Post-NICE 2008: Antibiotic prophylaxis prior to dental procedures for patients with pulmonary arteriovenous malformations (PAVMs) and hereditary haemorrhagic telangiectasia

Personalised stroke evaluation and management: tailoring individualised patient care for hereditary haemorrhagic telangiectasia

SummaryHereditary haemorrhagic telangiectasia (HHT) has an estimated prevalence of 1 in 5000-8000 individuals globally with pulmonary arteriovenous malformations (PAVMs) affecting approximately 15%-50% of HHT patients. Ischaemic stroke is a known complication of PAVMs that affects ≤30% of patients with PAVMs. Studies have shown that patients with PAVMs have ischaemic stroke a decade earlier than routine stroke. The predominant mechanism of ischaemic stroke in HHT patients is paradoxical embolism due to PAVMs, but most HHT-related PAVMs are asymptomatic. Additionally, HHT is often underdiagnosed in patients and poses a challenge to physicians due to its rarity. We present a case of a patient with ischaemic stroke who was subsequently diagnosed with HHT and found to have a PAVM on further evaluation. This case highlights the importance of using an individualised patient-centred stroke evaluation and screening for PAVMs in patients who had a stroke with possible or suspected HHT and definite HHT.

Oral manifestations and dental considerations of patients with hereditary hemorrhagic telangiectasia: a scoping review

OBJECTIVE

We examined the range, nature, and extent of research conducted regarding the oral and dental implications of hereditary hemorrhagic telangiectasia (HHT) to identify gaps in the research and knowledge of the field.

STUDY DESIGN

We performed a scoping review according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews and 2017 Guidance for the Conduct of Joanna Briggs Institute Scoping Reviews. We searched the MEDLINE and Web of Science databases for all full-text articles published in English from December 1946 to October 2022.

RESULTS

We identified 103 articles describing oral and dental considerations of patients with HHT, primarily case reports. Most reported oral telangiectasias of the tongue, lips, and palate. Many reported management of bleeding and the use or recommendation of prophylactic antibiotics before dental procedures.

CONCLUSIONS

Oral telangiectasias are commonly found in patients with hereditary hemorrhagic telangiectasia, and dental professionals may be the first to diagnose it in their patients. Early detection and diagnosis are important to prevent potentially fatal outcomes, and prophylactic antibiotics before procedures may be warranted.

Update on pulmonary arteriovenous malformations

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.

Hereditary haemorrhagic telangiectasia: an overview from an ear, nose and throat perspective

Patients with hereditary haemorrhagic telangiectasia can present with a multitude of symptoms caused by telangiectasia and arteriovenous malformations in the nose, brain, gastrointestinal tract, liver and spinal cord. Clinicians should be aware of the potential diagnosis of hereditary haemorrhagic telangiectasia and how to manage these patients both in the acute and chronic setting. Identifying these patients and optimising their management can help reverse the reduced life expectancy back to that of the normal population. The management of these patients is complex and often requires a multidisciplinary approach, with difficult discussions to be had around screening for arteriovenous malformations and genetic testing. The stepwise management ladder can be used in both the medical and surgical strategies; there are multiple pharmacological and surgical options available, all with their own side effects and risks. Patient education is key to help informed decision making. This article outlines the clinical characteristics of the disease and management options available.

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.

Cerebral Abscess Associated With Odontogenic Bacteremias, Hypoxemia, and Iron Loading in Immunocompetent Patients With Right-to-Left Shunting Through Pulmonary Arteriovenous Malformations

Background

Cerebral abscess is a recognized complication of pulmonary arteriovenous malformations (PAVMs) that allow systemic venous blood to bypass the pulmonary capillary bed through anatomic right-to-left shunts. Broader implications and mechanisms remain poorly explored.

Methods

Between June 2005 and December 2016, at a single institution, 445 consecutive adult patients with computed tomography–confirmed PAVMs (including 403 [90.5%] with hereditary hemorrhagic telangiectasia) were recruited to a prospective series. Multivariate logistic regression was performed and detailed periabscess histories were evaluated to identify potential associations with cerebral abscess. Rates were compared to an earlier nonoverlapping series.

