Auscultation is a fundamental medical practice involving listening to the internal sounds of the body, usually with a stethoscope. When applied to the heart, this technique helps health professionals evaluate the function of the four heart valves and blood flow through the cardiac chambers. Listening at specific points on the chest wall, known as auscultation sites, allows for the clearest detection of sounds produced by each individual valve. These locations do not correspond exactly to the underlying anatomical position of the valves themselves, but rather to where the sound is best transmitted to the chest surface.
Locating the Pulmonic Auscultation Site
The pulmonic auscultation site is located on the chest wall, or precordium, where the vibrations from the valve’s closure are projected most clearly. To find this spot, one first locates the sternal angle (Angle of Louis), a slight horizontal ridge where the manubrium joins the sternum. This ridge corresponds to the level of the second pair of ribs.
The space immediately below the second rib is the second intercostal space (ICS). The pulmonic area is situated at the second intercostal space, directly to the left of the sternal border. The sound of the pulmonic valve closing is best heard here because the pulmonary artery, which carries blood from the right ventricle, lies close to this point. This location is part of the “base” of the heart, referring to the superior aspect of the organ.
Identifying Normal and Abnormal Pulmonic Sounds
The primary sound heard at the pulmonic area is the second heart sound (S2), which marks the end of systole (the heart’s contraction phase). S2 is created by the near-simultaneous closure of the aortic valve (A2) and the pulmonic valve (P2). The component unique to this area is P2, the closure of the pulmonic valve.
The most characteristic finding here is the physiological splitting of S2. During normal inspiration, decreased chest pressure allows more blood into the right side of the heart. This increased volume slightly delays the closure of P2 relative to A2, causing S2 to briefly split into two distinct components. During expiration, the two valve closures become nearly synchronous again, and the split disappears.
Abnormal findings include pathological splitting, where A2 and P2 are separated in a non-physiological manner. Fixed splitting means the split remains wide and does not change with breathing, often suggesting an atrial septal defect. Paradoxical splitting occurs when the split is heard during expiration but disappears on inspiration, associated with conditions that delay the left side of the heart, such as a left bundle branch block.
Other abnormal sounds involve murmurs, which are sustained turbulent flow sounds. These can be caused by pulmonic stenosis (a narrowing of the valve) or pulmonic regurgitation (a leaky valve). An unusually loud P2 component can also indicate increased pressure in the pulmonary circulation (pulmonary hypertension).
Contextualizing the Four Primary Heart Areas
The pulmonic site is one of four primary areas used for cardiac auscultation, each named for the valve whose sound is best transmitted there. These locations collectively map the precordium:
- The Aortic Area is located at the second intercostal space, on the right side of the sternal border. Both the aortic and pulmonic areas form the “base” of the heart, where the S2 sound is loudest.
- The Tricuspid Area is typically found near the lower left sternal border, often around the fourth or fifth intercostal space. This is where sounds from the tricuspid valve (between the right atrium and right ventricle) are best heard.
- The Mitral Area, also known as the apex, is located at the fifth intercostal space in line with the mid-clavicular line. This site is the furthest point from the sternum and is where the sounds of the mitral valve (between the left atrium and left ventricle) are loudest.
Utilizing these four distinct areas allows a clinician to isolate and evaluate each valve in the cardiac cycle.
Techniques for Optimizing Pulmonic Auscultation
Clinicians employ specific techniques to optimize pulmonic auscultation. The diaphragm of the stethoscope is generally used here because the S2 sound (A2 and P2 components) is relatively high-pitched. The diaphragm filters out lower-frequency sounds, which helps accentuate these vibrations.
Patient positioning can also enhance audibility. Auscultating with the patient sitting upright and slightly leaning forward can sometimes bring the heart closer to the chest wall. The most important technique involves specific breathing instructions: the patient is asked to take a deep breath and hold it briefly. Listening during inspiration is done specifically to accentuate the physiological splitting of S2. This maneuver helps confirm the normal function of the pulmonic valve and differentiate physiological splitting from pathological variations.