The apical pulse represents the direct pulsation of the heart’s apex against the chest wall. Understanding its location and assessment provides valuable information about the body’s circulatory system.
What is the Apical Pulse?
The apical pulse is the rhythmic beat felt or heard at the lowest, outermost part of the heart, known as the apex. This pulsation originates from the forceful contraction of the left ventricle, the heart’s main pumping chamber. Unlike peripheral pulses, such as those felt at the wrist (radial pulse) or neck (carotid pulse), the apical pulse offers a direct measure of ventricular activity.
It reflects the actual number of times the heart muscle contracts per minute, rather than the pressure wave transmitted through arteries. This direct measurement makes the apical pulse a valuable indicator of cardiac function, allowing for an accurate assessment of the heart’s rate and rhythm at its source.
Locating the Apical Pulse
The apical pulse is situated in the fifth intercostal space, the narrow gap between the fifth and sixth ribs. To pinpoint this location, one can start by identifying the sternal notch at the top of the breastbone and moving downward. The second rib is found just below the sternal angle, a prominent ridge where the manubrium meets the body of the sternum.
From the second rib, one can count downwards along the chest wall to locate the fifth intercostal space. Horizontally, it is found along the midclavicular line. This imaginary vertical line extends directly downward from the midpoint of the clavicle, or collarbone, on the left side of the chest.
The combination of the fifth intercostal space and the midclavicular line defines the standard anatomical position for the apical pulse in most adults. This point, often called the point of maximal impulse (PMI), is where the heart’s apex comes closest to the chest wall, allowing for consistent and accurate assessment of cardiac activity.
Why the Apical Pulse is Important
Assessing the apical pulse offers a direct and precise evaluation of heart function. Healthcare professionals often auscultate, or listen to, this pulse with a stethoscope to determine the heart rate, rhythm, and the strength of its contractions. This method provides direct insight into the heart’s electrical and mechanical activity, bypassing issues that might affect peripheral pulse readings.
The apical pulse is useful when peripheral pulses, such as the radial pulse at the wrist, are difficult to feel due to low blood pressure, vascular disease, or irregular heart rhythms. In such cases, it provides a reliable count of heartbeats. Observing any discrepancy between the apical pulse rate and a peripheral pulse rate, known as a pulse deficit, can indicate certain cardiac conditions.
A pulse deficit suggests that not all heart contractions are strong enough to produce a palpable peripheral pulse, often seen in conditions like atrial fibrillation. The apical pulse’s accuracy in reflecting true cardiac activity makes it a valuable measurement in various clinical scenarios.
Factors Affecting Apical Pulse Location
Several physiological and pathological conditions can influence the exact position of the apical pulse. During pregnancy, the enlarging uterus pushes the diaphragm upwards, which can elevate the heart and shift the apical pulse slightly higher and more laterally. Similarly, an enlarged heart, known as cardiomegaly, can cause the apex to extend further to the left and sometimes downward, moving the apical pulse from its typical location.
Certain lung diseases can alter the apical pulse’s position. Conditions like emphysema, which involves overinflated lungs, can depress the diaphragm and shift the heart downward. A pneumothorax, or collapsed lung, can displace mediastinal structures, including the heart, leading to a noticeable shift in the apical impulse. Even an individual’s body build, such as being very thin or having a broad chest, can influence the precise palpation point. These variations highlight why healthcare providers consider multiple factors when assessing heart sounds and pulses.