Results

Thirty-seven of the 445 (8.3%) patients experienced a cerebral abscess at a median age of 50 years (range, 19–76 years). The rate adjusted for ascertainment bias was 27 of 435 (6.2%). Twenty-nine of 37 (78.4%) patients with abscess had no PAVM diagnosis prior to their abscess, a rate unchanged from earlier UK series. Twenty-one of 37 (56.7%) suffered residual neurological deficits (most commonly memory/cognition impairment), hemiparesis, and visual defects. Isolation of periodontal microbes, and precipitating dental and other interventional events, emphasized potential sources of endovascular inoculations. In multivariate logistic regression, cerebral abscess was associated with low oxygen saturation (indicating greater right-to-left shunting); higher transferrin iron saturation index; intravenous iron use for anemia (adjusted odds ratio, 5.4 [95% confidence interval, 1.4–21.1]); male sex; and venous thromboemboli. There were no relationships with anatomic attributes of PAVMs, or red cell indices often increased due to secondary polycythemia.

Conclusions

Greater appreciation of the risk of cerebral abscess in undiagnosed PAVMs is required. Lower oxygen saturation and intravenous iron may be modifiable risk factors.

Probiotics and infective endocarditis in patients with hereditary hemorrhagic telangiectasia: a clinical case and a review of the literature

Background

In the last decades, probiotics have been widely used as food supplements because of their putative beneficial health effects. They are generally considered safe but rare reports of serious infections caused by bacteria included in the definition of probiotics raise concerns on their potential pathogenic role in patients with particular predisposing factors. Patients with hereditary hemorrhagic telangiectasia (HHT) are exposed to infections because of telangiectasias and arteriovenous malformations (AVMs). We describe what is, to our knowledge, the first case of infective endocarditis (IE) caused by Lactobacillus rhamnosus in a patient with HHT. A systematic review of the relevant medical literature is presented.

Case presentation

A patient with HHT and an aortic bioprosthesis was admitted because of prolonged fever not responding to antibiotics. The patient had a history of repeated serious infections with hospitalizations and prolonged use of antibiotics, and used to assume large amounts of different commercial products containing probiotics. Weeks before the onset of symptoms the patient had been treated with nasal packings and with surgical closure of a nasal bleeding site because of recurrent epistaxis. A diagnosis of IE of the aortic bioprosthesis was made. All blood coltures were positive for L. rhamnosus. The patients responded to a cycle of 6 weeks of amoxicillin/clavulanate plus gentamicin. A systematic review of IE linked to consumption of probiotics, and of infective endocarditis in patients with HHT was conducted. 10 cases of IE linked to probiotics consumption and 6 cases of IE in patients with HHT were found.

Conclusions

Consumption of probiotics can pose a risk of serious infections in patients with particular predisposing factors. Patients with HHT can be considered at risk because of their predisposition to infections. Prophylaxis with antibiotics before nasal packings in patients with HHT can be considered.

Electronic supplementary material

The online version of this article (10.1186/s12879-018-2956-5) contains supplementary material, which is available to authorized users.

Contemporary Management of Pulmonary Arteriovenous Malformations

Pulmonary arteriovenous malformations (PAVMs) are atypical vascular structures involving a direct connection between the pulmonary arterial and venous circulations. While PAVMs are a relatively uncommon disorder, unmanaged cases are at risk for the development of serious complications including embolization and infection. Since their first description in 1897, PAVMs have been identified and treated in a variety of ways. Advancements in diagnostic methods and operative techniques have allowed for more effective treatment of the disease. Most recently, the use of vascular plug transcatheter embolization has been described as an effective therapeutic procedure in the management of PAVMs. In this report, we present our experience with nine cases of PAVMs treated at the University of Kentucky, including special consideration of an exemplary case that illustrates the typical course of treatment for the disease.

