LV pump failure after separation from CPB
After 3-vessel CABG, blood pressure fails to recover from CPB. Is the LV empty or failing to contract? Compare LVDd and LVDs against the preoperative baseline to sort five distinct patterns.
Intraoperative setup
67-year-old male, 3-vessel CABG (LAD, RCA, LCx). Blood pressure fails to recover immediately after separating from CPB. Norepinephrine has been uptitrated from 0.05 to 0.1 μg/kg/min, but systolic BP remains 70–80 mmHg. HR 95 bpm. Preoperative TTE: LVEF 45%, LVDd 58 mm, LVDs 42 mm (mild anterior hypokinesis). PA catheter in place: PAWP 16 mmHg, PA pressure 40/20 mmHg, CVP 12 mmHg. Cross-clamp time was 82 minutes. The surgeon asks you to check TEE.
What this case is really asking
- Is the LV cavity small or dilated right now — preload deficit or pump failure?
- How do LVDd and LVDs compare with the preoperative TTE — LVDs larger than preop means worse contractility; smaller means hyperdynamic
- Is there new RWMA, and in which territory — after CABG, the territory points to the graft at risk
- Is the RV enlarged or poorly contracting — high CVP with narrow PA pulse pressure is an RV failure signal
- Is SAM/LVOTO truly the driver — suspect it only when small LV, hypercontractile, accelerated LVOT flow, and inotrope escalation all converge
TEE clues to notice
- LVDd (end-diastolic diameter): preop 58 mm → now? Small cavity (< 40 mm) suggests preload deficit; normal-to-dilated (≥ 60 mm) suggests pump failure
- LVDs (end-systolic diameter): preop 42 mm → now? Larger than preop means reduced contractility; smaller than preop means hyperdynamic
- LVEF impression: severely reduced (< 30%), moderately reduced (30–50%), preserved (> 50%), or hyperdynamic?
- RWMA: anterior wall/apex (LAD territory), inferior/posterior wall (RCA territory), lateral wall (LCx territory) — was it present on the preoperative TTE?
- RV: enlarged (RV ≥ LV)? Reduced contractility? Septal shift (D-sign)?
- MR: new or worsening — combined with accelerated LVOT flow (Dagger waveform), suggests SAM
- Air echoes (bright flickering): near coronary distributions — air embolism after CPB
Likely pattern
Five patterns to organize the differential. In practice, they often overlap. Volume pattern: Small LVDd (smaller than preop) + small LVDs (hyperdynamic) + no new RWMA. PAWP < 12 mmHg supports the diagnosis. Volume loading first. LV pump failure pattern: Normal-to-dilated LVDd + LVDs larger than preop ('more LV left over at end-systole') + globally reduced contractility. PAWP ≥ 18 mmHg + elevated CVP strongly supports this. The intuitive bedside cue is not an LVEF number — it's 'LVDs is bigger than before.' Inotrope indication. Ischemia/RWMA pattern: New regional wall motion abnormality not present on the preoperative TTE. Anterior/apical → suspect LAD graft; inferior → suspect RCA graft failure, spasm, or air embolism; lateral wall → suspect LCx graft. The territory is the clue. Communicate with the surgical team immediately. RV failure pattern: RV enlargement + reduced RV contractility + septal shift (D-sign). CVP > 15 mmHg + narrow PA pulse pressure (PA diastolic ≈ PAWP, meaning RV cannot generate flow). When the LV appears to contract but BP is still low, look at the RV. SAM/LVOTO pattern (the trap): Small LV + hyperdynamic + accelerated LVOT flow + worsening MR + hemodynamic deterioration with inotropes — this specific combination is what makes SAM the answer, not any single finding. In CABG patients it typically emerges when dopamine or dobutamine is escalated, or when preload drops too far. Treat with volume loading, stop inotropes, and use norepinephrine carefully.
Common pitfall
Seeing a 'hyperdynamic' LV and escalating inotropes. When the LV is small and hypercontractile, that appearance is the entry point for preload depletion or SAM — not a sign of recovery. Inotropes worsen SAM. The distinction between transient post-CPB stunning and true pump failure requires comparing LVDd and LVDs against the preoperative baseline — LVEF alone misses the difference between a small high-EF cavity and a genuinely recovering ventricle.
Immediate intraoperative takeaway
- 'Hyperdynamic' is not reassuring when BP is low — small cavity + hypercontractile + hypotension is the first sign of volume depletion or SAM, not pump recovery
- LVDd tracks preload; LVDs tracks contractility — preoperative TTE comparison is the starting point for every post-CPB interpretation
- New RWMA after CABG: identify the territory (LAD/RCA/LCx), suspect graft failure or air embolism, and communicate with the surgical team immediately
- High CVP + narrow PA pulse pressure + RV enlargement = RV failure pattern — the LV view alone will miss it
- If SAM is suspected: volume loading + stop inotropes. Norepinephrine is acceptable; dopamine and dobutamine worsen the obstruction