Categories
techniques

The 10 Minute Renal PTAS

renal stenosis 1

The trick to doing a 10 minute renal PTAS is all in the planning and visualization. Firstly, the CTA with 3D reconstruction (TeraRecon) gives excellent diagnostic images for arteries above 2mm in diameter and therefore obviates the need for additional diagnostic imaging if obtained before the planned intervention. The arteriography for the intervention then is focused on confirming the pathologic findings of the CTA. This patient has had prior lower extremity revascularization and has been troubled by difficult to control hypertension (4 meds) and mild renal insufficiency. Renal duplex found elevated velocities consistent with a >60% stenosis of his right renal artery. CTA revealed this, but also demonstrated a wealth of information regarding his aorta, his aorto-bifemoral graft,  an asymptomatic SMA stenosis. So my initial plan was given his hypertension was to perform a focused renal arteriogram and intervention with minimal time and contrast.

Planning

The first thing I did was go to TeraRecon and plan out access and camera angles. The CTA can show troublesome plaque, tortuosity, or lesions that could spell trouble for access. I decided to access the right hood of his aorto-bifemoral bypass graft above the anastomosis of his fem-pop bypass. Scar tissue, which can be problematic for sheath entry, can aid in excellent hemostasis. The camera angles and location of the renal arteries were determined with TeraRecon. I angled the view to see the right renal artery (above) at a orthogonal plane to my perspective -this turned out to be 20 degrees (see below). renal stenosis 2
Without TeraRecon, this is possible with axial views by creating a clockface and generating an “o’clock” with each hour being about 30 degrees (see above). The origin of the right renal artery is about 9:30 by this scheme. This give me the camera angle to find the renal without shooting an aortogram solely for the purpose of locating the renal artery. We already have an aortogram in the form of a CTA. The 3D reconstruction also informs us that the renal artery comes off at the base of the L2 spinal body at about 15 degrees LAO.

renal stenosis 3
This processed image from TeraRecon shows the skeletal landmarks where the origin of the RRA would be. The LIMA catheter is drawn on.
Access

I performed ultrasound guided access of the right femoral graft limb. Ultrasound allowed me to avoid the fem-pop graft. A micropuncture kit uses a small guage needle which is allows for repuncture. The sheath that comes with this comes with a stiff variant which goes through scar tissue well. I place a 6F sheath and send a wire into the aorta over which I send a 6F LIMA guiding catheter. This is actually a “cardiology style” of access, and the way coronary arteries are accessed. The guide catheters do need to be set up with Touhy-Borst connectors and 3 way stopcocks.

With the camera properly pre-angled, when the LIMA catheter comes in full profile, it should aim the tip at the angle of the takeoff of the renal artery. Using a 0.14 wire (Spartacor) in my case, I start probing with the wire tip at the base of L2 -another important piece of preplanning data. Usually, access to the renal artery is very straightforward at this point. The Spartacor wire has the backbone to support passage of stents and balloons. I use a 145cm length wire, and stents mounted on rapid exchange catheters. Renal arteriography is done through the LIMA catheter with hand injection, and intervention is very straightforward.

renal stenosis 4
The predeployment arteriogram shows the renal orifice to be smaller than the 6F LIMA guide catheter. After stenting, the artery no longer has a stricture at the origin.
The rapid exchange systems allow for quick catheter exchanges. Wires and catheters are removed. Total procedure times 10-15 minutes, and total contrast volume 10-20mL of contrast. This camera prepositioning, catheter profiling, spinal body aiming technique also works well in EVAR if you don’t have the 3D mapping package. Extra arteriography in localizing the renal orifices can often be avoided.
Categories
PAD techniques

Completion Angiography –is it necessary?

