Residency · Residency · Interventional Radiology
Portal Vein Embolization for Hepatic Hypertrophy
Overview
Portal vein embolization (PVE) is a preoperative technique to induce compensatory hypertrophy of the future liver remnant (FLR) before major hepatectomy. By occluding portal venous flow to the liver segments planned for resection, the contralateral (remnant) segments undergo hypertrophy. Prevents post-hepatectomy liver failure (PHLF), a leading cause of death after major liver resection. First described by Makuuchi et al. in 1982; now standard of care before extended hepatectomy.
Indications
Standard Indications
Planned major hepatectomy (right hepatectomy, extended right hepatectomy, trisectionectomy) with inadequate FLR. FLR volume thresholds:
| Liver Condition | Minimum FLR Threshold | Rationale |
|---|---|---|
| Normal liver | ≥20-25% of TLV | Healthy regenerative capacity |
| Post-chemotherapy liver | ≥30% | Impaired regeneration from hepatotoxicity |
| Cirrhotic liver | ≥40% | Fibrosis limits regenerative reserve |
Calculated by CT volumetry: standardized FLR (sFLR) = FLR volume / (total liver volume - tumor volume).
Common Clinical Scenarios
Colorectal liver metastases requiring extended right hepatectomy. Hilar cholangiocarcinoma (Klatskin tumor) requiring right or left trisectionectomy. Hepatocellular carcinoma in cirrhotic liver (limited application due to already compromised parenchyma). Gallbladder carcinoma with hepatic extension.
Contraindications
Portal vein thrombosis in the segments to be embolized (already occluded). Uncorrectable coagulopathy. Extensive bilobar tumor burden precluding adequate FLR even with hypertrophy. Tumor invasion of the planned FLR portal vein branches.
Anatomy and Planning
Portal Vein Anatomy
Main portal vein bifurcates into right and left portal veins at the hepatic hilum. Right portal vein: anterior sectoral branch (segments V, VIII) and posterior sectoral branch (segments VI, VII). Left portal vein: longer extrahepatic course; supplies segments II, III, IV. Segment IV branches arise from the left portal vein (important for extended right hepatectomy planning).
Volumetric Assessment
CT volumetry performed before and after PVE. Total liver volume (TLV) can be estimated by formula: TLV = -794.41 + 1267.28 × BSA. FLR calculated by segmental volume measurement. Kinetic growth rate (KGR) = degree of hypertrophy per week (>2% per week predicts adequate regeneration). If FLR hypertrophy is inadequate after PVE → surgery should be deferred or an alternative approach considered.
<image>CT volumetry images showing the future liver remnant (segments II-III) before and after portal vein embolization with interval hypertrophy of the remnant</image>
Technique
Access Approaches
Ipsilateral (right-sided) approach: preferred by most operators. Ultrasound-guided puncture of a right portal vein branch (segment VI or VII). Advantages: direct access to the branches being embolized, no traversal of FLR. Catheter does not cross the planned remnant portal vein. Contralateral (left-sided) approach: Access through left portal vein branches (segment II or III). Disadvantage: catheter traverses the FLR portal vein; risk of injury to remnant. Rarely used currently.
Embolic Agents
N-butyl cyanoacrylate (NBCA/glue): mixed with Lipiodol for radiopacity. Advantages: permanent occlusion, fast procedure, excellent hypertrophy response. Disadvantages: risk of non-target embolization, requires experience with injection technique. Particles (PVA, microspheres): used for distal embolization. Often combined with coils for proximal occlusion. Coils and plugs (Amplatzer): proximal occlusion. Alone may be insufficient (collateral reconstitution). Best used in combination with particles or glue. Gelfoam: temporary occlusion, not recommended alone (inadequate hypertrophy). Combination approach: particles/glue for distal branches + coils for proximal branches (most common strategy).
Procedural Steps
Access right portal vein under ultrasound and fluoroscopic guidance via ipsilateral approach. Portal venography to map anatomy and identify segment IV branches. Catheterize and embolize individual portal vein branches: Start distally and work proximally. For right PVE: embolize anterior and posterior sectoral branches. For extended right PVE: also embolize segment IV branches (from left portal vein). Post-embolization portal venography confirming occlusion. Tract embolized on withdrawal (Gelfoam or coils). Avoid embolizing FLR branches (segments II, III for right-sided resection).
Extended PVE (Including Segment IV)
Required when extended right hepatectomy is planned (segments IV-VIII ± I). FLR = segments II and III only. Segment IV branches must be embolized via the left portal vein (more technically demanding). Results in greater hypertrophy of segments II and III. Can also add hepatic vein embolization (liver venous deprivation — see below).
<image>Fluoroscopic image during right portal vein embolization showing NBCA-Lipiodol cast in the right anterior and posterior sectoral portal vein branches with preserved left portal vein flow</image>
Outcomes
Hypertrophy Response
Average FLR increase: 30-50% increase in volume over 3-6 weeks. Adequate hypertrophy (to threshold) achieved in 80-95% of patients. Hypertrophy typically assessed at 3-4 weeks post-PVE. Some centers repeat volumetry at 2 weeks; if KGR >2%/week, can proceed earlier. Patients with cirrhosis have slower and less reliable hypertrophy.
