Pulmonary arteriovenous malformations in Rendu-Osler-Weber syndrome.

Rendu-Osler-Weber syndrome, also known as hereditary hemorrhagic telangiectasia, is an autosomal dominant hereditary disorder. It is characterized by presence of multiple arteriovenous malformations (AVMs) and telangiectasias. This article reports two cases of patients with Rendu-Osler-Weber syndrome who had pulmonary AVMs and underwent successful endovascular treatment. A brief review of the literature shows that up to 50% of patients with the syndrome have pulmonary AVMs and there is usually a positive family history in these patients. These pulmonary AVMs are multiple in 30% of cases and are associated with the most severe disease complications. Most patients are asymptomatic, even in the presence of AVMs with right-left shunts. When these shunts exceed 25% of the total blood volume, dyspnea, cyanosis, digital clubbing, and extracardiac murmurs may occur. Endovascular treatment is safe and offers control of complications from hereditary hemorrhagic telangiectasia and is currently the treatment of choice for these lesions.

Update on pulmonary arteriovenous malformations / Atualização sobre malformações arteriovenosas pulmonares

ABSTRACT This review aimed to provide an overview of pulmonary arteriovenous malformations, including the major clinical and radiological presentations, investigation, and treatment algorithm of the condition. The primary etiology of pulmonary arteriovenous malformations is hereditary hemorrhagic telangiectasia (HHT), also known as Rendu-Osler-Weber syndrome, with mutations in the ENG gene on chromosome 9 (HHT type 1) or in the ACVRL1/ALK1 complex (HHT type 2). Epistaxis should always be evaluated when repeated, when associated with anemia, and in some cases of hypoxemia. In the investigation, contrast echocardiography and chest CT are essential for evaluating this condition. Embolization is the best treatment choice, especially for correction in cases of hypoxemia or to avoid systemic infections. Finally, disease management was addressed in special conditions such as pregnancy. CT follow-up should be performed every 3-5 years, depending on the size of the afferent and efferent vessels, and antibiotic prophylactic care should always be oriented. Ultimately, knowledge of the disease by health professionals is a crucial point for the early diagnosis of these patients in clinical practice, which can potentially modify the natural course of the disease.

RESUMO Esta revisão teve como objetivo fornecer uma visão geral das malformações arteriovenosas pulmonares, incluindo as principais apresentações clínicas e radiológicas, investigação e algoritmo de tratamento da condição. A principal etiologia das malformações arteriovenosas pulmonares é a telangiectasia hemorrágica hereditária (THH), também conhecida como síndrome de Rendu-Osler-Weber, com mutações no gene ENG no cromossomo 9 (THH tipo 1) ou no complexo ACVRL1/ALK1 (THH tipo 2). A epistaxe sempre deve ser avaliada quando repetida, quando associada à anemia e em alguns casos de hipoxemia. Na investigação, a ecocardiografia e TC de tórax com contraste são essenciais para avaliar essa condição. A embolização é a melhor escolha terapêutica, especialmente para correção em casos de hipoxemia ou para evitar infecções sistêmicas. Por fim, o manejo da doença foi abordado em condições especiais, como a gravidez. O acompanhamento por TC deve ser feito a cada 3-5 anos, dependendo do tamanho dos vasos aferentes e eferentes, e a antibioticoprofilaxia deve sempre ser orientada. Em última análise, o conhecimento da doença pelos profissionais de saúde é um ponto crucial para o diagnóstico precoce desses pacientes na prática clínica, o que pode potencialmente modificar o curso natural da doença.

North American Study for the Treatment of Recurrent Epistaxis with Doxycycline: The NOSTRIL trial.

