Wiggers Diagram Generator

What is a Wiggers diagram?

A Wiggers diagram is the standard graph of the cardiac cycle: one heartbeat drawn as a stack of traces that share a single horizontal time axis. In its classic form the top panel holds three pressures in mmHg — aortic pressure, left ventricular pressure, and left atrial pressure — and below it come left ventricular volume in mL, the electrocardiogram, and a phonocardiogram of the heart sounds. Because the traces share one clock, any vertical line drawn through the diagram shows what every one of them is doing at the same instant, which is what makes the figure so powerful for teaching and so easy to get wrong.

The figure is named after Carl J. Wiggers, the American physiologist who recorded pressures in the heart chambers and great arteries with unusual precision in the early twentieth century and laid them out against one another on a common time base. Modern textbook versions, including the one in Guyton and Hall, are idealised redrawings of that layout. The values are those of a resting adult at about 75 beats per minute, so one cycle takes about 0.8 seconds.

Wiggers diagram labeled: the traces and what to mark

• Time axis: one shared x axis in seconds, about 0 to 0.8 s for one beat at 75 beats per minute.
• Pressure panel: aortic pressure swinging between about 120 and 80 mmHg, left ventricular pressure from near 0 up to about 120 mmHg, and left atrial pressure staying low, about 0 to 15 mmHg.
• Left ventricular volume: from an end-diastolic volume (EDV) of about 130 mL down to an end-systolic volume (ESV) of about 50 to 60 mL and back.
• ECG: the P wave, the QRS complex, and the T wave, each just ahead of the mechanical event it triggers.
• Heart sounds: S1 at the start of ventricular systole and S2 at its end; S3 and S4 only when they are the point of the figure.
• Valve events: four vertical lines through every row — mitral valve closes, aortic valve opens, aortic valve closes, mitral valve opens.
• Phases: named between the lines, either the seven phases of physiology textbooks or the four of introductory courses.
• Landmarks: the dicrotic notch on the aortic trace, and the a, c, and v waves on the atrial trace.

The four valve events: where the pressure lines cross

Heart valves are passive. They open and close only because the pressure on one side overtakes the pressure on the other, which is why every valve event on a Wiggers diagram sits exactly where two pressure traces cross. Learn the four crossings and the rest of the diagram follows from them.

First, the mitral valve closes when left ventricular pressure rises above left atrial pressure, a few hundredths of a second after the QRS complex begins. This is the first heart sound, S1, and the start of isovolumetric contraction. Second, the aortic valve opens when left ventricular pressure rises above aortic pressure, at about 80 mmHg — the diastolic pressure in the aorta — and ejection begins. Third, the aortic valve closes when the relaxing ventricle’s pressure falls back below aortic pressure, at about 100 mmHg; the brief backflow that snaps it shut makes the dicrotic notch on the aortic trace and the second heart sound, S2. Fourth, the mitral valve opens when left ventricular pressure falls below left atrial pressure, and filling begins. At 75 beats per minute these four lines fall at roughly 0.20, 0.25, 0.47, and 0.55 seconds after the start of the P wave.

Wiggers diagram explained: the cardiac cycle phase by phase

Atrial systole. The P wave spreads depolarisation through the atria, which contract and push the last 20 to 30 percent of the ventricle’s filling through the open mitral valve. The atrial trace shows the a wave, ventricular pressure and volume rise slightly, and the ventricle reaches its end-diastolic volume of about 130 mL. Isovolumetric contraction. The QRS complex triggers ventricular contraction; as soon as ventricular pressure exceeds atrial pressure the mitral valve closes with S1. With the aortic valve still shut, pressure climbs steeply from under 10 mmHg to about 80 mmHg while volume stays exactly the same, for about 0.05 seconds. The closing mitral valve bulging back into the atrium gives the small c wave.

Rapid and reduced ejection. When ventricular pressure passes aortic pressure the aortic valve opens. Blood leaves quickly at first, so volume drops steeply while both pressures rise together to a peak of about 120 mmHg; later the flow slows, the pressures fall, and the T wave of ventricular repolarisation appears. By the end, the ventricle holds its end-systolic volume of about 50 to 60 mL, and the stroke volume — about 70 mL — has gone into the aorta. Meanwhile the atrium is refilling from the pulmonary veins against the closed mitral valve, so atrial pressure climbs into the v wave.

Isovolumetric relaxation. As the ventricle relaxes its pressure falls below aortic pressure, the aortic valve closes with S2, and the aortic trace shows the dicrotic notch. Both valves are shut again, so ventricular pressure plunges at constant volume for about 0.08 seconds. Rapid filling and diastasis. When ventricular pressure drops below atrial pressure the mitral valve opens, the blood stored in the atrium rushes in, volume rises steeply, and the v wave collapses into the y descent; this is where an S3 would be heard. Filling then slows to a trickle until the next P wave starts the cycle again. Ventricular systole has taken about 0.27 seconds and diastole about 0.53 seconds, which matches OpenStax’s figures of roughly 100 ms atrial systole, 270 ms ventricular systole, and 430 ms of ventricular diastole after it.

Reading the volume trace: EDV, ESV, and stroke volume

The left ventricular volume trace is the quickest way to check whether a Wiggers diagram is honest. It has two perfectly flat stretches, one for each isovolumetric phase, because blood can only move when a valve is open. Between those stretches it tells the story of the beat: a steep fall in rapid ejection and a gentler one in reduced ejection, down to the end-systolic volume; a steep rise in rapid filling, a slow creep through diastasis, and a final small step from atrial systole up to the end-diastolic volume. The difference between the top and bottom plateaus is the stroke volume, about 70 mL at rest, and dividing it by the end-diastolic volume gives the ejection fraction, normally about 55 to 60 percent. If the plateaus slope, or the curve starts falling before the aortic valve opens, the diagram is wrong — unless it is deliberately showing a leaking valve.

