Cateteres venosos totalmente implantáveis: histórico, técnica de implante e complicações / Totally implantable venous catheters: history, implantation technique and complications

O acesso ao sistema venoso, seja para coleta de amostras de sangue ou para infusão de soluções, é de vital importância para o diagnóstico e tratamento de pacientes com as mais variadas condições clínicas. Desde que Harvey, em 1616, descreveu o sistema circulatório a partir de estudos em animais e que Sir Christopher Wren, 4 décadas depois, realizou a primeira infusão endovenosa em seres vivos, a evolução na técnica de acesso e nos dispositivos para infusão tem sido constante. Merece destaque a criação dos cateteres de longa duração na década de 1970, em especial os totalmente implantáveis, que revolucionaram o tratamento do câncer, aumentando a segurança e o conforto dos pacientes oncológicos. Este artigo tem como objetivo a revisão de dados históricos relativos ao acesso vascular e a discussão da técnica de implante e das principais complicações associadas ao procedimento de colocação e ao uso dos cateteres totalmente implantáveis

Access to the venous system is of vital importance for diagnosis and treatment of patients with the most varied range of clinical conditions, whether for taking blood samples or for infusion of solutions. In 1616, Harvey described the circulatory system on the basis of studies in animals and 4 decades later Sir Christopher Wren conducted the first intravenous infusions in living beings. Since then there has been constant evolution in access technique and infusion devices. Of particular note is the creation of long-term catheters in the 1970s, particularly totally implantable devices, which revolutionized cancer treatment, increasing both safety and comfort for oncology patients. The objectives of this article are to review historical data on vascular access and discuss the implantation technique and the main complications associated with procedures for placement and use of totally implantable venous access devices

Effects of exercise training on stress-induced vascular reactivity alterations: role of nitric oxide and prostanoids

Background: Physical exercise may modify biologic stress responses. Objective: To investigate the impact of exercise training on vascular alterations induced by acute stress, focusing on nitric oxide and cyclooxygenase pathways. Method: Wistar rats were separated into: sedentary, trained (60-min swimming, 5 days/week during 8 weeks, carrying a 5% body-weight load), stressed (2 h-immobilization), and trained/stressed. Response curves for noradrenaline, in the absence and presence of L-NAME or indomethacin, were obtained in intact and denuded aortas (n=7-10). Results: None of the procedures altered the denuded aorta reactivity. Intact aortas from stressed, trained, and trained/stressed rats showed similar reduction in noradrenaline maximal responses (sedentary 3.54±0.15, stressed 2.80±0.10*, trained 2.82±0.11*, trained/stressed 2.97± 0.21*, *P<0.05 relate to sedentary). Endothelium removal and L-NAME abolished this hyporeactivity in all experimental groups, except in trained/stressed rats that showed a partial aorta reactivity recovery in L-NAME presence (L-NAME: sedentary 5.23±0,26#, stressed 5.55±0.38#, trained 5.28±0.30#, trained/stressed 4.42±0.41, #P<0.05 related to trained/stressed). Indomethacin determined a decrease in sensitivity (EC50) in intact aortas of trained rats without abolishing the aortal hyporeactivity in trained, stressed, and trained/stressed rats. Conclusions: Exercise-induced vascular adaptive response involved an increase in endothelial vasodilator prostaglandins and nitric oxide. Stress-induced vascular adaptive response involved an increase in endothelial nitric oxide. Beside the involvement of the endothelial nitric oxide pathway, the vascular response of trained/stressed rats involved an additional mechanism yet to be elucidated. These findings advance on the understanding of the vascular processes after exercise and stress alone and in combination. .

Receptores de la serotonina que inhiben el tono simpático vasopresor en la rata descerebrada y desmedulada / Role of serotonin receptors in vascular tone in the pithed rat

