Pulmonary AVMs (PAVMs)

PVAMs are a common manifestation of HHT and primarily affect the lungs.

About HHT

Hereditary Hemorrhagic Telangiectasia (HHT), also known as Osler-Weber-Rendu syndrome, is a rare genetic disorder characterised by the development of abnormal blood vessels (telangiectases) and arteriovenous malformations (AVMs) in various organs.

Genetic Basis

HHT is an autosomal dominant genetic disorder, meaning that an individual only needs one copy of the faulty gene from either parent to develop the condition. Mutations in the ENG (endoglin) or ACVRL1 (activin receptor-like kinase 1) genes are commonly associated with HHT.

Development of Pulmonary AVMs

PAVMs are abnormal connections between the pulmonary arteries and veins in the lungs. In individuals with HHT, these malformations often lack the normal capillary bed, leading to direct shunting of blood from the arteries to the veins. This can result in poorly oxygenated blood reaching the systemic circulation.

Clinical Presentation

Patients with PAVMs may remain asymptomatic, or they may experience a range of symptoms. Common manifestations include dyspnea (shortness of breath), fatigue, and cyanosis (bluish discoloration of the skin and mucous membranes). Some individuals may develop complications such as stroke or brain abscess due to paradoxical emboli, where abnormal blood clots travel from the veins to the arteries.

Diagnostic Approaches

Various imaging techniques are employed to diagnose and assess PAVMs in HHT patients. Contrast echocardiography, computed tomography (CT) angiography, and magnetic resonance imaging (MRI) are commonly used to visualize the abnormal blood vessels and assess the severity and distribution of PAVMs.

Treatment Options

The primary goal of treating PAVMs in HHT patients is to prevent complications related to abnormal shunting of blood. Embolization, a minimally invasive procedure, is often employed to occlude the abnormal vessels using coils or other embolic materials. Regular follow-up is crucial to monitor the effectiveness of treatment and identify any new PAVMs that may develop over time.

Genetic Counseling

Since HHT is a hereditary condition, genetic counseling is recommended for affected individuals and their families. Understanding the genetic basis can help in family planning decisions and early detection of the condition in at-risk relatives.

Multidisciplinary Care

Managing PAVMs in HHT patients often requires a collaborative approach involving pulmonologists, interventional radiologists, cardiologists, and genetic counselors. Regular monitoring and coordination between specialists are essential for optimal patient care.

Summary

In summary, pulmonary AVMs are a significant clinical feature of HHT, and their management involves a combination of imaging studies, interventional procedures, and a multidisciplinary healthcare approach to improve patient outcomes and quality of life.

VASCERN HHT AVMs

VASCERN is the European Reference Network aiming at improving and homogenising care of patients with rare multi-systemic vascular diseases throughout Europe

HHT international Guidlines
CURE HHT

CureHHT recorded webinar on Pulmonary AVMs

CureHHT Factsheet

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CureHHT Pulmonary AVM Care Checklist

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Dental work done on a patient with PAVMs,

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With regards to having any dental work done on a patient with PAVMs, we need to understand the reason why an antibiotic is recommended in instances where the treatment might elicit any bleeding.

It is not just to prevent a localised infection following the procedure. It is because if a HHT patient has a PAVM (which they could unknowingly have at the time of the dental procedure) then their blood-brain barrier becomes compromised. Any infection in the bloodstream could become a brain abscess and it is the risk of brain abscess which is reduced by taking the antibiotic.

Unfortunately overuse of antibiotics in other settings has led to many dentists and medics now being in a position of being (rightly) very reluctant to prescribe antibiotics.

It might be useful to remind them of the possibility of the blood-brain barrier being compromised by an undiagnosed PAVM.