The Lung in Hereditary Hemorrhagic Telangiectasia

Hereditary hemorrhagic telangiectasia (HHT) is a dominantly inherited genetic vascular disorder with an estimated prevalence of 1 in 6,000, characterized by recurrent epistaxis, cutaneous telangiectasia, and arteriovenous malformations (AVMs) that affect many organs including the lungs, gastrointestinal tract, liver, and brain. Its diagnosis is based on the Curaçao criteria, and is considered definite if at least 3 of the 4 following criteria are fulfilled: (1) spontaneous and recurrent epistaxis, (2) telangiectasia, (3) a family history, and (4) pulmonary, liver, cerebral, spinal, or gastrointestinal AVMs. The focus of this review is on delineating how HHT affects the lung.

Intravenous amoxicillin/clavulanate for the prevention of bacteraemia following dental procedures: a randomized clinical trial

OBJECTIVES

Although controversy exists regarding the efficacy of antibiotic prophylaxis for patients at risk of infective endocarditis, expert committees continue to publish recommendations for antibiotic prophylaxis regimens. This study aimed to evaluate the efficacy of four antimicrobial regimens for the prevention of bacteraemia following dental extractions.

METHODS

The study population included 266 adults requiring dental extractions who were randomly assigned to the following five groups: control (no prophylaxis); 1000/200 mg of amoxicillin/clavulanate intravenously; 2 g of amoxicillin by mouth; 600 mg of clindamycin by mouth; and 600 mg of azithromycin by mouth. Venous blood samples were collected from each patient at baseline and at 30 s, 15 min and 1 h after dental extractions. Samples were inoculated into BACTEC Plus culture bottles and processed in the BACTEC 9240. Conventional microbiological techniques were used for subcultures and further identification of the isolated bacteria. The trial was registered at ClinicalTrials.gov with ID number NCT02115776.

RESULTS

The incidence of bacteraemia in the control, amoxicillin/clavulanate, amoxicillin, clindamycin and azithromycin groups was: 96%, 0%, 50%, 87% and 81%, respectively, at 30 s; 65%, 0%, 10%, 65% and 49% at 15 min; and 18%, 0%, 4%, 19% and 18% at 1 h. Streptococci were the most frequently identified bacteria. The percentage of positive blood cultures at 30 s post-extraction was lower in the amoxicillin/clavulanate group than in the amoxicillin group (P < 0.001). The incidence of bacteraemia in the clindamycin group was similar to that in the control group.

CONCLUSIONS

Bacteraemia following dental extractions was undetectable with amoxicillin/clavulanate prophylaxis. Alternative antimicrobial regimens should be sought for patients allergic to the β-lactams.

Implications of an Incidental Pulmonary Arteriovenous Malformation

Introduction. Pulmonary arteriovenous malformations (PAVMs) have been associated with life-threatening complications, such as stroke and massive hemoptysis, thus posing significant morbidity if left untreated. We report a case of an incidental finding of a PAVM in a trauma patient newly recognized to have suspected hereditary hemorrhagic telangiectasia (HHT). Case Description. A 34-year-old man with a history of recurrent epistaxis presented with a sudden fall associated with seizure-like activity. Trauma imaging showed a large subdural hematoma and, incidentally, a serpiginous focus within the right upper lobe with a prominent feeding artery consistent with a PAVM. The patient was diagnosed with a simple PAVM related to possible or suspected HHT, an autosomal dominant trait with age-related penetrance. He underwent a pulmonary arteriography of the right upper and lower lobe with the use of a microcatheter system; however, the PAVM could not be visualized. Thus, he was managed medically. The patient was educated on the need for prophylactic antibiotics prior to dental procedures and surveillance imaging. Discussion. Our case highlights the importance of obtaining a complete past medical and family history in young patients with a history of recurrent epistaxis to elicit features of HHT. The diagnosis can be made clinically and directly affects family members, who would otherwise not receive appropriate screening.

Pulmonary Arteriovenous Malformations and Cerebral Abscess Recurrence in a Child With Hereditary Hemorrhagic Telangiectasia

BACKGROUND

A 17-year-old boy was referred to our center with a history of brain abscess (BA) recurring after 9 years. The patient reported 2 previous treatments for pulmonary arteriovenous malformations, sporadic nosebleeds, and familial history for epistaxis. Clinical investigations revealed arteriovenous malformations in lung, brain, and liver, as well as mucocutaneous telangiectases. A definite diagnosis of hereditary hemorrhagic telangiectasia was made based on clinical criteria and confirmed by genetic analysis. This is the first report of BA recurrence at the end of pediatric age.

