Influence of fibrinogen and hematocrit on the early outcome of angioplasty in patients with PAOD

Reversion of the Inflammatory Markers in Patients With Chronic Limb-Threatening Ischemia

BACKGROUND

Peripheral artery disease is characterized by an intense inflammatory process that can be associated with a higher mortality rate, particularly in chronic limb-threatening ischemia (CLTI). This study aims to compare the evolution of inflammatory markers between patients with claudication with those with CLTI at 3, 6, and 12 months.

METHODS AND RESULTS

An observational, single-center, and prospective study was conducted. A total of 119 patients with peripheral artery disease (65 with claudication and 54 with CLTI) were observed and inflammatory markers collected at admission and 3, 6, and 12 months. At admission, patients with CLTI, when compared with patients with claudication, had significantly higher serum levels of C-reactive protein and fibrinogen (positive acute-phase proteins) and lower serum level of albumin, total cholesterol, and high-density lipoprotein (negative acute-phase proteins): C-reactive protein (g/dL), 2.90 (25th-75th percentile, 2.90-4.90) versus 6.80 (25th-75th percentile, 2.90-53.26) (P=0.000); fibrinogen (mg/dL), 293.00 (25th-75th percentile, 269.25-349.00) versus 415.50 (25th-75th percentile, 312.00-615.75) (P=0.000); total cholesterol (mg/dL), 161.79±95% [152.74-170.85] versus 146.42%±95% [135.30-157.53] (P=0.034); high-density lipoprotein (mg/dL), 50.00 (25th-75th percentile, 41.00-60.00) versus 37.00 (25th-75th percentile, 30.00-45.50) (P=0.000); albumin (g/dL): 4.00 (25th-75th percentile, 3.70-4.20) versus 3.60 (25th-75th percentile, 3.10-4.00) (P=0.003). The association between CLTI and total cholesterol was lost after adjusting for confounders. Three months after the resolution of the CLTI, there was an increase in the levels of negative acute-phase proteins and a decrease in positive acute-phase proteins. These inflammatory proteins did not register an evolution in patients with claudication. The differences in the inflammatory proteins between groups disappeared at 6 months.

CONCLUSIONS

CLTI has an inflammatory environment that can be partially reverted after resolution of the ischemic process, emphasizing the importance of timely intervention.

Optimal hematocrit in an artificial microvascular network

BACKGROUND

Higher hematocrit increases the oxygen-carrying capacity of blood but also increases blood viscosity, thus decreasing blood flow through the microvasculature and reducing the oxygen delivery to tissues. Therefore, an optimal value of hematocrit that maximizes tissue oxygenation must exist.

STUDY DESIGN AND METHODS

We used viscometry and an artificial microvascular network device to determine the optimal hematocrit in vitro. Suspensions of fresh red blood cells (RBCs) in plasma, normal saline, or a protein-containing buffer and suspensions of stored red blood cells (at Week 6 of standard hypothermic storage) in plasma with hematocrits ranging from 10 to 80% were evaluated.

RESULTS

For viscometry, optimal hematocrits were 10, 25.2, 31.9, 37.1, and 37.5% for fresh RBCs in plasma at shear rates of 3.2 or less, 11.0, 27.7, 69.5, and 128.5 inverse seconds. For the artificial microvascular network, optimal hematocrits were 51.1, 55.6, 59.2, 60.9, 62.3, and 64.6% for fresh RBCs in plasma and 46.4, 48.1, 54.8, 61.4, 65.7, and 66.5% for stored RBCs in plasma at pressures of 2.5, 5, 10, 20, 40, and 60 cm H₂ O.

CONCLUSION

Although exact optimal hematocrit values may depend on specific microvascular architecture, our results suggest that the optimal hematocrit for oxygen delivery in the microvasculature depends on perfusion pressure. Therefore, anemia in chronic disorders may represent a beneficial physiological response to reduced perfusion pressure resulting from decreased heart function and/or vascular stenosis. Our results may help explain why a therapeutically increasing hematocrit in such conditions with RBC transfusion frequently leads to worse clinical outcomes.

Role and Management of Coagulation Disorders in Peripheral Arterial Disease

Peripheral arterial disease (PAD) has often underlying risk factors, of which diabetes and cigarette smoking are the most common. Enhanced platelet activation and interaction with vessel wall associate with atherothrombotic disease, but also increased fibrinogen levels, thrombin generation and fibrin turnover are typical for PAD. The pathogenic role of fibrinogen, thrombin formation and fibrin degradation is suggested not only in acute thrombotic complications, but also in the stable form of PAD, where these markers associate with the functional severity (ankle-brachial blood pressure index). The coagulation-specific etiologies of PAD should be suspected if the atherothrombotic disease has severe manifestations, especially while the traditional risk factors are absent, or if the patient has also a history of venous thromboembolism. Malignant disease may be present in form of peripheral arterial thrombosis as well. Thrombophilia may expose patients to idiopathic thrombosis – both spontaneously and after vascular interventions. The management of these patients includes often combination therapies with antiplatelet agents and anticoagulants. Obviously, the strict policy to avoid risk factors and to treat them well in avoidance of progression of arterial disease is highly important. In the absence of published follow-up data the evidence to support the management strategies is weak and individual tailoring of efficacious and safe antithrombotic drug therapy remains our challenge. These patients benefit from continuous medical attention by the experts in the field of angiology. Management of PAD is an excellent example of the multidisciplinary approach where the hematologist meets the vascular surgeon or interventional radiologist to secure the best available patient care.

Segmental blood flow and rheological determinants in diabetic patients with peripheral occlusive arterial disease

Vascular abnormalities are more prevalent in the lower extremities in diabetic patients and may cause diminished perfusion to surrounding tissues. We sought to identify blood flow abnormalities in the leg of diabetic patients with peripheral occlusive arterial disease (POAD) and to determine whether these were associated with abnormalities in rheological determinants, namely, plasma fibrinogen concentration (PFC), relative plasma viscosity (RPV), hematocrit (Hct), and whole blood viscosity (WBV). Seventeen diabetic patients with POAD were compared with 40 diabetic patients without POAD and 19 nondiabetic control subjects. Blood flow was measured by venous occlusion plethysmography, RPV was measured by capillary viscometry, WBV was measured by a Wells-Brooksfield viscometer [at high (230 s(-1)) and low (23 s(-1)) shear rates], and PFC was measured by the clot-weight method of Ingram [Ingram, G. I. C. (1961). A suggested schedule for the rapid investigation of acute haemostatic failure. Journal of Clinical Pathology, 14, 356-360]. Ankle blood flow (Q(ak)) was significantly lower in diabetic patients with POAD than in diabetic patients without POAD (P<.05). PFC was higher and Hct was lower in diabetic patients with POAD than in diabetic patients without POAD (P<.05). RPV was 1.97+/-0.15 versus 1.92+/-0.15 in diabetic patients with POAD and diabetic patients without POAD, respectively (P>.05). There was no significant difference in WBV at low or high shear rates between the groups studied. There was a correlation between WBV at low shear rate and arterial flow in the calf (Q(c)) (r=.94) and great toe (r=.95) in diabetic patients with POAD, and between Q(c) and WBV at high (r=-.465) and low (r=-.472) shear rates in diabetic patients without POAD (P<.05). We conclude that vasodilatation occurring in diabetic patients without POAD is severely restricted or absent in diabetic patients with POAD. Increased plasma fibrinogen and plasma viscosity may contribute to this phenomenon.