Serotonin (5-hydroxytryptamine; 5-HT) has been shown to produce vascular sympatho-inhibition in a wide variety of isolated blood vessels by activation of prejunctional 5-HT1 receptors. After considering the mechanisms involved in modulating neuroeffector transmission, the present review analyzes the experimental findings identifying the pharmacological profile of the 5-HT receptors that inhibit the sympathetically-induced vasopressor responses in pithed rats. Thus, 5-HT-induced sympatho-inhibition has been shown to be: (i) unaffected by physiological saline or by the selective antagonists ritanserin (5-HT2), MDL72222 (5-HT3) or tropisetron (5-HT3/4); (ii) blocked by methysergide, a non-selective 5-HT1/2 receptor antagonist; and (iii) potently mimicked by 5-carboxamidotryptamine (5-CT), a non-selective 5-HT1 receptor agonist, as well as by the selective agonists 8-OH-DPAT (5-HT1A), indorenate (5-HT1A), CP93,129 (5-HT1B), and sumatriptan (5-HT1B/1D). These findings show the involvement of prejunctional 5-HT1 receptors. With the use of selective antagonists, it has been shown subsequently that the sympatho-inhibition induced by indorenate, CP93, 129, and sumatriptan was selectively antagonized by WAY100635 (5-HT1A), cyanopindolol (5-HT1A/1B), and GR127935 (5-HT1B/1D), respectively. These results demonstrate that the 5-HT1 receptors mediating sympatho-inhibition on the systemic vasculature of pithed rats resemble the pharmacological profile of the 5-HT1A, 5-HT1B, and 5-HT1D subtypes.

Is mycophenolate more than just an immunosuppressant?--An overview.

The development of immunosuppressant compounds, such as cyclosporine and tacrolimus was crucial to the success of transplant surgery and for treatment of autoimmune diseases. However, immunosuppressant therapy may increase the concentrations of reactive oxygen species (ROS), inducing oxidative damage such as an increased vascular damage. The major source of ROS in the vascular endothelial cells is NADPH oxidase. The subunit structure and function of this enzyme complex in vascular cells differs from that in phagocytic leucocytes. The enzyme subunits Nox1, Nox2 and Nox4 are only found in vascular cells. The GTP-dependent protein subunit Rac 1 needs to be activated for this enzyme to function. Inhibiting this protein subunit should reduce NADPH oxidase-induced oxidative stress. In the cardiovascular system, oxidative stress is observed as hypertension, hypertrophy, fibrosis, conduction abnormalities and endothelial dysfunction, as well as cardiac allograft vasculopathy in transplant patients. In contrast to cyclosporine and tacrolimus, the immunosuppressant mycophenolate inhibits the Rac 1 subunit thus inhibiting NADPH oxidase in the vasculature. This may reduce oxidative stress, prevent the development of cardiac allograft vasculopathy, decrease the deterioration of vascular function and improve cardiovascular function chronically in transplant patients. This overview discusses whether this antioxidant immunosuppressive property could translate into a more general protective role for mycophenolate in the prevention of cardiovascular disease.

Envejecimiento cardiovascular: [revisión] / Cardiovascular aging: [review]

Aging produces its own cardiovascular changes, mainly remodelling of arteries, heart and the microcirculation. These progressive changes, detected since adolescence, represent a major rísk factor for the development of cardiovascular diseases. Remodelling of arteries produces a thickening of the intima-media with fracture of elastic fibers and their replacement by collagen. These alterations induce an increase of the pulse wave and aortic impedance, with greater resistance to ventrícular ejection, that in turns induces the remodelling of the left ventricle. Ventricular remodelling leads to systolic, diastolic and chronotropic dysfunctions that explain the reduced capacity of old people to increase cardiac output during exercise. These alterations together with oxidative endothelial dysfunction and somatic mitochondrial mutations in the skeletal muscle decrease aerobic capacity, especially in adults aged >70 years. On the other hand, the transmission of an increased pulse wave to microvessels, mainly of the brain and kidneys, damage these organs. There is a search for candidate genes associated to this phenotype, especially those associated with arterial structure. Atpresent no specific treatment is available for cardiovascular aging. Exercise preserves a better aerobic capacity but does not prevent its decline with age. Vasodilator drugs may decrease aortic impedance and perhaps delay remodelling. However there is no clinical evidence available to recommend these drugs in young healthy people. Finally new drugs that modify aortic molecular structure are been investigated.

La dimetilarginina asimétrica, estructura e implicaciones patológicas / Asymmetric dimethylarginine, structure and pathological implications

La ateroesclerosis, es una enfermedad crónica, sistémica, inmuno-inflamatoria que afecta a la íntima arterial. La disfunción endotelial es la primera fase en la ateroesclerosis La disfunción endotelial está caracterizada por un daño y pérdida de la monocapa celular que cubre el interior de los vasos sanguíneos, denominada endotelio. Uno de los principales mediadores ara el mentenimieno de la integridad del endotelio, es el óxido nítrico (ON). La Dimetilarginina asimétrica (DMMA), es un inhibidor endógeno de la enzima sintasa del Óxido Nítrico (SON); se ha sugerido que DMAA sirve como un marcador de disfunción endotelial en enfermedades cardiovasculares. Asimismo, la DMAA representa un factor de riesgo para mortalidad cardiovascular, progresión de enfermedad crónica renal. Se ha encontrado valores elevados de DMAA en diferentes condiciones como hipercolesterolemia, aterosclerosis, hipertensión, insuficiencia renal crónica, insuficiencia crónica del corazón, diabetes y disfunsión eréctil.

