abnormalities of uraemia could not be correlated with either the severity of the measurable biochemical derangement or the qualitative platelet defect.An unexpected, but statistically significant, pattern appeared when patients were divided according to their ABO blood groups. The rate of degradation of the thrombus formed at 60 cycles/min differed significantly between 0 and A and between B and A blood groups (p < 0.01). The rate of formation of the white thrombus at 180 cycles/ min differed significantly (p < 0.05) between 0 and A blood groups. Simultaneously, the platelet count differed between blood groups 0 and B (p = 0.05) and between 0 and A (p < 0.005).Effect of blood groups on the VFTV parameters is evident even in the normal controls; here, the rate of degradation of the thrombus formed at 60 cycles/min showed significant difference between blood groups A and B (p < 0.005) and a smaller difference between 0 and B(0.05 < p <0.1).We consider that the demonstration that the consistency of white thrombi is twice as high in uraemic patients than in normals, and that the rate of degradation of the red-white thrombi is nearly ten-fold greater is of fundamental importance. Both these phenomena might be associated with the known platelet defects of uraemia, or with a possible further abnormalities of fibrinogen, caused by the presence of one or more of the chemical substances which accumulate in the uraemic state.

Formation, Viscosity and Degradation of Artificial Thrombi after Cadaveric-Donor Kidney Transplantation

“…The results are grouped under two headings. In the first are described measurements made with the VFTV on thrombus formation and degradation of pre-transplant and successful and 'complicated' groups of post transplant patients, and in the second, a statistical comparison of these results with those reported previously (6) .…”

“…Further clinical, haematological and biochemical data on the patients are given in Table 1. The methods used were the same as in the previous study of VFTV patterns in renal failure (6) . Blood was obtained from the patients by clean venepu ncture, using siliconized needles and plastic disposable syringes in a two-syringe method.…”

Blood Viscosity Factors and Occlusive Arterial Disease in Renal Transplant Recipients

“…Transient and intermittent elevation of blood viscosity, in any localized area or tissue, can be due to a sudden development of platelet aggregation, changes in osmolarity or pH, presence of microthrombi or microemboli. The latter are actually a feature of severe renal failure [9], Blood viscosity factors are ab normal in uraemia but return to normal following uncomplicated successful transplantation [9][10][11],…”

“…1 ml of blood was placed immediately in the variable-frequency thromboviscometer (VFTV) [7,9], and the latent clotting time (r), total thrombus formation time (r+ s), and maximum apparent thrombus viscosity (A) defined at 60 cpm; a second sample being used for a similar test carried out at 180 cpm (the corresponding mean shear rates, at total amplitude of 110°, being 26.8 and 80 sec-1, respectively).…”

“…In renal allograft recipients, occlusive arterial disease is responsible for between 4 and 12% of deaths [1.2], In uraemia abnormal blood viscosity is frequently present, formation and viscosity of artificial thrombi are greatly elevated [9] but return to normal following successful kidney transplantation [10]. Patients who have serious medical complications with transplantation show, however, a pattern of viscosity factors similar to that of uraemia subjects.…”