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.