What are the typical cardiac catheterization findings in patients with primary idiopathic pulmonary hypertension?

From the Guidelines

Cardiac catheterization in patients with primary idiopathic pulmonary hypertension typically reveals elevated mean pulmonary artery pressure (mPAP) greater than 25 mmHg at rest, with markedly increased pulmonary vascular resistance (PVR) above 3 Wood units, and normal pulmonary capillary wedge pressure (PCWP) ≤15 mmHg. The diagnosis of pulmonary hypertension (PH) is made when mPAP is greater than 20 mmHg at rest, as measured by right heart catheterization 1. In patients with primary idiopathic pulmonary hypertension, also known as pulmonary arterial hypertension (PAH), cardiac catheterization findings include:

• Elevated mPAP, often exceeding 40-50 mmHg in advanced disease
• Markedly increased PVR, typically above 3 Wood units (or 240 dynes·sec·cm⁻⁵)
• Elevated right atrial pressure, commonly above 8 mmHg, reflecting right ventricular dysfunction
• Normal PCWP (≤15 mmHg), distinguishing PAH from pulmonary hypertension due to left heart disease
• Reduced cardiac output, particularly in advanced disease, with values below 4 L/min
• Normal systemic arterial saturation, but decreased mixed venous oxygen saturation due to low cardiac output

Vasoreactivity testing is also performed during catheterization to identify patients who may respond to calcium channel blockers 1. A positive acute response is defined as a decrease in mPAP by at least 10 mmHg to a value below 40 mmHg with an increased or unchanged cardiac output. These hemodynamic parameters are crucial for confirming the diagnosis, assessing disease severity, guiding therapy, and determining prognosis in PAH patients 1.

From the FDA Drug Label

CI (L/min/m2) 2 2 0.3†† -0. 1 PAPm (mmHg) 60 60 -5† 1 PVR (Wood U) 16 17 -4† 1 SAPm (mmHg) 89 91 -4 -3 SV (mL/beat) 44 43 6† -1 TPR (Wood U) 20 21 -5† 1 CI (L/min/m2) 1.9 2.2 0.5* -0. 1 PAPm (mmHg) 51 49 -5* 1 RAPm (mmHg) 13 11 -1* 1 PVR (Wood U) 14 11 -5* 1 SAPm (mmHg) 93 89 -8* -1 CI (L/min/m2)2.4 ± 0.882.2 ± 0.74+0.12 ± 0.58* -0.06 ± 0.55 PAPm (mmHg)62 ± 17.660 ± 14.8-2.3 ± 7.3*+0.7 ± 8. 5 PVR (mmHg/L/min/m2)26 ± 1325 ± 13-3.5 ± 8.2*+1.2 ± 7.9

The typical cardiac catheterization findings in patients with primary idiopathic pulmonary hypertension include:

• Elevated mean pulmonary arterial pressure (PAPm): 60 mmHg 2 and 62 mmHg 3
• Elevated pulmonary vascular resistance (PVR): 16 Wood U 2 and 26 mmHg/L/min/m2 3
• Low cardiac index (CI): 2 L/min/m2 2 and 2.4 L/min/m2 3 These findings are consistent with pulmonary hypertension and right heart dysfunction. However, it is essential to note that these values can vary depending on the individual patient and the severity of their disease.

From the Research

Cardiac Catheterization Findings in Primary Idiopathic Pulmonary Hypertension

The typical cardiac catheterization findings in patients with primary idiopathic pulmonary hypertension include:

• Elevated mean pulmonary artery pressure (mPAP) greater than 25 mmHg at rest 4
• Normal pulmonary capillary occlusion pressure (less than 15 mmHg) 4
• Elevated pulmonary vascular resistance (PVR) greater than 3 Wood units 4
• Low cardiac index (CI) 5, 6
• Low mixed systemic venous oxygen saturations (SvO2) 7

Hemodynamic Responses to Vasodilator Testing

Vasodilator testing using agents such as epoprostenol, iloprost, and nitric oxide can help assess pulmonary vasoreactivity:

• A positive response to vasodilator testing is defined as a reduction of 10 mmHg in mean pulmonary arterial pressure or achieving a mean pulmonary artery pressure of less than 40 mmHg, with no change or an increase in cardiac output 4
• Patients with a positive response may also show a sustained response to calcium channel blockers 4
• Acute vasodilator testing with inhaled iloprost can provide prognostic value for long-term survival in children with idiopathic pulmonary arterial hypertension 7

Prognostic Value of Cardiac Catheterization

Cardiac catheterization and acute vasodilator testing can provide important prognostic information:

• Lower pulmonary vascular resistance index (PVRI), PVRI/systemic vascular resistance index (SVRI), and mean pulmonary arterial pressure (mPAP)/mean systemic arterial pressure are associated with improved survival 7
• Higher cardiac index (CI), mixed systemic venous oxygen saturations (SvO2), and acute vasodilator response (AVR) are also associated with improved survival 7