Pulmonary hypertension is a serious and progressive disease that is difficult to treat and diagnose, mainly because its symptoms are nonspecific and often delay recognition. Early diagnosis is a major challenge. Although several tests may suggest the disease, the definitive diagnosis still requires right heart catheterization, an invasive procedure that directly measures pulmonary hemodynamics such as pulmonary artery pressure, cardiac output, and vascular resistance.

Electrical impedance tomography (EIT) is a non-invasive, radiation-free bedside monitoring method that can evaluate ventilation and pulmonary perfusion. The number of studies investigating perfusion with EIT has been increasing, since the possibility of having a safe, radiation-free, and repeatable method available at the bedside is of great clinical interest in different fields of medicine.

Our hypothesis is that EIT provides information that correlates with the findings of right heart catheterization in patients with suspected pulmonary arterial hypertension (PAH). EIT may serve as a useful screening tool prior to catheterization and may also help in risk stratification of patients with pulmonary hypertension

This single-center, prospective diagnostic study is designed to investigate whether EIT-derived measures correlate with invasive hemodynamic parameters obtained by RHC. Adult patients referred for RHC due to suspected PAH or for disease staging will undergo standard catheterization, followed by short-term EIT monitoring. Some patients will additionally receive a hypertonic saline injection during a respiratory pause to enhance the perfusion signal. All EIT data will be processed offline using dedicated algorithms to separate ventilation and perfusion signals and to extract pulsatility-related parameters (e.g., amplitude, area, inflection points). These values will then be compared with RHC-derived hemodynamic measures such as mean pulmonary artery pressure (mPAP), pulmonary vascular resistance (PVR), cardiac output (CO), and stroke volume (SV).

The primary outcome of this study is to determine the diagnostic accuracy of EIT for detecting pulmonary hypertension, aiming at high sensitivity and clinical utility as a screening tool prior to invasive catheterization. Secondary analyses will include exploration of additional EIT-derived perfusion and pulsatility indices, assessment of diagnostic thresholds for different levels of PAH severity, and evaluation of prognostic implications.

Risks associated with participation are minimal, as EIT is non-invasive and safe. The risks of RHC are those inherent to the procedure and are independent of the study. While no direct benefit is expected for individual participants, the findings may provide important insights into the use of EIT as a less invasive diagnostic strategy for PAH, with potential implications for clinical practice and patient care.

Inclusion Criteria:

• Patients with a diagnosis or clinical suspicion of pulmonary arterial hypertension (PAH) and with a medical indication for right heart catheterization.
• Patients evaluated at the Pulmonology Service of InCor-HCFMUSP.

Exclusion Criteria:

• Pregnancy.
• Structural heart disease, such as atrial septal defect, ventricular septal defect, or valvular disease.
• Cardiac arrhythmias.
• Presence of a cardiac pacemaker or other implantable electronic device.
• Skin lesions at the thoracic region that would prevent placement of the EIT electrode belt.
• WHO functional class IV of new york heart association (NYAH)..
• Inability to perform a voluntary respiratory pause (apnea) of at least 30 seconds or inability to understand and follow instructions required.
• Decline to participate in the study by not signing the informed consent form or refusal by the attending medical team.