Connective Tissue Disorders and Cardiovascular Complications: The Indomitable Role of Transforming Growth Factor-β Signaling

Marfan Syndrome (MFS) and Loeys-Dietz Syndrome (LDS) represent heritable connective tissue disorders that segregate with a similar pattern of cardiovascular defects (thoracic aortic aneurysm, mitral valve prolapse/regurgitation, and aortic dilatation with regurgitation). This pattern of cardiovascular defects appears to be expressed along a spectrum of severity in many heritable connective tissue disorders and raises suspicion of a relationship between the normal development of connective tissues and the cardiovascular system. With overwhelming evidence of the involvement of aberrant Transforming Growth Factor-beta (TGF-β) signaling in MFS and LDS, this signaling pathway may represent the common link in the relationship between connective tissue disorders and their associated cardiovascular complications. To further explore this hypothetical link, this chapter will review the TGF-β signaling pathway, the heritable connective tissue syndromes related to aberrant TGF-β signaling, and will discuss the pathogenic contribution of TGF-β to these syndromes with a primary focus on the cardiovascular system.

Successful treatment of bilateral multiple pulmonary arteriovenous malformations in a patient with brain abscess and severe hypoxemia using a combination of transcatheter embolotherapy and surgical resection: a case report

Background

A pulmonary arteriovenous malformation is an abnormal dilated blood vessel that makes direct communication between a pulmonary artery and pulmonary vein and can be associated with hypoxemia or neurological complications, including brain abscess and cerebral infarction. Treatment of pulmonary arteriovenous malformation includes surgical resection and transcatheter embolotherapy, however the adaptation of therapies should be considered when a patient is in bad condition.

Case presentation

A 51-year-old man was admitted after developing fever, consciousness disorder, and hypoxemia. Magnetic resonance imaging of the brain showed a brain abscess. Bilateral pulmonary arteriovenous malformations were found by contrast computed tomography. Because of a family history of pulmonary arteriovenous malformation, a history of epistaxis, and the existence of oral mucosa telangiectasia, he was diagnosed with hereditary hemorrhagic telangiectasia and brain abscess caused by intrapulmonary right-to-left shunt. The brain abscess improved with antibiotic treatment; however, the administration of oxygen did not ameliorate his hypoxemia. His hypoxemia was exacerbated by positive pressure ventilation. Considering his systemic and respiratory condition, we considered surgery to involve a high degree of risk. After controlling his brain abscess and pneumonia, transcatheter embolotherapy was performed. This improved his systemic condition, enabling surgical treatment.

Conclusions

This middle-aged patient suffering from brain abscess and severe hypoxemia with multiple pulmonary arteriovenous malformations was successfully treated by a combination of transcatheter embolotherapy and surgery. The adaptation and combination of therapies, as well as the sequence of treatments, should be considered depending on the patient status and lesions.

Sclerotherapy Versus Cautery/Laser Treatment for Epistaxis in Hereditary Hemorrhagic Telangiectasia

OBJECTIVES/HYPOTHESIS

Surgical interventions for epistaxis management in hereditary hemorrhagic telangiectasia (HHT) demonstrate short-term success and require repeated procedures for disease control. Although electrocautery and/or laser photocoagulation (C ± L) are most frequently performed, sodium tetradecyl sclerotherapy (STS) is emerging as a promising newer treatment. We hypothesized that in a 24-month time period, STS would require fewer treatments than C ± L to maintain epistaxis severity within the mild range.

STUDY DESIGN

Retrospective study.

METHODS

We retrospectively assessed 67 patients with HHT with moderate and severe epistaxis that were treated periodically with C ± L (34 patients) versus STS (33 patients). The primary outcome was the number of procedures needed to maintain the epistaxis severity score (ESS) as mild. Secondary outcomes assessed for differences in postoperative complications, hemoglobin levels, iron stores, hematologic support, and quality-of-life (QoL) scores.

