Patients with a disease that causes abnormal blood vessel formation in skin, mucous membranes and some organs are at risk of developing different types of pulmonary hypertension, a study shows.
The organs affected by the blood-vessel condition, hereditary hemorrhagic telangiectasia (HHT), include the lungs, liver and brain. The types of pulmonary hypertension that HHT patients can develop include pre-capillary PH, post-capillary PH, and a combined type.
Researchers published their study in the journal Plos One. It was titled “Pulmonary hypertension subtypes associated with hereditary haemorrhagic telangiectasia: Haemodynamic profiles and survival probability.”
Patients with HHT can develop post-capillary Group 2 hypertension, or high blood pressure in the blood vessels that supply oxygen to the lungs and return it to the heart. The condition develops due to high cardiac volume, or the amount of blood the heart pumps. It can lead to failure of the left side of the heart.
In rare cases, HHT patients can develop pre-capillary hypertension, also known as pulmonary arterial hypertension, or PAH. A mutation in the ACVRL1 gene that causes HHT is a risk factor for PAH.
Because little has been known about PH in the HHT population, French researchers decided to look into it. They wanted to know factors besides the mutation that increased the risk of HHT patients developing PH and what types of PH they can develop. They also wanted to determine how different kinds of PH affect HHT patients’ survival.
The study involved combing through the records of 2,598 patients in the French National Reference Center for HHT. In addition to HHT patients with PH, researchers looked at the records of patients with high systolic pulmonary arterial pressure, or sPAP, which is a sign of PAH.
Their first step was to identify 110 cases of suspected PH, based on patients’ echocardiogram scores. The team then performed right heart catheterizations, which measure pulmonary artery pressure, on 47 of the 110. This led to the researchers confirming PH in 38 of the 47.
The team found that 20 of the 38 patients had post-capillary PH. They also identified, for the first time, other types of hypertension in the HHT population. Three had PAH with slightly high pulmonary vascular resistance — or difficulty getting blood through the vessels. And four cases covered a combination of post- and pre-capillary PH.
As expected, HHT patients with PAH had a lower chance of surviving than HHT patients without the condition, researchers said. Interestingly, the team did not find any factors besides the ACVRL1 gene mutation that would increase the risk of an HHT patient developing PH.
“This study revealed the diversity of PH mechanisms in HHT,” the researchers wrote. They added that it suggested that “PH could be screened for by echocardiography in the case of unexplained dyspnoea [shortness of breath] and be confirmed” with right heart catheterization.
Studies dealing with current patients, rather than those looking only at previous records, “are required to explore the physiopathology of the occurrence of these new hemodynamic [blood flow] profiles, the respective proportions of each PH group, and differences in prognosis,” the team concluded.