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General Pharmacology Oct 1999Hypoxic vasoconstriction is unique to pulmonary circulation. The pulmonary response is part of a self-regulatory mechanism by which pulmonary capillary blood flow is... (Review)
Review
Hypoxic vasoconstriction is unique to pulmonary circulation. The pulmonary response is part of a self-regulatory mechanism by which pulmonary capillary blood flow is automatically adjusted to alveolar ventilation for maintaining the optimal balance of ventilation and perfusion. In pathological conditions, hypoxic pulmonary vasoconstriction may occur as an acute episode or as a sustained response with pulmonary hypertension and vascular remodeling. Vasoactive substances produced from the endothelial cells (prostanoids, nitric oxide, or endothelin) or other mediators such as 5 hydroxytryptamine have been examined as possible mediators of hypoxic vasoconstriction. These appear more likely to be modulators than mediators of the vasoconstrictor response to hypoxia. Recent hypotheses have emerged indicating that O2 levels per se can regulate ion channel activity. The modulation of both K+ and Ca2+ channels differs according to the conduit or resistance pulmonary vessel type, tending to extend the former and contract the latter, thereby opposing the ventilation to perfusion mismatching. In the absence of drugs that act selectively on pulmonary circulation, inhaled therapy is an alternative in the treatment of pulmonary hypertension. According to its short half-life and to its potential cytotoxicity, nitric oxide is only of value in the management of patients with acute respiratory disease. Aerosolized prostacyclin and iloprost result in a sustained efficacy of the inhaled vasodilator regimen in patients with severe pulmonary hypertension and offer a new strategy for treatment of this disease. At the moment, therapy aimed at reversing the structural remodeling and matrix deposition in pulmonary arteries remains experimental. New drugs such as potassium channel openers or endothelin receptor antagonists warrant further investigations as possible therapeutic candidates in the treatment of pulmonary hypertension.
Topics: Animals; Humans; Hypoxia; Lung; Pulmonary Circulation; Vasoconstriction
PubMed: 10523066
DOI: 10.1016/s0306-3623(99)00026-9 -
Anesthesiology Clinics Jun 2017Pulmonary hypertension (PH) is a complex disease process of the pulmonary vasculature system characterized by elevated pulmonary arterial pressures. Patients with PH are... (Review)
Review
Pulmonary hypertension (PH) is a complex disease process of the pulmonary vasculature system characterized by elevated pulmonary arterial pressures. Patients with PH are at increased risk for morbidity and mortality, including intraoperatively and postoperatively. Appreciation by the clinical anesthesiologist of the pathophysiology of PH is warranted. Careful and meticulous strategy using appropriate anesthetic medications, pulmonary vasodilator and inotropic agents, and careful fluid management all increase the likelihood of the best possible outcome in this challenging patient population.
Topics: Anesthesia; Humans; Hypertension, Pulmonary; Muscle, Smooth, Vascular; Nitric Oxide; Pulmonary Circulation; Vascular Resistance; Vasodilator Agents
PubMed: 28526144
DOI: 10.1016/j.anclin.2017.01.008 -
Renal Failure 2013Pulmonary hypertension in end-stage renal disease patients is associated with significantly increased morbidity and mortality. The prevalence of pulmonary hypertension... (Review)
Review
Pulmonary hypertension in end-stage renal disease patients is associated with significantly increased morbidity and mortality. The prevalence of pulmonary hypertension in dialysis patients is relatively high and varies in different studies from 17% to 49.53% depending on the mode of dialysis and other selection factors, such as the presence of other cardiovascular comorbidities. The etiopathogenic mechanisms that have been studied in relatively small studies mainly include arteriovenous fistula-induced increased cardiac output, which cannot be accomodated by, the spacious under normal conditions pulmonary circulation. Additionally, pulmonary vessels show signs of endothelial dysfunction, dysregulation of vascular tone due to an imbalance in vasoactive substances, and local as well as systemic inflammation. It is also believed that microbubbles escaping from the dialysis circuit can trigger vasoconstriction and vascular sclerosis. The non-specific therapeutic options that proved to be beneficial in pulmonary artery pressure reduction are endothelin inhibitors, phosphodiesterase inhibitor sildenafil, and vasodilatory prostaglandins in various forms. The specific modes of treatment are renal transplantation, size reduction or closure of high-flow arteriovenous fistulas, and transfer from hemodialysis to peritoneal dialysis-a modality that is associated with a lesser prevalence of pulmonary hypertension.
Topics: Humans; Hypertension, Pulmonary; Kidney Failure, Chronic; Pulmonary Artery; Pulmonary Circulation; Renal Dialysis
PubMed: 23405977
DOI: 10.3109/0886022X.2013.766559 -
Bulletin of Experimental Biology and... Aug 2019In experiments on isolated perfused rabbit lungs, we studied changes in the pulmonary microcirculation in response to carvedilol injection and after modelling pulmonary...
