A holosystolic murmur at the cardiac apex means which valve?

The cardiac apex sits at the left fifth intercostal space in the midclavicular line, and that spot is the mitral listening post. A holosystolic (pansystolic) murmur there that radiates to the axilla is mitral regurgitation. The common error is to map the apex to the tricuspid valve. Tricuspid is the left lower sternal border, one interspace up and toward the midline; the apex is mitral. Apex plus holosystolic plus radiation to the axilla equals mitral regurgitation.

How do you tell tricuspid regurgitation from mitral regurgitation at the bedside?

Both are holosystolic, but location and the breathing test separate them. Mitral regurgitation is loudest at the apex and radiates to the axilla. Tricuspid regurgitation is loudest at the left lower sternal border and gets louder with inspiration, which is the Carvallo sign. Inspiration increases venous return to the right heart, so it amplifies right-sided murmurs and leaves left-sided murmurs unchanged or softer. Louder on inspiration at the left lower sternal border equals tricuspid regurgitation.

Which systolic murmurs get louder with the Valsalva maneuver?

Valsalva strain decreases venous return and shrinks the left ventricular cavity. Almost every murmur gets softer because there is less blood to move. The two exceptions get louder: hypertrophic cardiomyopathy, because the smaller cavity brings the hypertrophied septum closer to the mitral leaflet and worsens the outflow obstruction, and mitral valve prolapse, where the click moves earlier and the murmur lengthens. If a systolic murmur intensifies with Valsalva or standing, think HOCM or MVP.

Why does aortic stenosis get softer with handgrip while mitral regurgitation gets louder?

Handgrip raises afterload by increasing systemic vascular resistance. In mitral regurgitation, the higher resistance pushes more blood backward through the leaky mitral valve, so the murmur gets louder. In aortic stenosis, the higher aortic pressure reduces the pressure gradient driving blood across the narrowed valve, so the murmur gets softer. The same maneuver moves the two in opposite directions, which is exactly how the board separates an apical regurgitant murmur from an ejection murmur radiating to the carotids.

What are the four cardiac listening posts and which murmur belongs to each?

Right upper sternal border at the right second interspace is the aortic post, where the crescendo-decrescendo ejection murmur of aortic stenosis radiates to the carotids. Left upper sternal border at the left second interspace is the pulmonic post, where pulmonic stenosis produces an ejection murmur louder with inspiration. Left lower sternal border around the fourth interspace is the tricuspid post, where tricuspid regurgitation is holosystolic and louder with inspiration and a VSD is harsh with a thrill. The apex at the left fifth interspace midclavicular line is the mitral post, where mitral regurgitation is holosystolic and radiates to the axilla.

Cardiology · Bedside Auscultation

Systolic Murmur Localizer

Where you put the stethoscope tells you which valve. Move two inches and the same noise means a different disease. The apex is not the tricuspid. Let us prove it.

The Miss · Identify Before You Learn

A 24-year-old man comes to the office because of fatigue that worsens after he plays soccer. His temperature is 37.0 C, blood pressure is 118/72 mmHg, and pulse is 76/min. On auscultation you work the standard order: right second interspace, left second interspace, left lower sternal border, then the apex. At the left fifth intercostal space in the midclavicular line you hear a coarse holosystolic murmur that radiates toward the left axilla and grows louder when he grips your hands hard. He runs the listening order in his head, lands on "holosystolic," and writes down tricuspid regurgitation.

Which of the following is the correct diagnosis?

Mitral regurgitation. The error was not the murmur. He heard it perfectly: holosystolic. The error was the map. The left fifth intercostal space in the midclavicular line is the cardiac apex, and the apex is the mitral listening post, not the tricuspid. A holosystolic murmur at the apex that radiates to the axilla and gets louder with handgrip is mitral regurgitation every time.

Tricuspid regurgitation is also holosystolic, but it lives one interspace up and toward the sternum at the left lower sternal border, and its tell is that it gets louder with inspiration (the Carvallo sign), not handgrip. He ran the order correctly and then dropped the last letter. The order is aortic, pulmonic, tricuspid, mitral. The apex is M, for mitral. Lock the map first, then the murmur means something.

