Pulmonary Hypertension for PA
Pulmonary Hypertension for the Physician Assistant Licensing Exam
Definition and Classification
- Pulmonary Hypertension (PH):
- Defined as mean pulmonary artery pressure (mPAP) ≥ 20 mmHg at rest, measured by right heart catheterization (RHC).
- WHO Classification:
- PH is divided into 5 groups:
- Group 1: Pulmonary Arterial Hypertension (PAH): Includes idiopathic, heritable, or associated with diseases like connective tissue disorders.
- Group 2: PH due to left heart disease: Includes heart failure and valvular diseases.
- Group 3: PH due to lung diseases or hypoxia: Includes COPD, interstitial lung disease (ILD), and sleep apnea.
- Group 4: Chronic thromboembolic pulmonary hypertension (CTEPH): Caused by unresolved pulmonary embolism.
- Group 5: Multifactorial causes: Includes sarcoidosis and hematologic disorders.
Pathophysiology
- Pulmonary Vascular Resistance (PVR):
- PH is caused by vasoconstriction, vascular remodeling, and thrombosis, increasing PVR and raising pulmonary artery pressure.
- Right Ventricular Hypertrophy:
- The right ventricle compensates for the increased pressure by hypertrophying, leading to right heart failure (cor pulmonale) if untreated.
- Hypoxic Vasoconstriction:
- Chronic hypoxia, as seen in Group 3 PH, triggers vasoconstriction, increasing pulmonary pressures.
Clinical Features
- Symptoms:
- Dyspnea on exertion: Most common presenting symptom.
- Fatigue, syncope, and chest pain in advanced disease.
- Peripheral edema, ascites, and jugular venous distention (JVD) indicate right heart failure.
- Physical Exam:
- Loud P2 (accentuated second heart sound) and right ventricular heave.
Diagnosis
- Echocardiography:
- The first-line screening test to estimate pulmonary pressures and assess right ventricular function.
- Right Heart Catheterization (RHC):
- The gold standard for diagnosis, confirming elevated mPAP and PVR.
- Pulmonary Function Tests (PFTs):
- Used to assess lung disease, especially in Group 3 PH.
- V/Q Scan:
- Essential for diagnosing CTEPH by identifying ventilation-perfusion mismatch.
Management
- Oxygen Therapy:
- Used in Group 3 PH to treat hypoxia.
- Diuretics:
- Help manage right heart failure symptoms like edema and ascites.
- Endothelin Receptor Antagonists (ERAs):
- Bosentan and ambrisentan are used in Group 1 PAH to reduce pulmonary vasoconstriction.
- Phosphodiesterase-5 Inhibitors:
- Sildenafil promotes vasodilation and improves exercise capacity.
- Pulmonary Endarterectomy:
- Surgical removal of chronic thromboembolic material in CTEPH.
Key Points
- Pulmonary hypertension is defined as mPAP ≥ 20 mmHg, classified into five groups based on etiology.
- Common symptoms include dyspnea on exertion, fatigue, and right heart failure (edema, ascites).
- Diagnosis is confirmed with right heart catheterization, though echocardiography is often the first step.
- Management includes oxygen therapy, diuretics, and group-specific treatments like endothelin receptor antagonists for Group 1 PAH.
- Surgical intervention like pulmonary endarterectomy is used in CTEPH.