Hereditary hemorrhagic telangiectasia (HHT): a practical guide to management

Hereditary hemorrhagic telangiectasia (HHT), the second most common inherited bleeding disorder, is associated with the development of malformed blood vessels. Abnormal blood vessels may be small and cutaneous or mucosal (telangiectasia), with frequent complications of bleeding, or large and visceral (arteriovenous malformations [AVMs]), with additional risks that can lead to significant morbidity and even mortality. HHT can present in many different ways and can be difficult to recognize, particularly in younger patients in the absence of a known family history of disease or epistaxis, its most common manifestation. HHT is commonly diagnosed using the established Curaçao clinical criteria, which include (1) family history, (2) recurrent epistaxis, (3) telangiectasia, and (4) visceral AVMs. Fulfillment of 3 or more criteria provides a definite diagnosis of HHT, whereas 2 criteria constitute a possible diagnosis of HHT. However, these criteria are insufficient in children to rule out disease due to the age-dependent development of some of these criteria. Genetic testing, when positive, can provide definitive diagnosis of HHT in all age groups. Clinical course is often complicated by significant epistaxis and/or gastrointestinal bleeding, leading to anemia in half of adult patients with HHT. The management paradigm has recently shifted from surgical approaches to medical treatments aimed at control of chronic bleeding, such as antifibrinolytic and antiangiogenic agents, combined with aggressive iron replacement with intravenous iron. Guidelines for management of HHT, including screening and treatment, were determined by expert consensus and originally published in 2009 with updates and new guidelines in 2020.

Pearls & Oy-sters: Cerebral Abscess Secondary to Pulmonary Arteriovenous Malformation in Hereditary Hemorrhagic Telangiectasia

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal-dominant condition which is linked to a myriad of neurological complications arising from vascular malformations of the brain, spinal cord, and lungs. Our case describes a previously healthy 3-year-old male who presented to hospital with fever of unknown origin and was found to have a brain abscess stemming from a pulmonary arteriovenous malformation (PAVM). This etiology was identified after a period of diagnostic delay; the medical team was suspicious for a proximal embolic source due to the presence of multiple tiny infarcts seen on MRI brain, but transthoracic echocardiogram and head and neck angiogram were unremarkable. Fortunately, an enhanced CT chest was performed, identifying a moderately-sized PAVM. PAVMs are associated with intracranial abscesses due to shunting and loss of the normal filtering effects of the lung capillary bed. Impaired pulmonary filtration can permit paradoxical thromboemboli and septic microemboli to enter systemic circulation, predisposing patients with PAVMs to cerebral abscess and ischemic stroke. Screening for PAVMs with contrast enhanced echocardiogram or enhanced CT chest may be considered in patients with cryptogenic brain abscess or recurrent embolic stroke of unknown origin. PAVMs are often associated with hereditary hemorrhagic telangiectasia (HHT). As many features of HHT have delayed clinical manifestation, genetic testing for HHT should be considered in patients with PAVM, even in the absence of other clinical features. In our case, genetic testing returned positive, confirming a new diagnosis of HHT type 1.

TIMolol nasal spray as a treatment for epistaxis in hereditary hemorrhagic telangiectasia (HHT) – study protocol of the prospective, randomized, double-blind, controlled cross-over TIM-HHT trial

BACKGROUND: Hereditary hemorrhagic telangiectasia (HHT) is an inherited orphan disease, in which the absence of capillary beds between arterioles and venules lead to arteriovenous shunts. Epistaxis is the core symptom. Several case reports have described the nonselective beta-adrenergic receptor antagonist timolol as a successful treatment method of nosebleeds due in HHT patients. OBJECTIVE: TIM-HHT is a single-site, prospective, randomized, placebo-controlled, double-blind, cross-over study to investigate whether the efficacy of standard laser treatment of epistaxis in HHT patients can be increased by the additional use of timolol nasal spray (1 mg/d). METHODS: Twenty patients will be randomly allocated to one of two treatment sequences. Primary outcome is the severity of epistaxis determined by the Epistaxis Severity Score (ESS). Secondary outcomes are subjective satisfaction, quality of life, as well as the hemoglobin, ferritin, and transferrin levels of the participating patients. Safety outcome is assessed by means of pulse, blood pressure, and adverse events. CONCLUSION: TIM-HHT will evaluate the efficacy and safety of timolol as an additional treatment of epistaxis in HHT patients in a three-month trial period. Benzalkonium chloride is used as a placebo, which has no documented positive effect on the nasal mucosa and hence on epistaxis in HHT patients (in contrast to saline). TRIAL REGISTRATION: German Clinical Trials Register (DRKS), DRKS00020994. Registered on 10 March 2020

Mutational and clinical spectrum of Japanese patients with hereditary hemorrhagic telangiectasia

Background Hereditary hemorrhagic telangiectasia (HHT) is a dominantly inherited vascular disorder characterized by recurrent epistaxis, skin/mucocutaneous telangiectasia, and organ/visceral arteriovenous malformations (AVM). HHT is mostly caused by mutations either in the ENG or ACVRL1 genes, and there are regional differences in the breakdown of causative genes. The clinical presentation is also variable between populations suggesting the influence of environmental or genetic backgrounds. In this study, we report the largest series of mutational and clinical analyses for East Asians. Methods Using DNAs derived from peripheral blood leukocytes of 281 Japanese HHT patients from 150 families, all exons and exon–intron boundaries of the ENG, ACVRL1, and SMAD4 genes were sequenced either by Sanger sequencing or by the next-generation sequencing. Deletions/amplifications were analyzed by the multiplex ligation-dependent probe amplification analyses. Clinical information was obtained by chart review. Results In total, 80 and 59 pathogenic/likely pathogenic variants were identified in the ENG and ACVRL1 genes, respectively. No pathogenic variants were identified in the SMAD4 gene. In the ENG gene, the majority (60/80) of the pathogenic variants were private mutations unique to a single family, and the variants were widely distributed without any distinct hot spots. In the ACVRL1 gene, the variants were more commonly found in exons 5–10 which encompasses the serine/threonine kinase domain. Of these, 25/59 variants were unique to a single family while those in exons 8–10 tended to be shared by multiple (2–7) families. Pulmonary and cerebral AVMs were more commonly found in ENG-HHT (69.1 vs. 14.4%, 34.0 vs. 5.2%) while hepatic AVM was more common in ACVRL1-HHT (31.5 vs. 73.2%). Notable differences include an increased incidence of cerebral (34.0% in ENG-HHT and 5.2% in ACVRL1-HHT), spinal (2.5% in ENG-HHT and 1.0% in ACVL1-HHT), and gastric AVM (13.0% in ENG-HHT, 26.8% in ACVRL1-HHT) in our cohort. Intrafamilial phenotypic heterogeneity not related to the age of examination was observed in 71.4% and 24.1% of ENG- and ACVRL1-HHT, respectively. Conclusions In a large Japanese cohort, ENG-HHT was 1.35 times more common than ACVRL1-HHT. The phenotypic presentations were similar to the previous reports although the cerebral, spinal, and gastric AVMs were more common.