Hepatic Artery Infusion Pumps: The Expected and Unexpected

Learning Objectives: Review current indications for and most common designs of hepatic artery infusion pumps (HAIPs).
Demonstrate expected and unexpected imaging findings following HAIP placement on CT, fluoroscopy, and nuclear medicine studies.
Describe techniques of pump assessment which require understanding of pump access and interrogation.
Identify complications of HAIPs including catheter tip dislodgment, catheter fracture, pseudoaneurysm formation, and pump leak.

Background: HAIPs are used in the treatment of primary and secondary hepatic malignancies, delivering chemotherapy directly to the liver in order to minimize systemic toxicity {1}. HAIPs consist of a subcutaneously implanted reservoir attached to a catheter which is inserted into the gastroduodenal artery. In general, approximately 1 cc of chemotherapeutic drug is delivered through the catheter each day, but a separate access port is available for catheter bolus. HAIPs take advantage of the fact that hepatic tumor blood supply is predominantly arterial {2}.
CT is often the first imaging modality to show a catheter-related complication such as catheter dislodgement, hematoma, or pseudoaneurysm. In cases with high suspicion of catheter malfunction but unclear diagnosis on CT, other modalities can be helpful for troubleshooting.

Clinical Findings/Procedure Details: Fluoroscopic assessment should begin with full evaluation of pump positioning and catheter course. Once the interrogation port is accessed with a specialized huber needle, residual chemotherapy in the catheter should be aspirated. Contrast can be injected to evaluate for catheter fracture or catheter dislodgement. Similarly, a nuclear medicine agent such as 99mTc-MAA can be injected for an infusion study.
Care should be taken to avoid over-pressurizing the system which can lead to catheter fracture and tip dislodgment. In general, no smaller than a 10 ml syringe is recommended for pump infusion. The ease of access, ability to aspirate, ease of flushing, catheter course, and washout of contrast at the arterial insertion site should be carefully evaluated and documented.
If there is catheter dislodgment with associated pseudoaneurysm or bleeding, angiography may be helpful in the diagnosis and treatment which may include embolization or stent graft placement.

Conclusion and/or Teaching Points: HAIPs are being used increasingly in the treatment of primary and secondary hepatic malignancy. Interventional and diagnostic radiologists should be aware of the expected and unexpected imaging findings following pump placement and understand how to safely access and interrogate these pumps.