The pernicious cycle of VLUs in Brazil: epidemiology, pathogeny and auxiliary healing methods.

Venous leg ulcers (VLUs) represent the most advanced stage of chronic venous insufficiency. Despite the large body of knowledge available regarding the risk factors and aetiopathogeny of the condition, patients referred to public health care systems in developing countries often do not receive adequate diagnosis or early treatment, leading to clinical evolution and disease recurrence. This review collates updated information about the epidemiology, risk factors, aetiopathogeny, diagnosis, ulcer healing methods and determinant factors of the pernicious cycle of VLUs in developing countries, with a focus on the Brazilian setting.

Total endovascular debranching of the aortic arch.

BACKGROUND: Significant morbidity and mortality are related to conventional aortic replacement surgery. Endovascular debranching techniques, fenestrated or branched endografts are time consuming and costly. OBJECTIVE: We alternatively propose to use endovascular approach with parallel grafts for debranching of aortic arch. METHODS: Under general anesthesia, 12 F sheaths were inserted in the femoral, axillary and common carotid arteries for vascular accesses. ViaBahn grafts 10 - 15 cm in length were placed into the aortic arch from right common carotid, left common carotid and left axillary arteries, until the tip of each graft reached into the ascending aorta. Through one femoral artery, the aortic stent -graft was positioned and delivered. Soon after, the parallel grafts were sequentially delivered. Self-spanding Wallstents(R) were used for parallel grafts reinforcement. Ballooning was routinely used for parallel grafts and rarely for aortic graft. RESULTS: This technique was used in 2 cases. The first one was a lady with 72 years old, with an aortic retrograde dissection from left subclavian artery and involving remaining arch branches. Through right common carotid artery a stent-graft was placed in the ascending aorta and through the left common carotid artery a ViaBahn was inserted parallel to the former. A thoracic endograft then covered all the aortic arch dissection extending into the ascending aorta close to the sinu -tubular junction. The second case was a 82 year old male patient with a 7 cm aortic arch aneurysm. Through both common carotid arteries ViaBahn grafts were introduced and positioned into the ascending aorta. Soon after, the deployment of the thoracic stent graft covered all parallel grafts of the aortic arch, excluding the aneurysm. Both cases did not have neurologic or cardiac complications and were discharged 10 days after the procedure. CONCLUSIONS: This technique may be a good minimal invasive off-the-shelf technical option for aortic arch ''debranching''. More data and further improvements are required before this promising technique can be widely advocated.

Incorrect use of thromboprophylaxis for venous thromboembolism in medical and surgical patients: results of a multicentric, observational and cross-sectional study in Brazil.

OBJECTIVES: Although effective strategies for the prevention of venous thromboembolism (VTE) are widely available, a significant number of patients still develop VTE because appropriate thromboprophylaxis is not correctly prescribed. We conducted this study to estimate the risk profile for VTE and the employment of adequate thromboprophylaxis procedures in patients admitted to hospitals in the state of São Paulo, Brazil. METHODS: Four hospitals were included in this study. Data on risk factors for VTE and prescription of pharmacological and non-pharmacological thromboprophylaxis were collected from 1454 randomly chosen patients (589 surgical and 865 clinical). Case report forms were filled according to medical and nursing records. Physicians were unaware of the survey. Three risk assessment models were used: American College of Chest Physicians (ACCP) Guidelines, Caprini score, and the International Union of Angiololy Consensus Statement (IUAS). The ACCP score classifies VTE risk in surgical patients and the others classify VTE risk in surgical and clinical patients. Contingency tables were built presenting the joined distribution of the risk score and the prescription of any pharmacological and non-pharmacological thromboprophylaxis (yes or no). RESULTS: According to the Caprini score, 29% of the patients with the highest risk for VTE were not prescribed any thromboprophylaxis. Considering the patients under moderate, high or highest risk who should be receiving prophylaxis, 37% and 29% were not prescribed thromboprophylaxis according to ACCP (surgical patients) and IUAS risk scores, respectively. In contrast, 27% and 42% of the patients at low risk of VTE, according to Caprini and IUAS scores, respectively, had thromboprophylaxis prescribed. CONCLUSION: Despite the existence of several guidelines, this study demonstrates that adequate thromboprophylaxis is not correctly prescribed: high-risk patients are under-treated and low-risk patients are over-treated. This condition must be changed to insure that patients receive adequate treatment for the prevention of thromboembolism.

Long-term histopathologic evaluation of inferior vena cava after modified Greenfield filter implantation. Experimental study in sheep.

