Pulmonary hypertension (PH) is defined as a mean pulmonary artery pressure (mPAP) of 20 mm Hg or more at rest, measured via right heart catheterization. This condition can be categorized into five groups based on etiology, pathophysiology, and therapeutic considerations:
Group 1: Pulmonary Arterial Hypertension (PAH)
PAH is idiopathic and heritable and is associated with conditions such as connective tissue diseases (e.g., scleroderma), HIV infection, congenital heart disease, and portal hypertension. It involves pathologic changes like endothelial dysfunction, vasoconstriction, and vascular remodeling, leading to increased pulmonary vascular resistance (PVR).
Group 2: PH Due to Left Heart Disease
This is the most common form of PH and results from left-sided heart disorders, such as left ventricular systolic or diastolic dysfunction, mitral or aortic valve disease, or left atrial hypertension. The backward transmission of elevated left atrial pressure causes increased pulmonary venous pressure, leading to secondary pulmonary hypertension.
Group 3: PH Due to Lung Diseases and Hypoxia
PH in this group is associated with chronic obstructive pulmonary disease (COPD), interstitial lung disease, sleep apnea, and other conditions causing chronic hypoxia. Chronic hypoxia induces vasoconstriction and vascular remodeling, contributing to increased PVR.
Group 4: Chronic Thromboembolic Pulmonary Hypertension (CTEPH)
CTEPH is caused by unresolved thromboembolism in the pulmonary arteries, leading to increased PVR and PH. It is a unique subtype because it is potentially curable with pulmonary thromboendarterectomy surgery or balloon pulmonary angioplasty.
Group 5: PH with Unclear Multifactorial Mechanisms
This group includes PH due to systemic, metabolic, or hematologic disorders (e.g., sarcoidosis, chronic hemolytic anemia) with unclear mechanisms.
Practical Example 1
Consider a 60-year-old patient with a history of mitral valve regurgitation scheduled for mitral valve repair. The patient has been diagnosed with Group 2 PH due to elevated left atrial pressures and secondary pulmonary hypertension. Preoperatively, the anesthesia provider must optimize the patient's volume status, manage pulmonary venous pressures, and plan for intraoperative monitoring that minimizes the risk of exacerbating PH and right heart failure.
| Group | Underlying cause | Mechanism or distinguishing point |
|---|---|---|
| 1 — Pulmonary arterial hypertension (PAH) | Idiopathic and heritable; connective tissue disease such as scleroderma, HIV infection, congenital heart disease, portal hypertension. | Endothelial dysfunction, vasoconstriction, and vascular remodeling raise pulmonary vascular resistance. |
| 2 — Left heart disease | Left ventricular systolic or diastolic dysfunction, mitral or aortic valve disease, left atrial hypertension. | The most common form; backward transmission of elevated left atrial pressure raises pulmonary venous pressure. |
| 3 — Lung disease and hypoxia | COPD, interstitial lung disease, sleep apnea, and other causes of chronic hypoxia. | Chronic hypoxia induces vasoconstriction and vascular remodeling, increasing pulmonary vascular resistance. |
| 4 — Chronic thromboembolic PH (CTEPH) | Unresolved thromboembolism in the pulmonary arteries. | Potentially curable with pulmonary thromboendarterectomy surgery or balloon pulmonary angioplasty. |
| 5 — Unclear multifactorial mechanisms | Systemic, metabolic, or hematologic disorders such as sarcoidosis and chronic hemolytic anemia. | Mechanisms remain unclear. |
