Constrictive vs Restrictive vs Tamponade

Three conditions raise the heart's filling pressures and look almost identical at the bedside — constrictive pericarditis, restrictive cardiomyopathy, and cardiac tamponade. The waveforms and a few respiratory tricks are how the cath lab tells them apart.

The short answer

See the three side by side

Open the interactive atlas below and switch between Constrictive pericarditis, Restrictive cardiomyopathy, and Cardiac tamponade in the condition list. Turn on Breathing and Connect peaks for constriction to watch the RV and LV systolic peaks move in opposite directions — the discordance that clinches the diagnosis.

Open the atlas full-screen →

What each condition is

The three differ by where the problem sits:

• Constrictive pericarditis — the pericardium becomes rigid and scarred, encasing the heart in a stiff shell. The ventricles fill normally at first, then hit that shell and stop abruptly.
• Restrictive cardiomyopathy — the heart muscle itself becomes stiff (from infiltration, fibrosis, or scarring), so the ventricles resist filling throughout diastole.
• Cardiac tamponade — fluid collects in the pericardial sac and compresses every chamber from the outside, limiting filling in early diastole.

All three raise filling pressures, which is why they mimic one another — and why the fine detail of the waveforms matters so much.

Constriction vs restriction: the key differences

These two share the most overlap — both show a prominent y descent and a dip-and-plateau. Three findings separate them:

1. Filling-pressure equalisation. In constriction the diastolic pressures of all four chambers land within about 5 mmHg of each other. In restriction the left ventricular end-diastolic pressure runs more than 5 mmHg above the right, because the left ventricle is usually the stiffer of the two.
2. Ventricular interdependence. This is the most specific sign. Because a rigid pericardium fixes the heart's total volume, constriction makes the ventricles compete — on inspiration the RV systolic pressure rises while the LV systolic pressure falls (discordance). In restriction the shell is intact, so the two ventricles rise and fall together (concordance).
3. Pulmonary pressures. Restriction tends to drive the PA systolic pressure higher (often above 55 mmHg); constriction usually keeps it lower.

Constriction vs tamponade: the y descent

Constriction and tamponade both equalise the filling pressures, but the atrial waveform gives them away:

• The y descent. Constriction preserves a steep, prominent y descent (the ventricle still fills rapidly in early diastole, then stops). Tamponade blunts or abolishes the y descent — the compressed heart can't expand at all in early diastole.
• Kussmaul's sign. Present in constriction (the rigid shell stops the right atrial pressure falling on inspiration) but typically absent in tamponade.
• Pulsus paradoxus. Marked in tamponade (systolic blood pressure falls more than 10 mmHg on inspiration) but usually mild or absent in constriction.

Our dedicated guide on cardiac tamponade hemodynamics goes deeper on the blunted y descent and Beck's triad.

How the cath lab confirms it

The definitive test is a simultaneous left- and right-ventricular pressure recording with a respirometer. The operator watches the two systolic pressures across the breathing cycle:

• Discordance (RV up as LV comes down on inspiration) — with a systolic-area index > 1.1 — is highly specific for constriction.
• Concordance (both move together) points to restriction.

You can rehearse the whole study — access, right-heart catheterisation, reading the M/W wave, the dip-and-plateau, Kussmaul's sign, and the discordance — in our step-by-step interactive tools, then test yourself on scenario questions.

Frequently asked questions

What is the main difference between constrictive pericarditis and restrictive cardiomyopathy?

In constriction the diastolic pressures equalise and the ventricles show respiratory discordance (RV rises as LV falls). In restriction the left ventricular end-diastolic pressure exceeds the right by more than 5 mmHg and the ventricles move concordantly. Constriction is a pericardial disease; restriction is a myocardial one.

How do you tell constriction from tamponade?

Both equalise filling pressures, but constriction preserves a prominent, steep y descent and Kussmaul's sign, while tamponade blunts the y descent, lacks Kussmaul's sign, and shows marked pulsus paradoxus.

What is ventricular discordance?

During inspiration in constriction, the right ventricular systolic pressure rises while the left ventricular systolic pressure falls — they move in opposite directions. This 'discordance' (systolic-area index >1.1) is the most specific catheterisation sign of constriction.

What is Kussmaul's sign?

A failure of the jugular venous (right atrial) pressure to fall — or a paradoxical rise — during inspiration. The rigid pericardium in constriction prevents the normal inspiratory drop. It is usually absent in tamponade.

Why is the y descent blunted in tamponade but prominent in constriction?

In tamponade the fluid compresses the heart so it cannot expand in early diastole, flattening the y descent. In constriction the ventricle still fills rapidly early on before hitting the stiff shell, so the y descent is steep and prominent.

Is constrictive pericarditis curable?

Often, yes. Unlike restrictive cardiomyopathy, constriction is frequently treated surgically by removing the thickened pericardium (pericardiectomy), which is why distinguishing the two matters so much.

What pulmonary artery pressure suggests restriction over constriction?

A pulmonary artery systolic pressure above roughly 55 mmHg favours restrictive cardiomyopathy; constriction usually keeps the PA systolic pressure lower.

Do all three conditions show a dip-and-plateau?

No. Constriction and restriction both show the dip-and-plateau (square-root sign) in the ventricular tracing, but tamponade does not.