Chapter 15: The Intravascular Ultrasound–Guided Direct Intrahepatic Portacaval Shunt The transjugular intrahepatic shunt (TIPS) procedure is one of the most technically challenging and potentially hazardous procedures performed by interventional radiologists. As initially described, the TIPS is created from a “blind puncture” through the liver, generally from the right hepatic vein to the right portal vein (PV). When major complications arise, they are most often related to this step of the procedure.1,2 Many techniques have been devised to identify and localize the PV to aid in the puncture.3 Unfortunately, most of these methods have their limitations, and most interventionalists continue to use “blind puncture” through the liver when performing the TIPS procedure. The intravascular ultrasound (IVUS)–guided direct intrahepatic portacaval shunt (DIPS) procedure was initially conceived as a modification of the TIPS procedure. The DIPS procedure was designed to replace the “blind puncture” step of the TIPS procedure, using a safer, image-guided (IVUS) approach. The first DIPS were created using a homemade balloon-expandable Palmaz stent graft covered with polytetrafluoroethylene (PTFE).4 Previous research at the Dotter Institute had demonstrated that a PTFE covering of the stent would dramatically increase the durability of a transhepatic portal caval shunt.5,6 The use of a balloon-expandable stent graft also allowed for precise control of the diameter shunt and therefore the derived porto-systemic gradient. This we termed balloon-expandable gradients. The author has performed hundreds of DIPS procedures over the past 15 years. During this time period, the procedure has undergone only minor modifications. Since originally described, the greatest improvements have occurred in the IVUS imaging and development of stent grafts. Currently, we use the Acu-Nav IVUS system now from Biosense Webster (Johnson & Johnson Medical) and the VIATORR stent graft from W.L. Gore. In the DIPS procedure, the IVUS is used to guide the PV puncture, and it is also a great aid in positioning and deployment of the stent graft. Today, with current equipment, the routine procedural time to perform the DIPS continues be just over 1 hour, with fluoroscopy times just over 10 minutes. The DIPS procedure offers advantages over the conventional TIPS procedure because of guidance of the PV puncture, ease of stent graft placement, reduction of fluoroscopy times, and increased shunt durability. Also, in certain anatomic conditions, such as Budd-Chiari syndrome, and avoidance of hepatic masses, the DIPS may be preferable over the TIPS procedure. I have previously described the “coaxial sheath” method for performing the DIPS procedure.7 In some patients, the coaxial sheath method improves the alignment of the Rösch-Uchida liver access set (RUPS) puncture needle and Acu-Nav IVUS guidance. With this method, the needle and IVUS are essentially “locked” together, similar to a biopsy guide, and the alignment of these two devices remains stable. It also provides more support to the system during the transcaval puncture. This can be helpful in patients with extremely tough hepatic parenchyma (liver transplant) or extremely resistant PVs (PV thrombus). The disadvantage is that the setup is longer and requires extra sheaths. In general, the author now performs the procedure “freehand,” as was first described, and uses the coaxial sheath method only in selective cases. The freehand method is simple, safe, and effective and will be presented here. The coaxial sheath method is described in some detail by Petersen.7 • 10-Fr sheath (Cook Medical) • IVUS device (Biosense Webster, Johnson & Johnson) • RUPS (Cook Medical) • 65-cm EchoTip Trocar needle (Cook Medical) • 65-cm 4-Fr CXI catheter (Cook Medical) • Platinum Plus 0.018 180-cm guidewire (Boston Scientific) • Amplatz 0.035 180-cm guidewire (Boston Scientific) • 5-Fr Marker Pigtail (Cook Medical) • VIATORR stent graft (W.L. Gore) • Powerflex 8 mm × 6 cm balloon catheter (Cordis, Johnson & Johnson) • Two pressure transducers (Merit Medical Systems) To facilitate the direct transcaval puncture, it is essential that the RUPS be modified by adding a secondary curve to the 14-gauge metal trocar ( The 5-Fr catheter and the 62.5-cm-long sharpened 0.038-in wire stylet of the RUPS is not used for