Browsing by Subject "Pulmonary circulation"

Now showing 1 - 3 of 3
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    Assessment of Right Ventricular Function in the Research Setting: Knowledge Gaps and Pathways Forward. An Official American Thoracic Society Research Statement
    (American Thoracic Society, 2018-08-15) Lahm, Tim; Douglas, Ivor S.; Archer, Stephen L.; Bogaard, Harm J.; Chesler, Naomi C.; Haddad, Francois; Hemnes, Anna R.; Kawut, Steven M.; Kline, Jeffrey A.; Kolb, Todd M.; Mathai, Stephen C.; Mercier, Olaf; Michelakis, Evangelos D.; Naeije, Robert; Tuder, Rubin M.; Ventetuolo, Corey E.; Vieillard-Baron, Antoine; Voelkel, Norbert F.; Vonk-Noordegraaf, Anton; Medicine, School of Medicine
    BACKGROUND: Right ventricular (RV) adaptation to acute and chronic pulmonary hypertensive syndromes is a significant determinant of short- and long-term outcomes. Although remarkable progress has been made in the understanding of RV function and failure since the meeting of the NIH Working Group on Cellular and Molecular Mechanisms of Right Heart Failure in 2005, significant gaps remain at many levels in the understanding of cellular and molecular mechanisms of RV responses to pressure and volume overload, in the validation of diagnostic modalities, and in the development of evidence-based therapies. METHODS: A multidisciplinary working group of 20 international experts from the American Thoracic Society Assemblies on Pulmonary Circulation and Critical Care, as well as external content experts, reviewed the literature, identified important knowledge gaps, and provided recommendations. RESULTS: This document reviews the knowledge in the field of RV failure, identifies and prioritizes the most pertinent research gaps, and provides a prioritized pathway for addressing these preclinical and clinical questions. The group identified knowledge gaps and research opportunities in three major topic areas: 1) optimizing the methodology to assess RV function in acute and chronic conditions in preclinical models, human studies, and clinical trials; 2) analyzing advanced RV hemodynamic parameters at rest and in response to exercise; and 3) deciphering the underlying molecular and pathogenic mechanisms of RV function and failure in diverse pulmonary hypertension syndromes. CONCLUSIONS: This statement provides a roadmap to further advance the state of knowledge, with the ultimate goal of developing RV-targeted therapies for patients with RV failure of any etiology.
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    A case report of hepatopulmonary syndrome in hereditary hemorrhagic telangiectasia (HHT): Not all right-to-left shunting in HHT is due to pulmonary arteriovenous malformations
    (Wolters Kluwer, 2018-08) Krishnan, Sheila; Lahm, Tim; Medicine, School of Medicine
    RATIONALE: Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant disorder characterized by abnormal vessel growth that results in telangiectasias and arteriovenous malformations (AVMs) in the skin, mucosa, and viscera. Up to 30% of patients with HHT exhibit pulmonary AVMs (PAVMs), clinically manifesting as right-to-left shunting and hypoxemia. PATIENT CONCERNS: We report an unusual and novel case of a patient with HHT who lacked clinical sequelae of portal hypertension but presented to clinic with hypoxemia without dyspnea. DIAGNOSES: Diagnostic workup revealed noncardiac right-to-left shunting due to hepatopulmonary syndrome (HPS) from HHT-induced portal hypertension rather than PAVMs. The diagnosis was confirmed by the absence of PAVMs on chest computed tomography and evidence of elevated portal pressures as noted by the presence of small esophageal varices on upper endoscopy and histologic findings on liver biopsy. INTERVENTION: Due to the patient's mild symptoms, no further intervention was required. He was closely followed up in the outpatient setting for changes in symptoms and underwent annual screening for development of PAVMs. OUTCOMES: The patient continues to do well clinically. He has not experienced worsening hypoxemia or dyspnea and has not developed PAVMs. LESSONS: Given that management of hypoxemia in HPS drastically differs from that of hypoxemia due to PAVMs, this case demonstrates the importance of evaluating HHT patients for HPS if they exhibit impaired oxygenation and noncardiac right-to-leftshunting in the setting of hepatic arteriovenous shunting.
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    Pulmonary vasodilation in acute pulmonary embolism - a systematic review
    (Sage, 2020-03-04) Lyhne, Mads Dam; Kline, Jeffrey A.; Nielsen-Kudsk, Jens Erik; Andersen, Asger; Emergency Medicine, School of Medicine
    Acute pulmonary embolism is the third most common cause of cardiovascular death. Pulmonary embolism increases right ventricular afterload, which causes right ventricular failure, circulatory collapse and death. Most treatments focus on removal of the mechanical obstruction caused by the embolism, but pulmonary vasoconstriction is a significant contributor to the increased right ventricular afterload and is often left untreated. Pulmonary thromboembolism causes mechanical obstruction of the pulmonary vasculature coupled with a complex interaction between humoral factors from the activated platelets, endothelial effects, reflexes and hypoxia to cause pulmonary vasoconstriction that worsens right ventricular afterload. Vasoconstrictors include serotonin, thromboxane, prostaglandins and endothelins, counterbalanced by vasodilators such as nitric oxide and prostacyclins. Exogenous administration of pulmonary vasodilators in acute pulmonary embolism seems attractive but all come with a risk of systemic vasodilation or worsening of pulmonary ventilation-perfusion mismatch. In animal models of acute pulmonary embolism, modulators of the nitric oxide-cyclic guanosine monophosphate-protein kinase G pathway, endothelin pathway and prostaglandin pathway have been investigated. But only a small number of clinical case reports and prospective clinical trials exist. The aim of this review is to give an overview of the causes of pulmonary embolism-induced pulmonary vasoconstriction and of experimental and human investigations of pulmonary vasodilation in acute pulmonary embolism.