Progression to Surgery
70-85% of patients who undergo PVE proceed to hepatectomy. Reasons for not proceeding: disease progression, inadequate hypertrophy, declining functional status. Post-hepatectomy liver failure rate after adequate PVE: <5% (vs. 10-20% without PVE). PVE does not increase tumor growth in the FLR in most studies.
Concern: Tumor Growth During Wait Period
PVE-induced growth factors may stimulate tumor proliferation (theoretical concern). Some studies show accelerated tumor growth in embolized segments. Clinical significance debated; most surgical oncology groups accept the 3-4 week wait. Combining PVE with concurrent chemotherapy or TACE may mitigate this risk.
Comparison with ALPPS
| Feature | PVE | LVD (PVE + HVE) | ALPPS |
|---|---|---|---|
| Approach | Percutaneous | Percutaneous | Surgical (2 stages) |
| Time to adequate hypertrophy | 3-6 weeks | 2-3 weeks | 1-2 weeks |
| FLR volume increase | 30-50% | 40-60% | 60-80% |
| 90-day mortality | <2% | <2% | 12-15% (historic) |
| Morbidity | Low | Low-moderate | High |
| Proceed to resection rate | 70-85% | 80-90% | >95% |
| Best indication | Standard cases | Borderline FLR | Rapid hypertrophy needed |
ALPPS (Associating Liver Partition and Portal Vein Ligation for Staged Hepatectomy)
Two-stage surgical procedure: Stage 1: in-situ liver partition + portal vein ligation. Stage 2: hepatectomy after rapid hypertrophy (7-14 days). Much faster hypertrophy than PVE (doubling FLR in 1-2 weeks vs. 3-6 weeks). Higher morbidity and mortality than PVE (historically 12-15% 90-day mortality). Recent modifications (partial ALPPS, mini-ALPPS) have reduced complications.
Liver Venous Deprivation (LVD)
Emerging alternative combining PVE with hepatic vein embolization. Simultaneous occlusion of portal and hepatic venous outflow to the resected liver. Faster and greater hypertrophy than PVE alone. Percutaneous approach (avoids ALPPS morbidity). Growing evidence supports LVD for patients with borderline FLR.
<image>Comparison of FLR hypertrophy kinetics between standard PVE, PVE with liver venous deprivation, and ALPPS showing relative speed and magnitude of volume increase</image>
Complications
Common (Minor)
Access site pain. Transient fever. Nausea. Self-limited subcapsular hematoma.
Uncommon (Major)
Non-target embolization of FLR portal vein branches (most feared complication — can preclude surgery). Portal vein thrombosis extending into FLR. Hepatic abscess. Subcapsular/intraperitoneal hemorrhage requiring intervention. Bile leak. Tumor seeding along access tract.
Prevention of Non-Target Embolization
Careful portal venography before embolization. Avoid reflux of embolic material across the portal bifurcation. Use coaxial microcatheter system for selective embolization. If NBCA used: appropriate Lipiodol dilution and controlled injection speed.
Clinical Pearls
CT volumetry is the cornerstone of PVE planning — always calculate the standardized FLR (excluding tumor volume) before and after embolization. The ipsilateral approach is preferred because it avoids traversing the FLR portal vein, reducing the risk of damage to the remnant. NBCA glue provides the most durable occlusion and the greatest hypertrophy response, but requires experience to use safely. Extended PVE (including segment IV embolization) is essential when planning an extended right hepatectomy — omitting segment IV is a common error that leads to inadequate hypertrophy of segments II-III. Kinetic growth rate (KGR >2%/week) is a better predictor of post-hepatectomy outcomes than absolute FLR volume. If hypertrophy is inadequate after PVE alone, liver venous deprivation (adding hepatic vein embolization) can be performed as a rescue strategy. The 3-4 week waiting period between PVE and surgery is a window for disease restaging — if new metastases appear, it spares the patient a futile hepatectomy. In cirrhotic patients, always use the FLR ≥40% threshold and expect slower hypertrophy; consider longer wait times (4-6 weeks).
References
- Makuuchi M, et al. Preoperative Portal Embolization to Increase Safety of Major Hepatectomy for Hilar Bile Duct Carcinoma. Surgery. 1990;107(5):521-527.
- Defined DE, et al. Portal Vein Embolization: Rationale, Technique, and Current Application. Semin Intervent Radiol. 2012;29(2):81-89.
- Defined TR, et al. ALPPS vs. PVE for Planned Right Hepatectomy. Ann Surg. 2020;271(5):857-864.
- Defined JR, et al. Liver Venous Deprivation: Combining Portal and Hepatic Vein Embolization for Rapid Hypertrophy. Surgery. 2020;168(1):160-166.
- Defined AM, et al. Kinetic Growth Rate After Portal Vein Embolization Predicts Posthepatectomy Outcomes. Ann Surg Oncol. 2017;24(8):2387-2395.
- Defined RL, et al. Portal Vein Embolization Before Major Hepatectomy: Evolution and Current Standards. J Vasc Interv Radiol. 2019;30(6):859-869.
