Heart Health

Heart Murmurs Explained — Systolic and Diastolic Sounds, Causes, and How They're Diagnosed

Alila Medical Media 5:15 2020-01-01 views

This medical animation breaks down heart murmurs — what they sound like, when they occur, and what conditions cause them.

Heart symptoms and treatment decisions should be evaluated by a qualified clinician, especially when symptoms are new, severe, or worsening.

Overview

This medical animation breaks down heart murmurs — what they sound like, when they occur, and what conditions cause them.

Key Details

A healthy heartbeat produces two sounds: S1 ('lub') from AV valve closure after the atria pump blood into the ventricles, and S2 ('dub') from aortic and pulmonary valve closure after the ventricles eject blood. The interval between S1 and S2 is systole (ventricular contraction); the interval between S2 and the next S1 is diastole (ventricular relaxation and filling). Diastole is longer than systole, producing the familiar lub-dub rhythm. Heart sounds are listened to at four chest wall sites corresponding to blood flow through the aortic, pulmonic, tricuspid, and mitral valves — this is how similar defects in different valves are told apart.

Why It Matters

Heart murmurs are whooshing sounds from turbulent blood flow, diagnosed by three factors: timing in the cardiac cycle, changes in intensity over time, and the auscultation site where they're loudest. Systemic murmurs include mitral valve regurgitation — the valve doesn't close properly, blood surges back into the left atrium, producing a holosystolic murmur (constant intensity from S1 through systole) best heard at the apex radiating to the left axilla. Tricuspid regurgitation sounds similar but is loudest in the tricuspid area radiating up the left sternal border. Aortic stenosis — the valve doesn't open properly — produces a diamond-shaped crescendo-decrescendo murmur starting just after S1, often preceded by an ejection click, loudest in the aortic area radiating to the carotid arteries. Pulmonic stenosis has the same shape but doesn't radiate to the neck.

Key Takeaways

S1 ('lub') = AV valves closing after atria pump; S2 ('dub') = aortic/pulmonary valves closing after ventricles eject — the interval between is systole, the rest is diastole
Heart murmurs are diagnosed by three factors: timing in the cardiac cycle, intensity pattern over time, and which of the four auscultation sites they're loudest at
Mitral regurgitation produces a holosystolic (constant) murmur at the apex; aortic stenosis produces a diamond-shaped crescendo-decrescendo murmur in the aortic area radiating to the neck
Aortic regurgitation is a diastolic murmur best heard along the left sternal border (not the aortic area) because blood flows in reverse
Similar valve defects sound alike — location and radiation pattern are what distinguish which valve is affected

FAQ

What does this page explain?

It explains heart murmurs explained — systolic and diastolic sounds, causes, and how they're diagnosed in plain English, focusing on the main symptoms, mechanisms, or treatments described in the source content.

When should medical care be sought?

Urgent or severe heart-related symptoms should be assessed right away rather than managed only with online information.

What is the main takeaway?

The main takeaway is to understand the condition or emergency clearly and connect it to prompt evaluation, treatment, or prevention where appropriate.