CONCLUSIONS

The present case and the literature review of all cases of BA thus far reported highlight the need to raise the suspicion of a pulmonary arteriovenous malformations, both isolated and in the context of a possible hereditary hemorrhagic telangiectasia, for any case of BA of unexplained etiology, in children as well as in adults.

Huge Pulmonary Arteriovenous Malformation, Venous Thromboembolism and Anticoagulation Treatment in a Patient with Hereditary Hemorrhagic Telangiectasia

Hereditary hemorrhagic telangiectasia (HHT) usually presents in association with pulmonary arteriovenous malformations (PAVMs). In addition, the incidence of venous thromboembolism tends to be increased in these patients. A 74-year-old female with HHT presented with cyanosis and hypoxemia. Contrast-enhanced multislice computed tomography (MSCT) revealed two left PAVMs and one in the right upper lobe. Both left PAVMs were treated with embolotherapy. Follow-up MSCT revealed an incidental pulmonary embolism in the right pulmonary branches. Deep venous thrombosis was confirmed and anticoagulation was initiated. Follow-up MSCT revealed the resolution of thromboembolism. Finally, embolotherapy was performed. This case illustrates the chronic adaptation to hypoxemia and adds further evidence to the relative safety of anticoagulation treatment in these patients.

Pulmonary arteriovenous malformations

Within the past decade, pulmonary arteriovenous malformations (PAVMs) have evolved from rare curiosities to not uncommon clinical states, with the latest estimates suggesting a prevalence of ~1 in 2,600. PAVMs provide anatomic right-to-left shunts, allowing systemic venous blood to bypass gas exchange and pulmonary capillary bed processing. Hypoxemia and enhanced ventilatory demands result, although both are usually asymptomatic. Paradoxical emboli lead to strokes and cerebral abscesses, and these commonly occur in individuals with previously undiagnosed PAVMs. PAVM hemorrhage is rare but is the main cause of maternal death in pregnancy. PAVM occlusion by embolization is the standard of care to reduce these risks. However, recent data demonstrate that currently recommended management protocols can result in levels of radiation exposure that would be classified as harmful. Recent publications also provide a better appreciation of the hematologic and cardiovascular demands required to maintain arterial oxygen content and oxygen consumption in hypoxemic patients, identify patient subgroups at higher risk of complications, and emphasize the proportion of radiologically visible PAVMs too small to treat by embolization. This review, therefore, outlines medical states that exacerbate the consequences of PAVMs. Chief among these is iron deficiency, which is commonly present due to concurrent hereditary hemorrhagic telangiectasia: iron deficiency impairs hypoxemia compensations by restricting erythropoiesis and increases the risk of ischemic strokes. Management of periodontal disease, dental interventions, pulmonary hypertension, and pregnancy also requires specific consideration in the setting of PAVMs. The review concludes by discussing to what extent previously recommended protocols may benefit from modification or revision.

Optimal management of hereditary hemorrhagic telangiectasia

Hereditary hemorrhagic telangiectasia (HHT), also known by the eponym Osler-Weber-Rendu syndrome, is a group of related disorders inherited in an autosomal dominant fashion and characterized by the development of arteriovenous malformations (AVM) in the skin, mucous membranes, and/or internal organs such as brain, lungs, and liver. Its prevalence is currently estimated at one in 5,000 to 8,000. Most cases are due to mutations in the endoglin (HHT1) or ACVRLK1 (HHT2) genes. Telangiectasias in nasal and gastrointestinal mucosa generally present with recurrent/chronic bleeding and iron deficiency anemia. Larger AVMs occur in lungs (~40%-60% of affected individuals), liver (~40%-70%), brain (~10%), and spine (~1%). Due to the devastating and potentially fatal complications of some of these lesions (for example, strokes and brain abscesses with pulmonary AVMs), presymptomatic screening and treatment are of utmost importance. However, due to the rarity of this condition, many providers lack an appreciation for the whole gamut of its manifestations and complications, age-dependent penetrance, and marked intrafamilial variation. As a result, HHT remains frequently underdiagnosed and many families do not receive the appropriate screening and treatments. This article provides an overview of the clinical features of HHT, discusses the clinical and genetic diagnostic strategies, and presents an up-to-date review of literature and detailed considerations regarding screening for visceral AVMs, preventive modalities, and treatment options.