Atherosclerosis is an immune inflammatory systemic, arterial disease. Endothelial dysfunction is the first stage in aterosclerosis. Atherosclerosis develops because of reactions occurring in vessel wall beginning with response to enothelial injury. Endothelial dysfunction is characterized with impairment and loss of monolayer cells covering the inside of the vessels, which is enothelium. One of the main mediators for the maintenance of the integrity of endothelium is Nitric Oxide (NO). The asymmtric Dimethilarginine (ADMA), is an endogenous inhibitor of the enzyme Nitric Oxide Synthase (NOS). ADMA has been suggested to serve as a biomarker of endothelial dysfunction in cardiovascular diseases. ADMA is a risk factor for endothelial dysfunction, cardiovascular mortality, and progression of chronic kidney disease. Elevated values of ADMA have been found in hypercholesterolemia, atherosclerosis, hypertension, chronic renal insufficiency, heart chronic failure, diabetes and erectile dysfunction.

Irrigação dos músculos papilares do ventrículo esquerdo do coração de caninos (Canis familiaris, L. 1758) / Blood supply of the papillary muscles of the left ventricle of the dog´s heart (Canis familiaris – L. 1758)

A irrigação dos músculos papilares tem informações incompletas sobre a distribuição dos vasos arteriais. Objetivando estabelecer a origem destas artérias e sua distribuição nos músculos papilares do ventrículo esquerdo, utilizamos 30 corações de cães adultos, machos e fêmeas de raça não definida e de várias idades. Após o óbito, o coração foi removido, lavado em água corrente e em seguida injetado através do óstio da artéria coronária esquerda com uma solução de acetato de vinil corado, neoprene látex 650 corado ou gelatina a 10%. Os músculos papilares em todas as técnicas utilizadas foram fixados com solução de formol a 10 %. A dissecação foi realizada de forma acelerada com o uso de solução de ácido sulfúrico a 40 %. Para realização das radiografias utilizamos injeção de mercúrio o que auxiliou a montagem dos esquemas da vascularização estudada. Utilizamos a técnica de diafanização de Spalteholz para melhor visualizar a irrigação cardíaca. Evidenciamos que os músculos papilares subauricular e subatrial são irrigados pelos ramos da artéria coronária esquerda. O subauricular pelos ramos interventricular paraconal e circunflexo e o subatrial predominantemente pelo ramo circunflexo. Os subsegmentos que suprem o subauricular do ramo interventricular paraconal são os ramos: colateral e ventriculares à esquerda; e do ramo circunflexo são os ramos: dorsais à esquerda e intermédio (marginal ventricular esquerdo) e mais raramente o ramo da borda ventricular esquerda (ramo diafragmático). Os subsegmentos do ramo circunflexo que suprem o subatrial são os ramos: intermédio (marginal ventricular esquerdo), da borda ventricular esquerda (ramo diafragmático), ramos dorsais direito e ramo interventricular subsinuoso. Em alguns casos observamos o ramo colateral e o próprio ramo interventricular paraconal atingirem a porção do vértice do subatrial.

The irrigation of the papillary muscles, has incomplete information on the distribution of the arterial vessels. Objectifying to establish the origin of these arteries and their distribution in the left ventricle papillary muscles, we used 30 hearts of adult, male and female mongrel dogs. After the death, the heart was removed, washed and injected through the left coronary artery opening with an acetate solution of stained vinyl, neoprene latex 650 colored or 10% gelatin. The papillary muscles in all the applied techniques had been fixed with 10% formaldehyde solution. The dissection was carried out with the aid of a 40% sulfuric acid solution. For accomplishment of the radiography, we used mercury injection what assisted the assembly of the studied vascularization projects. Clearing technique of Spalteholz was applied for better visualization of the cardiac irrigation. We evidenced that the subauricular and subatrial papillary muscles are irrigated by the left coronary artery branches. The subauricular papillary muscle was blood-supplied by the interventricular paraconal and circumflex branches and the subatrial papillary muscle mainly by the circumflex branch. The sub-segments that supply the subauricular papillary muscle from the interventricular paraconal branch are the left collateral and ventricular branches and from the circumflex branch: left dorsal branches and intermedial (left ventricular marginal) and rarely from the left ventricular ridge (diaphragmatic branch). The subsegments of the circumflex branch that supply the subatrial papillary muscle are: intermedial (left ventricular marginal), from the left ventricular ridge (diaphragmatic branch), right dorsal branches and subsinuous interventricular branch. In some cases we observed the collateral branch and the proper interventricular paraconal branch reaching the portion of the vertex of the subatrial papillary muscle.