BACKGROUND: Hereditary hemorrhagic telangiectasia (HHT) is a vascular bleeding disorder characterized by mucocutaneous telangiectasias and visceral arteriovenous malformations. A frequently debilitating symptom is spontaneous recurrent epistaxis. OBJECTIVE: To evaluate whether doxycycline therapy improves epistaxis in HHT by using a prospective, randomized, placebo-controlled crossover study design. PATIENTS/METHODS: Twenty-two eligible patients between December 2017 and July 2020 at a single center were randomized to one of two study arms: doxycycline treatment followed by placebo, or vice versa. Primary outcomes measured differences in epistaxis severity between treatments. Changes in quality of life, laboratory markers of bleeding, and number of monthly blood transfusions or iron infusions were assessed as secondary endpoints. Additional post hoc endpoints included frequency and duration of dripping epistaxis and gushing epistaxis. A post hoc longitudinal analysis assessed effects of doxycycline over time. RESULTS/CONCLUSIONS: Doxycycline was safe and well tolerated. However, there was no reduction in the three primary outcome measures, nosebleed frequency (p = .16), nosebleed duration (p = .05), and Epistaxis Severity Score (p = .19). Quality of life, hemoglobin level, and number of blood transfusions and iron infusions did not differ between groups. Post hoc analysis demonstrated reduction in instances of gushing (p = .02) with doxycycline, although this finding is of unclear clinical significance. Post hoc longitudinal analysis showed reduction in frequency (mean estimate of coefficient = -0.19, standard error = 0.07, p = .01) and duration (mean estimate of coefficient = -2.33, standard error = 1.08, p = .03) of epistaxis over time. Post hoc findings suggest possible benefit of doxycycline but should be interpreted with caution given the overall negative study. Further investigation is needed with a larger sample size and a longer treatment duration.

Hereditary hemorrhagic telangiectasia complicated by aortic sinus aneurysm caused by a pathogenic mutation in the ACVRL1 gene: a family survey / 中华皮肤科杂志

Objective:To investigate clinical and genetic characteristics of a family with hereditary hemorrhagic telangiectasia complicated by aortic sinus aneurysm, and to analyze causative genes.Methods:Clinical data and peripheral blood samples were collected from the proband and her relatives, and genomic DNA was extracted. Causative genes were screened by whole-exome sequencing, and then verified by Sanger sequencing.Results:A heterozygous mutation c.137G>A was identified at position 137 in exon 3 of the ACVRL1 gene in the proband, her daughter, grandson and granddaughter, which led to the substitution of cysteine by tyrosine at amino acid position 46 (p.C46Y) . The mutation was not found in any of the other 5 family members without clinical symptoms.Conclusion:A causative mutation c.137G>A (p.C46Y) in the ACVRL1 gene was identified in the family with hereditary hemorrhagic telangiectasia type 2 complicated by aortic sinus aneurysm, which had not been previously reported in Asian populations.

Ischemic Stroke in Patients With Pulmonary Arteriovenous Fistulas.

BACKGROUND AND PURPOSE: Pulmonary arteriovenous fistulas (PAVFs) are a treatable cause of acute ischemic stroke (AIS), not mentioned in current American Heart/Stroke Association guidelines. PAVFs are recognized as an important complication of hereditary hemorrhagic telangiectasia. METHODS: The prevalence of PAVF and hereditary hemorrhagic telangiectasia among patients admitted with AIS in the United States (2005-2014) was retrospectively studied, utilizing the Nationwide Inpatient Sample database. Clinical factors, morbidity, mortality, and management were compared in AIS patients with and without PAVF/hereditary hemorrhagic telangiectasia. RESULTS: Of 4 271 910 patients admitted with AIS, 822 (0.02%) were diagnosed with PAVF. Among them, 106 of 822 (12.9%) were diagnosed with hereditary hemorrhagic telangiectasia. The prevalence of PAVF per million AIS admissions rose from 197 in 2005 to 368 in 2014 (Ptrend, 0.026). Patients with PAVF were younger than AIS patients without PAVF (median age, 57.5 versus 72.5 years), had lower age-adjusted inpatient morbidity (defined as any discharge other than home; 39.6% versus 46.9%), and had lower in-hospital case fatality rates (1.8% versus 5.1%). Multivariate analyses identified the following as independent risk markers (odds ratio [95% CI]) for AIS in patients with PAVF: hypoxemia (8.4 [6.3-11.2]), pulmonary hemorrhage (7.9 [4.1-15.1]), pulmonary hypertension (4.3 [4.1-15.1]), patent foramen ovale (4.2 [3.5-5.1]), epistaxis (3.7 [2.1-6.8]), venous thrombosis (2.6 [1.9-3.6]), and iron deficiency anemia (2 [1.5-2.7]). Patients with and without PAVF received intravenous thrombolytics at a similar rate (5.9% versus 5.8%), but those with PAVF did not receive mechanical thrombectomy (0% versus 0.7%). CONCLUSIONS: Pulmonary arteriovenous fistula-related ischemic stroke represents an important younger demographic with a unique set of stroke risk markers, including treatable conditions such as causal PAVFs and iron deficiency anemia.