Wiggers diagram heart sounds and ECG: lining up the electrical and acoustic events

The ECG row records electrical activity, and electrical events always come just before the mechanical ones they cause. The P wave precedes atrial contraction and the a wave. The QRS complex precedes the rise in ventricular pressure and the closure of the mitral valve. The T wave, ventricular repolarisation, sits in the later part of ejection and ends at roughly the moment the aortic valve closes. A diagram that draws the QRS after ventricular pressure has already risen, or the T wave after S2, has the order backwards.

The heart sounds row is simpler still, because in a healthy heart the sounds come only from valves closing. S1, the “lub”, is the mitral and tricuspid valves closing and sits on the first valve line. S2, the “dub”, is the aortic and pulmonary valves closing and sits on the third line, at the dicrotic notch. Valve openings are silent. Two extra sounds are added only when they are the subject of the figure: S3 early in diastole, during rapid filling, and S4 late in diastole, during atrial systole just before S1.

The a, c, and v waves of atrial pressure

The atrial pressure trace is small but busy, and the same pattern appears in the jugular venous pulse that clinicians watch in the neck. The a wave is atrial contraction, following the P wave. The c wave is a small bump just after S1, as the closing atrioventricular valve bulges back into the atrium at the start of ventricular contraction. The x descent follows as the atrium relaxes and the valve ring is pulled down during ejection. The v wave builds slowly while venous blood fills the atrium against the closed valve; it keeps rising until the valve opens and then falls away — the y descent — as the stored blood empties into the ventricle. On a Wiggers diagram, the v wave peak should sit on the fourth valve line, where the mitral valve opens, never back at the end of ejection.

The right-heart Wiggers diagram

The right side of the heart runs the same cycle on the same clock, so a right-heart Wiggers diagram has the same shape with much smaller numbers. Right ventricular pressure peaks at about 25 mmHg, pulmonary artery pressure runs about 25 over 8 to 10 mmHg, and right atrial pressure sits around 0 to 5 mmHg. The valves are the tricuspid and the pulmonary instead of the mitral and the aortic. The two sides are not perfectly simultaneous: the pulmonary valve closes slightly after the aortic valve, so S2 has two parts, A2 then P2, and the gap widens on inspiration — the physiological splitting of the second heart sound.

Wiggers diagram vs pressure–volume loop

A pressure–volume loop takes two traces from the Wiggers diagram — left ventricular pressure and left ventricular volume — and plots them against each other instead of against time. One beat becomes a closed loop that runs anticlockwise. The bottom-right corner is mitral valve closure at the end-diastolic volume; the vertical right side is isovolumetric contraction; the top-right corner is aortic valve opening; the curved top is ejection; the top-left corner is aortic valve closure at the end-systolic volume; the vertical left side is isovolumetric relaxation; the bottom-left corner is mitral valve opening; and the bottom edge is filling. The loop’s width is the stroke volume and its area is the stroke work. The two figures answer different questions: the Wiggers diagram shows when things happen, and the loop shows how preload, afterload, and contractility change the work the ventricle does.

How valve disease changes the traces

Valve disease shows up on a Wiggers diagram as broken versions of the normal rules, which is why the figure is used in medical teaching. In aortic stenosis, left ventricular pressure rises far above aortic pressure during ejection, because the narrowed valve needs a pressure gradient to force blood through. In mitral stenosis, left atrial pressure stays well above ventricular pressure all through diastole. In mitral regurgitation, blood leaks back into the atrium during systole, producing a tall v wave, and in aortic regurgitation aortic pressure falls further in diastole as blood leaks back into the ventricle. The generator draws these only when your request names the condition; a standard Wiggers diagram is always a healthy resting heart.

How to draw a Wiggers diagram by hand

Drawing the Wiggers diagram yourself is the fastest way to learn it, and the order matters. Start with the time axis, 0 to 0.8 seconds, and stack empty rows above it for pressure, volume, the ECG, and the heart sounds. Draw the ECG first, because everything else hangs off it: a P wave near the start, a QRS complex at about 0.16 seconds, and a T wave ending at about 0.47 seconds. Next draw the four valve lines straight down through every row at about 0.20, 0.25, 0.47, and 0.55 seconds. Now add the pressures so that they cross on those lines: aortic pressure decaying to 80 mmHg at the second line, rising to 120, and notching at the third; ventricular pressure low in diastole, climbing between the first and second lines, peaking with the aorta, and plunging between the third and fourth; atrial pressure low with its a, c, and v bumps. Finish with the volume trace, flat between lines one and two and between lines three and four, and put S1 on the first line and S2 on the third.

Checking the alignment of a Wiggers diagram

• Is every valve line vertical, and does it cross every row from the top panel to the time axis?
• Does each line pass exactly through its pressure crossover — LV above LA, LV above aorta, LV below aorta, LV below LA?
• Is the volume trace flat between the first two lines and between the last two?
• Is the dicrotic notch on the aortic trace, on the third line, at about 100 mmHg?
• Is S1 on the first line and S2 on the third, with nothing on the opening lines?
• Does the QRS come just before the first line, and does the T wave end around the third?
• Does aortic pressure stay between about 80 and 120 mmHg, and left atrial pressure stay low?