Skip to content
Scrollchart
Health Science Rich #cardiac-cycle#systole#diastole

Cardiac Cycle

Atrial systole, ventricular systole, ventricular diastole - pressures, volumes, valve events.

A free, animated cardiac cycle you can read here or embed on any website, from Scrollchart.

Cardiac Cycle

Cardiac Cycle (Wiggers Diagram)One heartbeat (800 ms): pressures, LV volume, and valve eventsmL13055LV Volume

Wiggers diagram across one heartbeat: aortic, ventricular, and atrial pressure curves; ventricular volume; ECG; heart sounds. Valve events (mitral close, aortic open/close) annotated.

Good for

  • Cardiology textbook supplements
  • Heart-failure patient education
  • Athletic-heart adaptation articles

Source & accuracy

This cardiac cycle is an editorial illustration built to represent the concept accurately. Where it shows figures, they are typical or representative values chosen to make the relationship clear, not a single underlying dataset. The diagram and its explainer are reviewed and maintained centrally, and updated over time as understanding improves.

The phases of one heartbeat

The cardiac cycle is the sequence of events in a single heartbeat, divided into systole (contraction) and diastole (relaxation). Atrial systole tops off ventricular filling with the so-called atrial kick. Ventricular systole follows: pressure rises during isovolumetric contraction until it exceeds aortic and pulmonary pressure, the semilunar valves open, and blood is ejected. Ventricular diastole then begins with isovolumetric relaxation, the semilunar valves close, and the ventricles refill as the AV valves open.

Valve events generate the heart sounds: closure of the AV valves produces S1 and closure of the semilunar valves produces S2.

Pressure and volume relationships

Plotting ventricular pressure against volume produces the pressure-volume loop, which encloses the stroke work of each beat. End-diastolic volume minus end-systolic volume gives stroke volume, and stroke volume divided by end-diastolic volume gives the ejection fraction, a common clinical measure. This is general physiology information and not a substitute for medical advice; symptoms should be assessed by a qualified clinician.

Embed this diagram

Add this animated cardiac cycle to your own site. Copy one line of HTML, or use the embed builder for theme and sizing options.

Reference

What this is
A free, embeddable, animated cardiac cycle for any website.
Who uses it
Medical educators, Biology educators, Patient-info sites, Health blogs.
How to embed
Copy one line of HTML. No signup. No watermark. Works in WordPress, Webflow, Ghost, Substack, plain HTML.
File size
iframe embed, ~80 KB gzipped (loads on demand, does not block your page paint).
License
Free forever. Editorial explainer text included; updated centrally over time.
URL
scrollchart.com/diagram/cardiac-cycle

Embed format options

Copy the universal HTML snippet, the WordPress shortcode, or an iframe fallback - see the WordPress plugin page for details. Any format keeps the same Core Web Vitals profile and the same explainer text.

Embed snippet 
<div data-scrollchart="cardiac-cycle" data-scrollchart-v="1"></div>
<script src="https://scrollchart.com/embed.js" async></script>

By embedding, you acknowledge the diagram and explainer text are served from scrollchart.com and may be updated from time to time to reflect new research or to link to relevant sources within the explainer.

Frequently asked questions

Where can I get a free animated "Cardiac Cycle" for my website?
Scrollchart provides "Cardiac Cycle" as a free, embeddable animated diagram you can add to any website with one line of HTML. No signup is required and there is no watermark. The diagram and its explainer text are served from scrollchart.com, so the embed stays current without any maintenance on your end.
How do I embed a cardiac cycle diagram in a health or wellness blog?
Copy the HTML snippet from the Scrollchart diagram page and paste it into any post or page in your CMS. It works in WordPress, Webflow, Ghost, Substack, and plain HTML without any plugin or account. The diagram renders as animated SVG directly in your page, so search engines can index the accompanying explainer text.
Related diagrams

Other health science explainers

See all health science →
Health Science Medium

ECG Waves: P-QRS-T

P (atrial depolarization), QRS (ventricular depolarization), T (ventricular repolarization).
Health Science Medium

Frank-Starling Curve

Stroke volume rises with end-diastolic volume up to a point; failing hearts shift the curve down.
Health Science Rich

Preload, Afterload, Contractility

Three independent levers determining stroke volume - mapped onto pressure-volume loops.