Defective Flow-Migration Coupling Causes Arteriovenous Malformations in Hereditary Hemorrhagic Telangiectasia.

BACKGROUND: Activin receptor-like kinase 1 (ALK1) is an endothelial transmembrane serine threonine kinase receptor for BMP family ligands that plays a critical role in cardiovascular development and pathology. Loss-of-function mutations in the ALK1 gene cause type 2 hereditary hemorrhagic telangiectasia, a devastating disorder that leads to arteriovenous malformations. Here, we show that ALK1 controls endothelial cell polarization against the direction of blood flow and flow-induced endothelial migration from veins through capillaries into arterioles. METHODS: Using Cre lines that recombine in different subsets of arterial, capillary-venous, or endothelial tip cells, we show that capillary-venous Alk1 deletion was sufficient to induce arteriovenous malformation formation in the postnatal retina. RESULTS: ALK1 deletion impaired capillary-venous endothelial cell polarization against the direction of blood flow in vivo and in vitro. Mechanistically, ALK1-deficient cells exhibited increased integrin signaling interaction with vascular endothelial growth factor receptor 2, which enhanced downstream YAP/TAZ nuclear translocation. Pharmacologic inhibition of integrin or YAP/TAZ signaling rescued flow migration coupling and prevented vascular malformations in Alk1-deficient mice. CONCLUSIONS: Our study reveals ALK1 as an essential driver of flow-induced endothelial cell migration and identifies loss of flow-migration coupling as a driver of arteriovenous malformation formation in hereditary hemorrhagic telangiectasia disease. Integrin-YAP/TAZ signaling blockers are new potential targets to prevent vascular malformations in patients with hereditary hemorrhagic telangiectasia.

Oral itraconazole for epistaxis in hereditary hemorrhagic telangiectasia: a proof of concept study.

The inhibiting effects of itraconazole, an antifungal drug on vascular endothelial growth factor (VEGF) have recently been discovered. By inhibiting VEGF, itraconazole has shown potential in clinical trials as anti-cancer treatment. In hereditary hemorrhagic telangiectasia (HHT) patients, VEGF levels are elevated and inhibition of VEGF can decrease bleeding. Itraconazole could potentially serve as anti-angiogenic therapy for HHT-related bleeding. We report a proof of concept study with HHT patients and severe epistaxis. Patients were treated with daily 200 mg orally administered itraconazole for sixteen weeks. Twenty-one HHT patients, 8 females (38%), 13 males (62%), median age of 59 years (interquartile range (IQR) 55-69) were enrolled. Of these patients, 13 (62%) were diagnosed with HHT type 1, seven (33%) with HHT type 2 and in one patient (5%), no pathognomonic HHT mutation was found. Four patients (19%) prematurely terminated the study (3 due to mild or moderate side-effects) resulting in 17 patients included in the analyses. The median epistaxis severity score significantly decreased during treatment from 6.0 (IQR 5.1-7.2) to 3.8 (IQR 3.1-5.2) (p = 0.006). The monthly epistaxis frequency decreased from 56 to 38 epistaxis episodes (p = 0.004) and the monthly duration from 407 to 278 minutes (p = 0.005). Hemoglobin levels did not significantly change. The quality of life showed a small but significant improvement. In conclusion, oral itraconazole significantly improved epistaxis in HHT patients. The potential benefit of itraconazole in HHT should be further investigated.

Integration of clinical parameters, genotype and epistaxis severity score to guide treatment for hereditary hemorrhagic telangiectasia associated bleeding.

