PMI stands for point of maximal impulse, the spot on the chest wall where you can feel the strongest pulsation of the heart beating. It is also called the apical impulse because it is produced by the apex, or tip, of the heart tapping against the inside of the chest with each contraction. In a healthy adult, the PMI is located at the fifth intercostal space (the gap between the fifth and sixth ribs) near the midclavicular line, which is the imaginary vertical line that drops straight down from the middle of the collarbone.
Why PMI Matters in Nursing Assessment
The PMI is a key landmark during a cardiovascular assessment. Its location, size, and quality give you a quick, noninvasive snapshot of how the heart is sitting in the chest and whether it may be enlarged. Because it requires no equipment beyond your hands, it is one of the first things evaluated during a cardiac physical exam, alongside auscultation with a stethoscope.
The PMI is also the ideal spot for listening to the apical heart rate, which is the most accurate way to count heart rate in patients with irregular rhythms. When you place a stethoscope at the PMI, you are directly over the mitral valve area, where the sounds of the left ventricle closing are loudest.
How to Locate and Palpate the PMI
Start with your patient lying flat on their back (supine). Place the pads of your fingers, not just the tips, lightly over the left side of the chest at the fifth intercostal space, roughly in line with the midpoint of the collarbone. You are feeling for a gentle, brief tap against your fingers that occurs once per heartbeat.
Here’s the reality: the apical impulse is palpable in fewer than half of normal adults when they are lying on their back. If you cannot feel it, ask the patient to roll partially onto their left side into what is called the left lateral decubitus position. This shifts the heart closer to the chest wall and makes the impulse much easier to detect. It is important to know, however, that this position also displaces the PMI slightly to the left, so do not interpret a laterally shifted impulse in this position as abnormal.
Normal Findings
A normal PMI feels like a gentle tap. It is brief, lasting only through the first part of the heartbeat, and covers a small area of about 1 to 2 square centimeters. You should feel one smooth outward pulsation per beat. A typical charting entry for a normal finding looks something like: “Gentle tap of apical impulse, short duration, one smooth pulsation, 1–2 cm² at apex.”
It is also perfectly normal to not feel an apical impulse at all, particularly in patients with a thicker chest wall or those who are obese. If you have repositioned the patient to the left lateral position and still cannot detect it, that finding is documented rather than treated as a concern on its own.
What a Displaced or Abnormal PMI Suggests
The location, size, and character of the PMI can change when the heart is under stress or structurally altered. A PMI that has shifted to the left of the midclavicular line, or downward below the fifth intercostal space, suggests the left ventricle has enlarged. This is seen in conditions like long-standing high blood pressure, heart valve disease, or heart failure, all of which force the left ventricle to work harder and grow bigger over time. An impulse that feels spread out over a wider area than the usual 1 to 2 square centimeters points in the same direction.
Beyond displacement, there are three abnormal sensations to watch for during palpation of the chest wall:
- Heave or lift: A sustained, forceful pushing sensation felt under the sternum or along the left side of the sternum. This suggests the right ventricle is significantly enlarged and is working harder than normal to pump blood.
- Thrill: A vibrating or buzzing feeling under your fingertips, similar to what you would feel if you placed your hand on a purring cat. A thrill indicates turbulent blood flow and typically corresponds to a loud heart murmur.
None of these findings, heaves, lifts, or thrills, should be present on a normal exam. A standard documentation note for expected findings reads: “No lifts, heaves, or thrills identified on inspection or palpation.”
Positioning and Patient Factors That Affect PMI
Body position matters. The supine position is preferred for an accurate PMI assessment because lying on the left side pushes the heart against the lateral chest wall and can distort findings. Always assess location with the patient on their back first, then use the left lateral position only to confirm presence if you could not feel anything initially.
Body habitus plays a significant role as well. In patients who are very muscular or have a larger body frame, the impulse may be dampened or undetectable. In very thin patients, the impulse is often easy to see as well as feel. Conditions that push the heart out of its normal position, such as a collapsed lung, a large amount of fluid around the heart, or severe scoliosis, can also shift the PMI without any change in heart size itself.
How to Document PMI Findings
When charting a PMI assessment, record four things: location (intercostal space and relation to the midclavicular line), size (in centimeters), amplitude (gentle tap versus forceful or sustained), and duration (brief or prolonged). If any abnormal pulsations such as heaves or thrills are present, note their location and character. If no impulse is palpable despite repositioning, document that clearly. A complete note gives the next clinician a reliable baseline to compare against future exams, which is especially valuable for patients being monitored for heart failure progression or valve disease.