From the Attending

Stop hunting for the fanciest diagnosis. Find the spot first. Apex, fifth space, midclavicular line, that is mitral. A pansystolic blow there heading for the armpit is mitral regurgitation, and handgrip drives it louder because you just raised the wall it has to push against. Tricuspid is a different address one rib up. Get the address right and the murmur tells you the disease. Get the address wrong and you will treat the wrong heart. Know your posts.

The Listening Posts

Tap a Post, Read the Valve

Four spots on the chest. Each one is a valve. Tap a listening post and the valve, the murmur it makes, the lesion, and the radiation all light up.

Listening post

Pick a post

Tap any glowing dot on the chest to load its valve, murmur, and lesion.

Valve

—

Systolic murmur

—

Lesion

—

Radiation

—

Best maneuver

—

Surface projection of the heart on the chest wall. The apex sits lowest and most to the patient's left: that is why it is the easiest post to misplace.

Surface anatomy of the heart projected onto the anterior chest wall, showing the four heart valves and their auscultation areas relative to the ribs and sternum — Surface projection of the valves on the chest wall. Sound travels with blood flow, so each valve is heard *downstream* of where it sits, not directly over it. Wikimedia Commons.

From the Attending

Why is the aortic valve heard up on the right when the valve itself is dead center? Because you hear a murmur where the blood is going, not where the valve sits. Aortic flow shoots up and to the right into the ascending aorta, so you listen at the right second space and follow it to the carotids. Mitral flow regurgitates back and to the left into the atrium, so you listen at the apex and follow it to the axilla. Radiation is just the murmur pointing at its own exit. Follow the blood.

Maneuver Simulator

Make It Louder, Name the Lesion

Location narrows it down. The bedside maneuver confirms it. Press a maneuver and watch every murmur grow or shrink. Two murmurs break the rules, and that is the whole point.

Mitral regurgapex, holosystolic

Tricuspid regurgLLSB, holosystolic

VSDLLSB, harsh + thrill

Aortic stenosisRUSB to carotids

Pulmonic stenosisLUSB, ejection

HOCMLLSB / apex, dynamic

Mitral prolapseapex, click + murmur

Resting state. Each bar is the baseline loudness of that murmur. Now pick a maneuver and watch which ones move.

From the Attending

Here is the one that wins points. Valsalva and standing drop blood return, so almost every murmur gets quieter. Two get louder instead: hypertrophic cardiomyopathy and mitral valve prolapse. Less blood means a smaller ventricle. A smaller ventricle lets the thick HOCM septum crowd the outflow, and it lets the floppy prolapse leaflet buckle sooner. So if a systolic murmur gets louder when the patient stands or strains, you are down to two answers. That distinction drives everything.

Right In, Left OutRight-sided murmurs (TR, PS) get louder with Inspiration. Left-sided murmurs get louder with Expiration. Breathe IN for the RIGHT heart. Stand for the CardiomyopathyStanding and Valsalva drop preload. Only HOCM and MVP get LOUDER. Everything else gets softer. Stand up to find the dynamic two. Grip Splits AS from MRHandgrip raises afterload. MR and VSD get LOUDER (more backward flow). AS and HOCM get SOFTER. One squeeze, opposite directions, instant separation.

The Field

Five Systolic Murmurs, One Tap Each

Same phase of the cycle, five different addresses. Tap a tab for the full profile: where, what, why, and which maneuver proves it.

Mitral Regurgitation

The apex holosystolic murmur. The one the case missed.

Where

Apex, left 5th ICS in the midclavicular line. Use the diaphragm.

Sound

Holosystolic (pansystolic) blowing murmur, even loudness from S1 to S2. Often a soft S1 and a wide split S2; an S3 if the leak is large.

Radiation

To the axilla (back-and-left, the direction the regurgitant jet travels into the left atrium).

Maneuvers

Louder: handgrip and squatting (raise afterload, more blood goes backward). Softer: Valsalva and standing.

