# Cardiac tamponade

Source: saved session `01a13959-7cbf-7486-8848-e24365d67d7f`, October 14, 2026.

The original detailed write-up is preserved verbatim below. Desktop paths and verification claims refer to that original session, not this import. Educational material only; not a clinical protocol or medical device. Clinical statements, diagnostic thresholds, and treatment recommendations have not been independently verified during import. Original model assumptions and limitations are preserved; independent clinical review is required before teaching or patient-care use.

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I built the tamponade figure as an interactive page. Open `~/Desktop/anatomy-tamponade/tamponade-light.html` (a dark version, `tamponade.html`, is beside it).

**The figure** is a bench model of the heart in its sac. A rigid frame is the fibrous pericardium. Inside it, in a row, sit a fluid bladder (the effusion), the right-ventricle bellows, a floating septum plate and the left-ventricle bellows. A stiff spring at the far end lets the frame give a little, then go solid. That's the sac's J-shaped pressure–volume curve.
- **Syringe on the bladder:** pericardiocentesis.
- **Dial:** pericardial pressure (Pp), with a red band from 15 to 25 mmHg.
- **Column on the left:** venous pressure (CVP, standing in for JVP).
- **Scale along the base:** volume, one tick per 10 mL.

**Controls:**
- Hover left to right to set the effusion from 25 to 220 mL.
- Click, or press Space, to drain 60 mL with the syringe.
- Arrow keys step 10 mL (Shift for 50).
- Left alone, it runs a 22-second loop: normal, effusion builds, a tap, then it clears.

**Numbers from the model.** These are teaching values tuned to textbook ranges, not patient data, and the beats play at half speed.

| Effusion (mL) | Pp | CVP | LV stroke volume (mL) | Heart rate | Systolic BP | Pulsus |
|---|---|---|---|---|---|---|
| 25 | 0 | 7 | 76 | 72 | 112 | 2 |
| 150 | 9 | 12 | 45 | 94 | 87 | 13 |
| 200 | 13 | 14.5 | 29 | 106 | 74 | 18 |

Pressures are in mmHg. As the effusion grows:
- Venous pressure climbs to just above Pp, so diastolic pressures roughly equalise.
- Stroke volume falls and the heart rate rises.
- Pulsus paradoxus goes over 10 mmHg from about 130 mL. On inspiration the right bellows takes more room, the septum shifts left and left stroke volume drops.
- Draining 60 mL at 210 mL drops Pp from 14 to 9 mmHg and lifts stroke volume from 26 to 45 mL. That's the steep end of the J-curve.

I capped the slider at 220 mL. Past that, pulsus fell back below 10 in the model. That comes from a minimum stroke volume I set, not from real physiology.

**Checks:**
- **Loose lines:** the skill's check found none, in both themes, at rest, mid-beat, at 220 mL and after a tap.
- **Rendering and behaviour:** screenshots at desktop and phone width came out clean, with no console errors. Reduced-motion mode shows a still frame at end of filling.
- **Bug found and fixed:** a 4× close-up showed the syringe's clamp band painted over the barrel, so I split the barrel around it.

I didn't run the skill's geometry audit; it's meant for figures with pipes and turned parts, and this one has none. Files are in `~/Desktop/anatomy-tamponade/`, outside your repo:
- tamponade-light.html
- tamponade.html
- build.mjs (`node build.mjs --light` rebuilds)
- preview-light.png
- preview-dark.png