AIM: The authors assess a modified Greenfield filter (GF) for the long-term patency, filter tilting and histopathologic alterations of the inferior vena cava (IVC). METHODS: Adult sheep (n=7) underwent modified GF placement in the IVC. Cavograms were obtained every 3 months and pulmonary angiography at 12 months. Histopathologic and scanning electron microscopy (SEM) analyses were performed on the IVC explanted at 12 months. RESULTS: Cavograms showed that all IVC were patent at the end of the study. Filter tilting occurred in 2/7 animals and extrusion of struts was not observed. Macroscopic examination at explantation showed minimal venous wall thickening. Microscopic examination showed minimal IVC fibrosis and intimal hyperplasia. SEM showed endothelium on the IVC surface at the filter implantation site and a presumed endothelial layer covering partially or totally the struts. The interface filter-IVC was covered by deposits of leucocytes and platelets. No signs of pulmonary embolism were found in all pulmonary angiograms of both groups. CONCLUSION: The modified filter presented good biocompatibility, stability and absence of thrombogenicity at 12 months. It presented low tendency to tilting and extrusion of struts. The long-term histopathologic alterations in vena caval wall were minimal and the appearance of the studied filters in the IVC was similar to stents placed in the arterial system.

Healing process in anastomosis of homologous venous grafts preserved in glutaraldehyde implanted aorta of rabbits.

AIM: Autologous vein (AV) is sometimes not suitable or present for a vascular restoration. Homologous vein preserved in glutaraldehyde may be an alternative to AV, but little is yet known about this graft and its healing process after implantation in arteries. The purpose of this study was to compare the initial healing process of glutaraldehyde-tanned homologous venous grafts (group 1) with fresh autologous venous grafts (group 2), at 4 or 15 days. METHODS: Forty Norfolk rabbits were allocated in 2 groups of 20 animals each. The grafts was interposed in the infrarenal aorta of the rabbit. Anastomotic tensile strength (TS), hydroxyproline (HP) determination, and histology (HA) were performed. RESULTS: TS increased in both groups, from the 4th to 15th day, (p<0.01) in both proximal (G1: from 364.5+/-98.3 g to 491.8+/-107.3 g; G2: from 366.26+/-85.15 g to 518.46+/-82.79 g) and distal anastomosis (G1: from 363.53+/-96.26 g to 507.32+/-91.01 g; G2: from 352.30+/-102.41 g to 528.67+/-48.58 g), with no difference between the groups. HP did not change (p>0.10) in this same period and was similar in both groups, in the proximal (G1: from 677.99+/-153.98 microg/100 mg to 914.92+/-459.83 microg/100 mg; G2: from 668.65+/-170.28 microg/100 mg to 669.46+/-319.80 ug/100 mg) as well as in the distal anastomosis (G1: from 740.07+/-213.53 microg/100 mg to 923.52+/-270.57 microg/100 mg; G2: from 737.66+/-266.76 microg/100 mg to 707.68+/-171.25 microg/100 mg). Initial inflammatory and reparative features of the anastomosis were similar in both groups. CONCLUSION: We can conclude that the healing process of the glutaraldehyde-tanned homologous vein graft was similar to that of the fresh autologous venous graft.

Effect of alpha-tocopherol, taurine and selenium on the attenuation of ischemia/reperfusion injury of splanchnic organs.

BACKGROUND: Splanchnic artery occlusion shock is caused by increased capillary permeability and cellular injury precipitated by oxygen derived free radicals following ischemia and reperfusion of splanchnic organs. The purpose of this study was to assess the role of several well-known oxygen-derived free radical scavengers in ameliorating or preventing this syndrome. STUDY DESIGN: Anesthetized rats were subjected to periods of occlusion of the visceral arteries and reperfusion. Tocopherol, taurine, selenium or a 'cocktail' of these three agents was injected subcutaneously for 4 consecutive days prior to operation. Mean arterial blood pressure was measured throughout the experimental period. Fluorometry and technetium-99m pyrophosphate counting of the visceral organs were performed as well as a histologic grading system for intestinal viability. RESULTS: Final mean arterial blood pressure associated with the 'cocktail' and selenium groups was 79.1 +/- 27.4 mmHg and 83.6 +/- 17.8 mmHg, respectively. These values were significantly higher than the control group, 40.8 +/- 11.4 mmHg (P < 0.05). Similar patterns of the benefit of selenium in contrast with the other groups were obtained with fluorescein perfusion, radioisotopic activity and histologic analysis. CONCLUSION: Pretreatment with selenium of splanchnic ischemia and reperfusion in the rat improves mean arterial blood pressure and microcirculatory visceral perfusion. Further analysis of the precise protective mechanism of selenium for reperfusion injury will enable visceral organs to withstand the consequences of increased capillary leakage and oxidant injury.