Causes

Mitral valve prolapse (most common), prior rheumatic disease, papillary muscle rupture after inferior MI, dilated cardiomyopathy stretching the annulus, endocarditis.

Labeled diagram of the human heart showing the mitral valve between the left atrium and left ventricle, where regurgitant flow drives the apical holosystolic murmur — The mitral valve guards the left atrium. A systolic leak drives blood backward and the murmur points to the axilla. Wikimedia Commons.

Tricuspid Regurgitation · VSD

Two holosystolic murmurs that share the left lower sternal border.

Where

Left lower sternal border, around the 4th ICS. Both TR and a VSD live here, not at the apex.

TR sound

Holosystolic; the tell is louder with inspiration (the Carvallo signInspiration drops intrathoracic pressure and pulls more venous blood into the right heart. More flow across the leaky tricuspid valve makes a louder murmur. True for every right-sided murmur.). Look for a large jugular venous c-v wave, pulsatile liver, and edema.

VSD sound

Harsh holosystolic, often with a palpable thrill. Counterintuitive rule: a smaller defect is louder (more turbulence). Gets louder with handgrip (afterload raises the left-to-right shunt).

Causes

TR: pulmonary hypertension, right ventricular dilation, endocarditis in people who inject drugs (right-sided), carcinoid. VSD: congenital, or a septal rupture days after an anterior MI.

Anterior exterior view of the heart showing the right ventricle facing the sternum, which is why tricuspid regurgitation and a ventricular septal defect are heard at the left lower sternal border — The right ventricle is the chamber against the lower sternum, so its murmurs are loudest at the left lower sternal border. Wikimedia Commons.

Aortic Stenosis

The ejection murmur that points at the neck.

Where

Right upper sternal border, right 2nd ICS.

Sound

Crescendo-decrescendo ejection murmur (a diamond shape that rises then falls in mid-systole), harsh, with a soft single S2 and a slow-rising pulsus parvus et tardusA weak, late-peaking carotid upstroke. The narrowed valve takes time to push blood out, so the pulse is small and delayed. Classic for severe aortic stenosis. carotid.

Radiation

To the carotids (forward and up, the direction of ejected flow).

Maneuvers

Softer with handgrip (raised afterload shrinks the gradient): this is the single move that separates AS from MR, which gets louder. Louder with squatting.

Board triad

Syncope, Angina, Dyspnea (heart failure). Calcific in older adults; a bicuspid valve presents one to two decades earlier.

Gross pathology of a calcified, narrowed aortic valve producing the crescendo-decrescendo ejection murmur of aortic stenosis — A calcified, narrowed aortic valve. The tight orifice is what makes the murmur harsh and the carotid upstroke weak and late. Wikimedia Commons.

Pulmonic Stenosis

The right-sided ejection murmur up top on the left.

Where

Left upper sternal border, left 2nd ICS.

Sound

Crescendo-decrescendo ejection murmur, often with a widely split S2 and a systolic ejection click that, unlike most right-sided sounds, gets softer with inspiration.

Maneuvers

Louder with inspiration (right-sided rule). Radiates toward the left shoulder and back.

Causes

Usually congenital. Associations: Tetralogy of Fallot, Noonan syndrome, congenital rubella, carcinoid (right-sided).

Look-alike

A benign flow murmur or an atrial septal defect also sits here. The fixed split S2 points to an ASD; a click and a thrill point to true pulmonic stenosis.

HOCM · Mitral Valve Prolapse

The dynamic outliers. They get louder when blood return drops.

HOCM where

Left lower sternal border toward the apex. A harsh systolic murmur with no carotid radiation (separates it from AS).

HOCM tell

Louder with Valsalva and standing, softer with handgrip and squatting. Less blood means a smaller cavity, the septum crowds the outflow tract. Young athlete with syncope or sudden death.

MVP where

Apex: a mid-systolic click followed by a late systolic murmur.

MVP tell

Valsalva and standing move the click earlier and lengthen the murmur (smaller ventricle, leaflet buckles sooner). Squatting and handgrip move the click later. Young woman, often with a connective tissue trait.

