Clinical presentation

The clinical presentation may vary from severe congestive heart failure in the neonate to hypertension and stroke in adolescents and adults. Coarctation represents approximate 6-8% of patients with congenital heart disease. It may be associated with other congenital heart disease such as bicuspid aortic valve and most complex forms of congenital heart disease such as Shone syndrome with multiple sites of left ventricular inflow and outflow tract obstruction. There is a recognized male predominance, with male-to-female ratio between 1.3 and 1.7. A clear genetic influence has been recognized in patients with Turner Syndrome (45X) with about 35% of Turner patients affected and notably 5% of girls with coarctation having Turner Syndrome. NOTCH 1 and MCTP2 genetic mutations have been reported in left ventricular obstructive lesions such as bicuspid aortic valve, coarctation of the aorta, and hypoplastic left heart syndrome.

The histology of juxtaductal coarctation often consists of a thick intimal and medial ridge projecting posteriorly and circumferentially into the aorta. Intimal thickening, hyperplasia, and calcification can be observed in older patients. Cystic medial necrosis with disarray of the media elastic tissue may provide the substrate for aortic dilation, aneurysm formation, and dissection.

Noninvasive imaging assessment

The initial imaging assessment of coarctation of the aorta should include transthoracic echocardiography, and magnetic resonance imaging or CT angiography. The primary purpose of the echocardiographic study will be to define any associated lesions such as bicuspid aortic valve, mitral valve abnormalities, and severity of ventricular hypertrophy. Transthoracic echocardiography will allow some visualization of the aortic arch and upper descending aorta. Some assessment of severity and site of obstruction is evident with additional color-flow and continuous wave Doppler echocardiography ( Fig. 26.1 ). However, the ideal method of coarctation imaging, particularly beyond infancy, is magnetic resonance imaging, since excellent three-dimensional reconstructions of the aortic arch and descending aorta can be obtained. In addition the two-dimensional images can be incorporated into the x-ray imaging obtained at catheterization to assist in catheter, balloon, and stent placement.

A-D Echocardiographic-Doppler findings in 12-year-old male with severe juxtaductal coarctation of the aorta with a prominent posterior ridge. The color flow images in B illustrate the turbulence a the coarctation posterior ledge. The continuous wave Doppler (C) confirms a mean systolic gradient of 36 mmHg and the abdominal pulsed Doppler (D) demonstrates the typical low velocity delayed-continuous flow consistent with severe aortic obstruction.

During infancy, if satisfactory arch and coarctation images cannot be obtained with echocardiography, CT images provide the most rapid and high-resolution images to define the severity or arch hypoplasia and the anatomy of the coarctation site ( Fig. 26.2 ). Both MRI and CT imaging can provide 3D reconstruction images that can be viewed in a rotation cine format or with a three-dimensional printed models ( Fig. 26.3 , Video 26.1). Such imaging can be particularly helpful to allow structural visualization and interventional planning.

CT provides the most rapid and high resolution imaging of the anatomy of the coarctation site.

This gothic type aortic arch also has some arch hypoplasia.

A. CT angio image of a 12-year-old male with severe juxtaductal coarctation of the aorta clearly defined in the 2D image. There also is mild arch hypoplasia present. B,C. 3D images of CT angio in a 49-year-old female with associated bicuspid aortic valve. Note the extreme severity of the coarcted segment with multiple collateral vessels present.

The site of coarctation, severity, proximity to other vascular structures such as subclavian or carotid vessels, and the presence of arch hypoplasia are all anatomic features which will determine the interventional procedure. When the coarctation involves the origin of the left subclavian artery, some have suggested minor surgical transfer of the subclavian to the left carotid would preclude concerns for obstruction of the subclavian.

Published reports of multicenter study of coarctation intervention results have indicated that age, severity of coarctation, and presence of previously surgical intervention or vascular injury (aneurysm) would significantly affect decision-making concerning the type of procedure and type of stent to be considered. They defined a discrete coarctation anatomically as a stenosis ≤5 mm and aortic aneurysm as a 10% increase in the aortic dimension from the adjoining aortic lumen. In particular, they noted that the risk of encountering a technical complication increased in patients over the age of 40 years. . Thus the use of covered stents would be an important technical consideration for the older population of patients.

AHA guidelines

Workup for transcatheter intervention

Prior to catheter intervention, 3D rotational angiography has been particularly helpful to define the anatomy of the coarctation site, its length, and severity. Fig. 26.4 and Video 26.2 illustrates a 3D rotational angiography obtained during catheterization. These images assist the interventionist to better understand the location, length, and severity of the coarctation, which in this example is a more diffuse lesion over several centimeters. In addition, some arch hypoplasia is evident. Hemodynamic study prior to intervention also represents a significant part of the assessment documenting gradient and LVEDP. Studies have defined significant resting coarctation gradient as ≥20 mmHg. In addition, LVEDP ≥12 mmHg is supportive in recognizing significant long-term coarctation hemodynamic effects.