RESULTS

To maintain ESS in the mild range, 1.6 STS procedures (range, 1-4) were performed versus 3.6 C ± L procedures (range, 1-8) (P = .003). Significant postoperative differences included reduction in nasal crusting (3% vs. 32%, P = .001), foul odor (3% vs. 35%, P < .001), and septal perforation (3% vs. 29%, P = .006) after STS. There were no significant differences between the two treatments in hemoglobin levels, iron stores, hematologic support, or QoL scores.

CONCLUSION

STS is able to attain satisfactory epistaxis control with significantly fewer procedures and lower postoperative complications than C ± L. STS should be considered as the initial surgical intervention for epistaxis in patients with HHT.

LEVEL OF EVIDENCE

IV Laryngoscope, 2021.

Hereditary hemorrhagic telangiectasia: how to efficiently detect hepatic abnormalities using ultrasonography

INTRODUCTION

Hereditary hemorrhagic telangiectasia (HHT) is a multiorgan genetic angiodysplastic affection characterized by visceral vascular malformations. It affects mainly the brains, lungs, gastrointestinal tract, and nasal mucosa. Unlike those organs, hepatic involvement, although very frequently occurring, is insufficiently recognized, mainly because of the complex vascular structure of this organ. Thus, treating HHT patients requires a solid understanding of these hepatic anomalies. It is especially important for any general clinicians to be able to recognize clinical findings in HHT, which leads to a high suspicion of HHT and have an index of suspicion for liver abnormalities of HHT. For this purpose, keen awareness of clinical as well as hepatic sonographic (US) findings is paramount.

AIM

The aim of this review is to summarize previously reported findings on the hepatic US through a thorough analysis of related articles, and to (a) determine the role of US in the diagnosis of hepatic involvement in HHT patients and (b) propose the most simple and easy way to detect HHT-related abnormalities during routine US examinations.

CONCLUSION

Hepatic US serves to diagnose the detailed complex hepatic changes typical of HHT, and contributes to increased diagnostic confidence of hepatic changes in HHT patients, with the most simple way not to overlook HHT-related abnormalities being to find hepatic artery dilatation.

Emergency surgery for hemothorax due to a ruptured pulmonary arteriovenous malformation

Pulmonary arteriovenous malformation (PAVM) is a potential cause of hemothorax. The risk of PAVM rupture is reported to be higher during pregnancy for several reasons, including increased body fluid and a change in hormonal conditions. A 34-year-old pregnant woman suddenly felt right chest pain and dyspnea in the 28th week of gestation. Chest X-ray and computed tomography showed massive right pleural effusion. Her vital signs gradually deteriorated with hemorrhagic shock, necessitating emergency surgery. During exploratory thoracoscopy, active bleeding from the middle lobe was noticed and gauze packing was required to maintain her blood pressure. Following conversion to major thoracotomy, wedge resection of the middle lobe was performed with a linear stapler, and finally, her general condition became stable. Her postoperative course was uneventful. A histological examination of the resected specimen confirmed the diagnosis of ruptured PAVM. Her baby was successfully delivered at the 38th week of gestation.

Abdominal manifestations of hereditary hemorrhagic telangiectasia: a series of 333 patients over 15 years

PURPOSE

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant multi-organ vascular disorder that commonly affects the gastrointestinal tract and the liver resulting in telangiectasias and arteriovenous malformations (AVMs). Previous studies looking at the prevalence of liver and abdominal organ involvement in HHT have been limited by differing imaging techniques and sample size limitations. We sought to define the prevalence of HHT related abdominal vascular abnormalities using optimized multiphasic contrast-enhanced abdominal computed tomography (CT) exams in a large cohort of HHT patients.

METHODS

Between January 2001 and May 2015; we identified a total of 333 consecutive HHT patients who had undergone a dedicated HHT protocol multiphase abdominal CT at our institution. The CT exams were reviewed by three board certified abdominal radiologists for the presence of vascular abnormalities involving the liver, pancreas, spleen, and other abdominal organs. Vascular abnormalities involving the liver were further categorized as telangiectasias, large confluent vascular masses, perfusion abnormalities, or hepatic shunts.

