To auscultate an apical pulse, you place the diaphragm of a stethoscope over the point of maximal impulse (PMI) on the left side of the chest and count heartbeats for a full 60 seconds. The PMI sits at the fifth intercostal space along the left midclavicular line, which is roughly between the fifth and sixth ribs when counting down from the top. This method gives the most accurate heart rate reading available without electronic monitoring.
Finding the Point of Maximal Impulse
The PMI is the spot on the chest wall where you can feel or hear the heartbeat most strongly. To locate it, start at the top of the sternum (breastbone) and count down along the left side of the chest until you reach the space between the fifth and sixth ribs. Then move laterally to the midclavicular line, an imaginary vertical line running through the middle of the left collarbone. That intersection is your landmark.
In practice, this usually falls just below and slightly to the left of the left nipple in adults. Before placing the stethoscope, you can often feel a gentle tap or pulsation against your fingertips at this spot, which confirms you’re in the right location. If you can’t feel it, positioning the person on their left side shifts the heart closer to the chest wall and makes the impulse easier to detect.
In infants and young children, the heart sits slightly higher and more centrally in the chest. For children under seven, the PMI is typically found at the fourth intercostal space, just left of the midclavicular line. By about age seven, the heart settles into the adult position at the fifth intercostal space.
Positioning and Preparation
Have the person sit upright or lie at a 45-degree angle (semi-Fowler’s position). Either position works, but sitting upright tends to bring the heart closer to the anterior chest wall. The chest needs to be exposed enough to place the stethoscope directly on skin. Listening through clothing muffles heart sounds and introduces friction noise that can throw off your count.
Warm the stethoscope’s chest piece in your hands for a few seconds before placing it. A cold metal disc on bare skin causes an involuntary flinch and muscle tension, which can temporarily speed the heart rate and make the reading less accurate. Make sure the environment is as quiet as possible, since heart sounds are subtle and easily masked by ambient noise or conversation.
Which Stethoscope Side to Use
The flat diaphragm side of the stethoscope is the standard choice for counting an apical pulse. It picks up the higher-frequency components of normal heart sounds clearly enough for an accurate count.
The bell side (the smaller, concave cup) has a different purpose. When pressed lightly against the skin with just enough pressure to create an air seal, it amplifies low-frequency sounds. At the apex, this makes the first heart sound seem noticeably deeper and more booming compared to the second. Clinicians use the bell when they’re specifically listening for abnormal low-pitched sounds like gallops or murmur rumbles, but for a standard pulse count, the diaphragm is all you need.
Counting the Heartbeat
Once the stethoscope is positioned over the PMI, you’ll hear two sounds repeating in a cycle: a “lub” followed by a “dub.” The “lub” (called S1) comes from the heart’s intake valves snapping shut as the ventricles begin to contract. The “dub” (called S2) comes from the outflow valves closing after the ventricles finish pushing blood out. At the apex, S1 is normally louder than S2.
Each lub-dub pair equals one heartbeat. Count beats for a full 60 seconds while watching a clock or timer. A 30-second count multiplied by two is sometimes used as a shortcut, but the full minute is necessary whenever the rhythm feels irregular, the rate seems unusually fast or slow, or you’re assessing someone on heart medication. Irregular rhythms can have stretches of normal beats interrupted by pauses or extra beats, and a shorter counting window can miss those variations entirely.
Note both the rate (total beats in 60 seconds) and the rhythm (whether the spacing between beats is regular or irregular). If you notice occasional skipped or early beats, note how frequently they occur. This information matters more than the number alone.
Normal Resting Heart Rate by Age
What counts as a normal apical pulse depends heavily on age. Younger hearts beat faster at rest because they’re smaller and pump less blood per contraction.
- Newborns (birth to 4 weeks): 100 to 205 bpm
- Infants (1 month to 1 year): 100 to 180 bpm
- Toddlers (1 to 3 years): 98 to 140 bpm
- Preschool age (3 to 5 years): 80 to 120 bpm
- School age (5 to 12 years): 75 to 118 bpm
- Adolescents (13 to 17 years): 60 to 100 bpm
- Adults (18 and older): 60 to 100 bpm
These ranges apply when the person is awake and at rest. Rates drop during sleep and rise with activity, anxiety, fever, or pain.
Why Apical Pulse Matters
A radial pulse (taken at the wrist) is quicker and easier, but it doesn’t always tell the full story. Some heartbeats are too weak to generate a pulse wave that travels all the way to the wrist. This means the radial count can come in lower than the actual heart rate. The difference between the apical rate and the radial rate is called the pulse deficit, and it signals that the heart isn’t pumping effectively with every contraction.
Apical pulse assessment is the preferred method for infants and young children because their small wrist arteries make radial pulses difficult to palpate reliably. It’s also standard practice before giving medications that affect heart rate or rhythm. If the apical rate falls below a specific threshold (often 60 bpm in adults), certain cardiac medications are held because slowing the heart further could be dangerous.
Common Mistakes to Avoid
The most frequent error is placing the stethoscope too high or too far to the left. If you’re hearing heart sounds faintly or not at all, recount your rib spaces from the top. The first intercostal space sits just below the collarbone, and it’s easy to lose count in the middle ribs.
Pressing the stethoscope too hard is another common problem. Firm pressure is unnecessary with the diaphragm and actually counterproductive with the bell (heavy pressure on the bell stretches the skin taut, turning it into a makeshift diaphragm and filtering out the low-frequency sounds it’s designed to capture). A steady, moderate seal is all you need.
Finally, avoid rounding or estimating. If you lose count, start over rather than guessing. A rate that’s off by even five or six beats per minute can change clinical decisions, especially in pediatric patients or people on cardiac medications.