A pulse is the rhythmic expansion of arteries as blood is pushed through them with each heartbeat. The apex pulse offers a direct assessment of heart activity. It differs from other pulse points by allowing direct listening to the heart’s contractions, providing a precise measure of cardiac function that reflects the heart’s actual movement.
Locating and Understanding the Apex Pulse
The apex pulse, also known as the apical pulse or point of maximal impulse (PMI), is found at the lowest and outermost point on the chest where the heart’s impulse can be felt. This location corresponds to the apex, or tip, of the left ventricle. In adults, this point is situated in the fifth intercostal space (between the fifth and sixth ribs) to the left of the sternum, along the midclavicular line.
Measuring the pulse at this location is significant due to its direct connection to the heart’s powerful left ventricle. When the left ventricle contracts, it pushes blood into the aorta, creating a palpable or audible impulse against the chest wall. This direct action provides a reliable measure of the actual heart rate and rhythm, unlike peripheral pulses which can be influenced by factors like arterial elasticity or blood flow. For children under seven, the apex is located slightly higher, in the fourth intercostal space.
When Apex Pulse Measurement is Used
Measuring the apex pulse is preferred when peripheral pulses, such as those felt at the wrist or neck, may not accurately assess heart activity. This includes individuals with irregular heart rhythms, like atrial fibrillation, where the peripheral pulse might be weaker or less frequent than the actual heartbeats. The apex pulse directly reflects each heart contraction, providing a reliable count in these cases.
This method is also used for infants and young children, as their peripheral pulses can be difficult to locate and accurately count due to their smaller size and faster heart rates. For individuals with obesity, where peripheral pulses may be challenging to palpate, the apex pulse offers a clearer and more accessible measurement. Healthcare providers also measure the apex pulse to monitor the effects of certain cardiac medications, such as digoxin, or as part of a comprehensive cardiovascular assessment.
How to Measure Apex Pulse
Measuring the apex pulse requires a stethoscope and a watch with a second hand. The individual should be positioned comfortably, either lying flat on their back or sitting upright. If lying down, rolling slightly to their left side can help bring the heart closer to the chest wall, making the pulse easier to locate.
To find the correct anatomical landmark, a healthcare professional will locate the sternal notch and move down to the angle of Louis, then along the left sternal border to the fifth intercostal space. This point, along the midclavicular line, pinpoints the heart’s apex. The diaphragm of the stethoscope is placed firmly on this spot, ensuring a complete seal. The “lub-dub” sounds of the heart are then counted for a full 60 seconds to ensure accuracy.
Interpreting Apex Pulse Readings
Interpreting apex pulse readings involves considering the rate, rhythm, and character of the heartbeat. For most adults, a normal resting apex pulse rate falls within the range of 60 to 100 beats per minute (bpm). Children have higher resting heart rates, with newborns ranging from 70 to 190 bpm, gradually decreasing with age. For example, a 1-year-old might have a normal range of 80-160 bpm, and a 5-year-old, 75-115 bpm.
A pulse rate faster than the normal range is referred to as tachycardia, while a rate slower than normal is called bradycardia. The regularity of the beats is also observed; a consistent, evenly spaced rhythm indicates regularity, while unevenly spaced beats suggest an irregular rhythm. Any significant deviation from typical rates or a noticeable irregularity can provide information about cardiac function, though further medical evaluation is necessary for a diagnosis.