Terms related to heart function can be confusing, especially when discussing the apical pulse and the mitral valve. While both relate to heart activity and are often assessed in similar chest regions, they represent distinct aspects of cardiac function. This article clarifies the differences between the apical pulse and the mitral valve, explaining what each signifies and how they relate to the heart’s overall operation.
Understanding the Apical Pulse
The apical pulse, also known as the point of maximal impulse (PMI), is the physical beat or pulsation felt or heard at the lowest, outermost part of the heart. It reflects the rhythmic contraction of the left ventricle as it pushes blood out to the body. This impulse is felt where the heart’s apex comes closest to the chest wall.
For adults, the apical pulse is usually located at the fifth intercostal space, which is the space between the fifth and sixth ribs, along the left midclavicular line. This imaginary line runs vertically down from the middle of the collarbone. In young children, its location may be slightly higher, often at the fourth intercostal space. Healthcare professionals assess the apical pulse by either feeling the chest wall (palpation) or listening with a stethoscope (auscultation). This assessment provides a measure of heart rate and offers insights into the heart’s pumping action.
Understanding the Mitral Valve
The mitral valve is one of the heart’s four valves, directing blood flow. It is situated within the left side of the heart, between the left atrium and the left ventricle. This valve is also referred to as the bicuspid valve because it consists of two flaps.
The mitral valve regulates the flow of oxygen-rich blood. During the heart’s relaxation phase (diastole), the mitral valve opens to allow blood to move from the left atrium into the left ventricle. When the left ventricle contracts during systole, the mitral valve closes firmly. This closure prevents blood from flowing backward into the left atrium, ensuring efficient forward movement of blood into the aorta. The closure of the mitral valve, along with the tricuspid valve, generates the first heart sound, “lub” or S1.
Clarifying the Connection
The apical pulse and the mitral valve are distinct, yet often associated due to their anatomical proximity during assessment. The apical pulse is a physical manifestation, representing the beat of the heart’s left ventricle as it contracts against the chest wall. It is a palpable or audible sign of the heart’s mechanical activity.
In contrast, the mitral valve is an anatomical structure that directs blood flow. While the mitral valve does not produce a pulse, its closure contributes to the first heart sound (S1). This “lub” sound is heard most clearly with a stethoscope at or near the location where the apical pulse is felt. The connection is that the sound produced by the mitral valve’s action is best detected in the same region where the heart’s strongest physical impulse is observed.