BACKGROUND: Hereditary Hemorrhagic Telangiectasia (HHT) is a rare inherited disorder characterized by development of mucocutaneous telangiectases and visceral organ arteriovenous malformations, which can lead to recurrent, spontaneous bleeding and development of iron deficiency anemia. The primary objective of this study was to ascertain the relationship between epistaxis severity scores (ESS), laboratory values, genotype, and phenotype in HHT. Our secondary objective was to assess efficacy of systemic antifibrinolytic therapy in reducing ESS in HHT. METHODOLOGY: We conducted a retrospective review of patients seen at the UNC HHT Center from January 1, 2009 to February 28, 2015. ESS, demographics, and results of genetic testing were abstracted from the medical record. Response to antifibrinolytic therapy was evaluated by comparing pre-post ESS. RESULTS: One hundred and forty nine patients were eligible with 116 having genetic testing and 33 without. Age, hemoglobin and ferritin levels were predictive of ESS. Of the 116 patients that underwent genetic testing: 63 had an ACVRL1 mutation, 40 had an ENG mutation, 2 had a SMAD4 mutation, and 11 patients had no pathologic HHT genetic variation detected. Compared to patients without a detectable HHT-associated genetic variation, patients with a HHT-associated genetic variation had higher ESS scores (p < 0.05). Neither ESS nor genotype was predictive of pulmonary or brain AVMs. Twenty-four HHT patients with ESS > 4 were started on antifibrinolytic therapy (tranexamic acid or aminocaproic acid) and had a post-treatment ESS recorded. All patients had a decrease in ESS of > 0.71 (minimal meaningful difference), but patients taking antifibrinolytics displayed larger decreases. No patients on antifibrinolytics experienced a VTE with median follow up of 13 months. CONCLUSIONS: We demonstrate that the ESS correlates with age, hemoglobin and ferritin. Additionally, we demonstrate that HHT patients with genetic mutations have higher ESS scores. Our data demonstrate that antifibrinolytics are effective in decreasing epistaxis severity and safe with long-term use in HHT patients.

CT dose optimization for the detection of pulmonary arteriovenous malformation (PAVM): A phantom study.

PURPOSE: To determine the lowest suitable dose level for the detection of pulmonary arteriovenous malformation (PAVM) using a task-based image quality assessment. MATERIAL AND METHODS: A phantom was scanned using the standard chest protocol (STD) and 4 other ultra-low dose protocols (ULD) using various kVp. Raw data were reconstructed using level 5 of the hybrid iterative reconstruction algorithm (iDose4) for the STD protocol, and level 6 of iDose4 and levels 1 to 3 of model-based iterative reconstruction (IMR) for the ULD protocols. Both quantitative criteria and qualitative analysis were used to compare protocols. Noise-power-spectrum and Task-based transfer function were computed using imQuest software. The detectability-index (d') was computed for the detection of PAVM. A subjective analysis was performed by 2 chest radiologists to validate the image-quality obtained on the anthropomorphic phantom for all protocols. RESULTS: Similar d' values were found for ULD-140 using iDose4 6 compared to STD protocol. Greater d' values were found for all ULD protocols using IMR compared to STD. Subjective image quality was rated as acceptable to excellent for ULD-140 and ULD-120 for all reconstruction types, for ULD-100 and ULD-80 using IMR2, and for ULD-100 using IMR1. Image smoothing was poor for IMR3 for ULD-100 and ULD-80. Finally, the ULD-80 protocol reconstructed with IMR2 was chosen for the detection of PAVM. With this protocol, the dose (CTDIvol of 0.3mGy) was reduced by 91% compared with the STD protocol. CONCLUSION: A dose level as low as 0.3mGy reconstructed with IMR2 provides an image quality suitable for the detection of PAVM.

Bevacizumab as a treatment option in gastrointestinal bleeding associated to hereditary hemorrhagic telangiectasia. Case Report / Bevacizumab como opción terapéutica en sangrado gastrointestinal asociado a telangiectasia hemorrágica hereditaria. Reporte de caso

Abstract Introduction: Hereditary Hemorrhagic Telangiectasia (HHT) is an autosomal dominant genetic disease characterized by the presence of arteriovenous malformations in the nasal mucosa, the tips of fingers, and sometimes in the lungs, the gastrointestinal tract, the liver, the pancreas, the marrow and the brain. Its treatment is based on symptomatic control measures, but recently, the administration of anti-vascular endothelial growth factor (VEGF) molecules has been proposed as a treatment alternative, especially in patients with recurrent bleeding. Case presentation: The case of a 67-year-old man diagnosed with HHT and suffering from potentially life-threatening gastrointestinal GI bleeding is presented. The patient underwent several esophagogastric cauterization procedures but not positive outcomes were obtained, so he had to go to the Emergency Service of the hospital multiple times due to having low levels of hemoglobin (as low as 3.5g/dL). A bevacizumab based treatment was started by using a novel dosage regimen consisting of the administration of 6 5mg/kg bevacizumab dosages every 14 days. During the first week of treatment, hemoglobin levels increased to 14g/dL and the condition was stabilized. Conclusions: The findings reported here suggest that bevacizumab may be a therapeutic choice to be considered when treating patients with recurrent and refractory GI bleeding caused by HHT. However, a larger sample is required to determine if administering this medication is safe for these patients, as well as the appropriate dosage.