RESULTS

In patients with abdominal vascular abnormalities, the liver was the most commonly involved organ, with 180 out of 333 (54.1%) patients demonstrating at least one hepatic vascular abnormality (telangiectasia, confluent vascular mass, transient perfusion abnormalities, and hepatic shunts), with most (70.0%) demonstrating multiple hepatic vascular abnormalities. The other most common organs involved included the pancreas (18.0%), spleen (6.3%), and small bowel (4.5%).

CONCLUSION

In patients with the clinical diagnosis of HHT, greater than half demonstrate an abdominal vascular abnormality, with the most commonly involved organ being the liver. These may be under recognized on routine or single phase contrast-enhanced CT of the abdomen. This supports the use of optimized multiphasic abdominal CT exams as an important tool for the evaluation and screening of patients with HHT.

Pulmonary arteriovenous malformations

Pulmonary arteriovenous malformation, a condition most commonly associated with hereditary hemorrhagic telangiectasia, is an abnormal communication between the pulmonary artery and pulmonary vein without an intervening capillary communication. Although asymptomatic in ~ 50% individuals, it can present with the dreaded complications of stroke or intracranial abscess in high-risk individuals including pregnant women, if untreated. The mainstay of treatment is now endovascular embolization of the feeding artery which can alleviate the symptoms and prevent these complications. In this review, we describe the pathophysiology, methods of screening, diagnostic workup and treatment of these vascular lesions with a particular focus on the currently used embolization techniques and their outcomes.

Hereditary hemorrhagic telangiectasia and pulmonary arteriovenous malformations: clinical aspects

Hereditary hemorrhagic telangiectasia (HHT) is a genetic disorder of blood vessel formation resulting in mucocutaneous telangiectasias and visceral arteriovenous malformations. Nearly half of patients with HHT will have pulmonary arteriovenous malformations (PAVM) that place them at risk for potentially fatal complications that can occur when blood bypasses the pulmonary capillary circulation or as a result of PAVM rupture. Other manifestations of HHT outside the lung may increase the rate and severity of PAVM complications, creating unique clinical challenges. Management hinges on timely screening and diagnosis, followed by treatment of amenable PAVMs with transcatheter embolization in conjunction with medical management and prophylactic measures to treat and prevent complications. The purpose of this review is to highlight the clinical manifestations of PAVMs specific to patients with HHT and to detail screening and treatment strategies that can reduce the risk of developing life-threatening complications.

Gastrointestinal Manifestations of Hereditary Hemorrhagic Telangiectasia (HHT): A Systematic Review of the Literature

Hereditary hemorrhagic telangiectasia (HHT), also called Osler-Weber-Rendu syndrome, is an autosomal dominant genetic disease that affects the vasculature of numerous organs. The prevalence of HHT is estimated to be between 1.5 and 2 persons per 10,000. While there is still much to learn about this condition, there is an increasing understanding its underlying pathophysiology, genetic basis, presentations, and management. Recognizing that the clinical manifestations of HHT can involve a number of organ systems will provide clinicians with a higher index of suspicion for the disease. This early diagnosis and genotyping can greatly reduce mortality for a patient with HHT through appropriate screening for complications. This review will focus on the gastrointestinal manifestations of HHT and how these can dictate treatment and prognosis.

Mutation affecting the proximal promoter of Endoglin as the origin of hereditary hemorrhagic telangiectasia type 1

Background

Hereditary hemorrhagic telangiectasia (HHT) is a vascular multi-organ system disorder. Its diagnostic criteria include epistaxis, telangiectases in mucocutaneous sites, arteriovenous malformations (AVMs), and familial inheritance. HHT is transmitted as an autosomal dominant condition, caused in 85% of cases by mutations in either Endoglin (ENG) or Activin receptor-like kinase (ACVRL1/ACVRL1/ALK1) genes. Pathogenic mutations have been described in exons, splice junctions and, in a few cases with ENG mutations, in the proximal promoter, which creates a new ATG start site. However, no mutations affecting transcription regulation have been described to date in HHT, and this type of mutation is rarely identified in the literature on rare diseases.