Important recent advances in cardiovascular adrenergic mechanisms

Five sub-areas were taken into consideration: Adrenoceptor subclassification: Presently, 10 different adrenoceptor subtypes have been characterized by pharmacological and molecular biology studies: Ó1A-, Ó1B-, Ó1D-, Ó2A/D, Ó2B-, Ó2C-, ß1-, ß2-, ß3- and ß4-adrenoceptors. Intracellular signaling: the adrenoceptors are members of a large superfamily of receptors linked to guanine-nucleotide proteins (G proteins), Ó1-adrenoceptors are coupled to Gq proteins and activate phospholipases, especially phospholipase Cß, Ó2-adrenoceptors are coupled to G1 proteins and inhibit adenylyl cyclase and in some tissues regulate potassium and calcium channels. Both ß1 and ß2-adrenoceptors are preferentially coupled to adenylyl cyclase through GS proteins and ß3-adrenoceptors appear to be coupled to K+ channel through a pertussis toxin-sensitive G1 protein. ß4-Adrenoceptors appear to be coupled positively to a cyclic AMP-dependent cascade and can undergo desensitization. Influence of maturation and ageing: From birth to old age important changes occur in animal models as in humans at the receptor level, neurotransmitter process and catecholamine disposition. In general terms, one can say that maturation is associated with a gradual increase of adrenergic influence, while ageing is associated with a reduction in the role of the adrenergic system on the regulation of physiologic processes. Cotransmission: ATP and the neuropeptide Y are cotransmitters with noradrenaline. While noradrenaline is the main transmitter in vascular tissues, ATP has functional relevance in some vessels and neuropeptide Y is mainly a modulator of noradrenaline release; it seems that it has an increased role under pathophysiological conditions like ischemia. Role of endothelium on noradrenaline release: Many substances produced by the endotelium or acting through the endothelium are able to influence noradrenaline release from sympathetic nerve varicosities of the blood vessel wall: some of them, like bradykinin and angiotensin II, exert a facilitatory, while others like NO and endothelin have an inhibitory effect on noradrenaline release evoked electrical nerve stimulation.

Pre-and postjunctional alpha-adrenoceptors in rabbit articular blood vessels

Previous in vitro work on rabbit knee joint vessels showed that vasoconstrictor effects of nerve stimulation and administration of a-adrenoceptor agonists were mediated predominantly by alpha1-adrenoceptors. The present experiments were performed to assess the nature of alpha -adrenoceptor subtypes within these blood vessels in vivo. Dose/response relationships for adrenaline and noradrenaline produced a similar pattern of increasing constriction of articular vessels with increasing doses of drug. The alpha 1 agonist phenylephrine also produced dose-dependent constrictor responses which were diminished by prazosin. Using the alpha 2 agonists clonidine and UK -14304, responses in vivo differed from those previously observed in vitro. There was virtually no response to clonidine in vitro while responses were obvious in vivo. Although UK-14304 was found to have small effects in vitro, but only at high doses, this agent exerted more potent effects in vivo, significantly greater than those obtained with phenylephrine. Responses to the alpha 2 agonists were not altered significantly by prazosin but were reduced by rauwolscine. Following injection of UK-14304, the constrictor response to nerve stimulation was reduced. The results suggest that both alpha 1 and alpha 2 adrenoceptors are present postjunctionally within articular blood vessels, and also that prejunctional alpha 2 receptors are present which presumably regulate neurotransmitter release from sympathetic nerve endings in the joint capsule

Computerized analysis of isometric tension studies provides important additional information about vasomotor activity

Concentration-response curves of isometric tension studies on isolated blood vessels are obtained traditionally. Although parameters such as Imax, EC50 and pA2 may be readily calculated, this method does not provide information on the temporal profile of the responses or the actual nature of the reaction curves. Computerized data acquisition systems can be used to obtain average data that represent a new source of otherwise inaccessible information, since early and late responses may be observed separately in detail.

Vascular mediation of gastric mucosal damage and cytoprotection.

This review addresses questions surrounding the role of the mucosal circulation in damage and protection against chemical injury to the stomach. The modern history of the topic is briefly summarized, and widely used methods are appraised critically. The role of the circulation is examined in mucosal injury and in cytoprotection, and a new conceptual model is described which involves the vasculature and inflammatory mediators.