Ischaemic strokes in patients with pulmonary arteriovenous malformations and hereditary hemorrhagic telangiectasia: associations with iron deficiency and platelets

Background

Pulmonary first pass filtration of particles marginally exceeding ∼7 µm (the size of a red blood cell) is used routinely in diagnostics, and allows cellular aggregates forming or entering the circulation in the preceding cardiac cycle to lodge safely in pulmonary capillaries/arterioles. Pulmonary arteriovenous malformations compromise capillary bed filtration, and are commonly associated with ischaemic stroke. Cohorts with CT-scan evident malformations associated with the highest contrast echocardiographic shunt grades are known to be at higher stroke risk. Our goal was to identify within this broad grouping, which patients were at higher risk of stroke.

Methodology

497 consecutive patients with CT-proven pulmonary arteriovenous malformations due to hereditary haemorrhagic telangiectasia were studied. Relationships with radiologically-confirmed clinical ischaemic stroke were examined using logistic regression, receiver operating characteristic analyses, and platelet studies.

Principal Findings

Sixty-one individuals (12.3%) had acute, non-iatrogenic ischaemic clinical strokes at a median age of 52 (IQR 41–63) years. In crude and age-adjusted logistic regression, stroke risk was associated not with venous thromboemboli or conventional neurovascular risk factors, but with low serum iron (adjusted odds ratio 0.96 [95% confidence intervals 0.92, 1.00]), and more weakly with low oxygen saturations reflecting a larger right-to-left shunt (adjusted OR 0.96 [0.92, 1.01]). For the same pulmonary arteriovenous malformations, the stroke risk would approximately double with serum iron 6 µmol/L compared to mid-normal range (7–27 µmol/L). Platelet studies confirmed overlooked data that iron deficiency is associated with exuberant platelet aggregation to serotonin (5HT), correcting following iron treatment. By MANOVA, adjusting for participant and 5HT, iron or ferritin explained 14% of the variance in log-transformed aggregation-rate (p = 0.039/p = 0.021).

Significance

These data suggest that patients with compromised pulmonary capillary filtration due to pulmonary arteriovenous malformations are at increased risk of ischaemic stroke if they are iron deficient, and that mechanisms are likely to include enhanced aggregation of circulating platelets.

Management of patients with hereditary hemorrhagic telangiectasia undergoing general anesthesia: a cohort from a single academic center's experience

PURPOSE

Hereditary hemorrhagic telangiectasia is a rare autosomal dominant disease characterized by capillary malformation leading to multisite cutaneomucosal telangiectasias and multiorgan arteriovenous malformations, which can present challenges to anesthetic care. The primary aim of this report is to present a large cohort of patients with hereditary hemorrhagic telangiectasia undergoing general anesthesia at our institution in regard to comorbid conditions and complications of surgical and anesthetic management.

METHODS

A computerized search from January 1, 2002 through December 31, 2011 of the Mayo Clinic medical records database was performed for patients with hereditary hemorrhagic telangiectasia who underwent general anesthesia. Medical records were reviewed. Eligibility criteria included patients with definite or suspected hereditary hemorrhagic telangiectasia based on the Curacao diagnostic criteria who underwent general anesthesia during the study period.

RESULTS

We identified 74 patients with hereditary hemorrhagic telangiectasia who underwent 163 surgeries. The majority had pulmonary arteriovenous malformations (56.7%) and iron deficiency anemia (64.7%), and high levels of disease burden with a median American Society of Anesthesiologist Physical Status score of 3. Most surgeries were related to treating conditions associated with hereditary hemorrhagic telangiectasia, with the majority being procedures to the nasal mucosa for recurrent epistaxis (47.2%). A sizeable proportion of procedures to the nasal mucosa required transfusion of blood (12/77). One case of epistaxis required 11 units of blood until it was successfully controlled. Another notable complication included migration of a coil to pulmonary arteriovenous malformations into the cerebral circulation.

