Sunday, December 6, 2015

Vascular Access / Arteriotomy Closrue Devices

Any arterial case, whether for a diagnostic 4-vessel angiogram, coronary catheterization, or transarterial chemoembolization, will require access into an artery, most commonly the right common femoral artery. After the case ends, the artery needs to be closed to achieve hemostasis and prevent further bleeding. The most basic closure "device" is manual pressure for 15 minutes. While this is effective, the downsides include no true closure of the wound in the vessel wall, operator dependence, and limited reliability in patients with large body habitus.

Closure devices have been developed to both mitigate the risks of bleeding as well as reduce the suite time required for such cases. Below are step by step instructions (and links to videos) for several common devices:

StarClose

This device functions by placing a metallic clip around the arteriotomy. While effective, the drawback is that a permanent device is left within the patient, potentially limiting future access. 

  1. Video: http://www.abbottvascular.com/us/video/starclose-video.html
  2. Prep groin, kit by flushing introducer stylet into hub
  3. Exchange 5/6Fr sheath over wire for introducer
  4. Remove wire and stylet together, leaving stylet. Fix left hand against patient.
  5. Attach StarClose to introducer [#1] and switch left hand to device.
  6. With R hand, push [#2] to break the seal and deploy footplate.
  7. GENTLY RETRACT DEVICE UNTIL TENSION FELT - footplate now against inner wall.
  8. With R#2 above, #3+4 on handle, use R thumb to depress [#3] to fully break seal
  9. Tilt handle straight up, then push [#4] to deploy clip.
  10. Hold manual pressure for 2 minutes.


PerClose

This device is suture mediated. The suture is absorbable, and multiple PerClose's can be used to close larger arteriotomies. 

  1. Video: http://www.abbottvascular.com/us/video/proglide-shc-video.html
  2. Prep groin; prep kit with saline into sideport where blood will come, wet introducer part
  3. Exchange 5/6Fr sheath over wire for introducer
  4. Once white triangle reached, remove wire
  5. Advance until *pulsatile* blood return seen - Retract [#1] to deploy footplates
  6. Retract device until blood return disappears
  7. Deploy [#2] to advance suture through wall
  8. Deploy [#3] to loop suture through arteriotomy. Pull out stylet and cut suture
  9. Depress [#4] to close footplate
  10. Pull back device to free both sutures, then pull through. Remove device.
  11. Put knot pusher on LONG thread and push down with LEFT thumb on top of device
  12. Synch down on suture with short thread.
  13. Take knot pusher off long thread and place on both. Repeat motion, but now cut knot.


Mynx GRIP

This device functions by placing an absorbable polyethylene glycol plug in the tissue tract above the arrteriotomy.  


  1. Video: https://www.youtube.com/watch?v=_kcJM1lnQo8
  2. Prep groin; prep kit with saline into sideport where blood will come, wet introducer part
  3. Draw 3 cc NS into syringe
  4. Introduce wire/balloon through existing sheath until white marker.
  5. Inflate balloon until inverse Oreo (white-black-white) seen at back of device. Close stopcock
  6. Grasp black handle and pull back two stops (balloon to sheath tip; balloon-sheath to vessel wall)
  7. Open sheath sidearm to confirm temporary hemostasis
  8. Advance shuttle to definitive stop, then withdraw sheath back to starting position
  9. Grasp the white tube at skin level and advance until green marker fully expose to tamp PEG grip tip onto vessel wall
  10. Hold in place for 30 seconds, then lay down for 90 seconds
  11. WIthdraw syringe to full negative, open stopcock, and withdraw through pusher device.
  12. Withdraw pusher device while holding pressure on vessel up to 60 seconds


To learn more about these closure devices and IR procedures in general, check out the Handbook of Interventional Radiologic Procedures:


Monday, November 23, 2015

Pull Percutaneous Gastrostomy Tube

A prior post detailed how to place a conventional gastrostomy tube as an interventional radiologist. However, a variant based on the approach endoscopists use is the pull percutaneous gastrostomy tube. Other names for this technique are the mushroom or Ponsky gastrostomy tube. The steps are as follows:

  1. Verify an appropriate window for the gastrostomy tube on pre-procedure imaging. In particular, make sure that the transverse colon does not lie between the anterior abdominal wall and the stomach. Alternatively, use ultrasound to check for liver margin and a rectal enema to opacify the transverse colon. 
  2. Check if the patient has a nasogastric tube. If not, using anesthetic gel and a glidewire, a Kumpe catheter can be fluoroscopically guided into the stomach. Have an assistant use the tube to insufflate the stomach. Point the Kumpe straight back with the tip facing down, then flip it 180 degrees to lead away from the trachea.
  3. Once the stomach is sufficiently inflated, anesthetize the skin. A good location is midway along the greater curve as the passes will aim towards the fundus.
  4. Use a 19G Chiba needle to access the stomach. Once intraluminal position confirmed, direct the needle posteriomedially towards the NG tube (ideally, nudge it under fluoro). 
  5. Leading with an 0.035” Amplatz, direct the wire retrograde up the esophagus. 
  6. An assistant will retrieve the wire from the mouth. Once outside, attach a snare (comes in kit) to the back end of the wire near the stomach and pull the snare through to the mouth. 
  7. Release the snare from the wire, then tie a hitch knot to the gastrostomy tube. 
  8. Pull the gastrostomy tube antegrade through the esophagus into the stomach. 
  9. Store a fluoro image with contrast injection to verify location.

Be mindful that a near absolute contraindication to this procedure is any patient with skull base, head and neck, or esophageal cancer / obstruction.

There are several benefits to placing a primary gastrostomy tube in this manner:
  • No T-Tacks to cut
  • 20 Fr instead of 14 Fr, so decreased risk of clogging
  • More durable
  • No pigtail within the gastric lumen, so less concern for gastric outlet obstruction
  • Generally less messy because no dilatation needed, and only one stick into the abdominal wall
Bard's Version of the Pull G-Tube (Copyright Bard)



Monday, June 22, 2015

Lymphangiogram

A lymphangiogram is an uncommon procedure that can be performed by interventional radiologists, typically to identify and potentially treat the source of a chylous leak.

Pre Procedure

  • Indications: Thoracic duct injury, usually from surgery, causing chylous effusion / chylothorax, or recurrent chylous ascites
  • Surgical management (direct fix of the leak intraoperatively if visualized) and medical management should be optimized first. 
  • Specifically, the patient should be on a low fat / medium chain triglyceride diet. Long chain triglycerides are absorbed by the lymphatics, which leads to extra lymph production. Medium chain triglycerides however are absorbed by the portal veins, reducing the production of lymph.  

Procedure

  • Transpedal approach: prep the feet
  • Inject 50/50 mix of isosulfan blue and lidocaine into the webbing between toes and wait 10-15 minutes for dye to be picked up by lymphatics
  • Make incision parallel to lymphatic
  • Strip away fat/tissue parallel to lymphatic
  • Insert backing (cardboard/plastic) underneath lymphatic
  • Insert 30 gauge needle into lymphatic and inject 100% lidocaine
    • Bubble test: watch to see if air goes into lymphatics, or if it fizzes
  • Take serial x-rays of lower extremities and abdomen to see lymphatics and eventually cysterna chyli fill
  • Once filled, can insert 21 gauge needle directly into cisterna chyli and perform embolization, usually with coils and/or N-butyl cyanoacrylate glue

Post Procedure

  • Evaluate for recurrent leak

Monday, June 15, 2015

A Simplified Approach To Spinal Masses

Spinal cord masses can be confusing at times, especially if not encountered routinely. While it may be difficult to arrive at a specific diagnosis, a narrowed differential can often be very helpful to the referring clinician. Clinical history is also quite useful at narrowing the differential.

The first question to ask is where exactly is the tumor located within the spinal canal. The broad categories are: intramedullary, intradural-extramedullary, and extradural. An intramedullary mass will be centered within the substance of the spinal cord itself, which has been described as the claw sign. An intradural-extramedullary mass will form a meniscus with the cord and push it away. An extradural mass will be outside the thecal sac. Vertebral body or clear epidural involvement suggests an extradural location. In cases where the distinction is difficult, assess the cord above and below the mass.

Once that determination has been made, the chart below can help generate a differential by focusing on both the imaging characteristics and clinical context:


The chart is not comprehensive, but it does list the most common primary masses to be found within those locations within the spine. As always, metastases are a consideration in any of these locations. Making the distinction can be challenging at times, especially when the mass is large and distorts normal structures.


References:

Monday, June 8, 2015

Leptomeningeal FLAIR Hyperintensity Differential Diagnosis

Hyper intensity in the subarachnoid space can have a wide range of causes. The finding may be subtle to detect at times. However, identifying it can be crucial in altering a patient's management. The mnemonic FLAIR can be used to recall the common causes of this finding:

DiseaseNotes
FFiO2 highNo contrast enhancement
LLeptomeningeal spread of tumorGEMCLOG: glioblastoma, ependymoma, medulloblastoma, choroid plexus tumor, lymphoma, oligodendroglioma, germinoma
AAneurysmal bleedNo contrast enhancement
IInfection (meningitis)
RpRopofolNo contrast enhancement, may also be due to increased oxygen