Fig. 22.1
Aortic coarctation in LAT and AP projections
8.
Measurements (lateral projection is most commonly used): diameters of transverse arch distal to the brachiocephalic artery, distal to the left carotid artery, and distal to the left subclavian artery and minimum diameter of the coarctation, aorta below the coarctation, and the descending aorta at the level of diaphragm.
9.
The stiff exchange wire (such as Amplatz Super Stiff) is positioned across the coarctation with the soft J-curve in the ascending aorta or in the right or the left subclavian artery (depending on the anatomy).
10.
Selection of the balloon catheter:
Balloon diameter should not exceed the diameter of the aorta above the coarctation or at the level of the diaphragm.
It should not also exceed three times the diameter of the coarctation.
Low-profile balloon catheters should be used (such as Tyshak balloons). Low-pressure balloons may be effective in younger children, while high-pressure balloons are more effective in older children and patients with recurrent coarctation.
11.
Preparation of the balloon catheter: flush the guidewire lumen and remove the air from the balloon with syringe by creating vacuum.
12.
Over the wire, exchange the angiography catheter for the balloon catheter.
13.
Place the balloon at the level of the coarctation. Inflate the balloon with diluted contrast material (25 % contrast + 75 % saline). Appearance of the waist on the balloon indicates the site of coarctation. The balloon should be inflated till the waist disappears. Balloon should be kept inflated for approximately 10–15 s. After this time, the balloon should be deflated as quickly as possible. Additional balloon inflation is not recommended in the most cases but may be required if the balloon slips during inflation or the waist has not been completely abolished.
14.
After all the contrast material is removed from the balloon, it should be withdrawn through the sheath (continuous negative pressure is applied on the balloon lumen to diminish its profile).
15.
Exchange wire position should be maintained.
16.
Multitrack catheter is inserted over the wire to the ascending aorta.
17.
Repeat aortography in the same projection as prior to balloon dilation to check the anatomic result of dilation. Measure the diameter of coarctation.
18.
Repeat the hemodynamic measurements – pressures in the ascending and the descending aorta with pullback method.
22.6.3 Expected Results
1.
Systolic pressure gradient less than 10 mmHg.
2.
Increase diameter of aorta at the level of the coarctation.
22.6.4 Hints
1.
In infants less than 3 months of age, balloon dilation can only be recommended as palliation when these patients have severe left ventricular dysfunction or are at a high risk for surgery. It should be recognized that in this group of patients the restenosis rate is higher.
2.
If crossing the coarctation with guidewire from femoral artery proves difficult or impossible, try to cross it from above (through an axillary or brachial artery approach).
3.
Femoral artery pressure monitoring through the side port of the arterial sheath is very helpful in immediate assessment of dilation result.
4.
Rapid right ventricular pacing may be useful for stabilization of the balloon position during inflation, particularly in older patients.
5.
An Indeflator is useful to control and monitor the balloon pressure, but manual inflation can be performed with low-pressure balloons. This depends on individual operator’s experience.
6.
Avoid manipulation of the tip of catheters or guidewires in the dilated area or losing guidewire position and then trying to recross the dilated lesion.
7.
In older patients, the risk of wall complications increases, so stent implantation should be considered as the primary treatment, or covered stents should be available.
22.6.5 Pitfalls
1.
In patients with large collaterals, the guidewire and the diagnostic catheters may pass easily into the collaterals instead of the coarctation.
2.
Measurements needed to determine the size of the balloon should be accurate as errors in measurements may lead to complications.
22.6.6 Limitations
1.
Patients with coarctation of the aorta coexisting with marked transverse aortic arch hypoplasia should be referred for surgery.
2.
Patients with tubular or diffuse coarctation of the aorta and patients with aortic isthmus hypoplasia should be treated with stent implantation, especially in the older age group.
22.6.7 Main Complications
1.
Aortic wall dissection
Small dissection – additional balloon inflation for longer time (approximately 1–2 min). Repeat CT or magnetic resonance scan to follow the progress of the dissection and if necessary implantation of a bare or covered stent.
Larger dissection – implantation of a bare or covered stent during the same procedure.
2.
Small aneurysm
Repeat CT or magnetic resonance imaging scans to follow the progress of the aneurysm.
If necessary (when the diameter increases or there is a spiral aneurysm), implantation of a stent may be indicated.
3.
Larger or increasing aneurysm
Immediate implantation of a covered stent.
4.
Other complications include aortic rupture (emergency surgery or covered stent implantation) and femoral artery damage (thrombolysis or surgical repair).
22.6.8 After the Procedure
Antihypertensive treatment (same as before the procedure)
CT scan or magnetic resonance imaging assessment before discharge if there have been any complications during the procedure or 1 year later if the procedure was uncomplicated
22.7 Stent Implantation
First reported in 1991 [1], stenting aortic coarctation has proven to be an effective procedure for both residual and native lesions, providing excellent immediate relief of the obstruction and continuing to provide beneficial effects at medium-term follow-up, mainly in patients weighing more than 20 kg [2].
< div class='tao-gold-member'>
Only gold members can continue reading. Log In or Register to continue
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