Short axis section of the heart showing thickened left ventricular walls, the hypertrophy that produces the dynamic outflow murmur of hypertrophic cardiomyopathy — Thickened ventricular walls. The smaller the cavity gets, the worse the outflow obstruction, which is why HOCM is the murmur that loves Valsalva. Wikimedia Commons.

Self Test

Predict the Row, Then Reveal

The grid is blurred on purpose. For each lesion, say the location, radiation, and key maneuver out loud, then tap the row to check yourself. One row at a time.

Lesion	Where	Sound	Radiation	Key maneuver
Mitral regurgitation	Apex, 5th ICS midclavicular	Holosystolic blow	To the axilla	Louder with handgrip
Tricuspid regurgitation	Left lower sternal border	Holosystolic	Little; large JVP c-v wave	Louder with inspiration (Carvallo)
Ventricular septal defect	Left lower sternal border	Harsh holosystolic + thrill	Across the precordium	Louder with handgrip
Aortic stenosis	Right upper sternal border	Crescendo-decrescendo	To the carotids	Softer with handgrip
Pulmonic stenosis	Left upper sternal border	Crescendo-decrescendo	Left shoulder / back	Louder with inspiration
HOCM	LLSB toward apex	Harsh, no carotid radiation	None to carotids	Louder with Valsalva / standing
Mitral valve prolapse	Apex	Mid-systolic click + late murmur	Axilla if it leaks	Click earlier with Valsalva

Tap any blurred row to reveal just that row. Predict before you peek.

Where Points Are Lost

The Three Traps

Each one is a place the exam writer separates the people who localized from the people who pattern-matched.

Trap 1: The apex is mitral, not tricuspid

A holosystolic murmur is correctly heard, but the spot gets mislabeled. The apex (left 5th ICS, midclavicular) is the mitral post. Tricuspid is the left lower sternal border one interspace up and toward the sternum. If the murmur radiates to the axilla, it is mitral regurgitation. If it gets louder with inspiration, it is tricuspid. Same phase, different address.

Trap 2: A systolic murmur louder with Valsalva is not aortic stenosis

AS and HOCM can both be harsh systolic murmurs near the sternum. But AS gets softer with Valsalva and radiates to the carotids, while HOCM gets louder with Valsalva and standing and does not radiate to the carotids. A young athlete with syncope and a murmur that grows when he stands is HOCM until proven otherwise. Do not reach for AS.

Trap 3: Handgrip and Valsalva point opposite directions

Handgrip raises afterload and increases MR and VSD while decreasing AS and HOCM. Valsalva drops preload and increases only HOCM and MVP while softening the rest. Memorize the two odd ones (HOCM and MVP love a small ventricle) and everything else falls out of the rule that less flow equals a quieter murmur.

Decision Tool

Localize the Systolic Murmur

Tap through the discriminators. The tree lands on the lesion. Every leaf states the diagnosis and the one rule that seals it.

Step 1: What is the shape of the murmur across systole?

Flat, equal loudness from S1 to S2 (holosystolic)

Rises then falls in mid-systole (crescendo-decrescendo ejection)

Mid-systolic click, then a late systolic murmur

Holosystolic means a pressure gap that stays open the entire beat: mitral or tricuspid regurgitation, or a VSD. Location is the next fork. Move to Step 2.

Crescendo-decrescendo is blood forced through a tight outflow: aortic stenosis, pulmonic stenosis, or dynamic HOCM. Move to Step 3.

MITRAL VALVE PROLAPSE (MVP). A mid-systolic click at the apex followed by a late systolic murmur is the MVP signature. The click moves EARLIER toward S1 with standing and Valsalva (smaller ventricle, leaflet buckles sooner) and LATER with squatting and handgrip. Rule: click that migrates earlier on standing = MVP.

The Tracing

Where Systole Lives

Systolic means between S1 and S2, while the ventricle ejects. Holosystolic fills that whole gap; an ejection murmur peaks in the middle of it. See it on the phonocardiogram and the cardiac cycle.