Resumen Introducción. La telangiectasia hemorrágica hereditaria (HHT) es una enfermedad genética autosómica dominante que se caracteriza por la presencia de malformaciones arteriovenosas en mucosa nasal, dedos y, algunas veces, pulmones, tracto gastrointestinal, hígado, páncreas, médula ósea y cerebro. El tratamiento se basa en el control sintomático, pero recientemente se ha propuesto la administración de moléculas anti-factor de crecimiento de endotelio vascular (VEGF), en especial en pacientes que presentan sangrado recurrente. Presentación del caso. Paciente masculino de 67 años con diagnóstico de telangiectasia hemorrágica hereditaria (HHT) y hemorragia gastrointestinal severa potencialmente mortal. El paciente recibió múltiples cauterizaciones esofagogástricas sin obtener respuesta, por lo que ingresó en múltiples oportunidades al servicio de urgencias con niveles de hemoglobina incluso tan bajos como 3.5g/dL. Se inició tratamiento con bevacizumab con un novedoso esquema de 6 dosis de 5mg/k cada 14 días, lográndose aumentar los niveles de hemoglobina a 14g/dL durante la primera semana de tratamiento y estabilizando la enfermedad. Conclusiones. Los hallazgos sugieren que el bevacizumab puede ser una opción terapéutica en sangrado gastrointestinal recurrente y refractario secundario a HHT. Sin embargo, se requiere incluir una cohorte de pacientes más amplia para establecer la seguridad del medicamento y la dosificación apropiada para este tipo de pacientes.

Current Status of Clinical Diagnosis and Genetic Analysis of Hereditary Hemorrhagic Telangiectasia in South Korea: Multicenter Case Series and a Systematic Review.

PURPOSE: Hereditary hemorrhagic telangiectasia (HHT), a rare genetic vascular disorder, has been rarely reported in South Korea. We investigated the current prevalence and presenting patterns of genetically confirmed HHT in South Korea. MATERIALS AND METHODS: We defined HHT patients as those with proven mutations on known HHT-related genes (ENG, ACVRL1, SMAD4, and GDF2) or those fulfilling 3 or 4 of the Curaçao criteria. A computerized systematic search was performed in PubMed and KoreaMed using the following search term: ("hereditary hemorrhagic telangiectasia" AND "Korea") OR ("Osler-Weber-Rendu" AND "Korea"). We also collected government health insurance data. HHT genetic testing results were collected from three tertiary hospitals in which the genetic tests were performed. We integrated patient data by analyzing each case to obtain the prevalence and presenting pattern of HHT in South Korea. RESULTS: We extracted 90 cases from 52 relevant articles from PubMed and KoreaMed. An additional 22 cases were identified from the three Korean tertiary hospitals after excluding seven cases that overlapped with those in the published articles. Finally, 112 HHT patients were identified (41 males and 71 females, aged 4-82 years [mean±standard deviation, 45.3±20.6 years]). The prevalence of HHT in South Korea is about 1 in 500,000, with an almost equal prevalence among men and women. Forty-nine patients underwent genetic testing, of whom 28 had HHT1 (ENG mutation) and 19 had HHT2 (ACVRL1 mutation); the other two patients were negative for ENG, ACVRL1, and SMAD4 mutations. CONCLUSION: The prevalence of HHT is underestimated in Korea. The rate of phenotypic presentation seems to be similar to that found worldwide. Korean health insurance coverage is limited to representative genetic analysis to detect ENG and ACVRL1 mutations. Further genetic analyses to detect HHT3, HHT4, and other forms of HHT should be implemented.

Angiopoietin-2 Inhibition Rescues Arteriovenous Malformation in a Smad4 Hereditary Hemorrhagic Telangiectasia Mouse Model.

