The hepatic involvement of HHT (Hereditary Haemorrhagic Telangiectasia) disease is characterised by the formation of arterio-sus-hepatic shunts which lead to dilatation of the hepatic artery and may result in high output heart failure. This evolves silently for long-standing period from left ventricular cavities dilatation to advanced heart failure with post-capillary pulmonary hypertension (PH) (more rarely pre-capillary), and its evolution is poorly understood. The specific treatment options for HHT disease are either the use of anti-angiogenic therapy (bevacizumab) or liver transplantation. As rest echocardiography can only detect advanced cases or heart failure with rest PH, the investigators speculate that exercise echocardiography can provide additional information in patients without rest PH. The hypothesis is that an exaggerated pulmonary pressure increase during exercise may precede the occurrence of rest PH in the course of the disease. It could identify patients with substantial heart failure at an earlier stage and may facilitate the access to liver transplantation. These parameters have never been studied in this context and it seems interesting to evaluate them in this pilot study.

The investigators hypothesise that HHT (Hereditary Haemorrhagic Telangiectasia) patients with hepatic involvement and cardiac high output will have significantly greater and/or earlier elevation of exercise pulmonary arterial pressures than those with normal cardiac output.

Inclusion Criteria:

• HHT patient > 18 yo
• Hepatic involvement (hepatic artery diameter > 6mm)
• Patient having received the information and signed the informed consent form
• Patient affiliated to a social security scheme or beneficiaries of a similar scheme

Exclusion Criteria:

• Haemoglobin < 90 g/L
• Active Infection
• Atrial Fibrillation permanent or persistent
• Known cardiopathy
• Pregnant or breastfeeding woman (by questioning)
• Adult subject to a legal protection measure (guardianship)
• Participation in another clinical trial that may interfere with the proposed trial (investigator judgment)
• Patient physically unable to pedal
• Patient with Pulmonary arteriovenous malformations awaiting embolization
• Patient treated with beta-blockers

Secondary Exclusion Criteria verified on rest ultrasound

• PAH (Pulmonary Arterial Hypertension) at rest (Vmax > 2.8 m/sec)
• Inability to obtain a stream of IT at rest
• Patient with atrial fibrillation (AF)