Tensile strength and histological changes of abdominal aorta of malnourished rats.

The resistance of the abdominal aorta of rats after 6, 7 and 8 weeks of malnutrition, compared with control animals, was evaluated by longitudinal tensiometry. Weakness of this vessel in malnourished rats was demonstrated; microscopic examination of the aorta stained by Masson, Calleja and hematoxylin-eosin methods showed a decrease in amorphous ground substance and an increase in the width of elastic laminae. There was no visible alteration either in the endothelial lining layer or in the smooth muscle fibers. Such alterations of the aorta are, to the authors' knowledge, the first reported modifications in the peripheral vasculature after malnutrition.

Arteriovenous fistula between the right internal mammary artery and the subclavian vein: percutaneous closure with detachable balloon-catheter embolization.

A case of iatrogenic fistula from the right internal mammary artery to the subclavian vein following subclavian vein catheterization is reported. The patient had undergone percutaneous Intracath catheterization of the subclavian vein to treat hypovolemic shock during the surgical treatment of ectopic pregnancy. She had remained symptom-free for 7 years and then started to complain of effort dyspnea. The patient was found to have a thrill and a bruit at the subclavian region, and arteriography demonstrated a fistula between the right internal mammary artery and the subclavian vein. The fistula was successfully closed by embolization with a percutaneous detachable balloon catheter.

Heparin, heparin plus ASA and dipyridamole, and arteriovenous fistula as adjuvant methods to prevent rethrombosis after venous thrombectomy. Experimental study in rabbits.

Venous rethrombosis following thrombectomy is a common event. The aim of the present study was to verify the action of heparin, heparin plus acetyl salicylic acid (ASA) and dipyridamole, and of an arteriovenous fistula (AVF) in the prevention of this complication. Thrombosis was induced in 48 male rabbits by the injection of thrombin in a segment of the left jugular vein, in which the blood flow was arrested for 10 minutes. After 48 hours, the animals were randomly allocated into one of 4 groups of treatment: (1) control, (2) subcutaneous heparin (600 S.I. Units/kg--8/8 hours), (3) heparin, in the same dose, plus ASA (10 mg/kg/once a day), and dipyridamole (0.5 mg/kg thrice a day), (4) an AVF was surgically constructed between the left carotid artery and the left maxillar vein. After 30 minutes, thrombectomy was performed. The venous blood flow, the hematocrit, activated partial thromboplastin time and thrombin time tests were performed before, right after the thrombectomy and 48 hours after thrombectomy. Venography was performed after thrombectomy and at the end of the experiment. The animals were killed 48 hours after thrombectomy and the veins were examined macroscopically. Venous rethrombosis was significantly prevented only in the AVF group (9/12), when compared to control group (0/12), heparin group (1/12) and heparin plus antiaggregating agents group (2/12). These results validate further clinical and experimental investigations with the use of AVF to prevent rethrombosis after venous thrombectomy, when a reduction of venous flow is present.

Platelet activation following application of an Esmarch bandage and tourniquet in rabbits.

The present study evaluates platelet activation following application of an Esmarch bandage and a tourniquet, procedures commonly employed to provide a bloodless operative field during limb surgery. Platelet aggregation was increased in blood samples taken from rabbits 60 min after an Esmarch bandage was applied to one thigh and immediately released. When this treatment was combined with the application of a tourniquet for 60 min, a procedure which alone did not affect platelet aggregation, results were similar to those obtained following the Esmarch bandage alone. These data suggest that tissue compression produced by application of an Esmarch bandage, but not the ischemia derived from the tourniquet, produced platelet aggregation.

Platelet activation following application of an esmarch bandage and tourniquet in rabbits

The present study evaluates platelet activation following application of an Esmarch bandage and a tourniquet, procedures commonly employed to provide a bloodless operative field during limb surgery. Platelet aggregation was increased in blood samples taken from rabbits 60 min after an Esmarch bandage was applied to one thigh and immediately released. When this treatment was combined with the application of a tourniquet for 60 min, a procedure which alone did not affect platelet aggregation, results were similar to those obtained following the Esmarch bandage alone. These data suggest that tissue compression produced by application of an Esmarch bandage, but not the ischemia derived from the tourniquet, produced platelet aggregation

Comparative study of the action of topical heparinoids on the evolution of experimental thrombophlebitis.