CONCLUSION

Surgical patients with hereditary hemorrhagic telangiectasia often present with multiorgan involvement. The anesthesia provider needs to be aware of the high prevalence of pulmonary arteriovenous malformations, which may be asymptomatic but can lead to embolic complications. Hemorrhage from epistaxis can be severe, and relatively focal procedures to the nasal mucosa can require blood transfusions.

Brain abscess caused by Enterococcus faecalis following a dental procedure in a patient with hereditary hemorrhagic telangiectasia

Hereditary hemorrhagic telangiectasia (HHT) is a disease characterized by arteriovenous malformations (AVMs). Brain abscess is a complication of HHT with AVMs. Literature provides evidence that Enterococcus faecalis can cause endodontic infections. We present the case of an HHT patient who developed brain abscess due to E. faecalis after a dental procedure.

Pulmonary Arteriovenous Malformation (AVM) Causing Tension Hemothorax in a Pregnant Woman Requiring Emergent Cesarean Delivery

Pulmonary arteriovenous malformations (PAVMs), although most commonly congenital, are usually detected later in life. We present a case of a 25-year-old woman with no previous history of AVM or telangiectasia, who presented with life-threatening hypoxia, hypotension, and pleuritic chest pain in 36th week of gestation. Chest tube placement revealed 4 liters of blood. Patient was subsequently found to have bleeding pulmonary AVM as the source of hemothorax. Successful embolisation of the bleeding vessel followed by thoracoscopic evacuation of the organized clot relieved the hypoxia. Further screening for AVM revealed large splenic AVM for which patient underwent splenectomy in the coming months.

Hereditary haemorrhagic telangiectasia: pathophysiology, diagnosis and treatment

Hereditary haemorrhagic telangiectasia, inherited as an autosomal dominant trait, affects approximately 1 in 5000 people. The abnormal vascular structures in HHT result from mutations in genes (most commonly endoglin or ACVRL1) whose protein products influence TGF-ß superfamily signalling in vascular endothelial cells. The cellular mechanisms underlying the generation of HHT telangiectasia and arteriovenous malformations are being unravelled, with recent data focussing on a defective response to angiogenic stimuli in particular settings. For affected individuals, there is often substantial morbidity due to sustained and repeated haemorrhages from telangiectasia in the nose and gut. Particular haematological clinical challenges include the management of severe iron deficiency anaemia; handling the intricate balance of antiplatelet or anticoagulants for HHT patients in whom there are often compelling clinical reasons to use such agents; and evaluation of apparently attractive experimental therapies promoted in high profile publications when guidelines and reviews are quickly superseded. There is also a need for sound screening programmes for silent arteriovenous malformations. These occur commonly in the pulmonary, cerebral, and hepatic circulations, may haemorrhage, but predominantly result in more complex pathophysiology due to consequences of defective endothelium, or shunts that bypass specific capillary beds. This review will focus on the new evidence and concepts in this complex and fascinating condition, placing these in context for both clinicians and scientists, with a particular emphasis on haematological settings.

Hereditary hemorrhagic telangiectasia: from molecular biology to patient care

SUMMARY

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant vascular disorder characterized by severe and recurrent nosebleeds, mucocutaneous telangiectases, and, in some cases, life-threatening visceral arteriovenous malformations of various types, including pulmonary, hepatic, cerebral, and spinal. Gastrointestinal telangiectases are frequent and may cause severe bleeding. HHT type 1 results from mutations in ENG on chromosome 9 (coding for endoglin), and HHT type 2 results from mutations in ACVRL1 on chromosome 12 (coding for activin receptor-like kinase 1). Mutations of either of these two genes account for most clinical cases. In addition, mutations in MADH4 (encoding SMAD4), which cause a juvenile polyposis/HHT overlap syndrome, have been described, and recently, an HHT3 locus on chromosome 5 (5q31.3-5q32) has been reported. The mutated genes in HHT encode proteins that modulate transforming growth factor-beta superfamily signaling in vascular endothelial cells. Management of patients has changed considerably in the last 20 years, in terms of both treatment and the prevention of complications. The goal of this review was to describe the underlying molecular and cellular physiopathology, explore clinical and genetic diagnostic strategies for HHT, and present clinical management recommendations in order to treat symptomatic disease and to screen for vascular malformations.