Methods

Sequencing data from a family with HHT lead to single nucleotide change, c.-58G > A. The functionality and pathogenicity of this change was analyzed by in vitro mutagenesis, quantitative PCR and Gel shift assay. Student t test was used for statistical significance.

Results

A single nucleotide change, c.-58G > A, in the proximal ENG promoter co-segregated with HHT clinical features in an HHT family. This mutation was present in the proband and in 2 other symptomatic members, whereas 2 asymptomatic relatives did not harbor the mutation. Analysis of RNA from activated monocytes from the probands and the healthy brother revealed reduced ENG mRNA expression in the HHT patient (p = 0.005). Site-directed mutagenesis of the ENG promoter resulted in a three-fold decrease in luciferase activity of the mutant c.-58A allele compared to wild type (p = 0.005). Finally, gel shift assay identified a DNA-protein specific complex.

Conclusions

The novel ENG c.-58G > A substitution in the ENG promoter co-segregates with HHT symptoms in a family and appears to affect the transcriptional regulation of the gene, resulting in reduced ENG expression. ENG c.-58G > A may therefore be a pathogenic HHT mutation leading to haploinsufficiency of Endoglin and HHT symptoms. To the best of our knowledge, this is the first report of a pathogenic mutation in HHT involving the binding site for a transcription factor in the promoter of ENG.

Percutaneous left atrial appendage closure-An alternative strategy for anticoagulation in atrial fibrillation and hereditary hemorrhagic telangiectasia?

Many patients with hereditary hemorrhagic telangiectasia (HHT) are unable to sustain oral anticoagulation (OAC) because of severe epistaxis, gastrointestinal (GI) bleeding and the risk of life-threatening bleeding from cerebral arteriovenous malformations (CAVMs) or pulmonary arteriovenous malformations (PAVMs). In patients with atrial fibrillation (AF), most thromboembolic complications arise from the left atrial appendage (LAA) and percutaneous transcatheter LAA closure proved to be non-inferior to OAC at mid-term follow-up. We report our experience with LAA closure in HHT with a follow-up of 12 months. Percutaneous LAA closure was performed in five patients with both HHT and high thromboembolic risk AF (CHA2DS2-VASc score ≥2) without peri-procedural complications. At 3 months no thromboembolic event occurred. After 12 months one patient had a transient ischemic attack while another patient had recurrence of stroke, this latter patient had a significant stenosis of the carotid artery and an incomplete closure of the LAA without any signs of thrombus on echocardiogram. Both patients had a non-treatable pulmonary right-to-left shunt (RLS). Percutaneous closure of the LAA may provide an alternative strategy to long-term OAC therapy in HHT patients with AF induced high stroke risk and intolerance for OAC.

Blessing for the bleeder: bevacizumab in hereditary hemorrhagic telangiectasia

Hereditary hemorrhagic telangiectasia (HHT) is a genetic disorder characterized by uncontrolled multisystem angiogenesis with epistaxis, gastrointestinal bleeding, iron-deficiency anemia, and arteriovenous malformations, and is often associated with increased levels of vascular endothelial growth factor (VEGF). Bevacizumab, a VEGF inhibitor, reduces epistaxis, telangiectasias, and iron-deficiency anemia. We present the case of a woman with HHT and chronic gastrointestinal bleeding who required iron supplementation and multiple blood transfusions. Bevacizumab resulted in marked symptom improvement and transfusion-independence. Our report describes the dose schedule and calls for a randomized, controlled trial demonstrating the value of bevacizumab therapy.