The action of three different topical heparinoids on the evolution of experimental thrombophlebitis was studied. Thrombophlebitis was induced in the marginal vein of the ear of rabbits by stasis and injection of hypertonic glucose solution. Forty-eight hours later the animals were allocated to three treatment groups and a control group. The substances were applied over the affected vein three times a day for 6 days and the ears inspected daily by transilumination. After 7 days, the animals were killed and anatomopathological studies performed. No difference in thrombus frequency or inflammatory reaction was observed between the animals treated with heparinoids and the control groups, or among the treated groups.

Lumbar sympathectomy and distal arteriovenous fistula as adjuncts to prevent arterial rethrombosis after thrombectomy: experimental study in dogs.

The role of lumbar sympathectomy and distal arteriovenous fistula (AVF) in preventing rethrombosis of femoral arteries with intimal injury and poor run-off was studied in 21 dogs. Femoral artery thrombosis was induced by endothelial lesion in all animals (phase 1) and 24 hours later the arterial flow was restored by thrombectomy. The dogs were then randomly allocated into 3 experimental groups: control, sympathectomy, and AVF (phase 2). Critical stenosis of the popliteal artery was then created by a partially occluding ligature in all animals in order to simulate poor run-off. After 24 hours the femoral arteries were studied for the presence of rethrombosis (phase 3). At the end of phase 2 and during phase 3, femoral pressure and flow, fluorescein circulation time and paw temperature were measured, and arteriography was done. Arterial rethrombosis was significantly prevented in the AVF group (6/7) when compared to the control group (2/7) or the sympathectomy group (1/7). These data suggest an effective action of an adjuvant AVF, but not of sympathectomy in preventing rethrombosis after thrombectomy in arteries with poor run-off.

Comparative study of the action of topical heparinoids on the evolution of experimental thrombophlebitis

The action of threem different topical heparinoids on the evolution of experimental thrombophlebitis was studies. Thrombophlebitis was induced in the marginal vein of the ear of rabbits by stasis and inection of hypertonic glucose solution. Forty-eight hours later animals were allocated to three treatment groups and a control group. The substances were applied over the affected vein three times a day for 6 days and the ears inspected daily by transillumination. After 7 days, the animals were killed and anatomopathological studies performed. No difference in thrombus frequency or inflamatory reaction was observed between the animals treated with heparinoids and the control group, or among the treated groups

Varicose veins and chronic venous insufficiency in Brazil: prevalence among 1755 inhabitants of a country town.

The prevalence of varicose veins (VV) and of chronic venous insufficiency (CVI) was studied among 1755 adults over 15 years of age (443 men and 1312 women). These people attended the University Health Center in Botucatu, a country town in the State of Sao Paulo, Brazil, for routine examination or for any disease complaints. The prevalence of all grades of VV not including telangiectasis and reticular varices grade I was 47.6% (37.9% in men and 50.9% in non-pregnant women). The prevalence of VV recorded as moderate or severe was 21.2%. The more severe form of CVI with active or healed ulcer was present in 3.6% of the subjects (2.3% of men and 4% of women). For only 5.5% of the patients was VV or CVI the reason for medical consultation. The prevalence of VV increased with age and number of pregnancies and was greater among white than non-white people. Working posture or posture adopted for defaecation did not influence the prevalence of VV. Our data show the prevalence of VV and CVI to be higher or as high as the prevalence found in developed western countries. We therefore propose that studies of these conditions should be included in epidemiological surveys of other developing areas or countries, so that if data similar to ours are verified prophylaxis and early treatment could be included in health planning for these areas with the aim of reducing future morbidity and the related social onus.

Techniques for temporary shunting of carotid arteries: experimental study in dogs.

In order to study possible differences among temporary shunts for carotid artery surgery, 4 types of shunts were studied in an experimental canine model of extracranial cerebrovascular insufficiency. Twenty five dogs were operated on and divided in five equal groups: one control group without shunt, two groups of animals with a short internal shunt and two groups with a long external shunt, catheters of two different gauges being used for each type of shunt. These shunts were evaluated by systemic arterial pressure (SAP), stump pressure (SP) and carotid blood flow, which were measured before and after carotid clamping, and 5 and 10 minutes after the release of blood flow through the carotid artery or through the shunts. Multivariate analysis of variance showed that all but the shorter and wider shunt acted as a stenosis in the carotid artery, with a decrease of 50% in blood flow. The analysis of other parameters did not show differences among the shunts, suggesting that even acting as a stenosis, no functional pressure alteration occurred with the different shunts in this model.