Real prevalence of pulmonary right-to-left shunt according to genotype in patients with hereditary hemorrhagic telangiectasia: a transthoracic contrast echocardiography study

BACKGROUND

Transthoracic contrast echocardiography (TTCE) can detect pulmonary right-to-left shunting (RLS) and is used to screen for pulmonary arteriovenous malformations (PAVMs) in patients with hereditary hemorrhagic telangiectasia (HHT). We studied the prevalence and size of pulmonary RLS in HHT type 1, HHT type 2, and HHT-negative controls, and its positive predictive value (PPV) and negative predictive value (NPV) for PAVMs that can be treated by embolotherapy.

METHODS

In 343 consecutive persons referred for possible HHT as first-degree family members of index patients a TTCE and chest CT scan were performed. All persons were offered genetic analysis.

RESULTS

An HHT-causing mutation was confirmed in 92 (mean age 41 ± 15 y; 59% female) HHT1 relatives and in 97 (mean age 47 ± 14 y; 52% female) HHT2 relatives. TTCE showed a pulmonary RLS in 78 (85%) HHT1- and 34 (35%) HHT2-related mutation carriers, respectively (P < .0001). In HHT1 relatives, 29 of 53 (55%) PAVMs and in HHT2 relatives three of 17 (18%) PAVMS were treated, resulting in a PPV of TTCE for treatable PAVMs of 36.3% and 8.3%, respectively. The accompanying NPV was 100%. A minimal, moderate, or large shunt was present in 12 (13%), 24 (26%), and 42 (46%) HHT1-related, and in 20 (21%), 6 (6%), and 8 (8%) HHT2-related mutation carriers, respectively (P for trend < .0001). A large shunt predicted treatable PAVMs in 55.8% of HHT1 relatives and 37.5% of HHT2 relatives. TTCE was positive in four (6%) of 63 persons without HHT.

CONCLUSIONS

A pulmonary shunt on TTCE is more prevalent and larger in HHT1- compared with HHT2-related mutation carriers. Shunt grading is helpful to predict treatable PAVMs, particularly in the HHT2 group. TTCE is also positive in a small fraction of persons without HHT.

Hereditary haemorrhagic telangiectasia: a clinical and scientific review

The autosomal-dominant trait hereditary haemorrhagic telangiectasia (HHT) affects 1 in 5-8000 people. Genes mutated in HHT (most commonly for endoglin or activin receptor-like kinase (ALK1)) encode proteins that modulate transforming growth factor (TGF)-beta superfamily signalling in vascular endothelial cells; mutations lead to the development of fragile telangiectatic vessels and arteriovenous malformations. In this article, we review the underlying molecular, cellular and circulatory pathobiology; explore HHT clinical and genetic diagnostic strategies; present detailed considerations regarding screening for asymptomatic visceral involvement; and provide overviews of management strategies.

Hereditary haemorrhagic telangiectasia: a clinical and scientific review

The autosomal-dominant trait hereditary haemorrhagic telangiectasia (HHT) affects 1 in 5-8000 people. Genes mutated in HHT (most commonly for endoglin or activin receptor-like kinase (ALK1)) encode proteins that modulate transforming growth factor (TGF)-beta superfamily signalling in vascular endothelial cells; mutations lead to the development of fragile telangiectatic vessels and arteriovenous malformations. In this article, we review the underlying molecular, cellular and circulatory pathobiology; explore HHT clinical and genetic diagnostic strategies; present detailed considerations regarding screening for asymptomatic visceral involvement; and provide overviews of management strategies.