BACKGROUND: Hereditary hemorrhagic telangiectasia is an autosomal dominant vascular disorder caused by heterozygous, loss-of-function mutations in 4 transforming growth factor beta (TGFß) pathway members, including the central transcriptional mediator of the TGFß pathway, Smad4. Loss of Smad4 causes the formation of inappropriate, fragile connections between arteries and veins called arteriovenous malformations (AVMs), which can hemorrhage leading to stroke, aneurysm, or death. Unfortunately, the molecular mechanisms underlying AVM pathogenesis remain poorly understood, and the TGFß downstream effectors responsible for hereditary hemorrhagic telangiectasia-associated AVM formation are currently unknown. METHODS: To identify potential biological targets of the TGFß pathway involved in AVM formation, we performed RNA- and chromatin immunoprecipitation-sequencing experiments on BMP9 (bone morphogenetic protein 9)-stimulated endothelial cells (ECs) and isolated ECs from a Smad4-inducible, EC-specific knockout ( Smad4-iECKO) mouse model that develops retinal AVMs. These sequencing studies identified the angiopoietin-Tek signaling pathway as a downstream target of SMAD4. We used monoclonal blocking antibodies to target a specific component in this pathway and assess its effects on AVM development. RESULTS: Sequencing studies uncovered 212 potential biological targets involved in AVM formation, including the EC surface receptor, TEK (TEK receptor tyrosine kinase) and its antagonistic ligand, ANGPT2 (angiopoietin-2). In Smad4-iECKO mice, Angpt2 expression is robustly increased, whereas Tek levels are decreased, resulting in an overall reduction in angiopoietin-Tek signaling. We provide evidence that SMAD4 directly represses Angpt2 transcription in ECs. Inhibition of ANGPT2 function in Smad4-deficient mice, either before or after AVMs form, prevents and alleviates AVM formation and normalizes vessel diameters. These rescue effects are attributed to a reversion in EC morphological changes, such as cell size and shape that are altered in the absence of Smad4. CONCLUSIONS: Our studies provide a novel mechanism whereby the loss of Smad4 causes increased Angpt2 transcription in ECs leading to AVM formation, increased blood vessel calibers, and changes in EC morphology in the retina. Blockade of ANGPT2 function in an in vivo Smad4 model of hereditary hemorrhagic telangiectasia alleviated these vascular phenotypes, further implicating ANGPT2 as an important TGFß downstream mediator of AVM formation. Therefore, alternative approaches that target ANGPT2 function may have therapeutic value for the alleviation of hereditary hemorrhagic telangiectasia symptoms, such as AVMs.

Current Status of Clinical Diagnosis and Genetic Analysis of Hereditary Hemorrhagic Telangiectasia in South Korea: Multicenter Case Series and a Systematic Review / 신경중재치료의학

PURPOSE: Hereditary hemorrhagic telangiectasia (HHT), a rare genetic vascular disorder, has been rarely reported in South Korea. We investigated the current prevalence and presenting patterns of genetically confirmed HHT in South Korea. MATERIALS AND METHODS: We defined HHT patients as those with proven mutations on known HHT-related genes (ENG, ACVRL1, SMAD4, and GDF2) or those fulfilling 3 or 4 of the Curaçao criteria. A computerized systematic search was performed in PubMed and KoreaMed using the following search term: (“hereditary hemorrhagic telangiectasia” AND “Korea”) OR (“Osler-Weber-Rendu” AND “Korea”). We also collected government health insurance data. HHT genetic testing results were collected from three tertiary hospitals in which the genetic tests were performed. We integrated patient data by analyzing each case to obtain the prevalence and presenting pattern of HHT in South Korea. RESULTS: We extracted 90 cases from 52 relevant articles from PubMed and KoreaMed. An additional 22 cases were identified from the three Korean tertiary hospitals after excluding seven cases that overlapped with those in the published articles. Finally, 112 HHT patients were identified (41 males and 71 females, aged 4–82 years [mean±standard deviation, 45.3±20.6 years]). The prevalence of HHT in South Korea is about 1 in 500,000, with an almost equal prevalence among men and women. Forty-nine patients underwent genetic testing, of whom 28 had HHT1 (ENG mutation) and 19 had HHT2 (ACVRL1 mutation); the other two patients were negative for ENG, ACVRL1, and SMAD4 mutations. CONCLUSION: The prevalence of HHT is underestimated in Korea. The rate of phenotypic presentation seems to be similar to that found worldwide. Korean health insurance coverage is limited to representative genetic analysis to detect ENG and ACVRL1 mutations. Further genetic analyses to detect HHT3, HHT4, and other forms of HHT should be implemented.

