Mechanical Circulatory SupportQuestion Bank

Correct answer: B — Stepwise reduction by 1–2 P-levels every 4 hours to P2, with hemodynamic and echocardiographic monitoring at each step

Randhawa et al. describe two manufacturer-specified Impella weaning protocols: a rapid wean (substantial upfront reduction from P9 to P2) and a slow wean (gradual reduction by 1–2 P-levels every 4 hours to P2). Readiness-to-explant criteria include stable hemodynamics (CI, MAP, central venous oxygen saturation), imaging features (aortic VTI ≥12 cm, LVEF >25%, lateral mitral annulus velocity ≥6 cm/s), and adequate end-organ perfusion at P2. P1 should be avoided because it can allow retrograde flow through the device. SmartAssist technology can monitor LV end-diastolic pressure and total cardiac power output in real time during the wean — as native heart function recovers, total cardiac output should be maintained despite reduction in pump speed.

Board pearl: The key principle of Impella weaning: total cardiac output should be maintained despite reduction in pump speed, confirming that native heart function is recovering.

Correct answer: C — VA-ECMO is weaned first while Impella support is increased, followed by stepwise Impella weaning

The AHA scientific statement specifies that for patients supported with VA-ECMO and another platform, VA-ECMO is generally weaned first, and Impella support (in terms of P-level) may be increased to allow ECMO decannulation. Schrage et al. described this approach in their ECMELLA cohort: VA-ECMO flow was progressively reduced while Impella support was increased to maintain blood pressure and cardiac output; after successful VA-ECMO weaning, the Impella was then weaned through stepwise flow reduction. If severe myocardial dysfunction persists without recovery during the initial 5–7 days, transition from a femoral Impella CP to a subclavian Impella 5.0/5.5 can allow prolonged support and patient mobilization. Nathan et al. found that the "offload" configuration (Impella 5.0/5.5 with VA-ECMO) was associated with a marked increase in survival days until device removal.

Board pearl: In ECPELLA, wean ECMO first (increase Impella to compensate), then wean Impella — this preserves LV unloading throughout the transition.

Correct answer: B — RA pressure <10 mmHg, MAP ≥65 mmHg, cardiac index ≥2.2 L/min/m², lactate <2 mmol/L, and minimal vasoactive support

The AHA scientific statement recommends targeting a right atrial pressure under approximately 10 mmHg (or a substantial reduction from baseline), MAP at or above 65 mmHg with minimal or no vasoactive support, cardiac index at or above 2.2 L/min/m², and a normalizing lactate below 2 mmol/L before decannulation. These targets should be highly individualized — in some patients with chronic heart failure, optimization may occur at slightly higher filling pressures or with lower MAPs, assuming end-organ dysfunction has resolved. The statement emphasizes that no single validated score or metric can reliably determine successful tMCS weaning; rather, teams should integrate temporal trends in multimodal cardiac monitoring and markers of noncardiac organ hypoperfusion.

Board pearl: Hemodynamic targets for tMCS weaning should be individualized — chronic heart failure patients may tolerate slightly higher filling pressures if end-organ function is adequate.

Correct answer: B — CVP <12 mmHg (or substantially reduced from baseline), RV stroke work index improvement, and improved RV ejection fraction

Published Impella RP weaning protocols from the RECOVER RIGHT and postmarketing studies used stepwise flow reduction (0.5–1 L/min every 2–3 hours). Readiness-to-wean criteria required improved right-sided hemodynamics — CVP normalization (or a substantial reduction from baseline) and improved RV ejection fraction after 24–72 hours of support. Readiness-to-explant criteria required sufficient native RV ejection fraction at 1 L/min flows. Weaning trials should be performed with adequate monitoring including a Swan-Ganz catheter and echocardiography, and inotropic support may be used to avoid RV distension during flow reduction.

Board pearl: Impella RP weaning data are limited to a small number of published protocols — CVP normalization and RV EF improvement are the key right-sided readiness-to-wean thresholds.

Correct answer: B — Evaluate for durable LVAD or heart transplantation

The Randhawa et al. proposed algorithm states that if a patient is device-dependent after multiple failed wean attempts, the options are durable support (LVAD), heart transplantation, or palliation. This aligns with the AHA scientific statement, which similarly recommends that when weaning is unsuccessful, the interdisciplinary team should evaluate candidacy for advanced therapies. Indefinite temporary support increases device-related complications (hemolysis, infection, vascular injury) without addressing the underlying problem. Adding VA-ECMO would escalate rather than resolve the fundamental issue of non-recovery.

Board pearl: Failed weaning after multiple attempts shifts the question from "when to wean" to "what is the durable strategy" — LVAD, transplant, or palliation.