Percutaneous transvenous coil embolization (PTCE) for treatment of single extrahepatic portosystemic shunt in dogs

Abstract

Background: There is limited information regarding percutaneous transvenous coil embolization (PTCE) for single extrahepatic portosystemic shunt (PSS). This study aimed to describe the procedure and outcome of PTCE in dogs with a single extrahepatic PSS. Forty-two privately owned dogs were included in this study. All dogs were diagnosed with extrahepatic PSS by computed tomography (CT). Preoperative CT images were used to evaluate the diameter of the PSS for coil placement. A multipurpose balloon catheter was percutaneously inserted into the PSS via the jugular vein, and transvenous retrograde portography (TRP) and measurement of blood pressure in the PSS (pPSS) were performed during balloon inflation; one or more embolization coils were implanted via the catheter.

Results: In most cases, preoperative median fasting and postprandial serum total bile acid (TBA) concentrations were high (fasting, 86.5 μmol/L [ 3.7-250.0 μmol/L]; postprandial, 165.5 μmol/L [ 1.5-565.0 μmol/L]). CT revealed that 30 dogs had left gastrophrenic shunt; eight had left gastroazygos shunt; and one each had left gastrocaval, splenocaval, splenophrenic, and left colocaval shunt. TRP revealed that intrahepatic portal vascularity was clearly detectable in all dogs. The median values of pPSS before and during the balloon occlusion were 4.8 mmHg [2.0-13.0 mmHg] and 8.6 mmHg [5.0-18.0 mmHg], respectively. The median number and diameter of coils used were 2 coils [1 - 5 coils] and 8.0 mm [4.0 - 12.0 mm], respectively. The median times of irradiation and PTCE were 9 min [4-26 min] and 40 min [23-75 min], respectively. The median fasting and postprandial TBAs significantly decreased to 8.2 μmol/L [0.3-45.1 μmol/L, n = 38, p = 0.0028] and 19.8 μmol/L [0.3-106.7 μmol/L, n = 38, p = 0.0018], respectively, approximately 1 month after PTCE. The clinical success rate of PTCE without requirement for a second surgery was 95.2% (40/42 dogs). During revision surgery, one dog underwent surgical ligation and, in another dog, an ameroid constrictor was placed.

Conclusions: PTCE was clinically effective in treating single extrahepatic PSS in dogs. Preoperative CT and TRP prior to PTCE might be clinically valuable for choosing the size of embolization coils, deciding the appropriate location of coil implantation, and estimating the number of coils to be implanted. PTCE is a promising alternative to conventional surgical procedures for single extrahepatic PSS in dogs.

Keywords: Coil embolization; Dog; Extrahepatic; Portosystemic shunt.

Fig. 1

Three-dimensional computed tomography (CT) images of left gastrophrenic and gastroazygos PSS. A Ventrodorsal view of the left gastrophrenic PSS. Green color and white arrows indicate the left gastric vein, PSS, and phrenic vein (red = arteries and heart; blue = caudal vena cava, hepatic veins, and kidneys; purple = portal veins). Grade 2 intrahepatic portal vascularity was observed. B Lateral view of the left gastroazygos PSS. Green color indicates the left gastric vein, PSS, and azygos vein (red = arteries, heart, and kidneys; blue = caudal vena cava and hepatic veins; purple = portal veins). Grade 3 intrahepatic portal vascularity was observed. PSS: portosystemic shunt

Fig. 2

Transvenous retrograde portography (TRP) images of left gastrophrenic and gastroazygos PSS. Images were acquired in the digital subtraction angiography (DSA) mode. During balloon inflation, the contrast agent was injected via the balloon-tipped multipurpose catheter, which was advanced into the PSS. The PSS diameter was measured according to on the (A) ventrodorsal view of the left gastrophrenic PSS and (B) right lateral view of the left gastroazygos PS. White line shows the site at which the PSS diameter was measured. PSS: portosystemic shunt

Fig. 3

Pressure in the PSS before and during temporal occlusion of the PSS. The PSS pressure during the temporal occlusion was significantly higher than that before. Before = PSS pressure before balloon inflation; during = PSS pressure during balloon inflation. *p < 0.001. PSS: portosystemic shunt

Fig. 4

Radiographic images after percutaneous transvenous coil embolization (PTCE). A Ventrodorsal view: two 6-mm embolization coils were implanted into the left gastrophrenic PSS. B Right lateral view: two 10-mm and one 8-mm embolization coils were implanted into the left gastroazygos PSS. PSS: portosystemic shunt