Pulmonary arteriovenous malformations: diagnostic and treatment characteristics / Malformações arteriovenosas pulmonares: características diagnósticas e de tratamento

ABSTRACT Objective: To present a case series of pulmonary arteriovenous malformations (PAVMs), describing the main clinical findings, the number/location of pulmonary vascular abnormalities, the clinical complications, and the treatment administered. Methods: This was a retrospective observational study evaluating patients with PAVM divided into two groups: hereditary hemorrhagic telangiectasia (HHT); and idiopathic PAVM (iPAVM). Results: A total of 41 patients were selected for inclusion, but only 33 had PAVMs. After clinical evaluation, 27 and 6 were diagnosed with HHT and iPAVM, respectively. In the HHT group, the mean age was 49.6 years and 88.9% were female. In that group, 4 patients had an SpO2 of < 90% and the most common clinical finding was epistaxis. In the iPAVM group, the mean age was 48.1 years and 83.3% were female. In that group, 3 patients had an SpO2 of < 90%. Computed tomographic pulmonary angiography showed that most of the PAVMs were in the lower lobes: 56.4% in the HHT group and 85.7% in the iPAVM group. Embolization was performed in 23 patients (in both groups). At this writing, 10 patients are scheduled to undergo the procedure. One of the patients who underwent embolization was subsequently referred for pulmonary resection. Conclusions: In both of the PAVM groups, there was a predominance of women and of fistulas located in the lower lobes. Few of the patients had respiratory symptoms, and most had an SpO2 > 90%. The treatment chosen for all patients was percutaneous transcatheter embolization.

RESUMO Objetivo: Apresentar uma série de casos de malformações arteriovenosas pulmonares (MAVP) e descrever os principais achados clínicos, a quantidade e localização das MAVP, as complicações clínicas e os tratamentos realizados. Métodos: Estudo retrospectivo observacional que avaliou pacientes com MAVP divididos em dois grupos: telangiectasia hemorrágica hereditária (THH) e MAVP idiopática (MAVPi). Resultados: Foram avaliados 41 pacientes, sendo 33 pacientes portadores de MAVP. Após a avaliação clínica, 27 e 6 foram diagnosticados com THH e MAVPi, respectivamente. No grupo THH a média de idade foi de 49,6 anos e 88,9% eram do sexo feminino. Desses pacientes, 4 tinham SpO2 < 90% e o achado clínico mais frequente era epistaxe. No grupo MAVPi a média de idade foi de 48,1 anos, sendo que 83,3% eram do sexo feminino. Desses, 3 tinham SpO2 < 90%. Após a realização de angiotomografia de tórax observou-se que a maior parte das MAVP se situava nos lobos inferiores, totalizando 56,4% e 85,7% nos grupos THH e MAVPi, respectivamente. O tratamento por embolização foi realizado em 23 pacientes nos dois grupos, enquanto 10 aguardavam o procedimento até o momento da escrita deste estudo. Um paciente submetido à embolização foi encaminhado para ressecção pulmonar. Conclusões: Em ambos os grupos de pacientes com MAVP observou-se uma predominância de mulheres e de fístulas localizadas nos lobos inferiores. A maioria era assintomático respiratório com SpO2 > 90%. O tratamento de escolha para todos foi a embolização percutânea por cateter.

SMAD4 Prevents Flow Induced Arteriovenous Malformations by Inhibiting Casein Kinase 2.

BACKGROUND: Hereditary hemorrhagic telangiectasia (HHT) is an inherited vascular disorder that causes arteriovenous malformations (AVMs). Mutations in the genes encoding Endoglin ( ENG) and activin-receptor-like kinase 1 ( AVCRL1 encoding ALK1) cause HHT type 1 and 2, respectively. Mutations in the SMAD4 gene are present in families with juvenile polyposis-HHT syndrome that involves AVMs. SMAD4 is a downstream effector of transforming growth factor-ß (TGFß)/bone morphogenetic protein (BMP) family ligands that signal via activin-like kinase receptors (ALKs). Ligand-neutralizing antibodies or inducible, endothelial-specific Alk1 deletion induce AVMs in mouse models as a result of increased PI3K (phosphatidylinositol 3-kinase)/AKT (protein kinase B) signaling. Here we addressed if SMAD4 was required for BMP9-ALK1 effects on PI3K/AKT pathway activation. METHODS: The authors generated tamoxifen-inducible, postnatal, endothelial-specific Smad4 mutant mice ( Smad4iΔEC). RESULTS: We found that loss of endothelial Smad4 resulted in AVM formation and lethality. AVMs formed in regions with high blood flow in developing retinas and other tissues. Mechanistically, BMP9 signaling antagonized flow-induced AKT activation in an ALK1- and SMAD4-dependent manner. Smad4iΔEC endothelial cells in AVMs displayed increased PI3K/AKT signaling, and pharmacological PI3K inhibitors or endothelial Akt1 deletion both rescued AVM formation in Smad4iΔEC mice. BMP9-induced SMAD4 inhibited casein kinase 2 ( CK2) transcription, in turn limiting PTEN phosphorylation and AKT activation. Consequently, CK2 inhibition prevented AVM formation in Smad4iΔEC mice. CONCLUSIONS: Our study reveals SMAD4 as an essential effector of BMP9-10/ALK1 signaling that affects AVM pathogenesis via regulation of CK2 expression and PI3K/AKT1 activation.

