From the Guidelines
A palpable P2 (second heart sound) is typically seen in conditions associated with increased pressure in the pulmonary arteries, such as pulmonary hypertension, which can be caused by various factors including idiopathic pulmonary arterial hypertension (IPAH), congenital heart disease, or pulmonary veno-occlusive disease. This finding suggests increased pressure in the pulmonary arteries, causing a more forceful closure of the pulmonic valve that can be felt when placing a hand on the patient's chest. According to a study published in the European Respiratory Review 1, a 24-year-old female with suspected pulmonary hypertension presented with an accentuated second heart sound over the pulmonic valve, which was later confirmed to be due to pulmonary arterial hypertension (PAH) with a pre-capillary pulmonary artery pressure (Ppa) of 57 mmHg.
The palpable P2 occurs because the increased pressure in the pulmonary arteries causes the pulmonic valve to close more forcefully, creating a stronger vibration that can be felt through the chest wall. This finding is an important physical exam clue that should prompt further investigation for pulmonary hypertension or other conditions affecting right heart pressures. Other signs of increased pulmonary artery pressure include an early systolic ejection click, a midsystolic ejection murmur, a palpable left parasternal lift, a right ventricular S4 gallop, and a prominent jugular “a” wave suggesting high right ventricular filling pressure, as noted in a study published in Chest 1.
Pulmonary hypertension should be further evaluated with an echocardiogram and right heart catheterization to confirm the diagnosis and determine its severity. Treatment depends on the underlying cause but may include medications such as phosphodiesterase-5 inhibitors (e.g., sildenafil), endothelin receptor antagonists (e.g., bosentan), or prostacyclin analogues (e.g., epoprostenol). The use of noninvasive tests, such as electrocardiogram and Doppler echocardiography, can also aid in the detection of pulmonary hypertension, as noted in a study published in the American Journal of Respiratory and Critical Care Medicine 1.
Some key conditions associated with a palpable P2 include:
- Pulmonary hypertension
- Idiopathic pulmonary arterial hypertension (IPAH)
- Congenital heart disease
- Pulmonary veno-occlusive disease
- Atrial septal defects
- Patent ductus arteriosus
- Hypertrophic cardiomyopathy
It is essential to note that the presence of a palpable P2 should prompt further investigation to determine the underlying cause and to guide treatment.
From the Research
Conditions Associated with a Palpable P2
A palpable P2, or second heart sound, is associated with several conditions, including:
- Pulmonary hypertension (PH) 2, 3, 4, 5, 6
- Secondary pulmonary hypertension (SPHtn) due to abnormalities in structure or function of the heart or lung parenchyma 2
- Cor pulmonale associated with chronic obstructive pulmonary disease (COPD) 2
- Pulmonary vasculopathies 2
- Pulmonary embolus 2
- Interstitial lung disease 4
- Left heart disease, such as left ventricular failure and mitral valve disease 2, 6
- Lung disease, such as COPD and sleep apnea 2, 6
- Chronic thromboembolic PH 6
Diagnostic Tools
Several diagnostic tools can be used to evaluate a palpable P2, including:
- Echocardiography, which can estimate systolic pulmonary arterial pressure (SPAP) and evaluate right ventricular function 3
- Doppler echocardiography, which can noninvasively estimate SPAP and evaluate pulmonary vascular resistance (PVR) 3
- Phonocardiography, which can analyze the pulmonary component of the second heart sound 4
- Right heart catheterization, which is the gold standard for diagnosing PH 6
- Physical examination, which can include assessment of a loud P2, jugular venous distension, and tricuspid insufficiency murmur 5
Clinical Significance
A palpable P2 can be a significant finding in patients with PH, as it can indicate increased mortality risk 6. However, the physical examination is unreliable for determining the presence of PH, and further diagnostic testing is often necessary 5.