Discussion
The AngioVac system is recommended for use with centrifugal pumps because they are non-occlusive with no risk for cavitation of air. However, the present case was performed at the height of the COVID-19 pandemic, during which our hospital was experiencing a severe shortage in centrifugal pump heads due to the sudden increase in utilization for ECMO support in COVID patients. Given the urgent status of the procedure, we decided to use a roller pump as it was the only equipment available at the time. In addition, roller pumps have the added benefit of being significantly cheaper to use as they do not require replacement of a centrifugal pump head, which costs $12,600 per use.
Though the present case was technically successful and without complications, there are important safety considerations requiring careful evaluation with the use of roller pumps. First, roller pumps are occlusive and will continue to pump against any resistance, making them more likely to result in significant structural damage if the AngioVac catheter tip gets suctioned against an anatomic structure (i.e. inferior vena cava, right atrial free wall). Therefore, very gradual flow rate changes, capping at a low flow rate (2.5 L/ minute in our case), continuous visualization of the device and short advancements, with the operative team ready to make immediate adjustments, are required. Additionally, the AngioVac catheter has been reported to clog when used to evacuate solid or chronic thrombi.2 With a roller pump, a fully occluded tip may result in cavitation of air as well as trauma to blood elements due to shear stress from being suctioned around the occlusion.4 These considerations are especially important as introduction of air into the circuit can potentially be catastrophic in patients with PE who may already have RV dysfunction. While roller pumps may be more cost effective, safety is paramount. Thus, we recommend that this technique only be considered for soft, fresh thrombi in locations where navigation of the suction tip around delicate structures and long advancements of the device are not required.
In the present case, we demonstrate that AngioVac suction embolectomy can be safely and effectively performed with a roller pump to evacuate mobile, acute thrombi in the IVC and RA. In situations where centrifugal pumps are inaccessible, roller head pumps may be considered as an alternative under specific circumstances, granted precautions are taken to adjust for its limitations.