[Gene identification in a family of hereditary hemorrhagic telangiectasia].

Objective: To study the mutation of ENG, ACVRL1, and SMAD4 genes in one of a family of hereditary hemorrhagic telangiectasia (HHT) and explore its molecular pathogenesis. Methods: A family spectrum of a patient with a clinical diagnosis of HHT was surveyed. Peripheral blood samples from proband and their eldest were collected, and ENG, ACVRL1 and SMAD4 gene analysis was performed by chip capture high-throughput sequencing. The mutation detected was verified by Sanger. Results: 9 of the 71 family members were diagnosed with HHT with the main manifestation of recurrent nasal bleeding. Genetic analysis showed that the proband and the eldest son of ENG gene exon 9 frameshift mutation: c.1502-1503insGG (p.Gly501GlyfsX18) , and mutations in ACVRL1 and SMAD4 genes were not detected. Conclusion: The frameshift mutation c.1502-1503insGG (p.Gly501GlyfsX18) of the ENG gene is the genetic basis for the pathogenesis of this HHT family.

[Diagnosis and treatment of Osler's disease]. / Diagnostik und Therapie des M. Osler.

Osler's disease is an autosomal dominant hereditary syndrome which belongs to the group of orphan diseases. Affected patients suffer primarily from severe epistaxis. Diagnosis is based on the Curaçao criteria and molecular genetic tests. Organ manifestations can be found in the form of arteriovenous shunts in the lung, liver, and gastrointestinal tract; more rarely also in the central nervous system (CNS) and other parts of the body. Many patients with gastrointestinal and other organ manifestations are frequently clinically asymptomatic; therefore, organ screening is essential to avoid later complications and should be performed in centers with particular expertise. No curative therapy currently exists. From the otolaryngologist's perspective, nasal mucosa treatments and endonasal laser applications are important and effective therapeutic approaches to epistaxis. Pharmacological interventions are focused on compensation of haploinsufficiency as well as antiangiogenetic approaches. Severe side effects have to be considered.

Radiofrequency for Treatment of Refractory Epistaxis in Hereditary Hemorrhagic Telangiectasia.

Hereditary hemorrhagic telangiectasia is a rare multi-systemic autosomal dominant disorder characterized by dysplasia of the vascular connective tissue and recurrent bleeding tendency. Epistaxis is the most common and earliest symptom. It is usually mild to moderate, however, in some patients it can be severe with significant interference in quality of life. We report a case of a patient with hereditary hemorrhagic telangiectasia, in which an episode of refractory epistaxis was treated with radiofrequency and fibrin sealant. Control of acute bleeding and elimination of telangiectasia was possible with this technique. After six months follow-up, there was no epistaxis recurrence. Various treatments for epistaxis in this disease have been described in the literature, but there is no consensus about the gold-standard procedure. Radiofrequency ablation of telangiectasia is a recent technique that has shown to be safe, effective and well tolerated, even in patients who underwent other previous treatments.

A telangiectasia hemorrágica hereditária é uma doença autossómica dominante, multissistémica e rara, caracterizada pela displasia do tecido conectivo vascular com tendência à hemorragia recorrente. O sintoma mais comum e precoce é a epistaxis. Habitualmente é ligeira a moderada, no entanto, em alguns doentes, pode ser severa com interferência significativa na sua qualidade de vida. É reportado o caso de um doente com telangiectasia hemorrágica hereditária, em que um episódio de epistaxis refractária foi tratado com radiofrequência e um quelante de fibrina. Com esta técnica foi conseguido não só o controlo da hemorragia activa, mas também a eliminação das telangiectasias. Após seis meses de seguimento, não houve recorrência da epistaxis. Há vários tratamentos descritos na literatura para a epistaxis nesta doença, não havendo no entanto, consenso acerca do gold standard. A ablação com radiofrequência das telangiectasias é uma técnica recente que se tem mostrado segura, eficaz e bem tolerada, mesmo em doentes submetidos previamente a outros tratamentos.