Complications in the natural course — HHT · Osler’s disease

  • Chapter: HHT · Osler’s disease

    Article: 11 of 13

    Update: May 06, 2021

  • Author(s): Kühnel, Thomas

The most important complications involve patients with pulmonary AV shunts (pAVM). Pulmonary AVMs are found in up to 50% of HHT patients during their lifetime. The incidence is greater in HHT1 patients (85%). Even before development of dyspnea, which may be a leading symptom in this case, routine diagnostic testing should reveal a shunt. Shunts provide a direct connection between the arterial and venous branches of the pulmonary artery. The shunt leads to local failure of the capillary filter, so that emboli (paradoxical embolism) and septic particles can lead to brain abscess (8-19%) or stroke (10-36%). In advanced cases, the shunt can cause exertional dyspnea and cyanosis. Rupture of the aneurysmal portion of the pulmonary arteriovenous malformation can also result in massive hemorrhage in very rare cases. Pulmonary AVMs are treated prophylactically above a certain size to prevent intracerebral complications. In this way, brain abscesses are avoided with good outcomes, although the risk cannot be completely eliminated. Invasive procedures, even minor ones such as dental work, require antibiotic prophylaxis in patients with pAVM.

Hepatic vascular shunts (hVM) are rarely symptomatic but, when they are present, patients are severely affected. After the age of 40/50, the shunts also have hemodynamic relevance. Complications include biliary ischemia, portal venous hypertension, and also fatal high-output cardiac failures. Improved endoluminal therapy techniques have led to a significant decrease in complication rates. In individual cases, however, liver transplantation must be considered. Successful systemic administration of bevacizumab is increasingly reported in the literature.

Arteriovenous fistulas with cerebral manifestations are probably found mainly in children. These bleed with an extremely high risk. Complications of Osler spots in the cerebrum are much rarer; their prophylactic therapy is not without problems, since therapy is associated with an appreciable risk.

Spinal complications occur as neurologic deficits, headache, and stroke secondary to subarachnoid hemorrhage. In pregnant women, preferably before the onset of pregnancy, pulmonary AVMs should be ruled out or submitted to therapy. The risk of miscarriage, hemorrhage or stroke is increased during pregnancy and probably because of hormonal changes.

In the nose, treatments with lasers and other methods of sclerotherapy lead to scarring. The vascular pattern changes and the spots do not respond as well to treatment. With loss of normal mucosa, the nose also becomes drier, which in turn means loss of stability of the mucosa. As explained under “Typical accompanying symptoms”, nasal septal defect is also a typical and frequent complication.