Venoarterial extracorporeal membrane oxygenation (VA-ECMO) has become an essential life-saving therapy for patients with refractory cardiogenic shock. Despite advances in mechanical circulatory support, cardiogenic shock continues to carry mortality rates approaching 50%. As ECMO utilization has increased dramatically over the past two decades, attention has shifted toward optimizing procedural strategies—particularly the choice between peripheral and central cannulation.
This systematic review and meta-analysis by Chilingarashvili et al. (2026) rigorously evaluates the comparative safety profiles of peripheral versus central cannulation in VA-ECMO, focusing specifically on bleeding and vascular complications. The authors analyzed 15 studies encompassing 2,913 adult patients treated for cardiogenic shock between 2000 and 2024. The methodology adhered to PRISMA 2020 guidelines, with statistical pooling performed using a DerSimonian-Laird random-effects model. Quality assessment via the Newcastle-Ottawa Scale demonstrated that all included studies were categorized as low risk of bias (scores 7–9), strengthening confidence in the findings.
Key Clinical Findings
The most clinically significant finding was a clear procedural trade-off between bleeding risk and limb ischemia:
- Major Bleeding: Peripheral cannulation reduced bleeding risk by nearly half compared with central cannulation (RR 0.55, 95% CI 0.43–0.70).
- Limb Ischemia: Peripheral access increased limb ischemia risk (RR 1.43, 95% CI 1.17–1.75).
- Infection: No significant difference between strategies.
- Renal Replacement Therapy (RRT): No significant difference.
- Cerebrovascular Accidents (Stroke): No significant difference.
These findings highlight that access-related complications—rather than systemic complications—drive the primary differences between strategies.
Why Bleeding Differs Between Strategies
Central cannulation typically involves direct aortic and right atrial access through sternotomy or thoracotomy. This invasive approach exposes mediastinal tissues and frequently requires re-exploration for bleeding. Earlier series reported reoperation rates exceeding 40% in central ECMO cohorts. Even with contemporary heparin-bonded circuits and restrictive transfusion protocols, central cannulation continues to carry higher transfusion requirements and surgical bleeding risks.
Peripheral cannulation, usually via femoral vessels, avoids open chest exposure and is less surgically traumatic. This minimally invasive approach explains the consistently lower bleeding risk observed across studies.
The Limb Ischemia Trade-Off
Peripheral VA-ECMO alters normal arterial flow dynamics by introducing retrograde perfusion via the femoral artery. This can compromise distal limb perfusion, leading to ischemia, compartment syndrome, or even amputation if unrecognized. Variability in ischemic complication rates across studies was influenced by:
- Cannula size relative to artery diameter
- Operator expertise
- Use of distal perfusion catheters (DPCs)
- Structured vascular monitoring protocols
Institutions that implemented ultrasound-guided cannulation and routine DPC placement significantly reduced ischemic complications. Nevertheless, the ischemic “penalty” of peripheral ECMO remains measurable.
No Differences in Systemic Outcomes
Interestingly, systemic complications—including infection, renal failure requiring dialysis, and stroke—did not differ meaningfully between cannulation strategies. Heterogeneity in infection outcomes was substantial, but pooled analysis did not show statistical significance. Stroke rates clustered near unity with negligible heterogeneity.
This suggests that the cannulation site primarily affects local complications rather than systemic organ dysfunction.
Clinical Implications
The findings strongly support peripheral cannulation as the default strategy in most cases of cardiogenic shock due to:
- Faster bedside deployment
- Lower bleeding risk
- Avoidance of sternotomy
However, vigilance is essential to prevent limb ischemia. Best practices include:
- Routine distal perfusion catheter placement
- Ultrasound-guided vascular access
- Standardized limb surveillance protocols
Central cannulation remains important in select scenarios such as:
- Postcardiotomy shock
- Severe peripheral arterial disease
- Need for antegrade flow and direct ventricular unloading
Ultimately, cannulation strategy should be individualized, balancing hemorrhagic risk against ischemic risk while accounting for institutional expertise.
Limitations of the Evidence
Most included studies were retrospective observational cohorts, introducing potential selection bias and confounding. Central cannulation was often reserved for sicker postcardiotomy patients, complicating direct comparisons. Outcome definitions varied, and long-term functional outcomes were rarely reported.
Publication bias analysis using Doi plots and Egger’s regression suggested minor asymmetry, indicating modest small-study effects. Nevertheless, leave-one-out sensitivity analyses demonstrated robust findings.
Conclusion
This meta-analysis confirms a consistent and clinically meaningful procedural trade-off in VA-ECMO: peripheral cannulation reduces major bleeding but increases limb ischemia risk, while systemic complications remain similar between approaches. The decision should be tailored to patient-specific anatomy, clinical context, and institutional capabilities.
Future prospective multicenter trials and standardized registries are needed to refine patient selection, improve vascular protection strategies, and evaluate long-term survival and quality-of-life outcomes.