the transcaval puncture in the DIPS procedure. The wire 0.038-in stylet is replaced with a 65-cm-long EchoTip Trocar needle (Cook Inc.). The original EchoTip Trocar needle had a sharpened diamond tip, facilitating straight passage through tough liver parenchyma. The tip of the needle is scored, making it extremely echogenic ( A 5-Fr catheter will slip over this needle with a very smooth transition between the needle and catheter. The author first replaced the standard 5-Fr catheter of the RUPS with a hydrophilic 5-Fr catheter with a marker tip (Slip Cath, Cook, Inc.). The hydrophilic material aids in passage through the liver, and the marker tip aids in fluoroscopic visualization. The drawback to this approach is that the hub of the hydrophilic catheter must be cut off to make the appropriate length to match the trocar needle. This 5-Fr catheter must be cut to length, such that it is approximately 1 cm shorter than the trocar needle, such that the echogenic tip of the needle is not covered. More recently, the author has used 4-Fr crossing catheters, designed for peripheral vascular interventions, as a replacement for the 5-Fr hydrophilic catheter. These catheters are also manufactured at an inappropriate length for the procedure and must be cut to length as well. The 4 F CXI Support Catheter (Cook Inc.), placed over the 65-cm EchoTip Trocar needle has proven to be an excellent combination. Ideally, ultimately, a custom-made, crossing catheter of the appropriate length will be manufactured for this use. After the PV puncture, the passage of a 0.035-in lumen catheter (as described earlier) into the PV is probably the most difficult step of the procedure. This is because of the tough nature of the PV and because of working at a mechanical disadvantage from the neck. The creation of this needle puncture set is a very important modification of the RUPS. It allows upsizing from the 0.018-in lumen of the EchoTip Trocar puncture needle to 0.035-in guidewires necessary for the remainder of the procedure. For the DIPS procedure, an IVUS catheter is introduced into the right femoral vein and then into the IVC to the level of the PV. The IVUS is first used to guide a needle puncture from the IVC to the PV. This transcaval puncture is performed directly through the caudate lobe of the liver by the modified RUPS, which has been introduced through the right internal jugular vein. The IVUS catheter first used for the DIPS procedure was a 9-MHz mechanical probe from Boston Scientific. Similar to all other IVUS probes available at that time, it produced the typical 360-degree image oriented at 90 degrees from the transducer. When the DIPS was first performed, this probe was chosen because it was the lowest IVUS frequency probe available. Tissue penetration and visualization were adequate, and it was used successfully in the first 11 patients. Using this transducer, the average number of needle passes required to puncture the PV was from 1 to 3. With the “axial” type image produced by this transducer, the needle tip is visualized only by a bright reflector, crossing through the imaging plane, and as such, the entire needle path is not visualized ( Fig. 15.2 Cook EchoTip Trocar needle. The image demonstrates the scored, echogenic tip of the 65-cm EchoTip Trocar needle (Cook Inc.). This needle has the preferred diamond tip stylet in place. The most recent iterations have a beveled Chiba stylet. Regardless, this needle is much more echogenic than the 0.038-in sharpened wire needle of the standard Rösch-Uchida liver access set (RUPS) and traverses the liver much easier. It accepts a 0.018-in guidewire. The author no longer uses this IVUS imaging system but performs the DIPS with the Acu-Nav IVUS described later. However, the images presented in The Acu-Nav IVUS device first became available more than 10 years ago. It was initially marketed by the Acuson Company, then acquired by Siemens Corporation, and now marketed by Johnson & Johnson. It has replaced all other IVUS systems used for the DIPS procedure. It has advantages of improved resolution, lower frequency (variable 5–10 MHz), and color Doppler. Most importantly, it has a “side fire vector,” or sagittal imaging plane, such that the entire needle puncture tract through the liver may be visualized ( This device is designed for cardiac electrophysiology