Completion angiography fits into the range of things that many of us were taught to do because it might help avoid the problem of early graft failure. I remember a time in the nineties when vascular surgery was synonymous with terrifyingly long bypass operations that sometimes worked. Back in that preinternet era, all day bypass operations were capped at the end with a flat plate arteriogram. As with all things archaic and historic, I firmly believe that our trainees should feel comfortable with this type of on-table arteriography because not every place will have a corridor of rooms with robotic c-arms. I feel that each trainee should feel comfortable wheeling in a portable c-arm, assembling it, turning it on, put in patient information, and perform a study. But I digress. The completion arteriogram clearly has a role in bypass surgery, but I question its usage as a “I do it all the time” routine. When anything is written in stone, it immediately takes on a hallowed, sanctified aura, usually taken on during M&M’s when the person at the podium intones beatifically looking skyward, “the completion arteriogram showed no abnormalities.” Science is about questioning the status quo and backing up practice with evidence.

The purpose of the arteriogram is to evaluate the anatomy for treatable lesions. Screening for these lesions can be just as easily performed with handheld pulse Doppler and if needed, duplex ultrasound. In my experience, the triad of pink toes, palpable pedal pulses, and multiphasic signals in the distal anastomosis is more than enough evidence to start drying up and closing. In this particular case shown in the picture above, the anastomosis looked pristine, but the signals were weak and monophasic in the distal anastomosis despite palpable pulses. Arteriography reveals the reason below, but frankly, the arteriogram was dispensible even in this case (trainees –reason why?). In fact, arteriography takes care of the surgeon more than it does the patient. Tan et al [J Vasc Surg 2014;60:678-85] for the Vascular Study Group of New England, including my friend Dr. Alik Farber, reviewed the VSGNE database and found that a strategy of compulsive completion studies which included angiography or duplex ultrasonography, did not improve short term or 1 year graft patency.

Categories
CTA imaging PAD techniques training

Intuition Aquarius (TeraRecon) Trick -Applying Virtual Reality to Operative Planning

I have used many different flavors of image post processing software including Osiris, Vitrea, and now Aquarius, aka TeraRecon. But I notice that outside of endovascular planning, people rarely use the virtual 3D reconstructed images (the pretty pictures) for anything other than posting images for publication in JVS, and even there I think we have reached saturation.

I have found 3D reconstruction to be especially useful for open surgical planning, and that is by doing two things. First, on viewing the 3DVR data, I reorient and center on the surgeon’s perspective, using left button to rotate the picture around the zero at the center of the screen, and the right mouse button to grab the whole image and recenter as necessary.

Window Leveling.001
Surgeon’s eye OR view

I then window-level in tissue density -this is done by pressing both the right and left mouse buttons, but you can choose this off the menu.

Window Leveling.002

I can plan the incisions and exposures from any angle -in this case, I can see the saphenous vein and its relative proximity to the CFA to perform an in site bypass to the AK POP. And I see the loci of the tributaries that I may need to ligate.

Window Leveling.004

This is a powerful tool that is often overlooked.

Categories
AAA EVAR techniques TEVAR

Percutaneous EVAR and TEVAR -how to get there if you aren’t doing it right now.

24F Access pEVAR
22 French Percutaneous Access circa 2008

Percutaneous access for EVAR and TEVAR does several things. First, the procedure becomes shorter by an hour or two, and (don’t discount not having nursing count instruments because the case was percutaneous). Second, the patients experience far less discomfort and it is easier to discharge them the next day when they have a bandaid versus an incision. And this leads to the third thing: not having an incision means it is far less likely that a groin infection will occur, especially in the obese.

There are three things which you must do before undertaking pEVAR. First, you have to become comfortable with using the Perclose S device in 6F-8F access -about 5 to 10 successful closures will do. You should become facile with the deployment of the sutures and closure of the access point. Avoid small arteries or heavily calcified arteries. This leads to the second point -all of your groin access should be ultrasound guided -this has been shown to improve results in pEVAR (Ref 1). I am a firm believer that the source of groin access complications starts with the initial needle stick. The 18g needle is basically a short 11 blade rolled up into a cylinder, and during groin access without ultrasound imaging, one can shear branch arteries, skewer arteries, dissect plaque, and access too proximally or distally, or into the profunda femoris.

needle is scalpel

The third need is access to 3D reconstruction software and multislice CTA. This gives you powerful ability to predict which patients are more suitable for a percutaneous approach, and which should have a cut down, and with 3D virtual reality reconstructions, you can plan where the incisions will be. In the skinny patient, this is not a pressing issue, but in the merely obese and the frankly obese, and the super obese, choosing to go percutaneous and avoiding a groin complication, which may be the one thing that debilitates the patient far more than a stent graft deployment, becomes an easy decision with experience.

