The application of PC-ECLS in contemporary cardiac surgery has been progressively increasing. Its primary indication is the inability to discontinue cardiopulmonary bypass intraoperatively or the presence of cardiopulmonary failure of various etiologies during the early postoperative period.

Despite medical and technological advances, PC-ECLS mortality remains high, with in-hospital survival ranging from 25% to 46%. Beyond the feared and devastating cerebrovascular complications, multiple potential issues are related to the cannulation site. Central cannulation in PC-ECLS is associated with a high rate of early reoperation for bleeding. Peripheral cannulation mitigates this issue but is not without other complications that should be considered. The primary advantage of femoral cannulation lies in its rapid implementation in emergency circumstances, though disadvantages include the likelihood of lower limb ischemia, differential hypoxia (Harlequin syndrome), and limited patient mobilization. Axillary cannulation, which is more technically demanding and typically performed in the operating room, often has a higher rate of bleeding and arm hyperperfusion syndrome. However, its fundamental advantage is that it provides antegrade flow, reducing the risk of Harlequin syndrome. Due to its proximity to cerebral arteries, axillary cannulation may pose a potential source of cerebral embolism.

The objective of this study was to compare axillary and femoral cannulation in terms of cannulation site-related complications and the incidence and type of cerebrovascular events.

Of 573 consecutive patients requiring PC-ECLS between 2000 and 2019 at a single center, 436 were included in a retrospective analysis and grouped according to the primary peripheral arterial access chosen for PC-ECLS. In 250 patients (57.3%), indirect cannulation with a side graft anastomosed end-to-side to the axillary artery was performed, whereas the femoral artery was used as the primary arterial access in 186 patients (42.6%). No significant differences were observed in 30-day survival (axillary: 62% vs femoral: 64.7%; p = 0.561) or 1-year survival (42.5% vs 44.8%; p = 0.657). Cerebral computed tomography confirmed a significantly higher incidence of stroke with a modified Rankin Scale (MRS) ≥4 (moderate to severe disability) in the axillary group (axillary: n = 28, 11.2% vs femoral: n = 4, 2.2%; p = 0.0003). Stroke localization included right hemisphere (n = 20; 62.5%), left hemisphere (n = 5; 15.6%), bilateral (n = 5; 15.6%), or infratentorial (n = 2; 6.25%). Although no differences were found in the incidence of severe bleeding secondary to cannulation, the need for cannulation site change due to bleeding was more frequent in the axillary group (axillary: n = 13, 5.2%; femoral: n = 2, 1.1%; p = 0.03). Clinically evident limb ischemia was significantly more frequent in the femoral group (axillary: n = 12, 4.8%; femoral: n = 31, 16.7%; p < 0.0001).

The authors conclude that while survival was similar with both procedures, surgeons should be highly aware of the specific complications associated with each peripheral access when choosing PC-ECLS cannulation sites. Although axillary cannulation has a low arm ischemia rate and the apparent advantage of providing antegrade flow, the high incidence of right hemispheric strokes should be considered.

COMMENTARY:

The Achilles’ heel of ECLS is well-known to be its vascular and cerebral complications. This study is particularly relevant as it constitutes the largest series comparing the two most common types of ECLS cannulation (axillary vs. femoral artery) and establishes a strong association between axillary cannulation and stroke for the first time. The most notable findings include similar mortality when comparing both techniques, a significantly higher rate of stroke (odds ratio 4.5) with axillary cannulation, and a greater incidence of vascular complications with femoral cannulation.

The most innovative contribution of this study was the clinical and statistically significant association between axillary cannulation and stroke. Previous smaller studies had suggested this, while others did not conclude such an association. A clear methodological limitation was the use of an MRS ≥4 (moderate to severe disability) to classify stroke instead of the typically used MRS ≥2 (mild disability) in clinical trials on TAVI, potentially underestimating the actual incidence of this complication. The retrospective nature of the study may explain the lack of data regarding the timing of strokes and the absence of a specific anticoagulation protocol, leaving unanswered whether a significant portion of these strokes occurred during device explant or were caused by improper anticoagulation levels.

The rate of limb ischemia in femoral cannulation was notably high (16.7%). In several recently published series, the incidence of vascular complications has decreased to 5% with the use of distal perfusion catheters. The author does not provide information on the percentage of distal cannula use, but it is likely that its usage was minimal, especially in the first ten years. Given that limb ischemia rates may now be lower and considering the high incidence of strokes with axillary cannulation, it could be argued that femoral cannulation may be the preferred technique in most cases. However, to reach a similar conclusion, multicenter randomized studies comparing different cannulation strategies in ECLS would be necessary.

REFERENCE:

Schaefer AK, Distelmaier K, Riebandt J, Goliasch G, Bernardi MH, Zimpfer D, Laufer G, Wiedemann D. Access site complications of postcardiotomy extracorporeal life support. J Thorac Cardiovasc Surg. 2022 Nov;164(5):1546-1558.e8. doi:10.1016/j.jtcvs.2021.09.074.