🤓🫀We keep asking: “What’s the cardiac output?”
But maybe the better question is:
“How efficiently is the heart working?”
In septic shock, we often focus on:
Preload
Cardiac output
MAP
But we forget something fundamental:
👉 The heart doesn’t work alone.
👉 It works against the arterial system.
1. The missing concept: Ventriculo–arterial coupling (LVAC)
LVAC = interaction between:
Ees → contractility
Ea → arterial load
👉 Expressed as Ea / Ees
This ratio reflects:
How efficiently the heart converts energy into forward flow
2. What is “normal”?
LVAC ≈ 0.5 → optimal efficiency
LVAC ≈ 1 → maximal stroke work
LVAC > 1 → uncoupling (inefficient system)
But here’s the twist:
👉 In septic shock, LVAC is often >1
👉 Not just due to vasodilation—but also myocardial dysfunction
3. Why this matters clinically
Two patients can have:
Same MAP
Same CO
But completely different physiology:
✔ One → efficient coupling
❌ One → energy wasted, poor flow generation
4. The key insight
Septic shock is NOT just:
❌ “low preload”
❌ “vasodilation”
It is:
👉 A mismatch between heart and arterial system
5. Therapy changes the balance
Fluids → may improve coupling (↓ LVAC)
Norepinephrine → can improve OR worsen coupling
Inotropes → target Ees
Important:
👉 Increasing MAP ≠ improving flow
👉 Increasing pressure can worsen afterload
6. The most interesting part
From the data:
LVAC >1 can predict response to norepinephrine
But improving LVAC ≠ guaranteed tissue perfusion and outcomes follow a U-shaped curve
👉 Both too high AND too low LVAC can be harmful
7. The limitation we must respect
Even if you “optimize” LVAC:
👉 Microcirculation may still be impaired
👉 Lactate may still rise
👉 Shock may persist
Because: Macro ≠ micro
🤓Final message
We need to move from:
❌ “Fix the blood pressure”
To:
✅ “Optimize the interaction between heart and vessels”
LVAC doesn’t replace hemodynamics.
It completes it.
📃Reference
Caicedo Ruiz JD et al. Journal of Critical Care, 2026.
doi.org/10.1016/j.jcrc.2026.…