Phonocardiograms comparing normal and abnormal heart sounds, showing where systolic and diastolic murmurs fall relative to S1 and S2 — Systolic murmurs fall between S1 and S2. A holosystolic murmur (MR, TR, VSD) fills the whole interval; an ejection murmur (AS, PS) peaks in mid-systole. Wikimedia Commons.

Wiggers diagram of the cardiac cycle showing systole between S1 and S2 when ventricular pressure exceeds atrial and arterial pressure — The cardiac cycle. Systole runs from S1 to S2. Every murmur on this page lives in that window, which is why location and maneuver, not timing alone, name the lesion. Wikimedia Commons.

Walk It

Derive It, Then Prove It

First rebuild the localization logic one beat at a time. Then take a stack of board-style cases, one at a time, reshuffled every run.

Tap each beat. Build the framework the way you would talk yourself through it at the bedside.

Why does location come before everything else?

Because timing alone cannot separate the systolic murmurs: they all live between S1 and S2. Location is the first hard fork. The apex is mitral, the left lower sternal border is tricuspid and VSD, the right upper sternal border is aortic, the left upper sternal border is pulmonic. Fix the post first; only then does the sound mean something.

Why does radiation point to a specific place?

A murmur radiates in the direction its blood is moving. Aortic stenosis ejects forward and up the aorta, so it points to the carotids. Mitral regurgitation drives backward into the left atrium, which sits behind and to the left, so it points to the axilla. Radiation is the murmur showing you its exit.

Why does inspiration single out the right heart?

Breathing in lowers intrathoracic pressure and pulls more venous blood into the right atrium and ventricle. More flow across a right-sided lesion makes a louder murmur, so tricuspid regurgitation and pulmonic stenosis swell on inspiration. Left-sided murmurs do not. Louder on inspiration equals right-sided: that is the Carvallo sign.

Why do HOCM and MVP get louder when blood return drops?

Valsalva and standing shrink the left ventricle. A smaller cavity lets the thick HOCM septum crowd the outflow tract, worsening the obstruction, and it lets the floppy prolapse leaflet buckle sooner, moving the click earlier. Every other murmur gets quieter with less flow. The two that love a small ventricle are HOCM and MVP.

Put it together: what is the localizer in one line?

Find the post, follow the radiation, then run one maneuver to confirm. Apex plus axilla plus louder-with-handgrip is mitral regurgitation. Right upper sternal border plus carotids plus softer-with-handgrip is aortic stenosis. Louder-with-Valsalva, no carotid radiation, is HOCM. Location, radiation, maneuver. Every time.

Board-style cases, one at a time, reshuffled every run. Cross out the wrong choices first (right-click on desktop or long-press on mobile), then read the explanation for every option.

Rapid Fire

Localize on the Clock

Short board-style items pulled from a larger pool, reshuffled each run. Right-click or long-press to cross out, double-tap to highlight.

Lock It In

The Localizer in One Breath

Apex to the axilla is mitral regurgitation. Left lower sternal border louder on inspiration is tricuspid. Right upper sternal border to the carotids is aortic stenosis. Louder with Valsalva, no carotids, is HOCM. Location, radiation, maneuver.

From the Attending

You will never auscultate a label that says "mitral." You get a spot, a shape, a radiation, and one maneuver. That is enough. Put the bell where the apex actually is, follow the sound to the armpit, squeeze a hand, and the diagnosis writes itself. The student in our case heard the murmur perfectly and still missed it because he never fixed the address. Localize first. The heart will tell you the rest.

Medically reviewed by Fatima Ali, DO and Kaitlyn Cocuzzo, MD · Last reviewed June 2026

Sources: Bates' Guide to Physical Examination and History Taking · Harrison's Principles of Internal Medicine · Braunwald's Heart Disease · Gray's Anatomy.

Bone Wizardry is an independent educational resource for visual learning in the medical sciences. It is not affiliated with, endorsed by, or sponsored by any licensing or examination board, contains no real or recalled examination questions, and does not guarantee any educational or examination outcome.