In experiments on isolated perfused rabbit lungs, we studied changes in the pulmonary microcirculation in response to carvedilol injection and after modelling pulmonary thromboembolism under conditions of α- and β-adrenoceptor blockade with this drug. Carvedilol had mainly vasodilator effects on the pulmonary arterial vessels; the pulmonary venous resistance increased and the capillary filtration coefficient remained unchanged under these conditions. In case of pulmonary thromboembolism against the background of carvedilol treatment, the increase in precapillary resistance and the capillary filtration coefficient was more pronounced that in the control, but the postcapillary resistance increased to a lesser extent. The increase in the capillary filtration coefficient is a result of elevated precapillary resistance and enhanced endothelial permeability.
Topics: Animals; Carvedilol; Lung; Pulmonary Circulation; Pulmonary Embolism; Pulmonary Veins; Rabbits
PubMed: 31493251
DOI: 10.1007/s10517-019-04543-8 -
Jornal Brasileiro de Pneumologia :... 2011Knowledge of the structure and function of pulmonary circulation has evolved considerably in the last few decades. The use of non-invasive imaging techniques to assess... (Review)
Review
Knowledge of the structure and function of pulmonary circulation has evolved considerably in the last few decades. The use of non-invasive imaging techniques to assess the anatomy and function of the pulmonary vessels and heart has taken on added importance with the recent advent of novel therapies. Imaging findings not only constitute a diagnostic tool but have also proven to be essential for prognosis and treatment follow-up. This article reviews the myriad of imaging methods currently available for the assessment of pulmonary circulation, from the simple chest X-ray to techniques that are more complex and promising, such as electrical impedance tomography.
Topics: Diagnostic Imaging; Humans; Pulmonary Circulation
PubMed: 21755197
DOI: 10.1590/s1806-37132011000300017 -
Kidney & Blood Pressure Research 2007Numerous uremic patients on hemodialysis have pulmonary hypertension attributable to the presence of arteriovenous fistulas, vascular calcification, and endothelial... (Review)
Review
Numerous uremic patients on hemodialysis have pulmonary hypertension attributable to the presence of arteriovenous fistulas, vascular calcification, and endothelial dysfunction due to alterations in the balance between vasoconstrictive and vasodilatory substances. For these reasons, the effects of recombinant human erythropoietin, a drug widely used in patients on dialysis, on the pulmonary circulation were studied. Some authors maintain that recombinant human erythropoietin has an antihypertensive effect, while others have observed that this hormone induces a reduction in pulmonary arterial pressure due to its vasoactive and stimulatory effects on endothelial and smooth muscle cell precursors.
Topics: Animals; Antihypertensive Agents; Erythropoietin; Humans; Hypertension, Pulmonary; Pulmonary Circulation; Recombinant Proteins; Renal Dialysis
PubMed: 17587864
DOI: 10.1159/000104443 -
Clinical Physics and Physiological... 1990When in transit in the pulmonary capillaries, neutrophils can interact with the endothelium and gas in the alveoli. Neutrophils play a major role in lung defences and... (Review)
Review
When in transit in the pulmonary capillaries, neutrophils can interact with the endothelium and gas in the alveoli. Neutrophils play a major role in lung defences and have been implicated in the pathogenesis of lung injury, such as emphysema and the adult respiratory distress syndrome. Moreover, the pulmonary capillaries receive all of the circulating neutrophils. It is surprising therefore, that relatively little is known of the factors which influence the passage of neutrophils through the pulmonary circulation. This article reviews our knowledge of neutrophil kinetics in the lungs and describes techniques using radiolabelled cells to quantify neutrophil traffic in the pulmonary circulation which should help to elucidate the pathogenesis of conditions where neutrophils are thought to play a role in lung injury.
Topics: Humans; Kinetics; Neutrophils; Pulmonary Circulation; Smoking
PubMed: 2286043
DOI: 10.1088/0143-0815/11/4a/319 -
Revista Espanola de Cardiologia Feb 2010Since the right side of the heart and the pulmonary circulation are regarded as secondary components of the circulatory system, their role in disease has traditionally... (Review)
Review
Since the right side of the heart and the pulmonary circulation are regarded as secondary components of the circulatory system, their role in disease has traditionally not received the same attention as their counterparts in the systemic circulation. This was partly because precise noninvasive study of these structures was difficult. For many years, chest radiography and invasive angiography were the only techniques available for imaging the minor circulation. The development of transthoracic echocardiography and nuclear techniques has produced a significant leap forward for noninvasive imaging, particularly of the right ventricle. More recently, novel echocardiographic techniques, and advances in computed tomography and magnetic resonance imaging, in particular, have expanded our diagnostic armamentarium and provided new insights into the anatomy and function of the pulmonary circulation in both health and disease. This article contains a review of the current status of techniques for imaging the right side of the heart and the pulmonary circulation.
Topics: Coronary Angiography; Echocardiography; Heart; Humans; Magnetic Resonance Imaging; Pulmonary Circulation; Radiography, Thoracic; Radionuclide Imaging; Tomography, X-Ray Computed
PubMed: 20109418
DOI: 10.1016/s1885-5857(10)70039-6 -
Annali Italiani Di Medicina Interna :... 1988
Review
Topics: Adult; Blood Vessels; Exercise; Humans; Lung; Pulmonary Circulation
PubMed: 3152868
DOI: No ID Found -
Der Internist Jul 1999
Review
Topics: Animals; Humans; Lung Diseases; Models, Biological; Pulmonary Circulation
PubMed: 10429912
DOI: 10.1007/s001080050391