As you build your 6-8F Perclose experience, you may notice that having too tight and subcutaneous tract can result in the suture catching on SQ fat, and not closing, or that bleeding won’t surface properly and create a hematoma under Scarpa’s fascia, often after the patient gets to the recovery room. Expanding on this principle, as you leap to 12F access and preclosure, I recommend you try this -make a 10mm incision, and using a tonsil clamp, pop through Scarpa’s fascia and seat the tips of the clamp under ultrasound on top of the soft part of the CFA that you intend to access. Gently spreading creates the space that you need to deploy the sutures and ensure that any bleeding will exit the skin and not dive under the fascia. It amounts to an ultrasound guided dissection of the common femoral artery. Before you remove the tonsil, you gently maneuver a micropuncture (always) access needle between the tines of the tonsil clamp until it gets to the artery -this keeps the eventual wire going through the tunnel you just made.

12F can usually close with a single Perclose, but start practicing by placing two Perclose sutures in a 10 oclock and 2 oclock orientation. Once the sutures are in, I make sure the  two ends of the suture are pulled out and the end loop of the suture is on the artery and I clamp these sutures to the drapes medially and laterally depending on how I deploy the two sutures. This also helps avoid catching the suture and driving it into the aorta.

After performing EVAR or TEVAR, I remove the sheath, leaving a wire -typically the stiff wire originally supporting the sheath and deploy one of the sutures. This first suture should cinch down onto the artery and substantially decrease the bleeding coming from the access site. I then deploy the second suture, and if the bleeding has stopped or is a steady dribble, I remove the wire. If pulsatile bleeding persists, I recinch the sutures using the knot pushers. If this decreases flow, I remove the wire, otherwise, I place a dilator, stop the bleeding and cut down. Cutting down after SQ dissection means merely dividing skin and tissues over the dilator, and the artery is easily visible for suture placement. If I remove the wire and there is still some bleeding, and usually there is, I place Gel-Foam soaked in diluted thrombin into the tract, reverse heparin, and hold pressure for 10-20minutes. It is very rare to have to convert after this is done.

thrombin gelfoam
thrombin-gelfoam into tract

The skin is closed with an absorbable 4-0 monofilament suture, and skin glue. I usually use the micropuncture needle to give an ilioinguinal field block with Marcaine. This gives 24hrs of pain relief.

bandaids

A note about incisions. Usually, with 3D VR imaging of CTA, the CFA and its quality (size and absence of plaque), and location relative to the inguinal crease can be ascertained. I try to make the access point at the inguinal crease or distally, as this goes under the subpannus of groin fat rather than through it.

groinaccess
3D-VR imaging can pinpoint optimal access

I sincerely believe sheath size is not the limiting factor to percutaneous access. Rather, it is the common femoral and iliac artery. Zakko et al at the University of Florida just published their experience on the obese with percutaneous TEVAR (ref 2), and found that while the arteries were deeper, the technical success rate of staying percutaneous (over 90%) was no different between their obese patients non-obese patients. The predictors of failure were poor access artery quality and size. I believe that you can select for patients most likely to succeed and greatly reduce failure. In this population, groin complications are potentially life threatening, and avoiding an open groin exposure is valuable.

 

References

1. J Vasc Surg 2012;55:1554-61 (ultrasound guided access)

2. J Vasc Surg 2014;60:921-928 (p-TEVAR and obesity)