studies and interventions. It was originally manufactured as a 10-Fr device but is now available in both 8- and 10-Fr systems. The two catheters differ slightly in their sonic capabilities, but both give excellent imaging for the DIPS procedure. They are available only from Biosense Webster (Johnson & Johnson) but will connect to multiple different cardiac and traditional ultrasound units (Sequoia, Aspen, Cypress) all available from Siemens. Whereas the 10-Fr probe connected to the larger Sequoia unit has the most versatility, the smaller Cypress unit with the 8-Fr probe is more than adequate and is portable. The 8- and 10-Fr transducers are sold as single use only; however, the DIPS procedure is not taxing on either device, and if resterilized, they are capable of multiple uses. The DIPS procedure requires both right internal jugular and right common femoral venous access. If required, a combination of either contralateral jugular or femoral vein may be used. Use of either left jugular or femoral vein it is not recommended for novice interventionalists because alignment of the IVUS and modified RUPS needle may be difficult. Femoral vein access should be performed first. A 10-Fr, 40-cm sheath is placed into the access site. The Acu-Nav device should then be introduced into the IVC in a sterile fashion with the use of a cover over the handle. It is useful to support the cord of the transducer on the patient drape with the use of forceps, such that it will not be dislodged. The tip of the IVUS is placed near the intended site of puncture, the PV bifurcation. Next, all anatomy is verified with IVUS. The hepatic artery should be behind to the PV, which is anterior, because visualization is from the IVC. An aberrant replaced right hepatic artery may lie near the intended path of puncture and should be avoided. Color Doppler may be helpful to establish the patency of the PV, absence of thrombus, and other abnormalities but is generally not required because visualization is quite good. At low frequencies, the Acu-Nav has the ability to penetrate quite deep into the liver (>15 cm). Adjustment of both the magnification and frequency is required to achieve an image similar to
Introduction
Equipment
Femoral Access
Jugular Access
Equipment Modifications
Rösch-Uchida Liver Access Set
Fig. 15.1) of the set. This will form a “cobra” shape to the device. The secondary curve of the cobra shape aids the transcaval puncture by giving support off the back wall of the inferior vena cava (IVC). To bend the device, the RUPS is assembled, complete with the standard 5-Fr catheter, and a 0.035-in guidewire is inserted through the lumen. With the guidewire in place, simple hand pressure is used to bend the device. The secondary curve is placed at or near the junction of the 10-Fr sheath and 10-Fr introducing catheter. The guidewire in the lumen protects the 14-gauge metal trocar of the system from being “kinked” or narrowed. Either kinking of the 14-gauge metal trocar or forming too acute an angle of the cobra curve will cause friction on the puncture needle set and should be avoided. The goal is to make the curve as acute as possible while also allowing for easy passage of the needle set. Care must be used when introducing the newly curved device into the patient and straightening this new shape. Be aware that regardless of attempts to maintain an acute angle of the cobra shape, the relatively narrow width of the IVC tends to straighten, or flatten, this angle.
Needle and Catheter (Puncture Needle Set)
Fig. 15.2).
Intravascular Ultrasonography
Fig. 15.3). This imaging is similar to a jugular vein puncture performed under transcutaneous ultrasonography with the transducer held in a cross-sectional manner.
Fig. 15.3 are important because they are very similar to the images created by the 10-MHz system available from Volcano Industries today. This Volcano IVUS system may be used for the DIPS procedure if an Acu-Nav system is not available.
Fig. 15.4).
The Procedure
Step 1: Femoral Venous Access and Intravascular Ultrasound Placement
Fig. 15.4a. The Acu-Nav creates a sagittal image with cranial at the left-hand side of the image and caudal to the right. The ultrasound machines have the ability to invert left to right, so the operator should make sure that this is correct.
Thoracic Key
Fastest Thoracic Insight Engine
