Conditions Cardiomyopathy and pericardium

Tamponade, constriction and restriction

Three ways to raise and equalise filling pressures with different respiratory behaviour: tamponade (fluid compresses all chambers, pulsus paradoxus), constriction (a rigid shell shields the heart from pleural pressure), restriction (stiff myocardium, normal pericardium).

Experiment: Normal adult at rest · unchanged from its starting state

Key measurements

Mean pericardial pressure (model)

— mmHg

baseline not set

— mmHg

baseline not set

— mmHg

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— mL

baseline not set

— L/min

baseline not set

Inspect beats and technical detailsbeat selection, transient versus settled, timings

Position within the beat0.000 s

Early beats after a change are transient: the circulation is still re-balancing. A beat is called settled when three consecutive windows agree within the tolerance. Playback speed only moves the cursor over the finished simulation; it never changes the heart rate.

Compare scenariosbaseline, snapshots, axes, export

Baseline

No baseline is set.

Comparison snapshots

Keep up to three snapshots of states you want to compare with the baseline and the current state.

How comparisons are drawn

Side-by-side loops instead of an overlay Identical axes for every loop (turn off and each plot rescales to its own data)

Pressure–volume loop options

Show the ESPVR and EDPVR reference lines Shade stroke work Show the arterial elastance (Ea) line Show the right heart instead of the left

Export

Choose a version

Differences from normal: pericardium enabled (V0 480, φ 25) with a 340 mL effusion; ventricular interaction gain 0.05 → 0.12; spontaneous respiration 8 mmHg swing; heart rate 70 → 105; blood volume 5000 → 5400 and venous unstressed volume 2900 → 2600 (compensation). Expected: raised pericardial pressure with equalised diastolic pressures, small stroke volume, pulsus paradoxus > 10 mmHg, and resolution with drainage (reduce the effusion control).

What to look for

Tamponade: pericardial pressure ≈ diastolic pressures; pulsus paradoxus > 10 mmHg; relieved by drainage
Constriction: PV–LA gradient falls with inspiration (dissociation); low pleural transmission
Restriction: concordant respiratory variation; pleural pressure fully transmitted

Try it

Set values directly

Pericardial effusionmL

How this works

Fluid occupying the pericardial sac shifts the heart onto the steep part of the pericardial pressure–volume relation (tamponade). Drainage reduces it.

Changes: pericardium.effusion

Pericardial stiffness (φ)mL

How this works

Volume constant of the exponential pericardial relation; smaller φ = stiffer sac (constriction).

Changes: pericardium.phi

Pericardial volume threshold (V0)mL

How this works

Total heart volume (plus effusion) at which pericardial pressure equals the scale constant.

Changes: pericardium.v0

Pleural pressure transmission to chambersfraction

How this works

Fraction of intrathoracic pressure swing transmitted to the chambers; a constricting pericardium shields the heart (dissociation of intrathoracic and intracardiac pressures).

Changes: pericardium.transmission

Compare scenariosloads two scenarios side by side

Tamponade vs constriction

Both equalise pressures; only tamponade produces a large paradoxus here, and only tamponade is relieved by drainage.

Restriction vs constriction

Equalised pressures and a dip-and-plateau do not establish constriction; the respiratory behaviour and transmural pressures separate them.

Common misconception. Equalised diastolic pressures alone do not establish constriction; restriction and tamponade equalise too.

Apply it

Which finding most specifically favours constriction over restriction?

Dissociation of intrathoracic and intracardiac pressures with discordant ventricular systolic variationEqualised diastolic pressuresA dip-and-plateau pattern

← Obstructive hypertrophic cardiomyopathy Pulmonary hypertension and the right heart →

Sources & model detailsreview status, testing, limitations

Sources

Content review

Teaching text and answer keys: Proposed. None of the 2 source claims behind it has been expert reviewed. Where a question has more than one defensible answer, more than one is accepted.

Simulation testing

Finding Hemo closed-loop lumped-parameter model: Quantitatively tested. Software, conservation and qualitative pattern tests pass. Not expert reviewed; normal ranges and phenotype parameter sets are proposed teaching values.
Scenario “Normal adult at rest” is checked for: closed-system volume conservation (<0.1% over 100 beats); timestep sensitivity (<1% change in core stable measurements at dt/2); seeded repeatability; resting pressures, volumes and flows within stated textbook ranges; directional response to fluid bolus and afterload increase.

Passing these tests means the equations are solved correctly and behave as stated. It does not mean the teaching statements, parameter values or answer keys have been expert reviewed.

Limitations that matter here

Quantitative compartment model for tamponade (paradoxus, equalisation, drainage) and restriction; constriction reproduces equalisation and PV–LA dissociation but NOT the classic LV/RV discordance (identified as outside the active model).
Reflexes are off: no autonomic compensation follows a change (the optional baroreflex is not enabled).
Constant intrathoracic pressure -3 mmHg (respiratory swing disabled).

Technical details

Model: fh-closed-loop 0.4.0
App / content version: 0.5.0 / 0.5.0
Scenario id: normal-adult
Solver: rk4, dt 0.2 ms
Condition id: pericardial-disease