Measuring a person’s pulse is a fundamental practice in health assessment, providing a quick indication of heart function. Peripheral pulse sites, such as the wrist or neck, measure the pressure wave of blood moving through the arteries. The apical pulse offers a unique and direct perspective into the mechanical activity of the heart itself. Healthcare providers use this direct assessment when they need the most reliable data on the heart’s rhythm and rate.
Defining the Apical Pulse and its Location
The apical pulse represents the actual physical contraction of the heart, specifically the left ventricle, the heart’s main pumping chamber. It is not the pressure wave transmitted through peripheral arteries. Instead, it is the sound and impulse generated at the point where the heart comes closest to the chest wall, often called the Point of Maximal Impulse (PMI).
To locate this point in an adult, a healthcare provider places a stethoscope over the chest at the fifth intercostal space, between the fifth and sixth ribs. This site is positioned along the midclavicular line, an imaginary vertical line extending downward from the middle of the collarbone. Listening directly over the apex, or tip, of the heart provides a direct auditory assessment of the heart valves opening and closing.
Purpose of Initial Assessment: The Measure of True Cardiac Function
The primary purpose of initially assessing an apical pulse is to obtain the most accurate measure of the heart’s rate and rhythm. Peripheral pulses, such as the radial pulse, can be diminished, delayed, or absent due to factors outside the heart. By listening directly to the apical pulse, the provider bypasses the entire vascular system to count the exact number of ventricular contractions per minute.
This direct measurement accurately reflects the actual rate of the heart’s mechanical activity. If the heart’s contraction is too weak or too rapid, the resulting pressure wave may not be strong enough to travel to the wrist. This leads to an artificially low reading at a peripheral site, making the apical pulse the most truthful indicator of the heart’s output.
Patient Populations and Conditions Requiring Apical Assessment
The apical pulse is the preferred initial assessment in several clinical scenarios where peripheral pulses are unreliable or difficult to obtain.
- Infants and young children: The small size and rapid heart rate make an accurate radial pulse count challenging, requiring the more direct apical measurement.
- Cardiac arrhythmias: It is used for patients with known or suspected irregular heart rhythms where the rate may fluctuate rapidly.
- Medication administration: The apical pulse is assessed before administering certain cardiac medications, such as digitalis, where a precise count is necessary to ensure the drug is administered safely and effectively.
- Compromised circulation: In patients suffering from shock or severe peripheral vascular disease, decreased blood flow can make peripheral pulses faint or non-palpable.
Using the Apical Pulse to Identify a Pulse Deficit
A significant diagnostic application of the apical pulse is identifying a pulse deficit. This deficit is determined by simultaneously comparing the apical pulse rate with a peripheral pulse rate, usually the radial pulse, over one full minute. This comparison requires two healthcare providers working in coordination.
A pulse deficit is recorded when the radial pulse count is lower than the apical pulse count. This difference indicates that the heart is contracting, but some contractions are too weak to generate a pulse wave strong enough to be felt peripherally. This phenomenon is often seen in conditions like atrial fibrillation or premature ventricular contractions, where the heart rhythm is disorganized.