What is Chronic thromboembolic pulmonary hypertension (CTEPH), and why is it a serious condition?

Chronic thromboembolic pulmonary hypertension (CTEPH) is a serious condition where blood clots block the lungs, increasing pressure in the pulmonary arteries. This elevated pressure strains the heart, reducing activity levels. The implications are significant because CTEPH severely impacts daily life, limiting physical capabilities and overall well-being.

What is the purpose of Balloon pulmonary angioplasty (BPA), and why isn't it always a complete cure?

Balloon pulmonary angioplasty (BPA) is a procedure used to open blocked vessels in the lungs of Chronic thromboembolic pulmonary hypertension (CTEPH) patients, improving blood flow. Its importance lies in its potential to alleviate the strain on the heart and improve exercise capacity. However, this procedure does not always guarantee full recovery because other factors such as residual intrapulmonary shunting can still affect exercise capacity after BPA.

What is intrapulmonary shunting, and why is it a problem for some patients?

Intrapulmonary shunting occurs when blood flows through the lungs without picking up enough oxygen. This can happen even after a successful procedure like Balloon pulmonary angioplasty (BPA). The implications of intrapulmonary shunting are that it leads to inefficient oxygen transfer, which can significantly limit a Chronic thromboembolic pulmonary hypertension (CTEPH) patient's ability to exercise and enjoy a good quality of life, even when other measures of health improve.

What does a high alveolar-arterial oxygen gradient (A-aDO2) tell us about lung function?

A high alveolar-arterial oxygen gradient (A-aDO2) indicates that oxygen transfer from the air sacs in the lungs (alveoli) into the arteries is not happening efficiently. This measurement helps to evaluate how well the lungs are functioning in oxygenating the blood. This is important in the context of Chronic thromboembolic pulmonary hypertension (CTEPH) because a high A-aDO2 is linked to reduced exercise tolerance in patients even after undergoing treatment like Balloon pulmonary angioplasty (BPA). This finding helps pinpoint the cause of limited exercise capacity.

Illustration of lungs with glowing pathways, symbolizing improved lung function and exercise after pulmonary angioplasty.

Why Your Lungs Might Still Struggle After Pulmonary Angioplasty

Q: What is the main takeaway regarding the impact of the research findings on CTEPH patients?

The research revealed that while Balloon pulmonary angioplasty (BPA) improves heart function in Chronic thromboembolic pulmonary hypertension (CTEPH) patients, it doesn't always completely restore exercise capacity. The lingering issue of intrapulmonary shunting can limit a patient's ability to be active and enjoy a good quality of life. This underscores the need for additional strategies to improve outcomes and quality of life for CTEPH patients beyond BPA.

Lena Kashyap in Health & Wellness December 2025 • 4 min read.

"New research sheds light on why some CTEPH patients experience limited exercise capacity despite successful treatment, revealing a crucial link to lung oxygenation."

Chronic thromboembolic pulmonary hypertension (CTEPH) is a serious condition where blood clots accumulate in the lungs, leading to high blood pressure in the pulmonary arteries. This puts a strain on the heart and can significantly reduce a person's ability to be active. Balloon pulmonary angioplasty (BPA) has emerged as a valuable treatment, helping to open up blocked vessels and improve blood flow.

Many patients experience significant relief and improved heart function after BPA. However, a frustrating issue remains: some individuals continue to struggle with exercise, even when their heart pressures have returned to near-normal levels. This disconnect has puzzled doctors, prompting a search for other factors that might be limiting recovery.

New research investigates the link between lung function and exercise capacity in CTEPH patients after BPA. The study pinpoints a specific lung issue – inefficient oxygen transfer due to residual intrapulmonary shunting – as a key reason why some individuals don't regain their full exercise potential. Understanding this connection is crucial for developing strategies to improve outcomes and quality of life for CTEPH patients.

The Oxygenation Puzzle: Why Some Lungs Don't Fully Recover

Illustration of lungs with glowing pathways, symbolizing improved lung function and exercise after pulmonary angioplasty.

The core question this research tackles is: why do some CTEPH patients still have trouble with exercise after BPA, even when their pulmonary hemodynamics (blood flow and pressure) improve? The researchers hypothesized that the answer lies in respiratory function, specifically how efficiently the lungs are transferring oxygen into the bloodstream.

To investigate this, the researchers analyzed data from 62 CTEPH patients who underwent BPA and were followed for a year. They looked at various factors, including:

Pulmonary hemodynamics (pressures in the heart and lungs)
Respiratory function tests (lung capacity, airflow, and oxygen transfer efficiency)
Exercise capacity (measured by a six-minute walk test)

The study revealed that a high alveolar-arterial oxygen gradient (A-aDO2) was a significant predictor of reduced exercise tolerance after BPA. The A-aDO2 reflects how well oxygen is moving from the air sacs in the lungs (alveoli) into the arteries. A high A-aDO2 indicates that oxygen transfer is not happening efficiently. Further analysis pinpointed the cause of the high A-aDO2 to residual intrapulmonary shunting – a condition where blood flows through the lungs without picking up enough oxygen.

What This Means for CTEPH Patients and Future Treatment

This research underscores that successful BPA, while improving heart function, doesn't always guarantee a full return to exercise capacity. The lingering issue of intrapulmonary shunting can significantly limit a patient's ability to be active and enjoy a good quality of life.

The study highlights the importance of assessing lung function, specifically oxygenation efficiency, in CTEPH patients after BPA. Monitoring A-aDO2 and Qs/Qt (intrapulmonary shunt fraction) can help identify individuals who may benefit from targeted therapies to improve lung oxygen transfer.

While there isn't yet a specific treatment to directly address intrapulmonary shunting in this context, recognizing it as a limiting factor opens avenues for future research. Strategies to improve lung function and oxygenation in CTEPH patients after BPA could include pulmonary rehabilitation programs or, potentially, targeted drug therapies. Further research is needed to explore these possibilities and optimize recovery for all CTEPH patients.