Fig. 6.1
Fluoroscopy in AP view demonstrates a guidewire (long arrow) advanced through the femoral and iliac arteries toward the aorta. The sheath (delineated by the opposing small arrows) is already in place enabling convenient advancement of wires, catheters, and other devices. The hub of the sheath is faintly visible (arrowhead). The diagnostic catheter (thick arrow) has just been introduced over the guidewire into the sheath. The tip of the catheter is just beyond the hub. Usually, catheters are advanced with the guidewire leading and retracted with the guidewire tip within the catheter
To ensure maximal control, advance the wire or the catheter independently while stabilizing the other.
When manipulating/rotating catheter, ensure that the catheter outside the patient is completely straight. This will prevent counter torque from developing.
Aortic Arch
When advancing an angled catheter, ensure the tip is pointing downwards and the wire is distal to the catheter tip so that it does not inadvertently scrape the vessel wall.
When retracting the catheter to select a vessel, turn it approx 15° counterclockwise, so the tip is pointing upwards and withdraw slowly until the catheter ‘jumps’ into position indicating catheter engagement in the great vessel origin.
The origin of a vessel is identified by the anatomical landmarks, e.g., the brachial trunk is usually at the level of right second rib head in the LAO view.
We usually do not perform aortic angiograms except for situations such as aberrant anatomy, stenosis of the great vessel origins, or stroke (when CTA of head and neck has not been performed), where the aortic arch and the entire brachiocephalic vasculature bilaterally is visualized in a single AP run.
In case of difficulty catheterizing the vessel arising of the aortic arch, ask the patient to take a deep breath and hold it.
A Simmons 2 catheter may also be used, if the usual catheters are unsuccessful in catheterization. It is used as follows:
Advance the catheter over wire into the aorta.
When the catheter is in the ascending aorta, retract the wire well into the shaft. However, do not withdraw the wire completely out of the catheter.
Rotate the catheter counterclockwise, which will result in the distal aspect of the catheter acquiring a
like shape.
Maintaining this shape, gradually withdraw the catheter until it is positioned almost vertically in the descending aorta, with its tip just short of the aortic arch.
Advance the guidewire through the catheter and continue to advance until the tip of the catheter drops into the descending aorta. The distal aspect of the catheter will have reformed into an ‘inverted U’ shape with the convexity of the U leading.
Withdraw the wire from the catheter completely.
Advance the reformed catheter into the ascending aorta with the convexity leading and tip inferior.
Turn the catheter clockwise so that the tip points upwards.
Now gradually retract the catheter.
The tip will be seen to ‘catch’ the origin of brachiocephalic (BCT).
Pulling the catheter further will cause the catheter to advance further up in BCT.
Turning the tip medially or laterally during manipulation will result in selection of common carotid arteries (CCA) or Subclavian artery (SCA).
To retract the catheter from BCT, push/advance forward. Due to the shape of catheter, this will narrow the secondary curve resulting in the tip’s retraction out of BCT.
Keeping the tip pointing downward retracts the catheter until it is proximal to BCT origin and then rotates the catheter to point the tip up again. Further retraction will result in selection of left CCA.
After selection of CCA, further retraction of catheter will result in its advancement further into CCA.
As indicated above, pushing the catheter forward will result in its retraction from the CCA and then pointing the tip down, pulling it back, pointing the tip up and pulling further still result in selection of left SCA. When removing the catheter out, simply withdraw the catheter to lose the secondary curve format (taking care not to allow the tip to advance unsafely first) or reinsert the wire just short of the tip, so that it does not inadvertently reform in the descending aorta while being withdrawn, and select branches such as renal artery.
One of the authors does not attach a Simmons 2 catheter to the flush system, to enable greater manipulation. This necessitates even greater vigilance to ensure against emboli. If the intention is to maintain the Simmons as a Guidecatheter or if the navigation is protracted, then it must be connected to a continuous flush of heparinized saline.
During difficult catheterization, one may also do an aortic angiogram and use it as an ‘image overlay’. For aortic angiography a pigtail catheter should be used, the rate of injection is 20 ml/s for a total of 30 ml (‘20 for 30’). The usual diagnostic catheters may burst at this rate of injection. In such a case, exchange the pigtail catheter over exchange length catheter for the Simmons or other selected catheter because the table cannot be moved to follow the catheter up from the groin.
In difficult navigation, using a stiffer guidewire may help.
Brachiocephalic Trunk
Once the brachiocephalic trunk is selected with the catheter tip, advance the wire and then the catheter over it, e.g., may advance the wire well into subclavian or brachial artery so that it gives the catheter good support as it is advanced.
Usually, the right SCA and CCA can be catheterized without angiographic visualization. However, roadmapping may be performed, if needed.
To catheterize the SCA, the catheter tip is pointed laterally and it is advanced over the wire that has been advanced well into the SCA.
If the catheter tip is maintained in the subclavian, proximal to the vertebral artery (VA), the VA is frequently clearly visualized on angiography without having to catheterize it. If the catheter tip is distal to the VA, or the VA is not clearly visualized, then a blood pressure cuff may be applied to that arm and inflated. This will result in contrast reflux into the VA and better visualization.
For angiography in the brachiocephalic trunk, we use an injection rate of 6 ml/s for a total of 8 ml (‘6 for 8’). The frame rate is between 2 and 4/s with a rate rise of 0.4 s.
If the contrast injection is causing the catheter to kick out of the vessel, then the rate rise may be increased.
If the pathology is not clearly visualized, then one remedy may be to increase the number of frames/s.
Subclavian Artery
If difficulty is encountered in catheterizing the right SCA, the catheter is initially placed in the CCA. The wire is retracted into the shaft, and then the catheter is gradually retracted with the tip pointing laterally (to the patient’s right). A slight jump will be visualized as the catheter enters the subclavian ostium. Advance the wire into the subclavian, followed by the catheter.
The presence of wire in the shaft of the catheter diminishes the likelihood of its prolapse into the aorta.
In case a tortuous artery makes subclavian artery catheterization difficult, try a catheter with a sharper angle at its tip, e.g., HeadHunter H1.
The left subclavian artery is usually quite easy to catheterize. It is often in line with the descending aorta, and therefore frequently may be catheterized when the catheter is being advanced in the descending aorta. Should this happen, complete any required angiography via left SCA before retracting the catheter, in order to prevent repeat catheterizations.
For SCA angiography, the injection rate usually remains 6 ml/s for a total of 8 ml (‘6 for 8’). The frame rate is usually 4/s with a rate rise of 0.4.
Vertebral Arteries
If VA needs to be catheterized, the catheter is advanced over wire into the SCA, the wire is retracted into the catheter, the tip of catheter pointed upwards, and then the catheter slowly retracted back until the tip catches the VA origin.
There is no need to unnecessarily advance the catheter further into the VA beyond its origin.
On either side, the VA is diagonally across the internal mammary artery.
Visualization of the vertebral artery origin may be easier from a slight contralateral oblique AP view because it arises posteriorly and medially from the subclavian artery.Related posts:
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