A,B. 3D reconstruction of a rotational angiogram obtained in the catheterization laboratory in a 15-year-old male who had coarctation repair in infancy with a left subclavian flap technique. The reconstruction demonstrates the severity of a long segment of obstruction consistent with the type O repair used. There is also mild arch hypoplasia. C illustrates a rotational reconstruction after placement of a 36-mm bare metal stent and dilated to 15 mm to completely relieve the obstruction.

Interventional techniques

During intervention, initial wire placement may provide better stability by placing the wire in the opposite subclavian artery. A simple juxtaductal coarctation that is distant from the arch and is approximately a 50% stenosis is demonstrated in Fig. 26.5 in a teenage patient with associated bicuspid aortic valve. The coarctation had been balloon dilated 6 years previously. The obstruction and gradient were completely eliminated with placement of a 36-mm bare metal stent dilated to approximately 16 mm. For a larger patient, subsequent stent redilation may be necessary to accommodate further growth. With native coarctation, a bare metal stent can be considered when complete dilation of the coarctation site may be limited by the dilation pressure necessary. Some investigators have considered 6 atms a reasonable pressure limit for initial dilation to avoid significant aortic wall injury.

A,B. Anterior-posterior and lateral views of placement wire located in the right subclavian artery for stent intervention. C illustrates an A-P view of the juxtaductal coarctation that represents approximately a 50% stenosis. D shows an A-P view of a 36-mm bare metal stent dilated to 15 mm with no evidence of residual aortic obstruction and no evidence of aortic wall unjury.

Procedural steps

Trancatheter aortic coarctation repair may require general anesthesia for hemodynamic stability and because of significant pain associated with aortic dilation. Femoral arterial access is established with ultrasound guidance. Patients are heparinized with 100units/kg, aiming for an ACT>250s.

The sheath size is determined by the anticipated final diameter to be achieved with the stent dilation; however, a 14 Fr sheath may be reasonable in instances where a covered stent may be necessary.

Depending on the anatomy and severity of the aortic coarctation, we select a pigtail (for less severe stenosis) or multipurpose or JR4 6F catheter and an 0,035” angle glide wire to cross the coarcted segment. This is advanced into the aortic root.

A. Aortic angiography or rotational angiography is performed to accurately delinate the aortic anatomy. The left ventricular pressure is recorded. A simultaneous gradient across the coarctation can be measured using the pigtail catheter in the ascending aorta and the sheath in the descending aorta.

A stiff exchange wire (e.g., Amplatzer extra stiff) is inserted. During intervention, initial wire placement may provide better stability by placing the wire in the opposite subclavian artery. If the stenosis is severe, predilation may be required before the sheath and stent can be advanced through the coarcted segment.

A long Mullin’s type sheath is advanced across the coarctation.

This is used to deliver the stent.

Once the stent is deployed, the pigtail catheter can be readvanced over the exchange wire and positioned in the aortic root to measure pressure and assess for any residual gradient.

If a residual gradient exists, postdilatation may be performed or a determination may be made to wait several months for a safer further dilation later.

More complex coarctation is illustrated in Fig. 26.12 . The patient is a 21-year-old male with biscuspid aortic valve and previously coarctation surgical repair at age 1 week. His hemodynamic cath demonstrates a 50 mmHg gradient primarily evident in the mid arch distal to the left carotid artery. The transverse aortic arch was 15-18 mm in diameter while the area of recoarctation was 7.5 mm in diameter. The descending aorta was 22 mm in diameter. A 36-mm open cell bare metal stent (eV3 Intrastent LD. max) was implanted in the coarctation with a 16-mm high-pressure balloon and dilated with up to 6-8 atms in pressure. The stent ends were flared with a 20-mm low-pressure balloon to approximate the stent to the aortic wall. The right subclavian artery originated anomalously at the stenosis and was dilated to 7-mm through an open stent cell. The nearly occluded left subclavian, which originated above the stenosis, was also dilated through an open stent cell with a 7-mm balloon. After stent placement there was a residual 7-mmHg gradient and mild stenosis as observed in the post-catheter CT angiogram reconstruction. Although advised to consider redilation of the stent, this was not performed, and 5 years post intervention he remains normotensive and on no medication.

A,B. CT angio in a 21-year-old male who had surgical repair of coarctation of the aorta at age 1 week. There is severe obstruction in the aortic arch just distal to the left carotid artery, and there is near occlusion of the left subclavian artery at the site of obstruction. There is anomalous origin of the right subclavian artery just distal in the descending aorta. C presents the hemodynamics measured at catheterization demonstrating a 50 mmHg gradient across the coarctation. D illustrates the angiographic definition of the major site of obstruction and its relationship to the subclavian arteries. E, F illustrates selective dilation of opened stent cells for the right and left subclavian arteries. G presents a follow-up CT angio after stent placement showing relief of the arch obstruction and widely patent access to both subclavian arteries.

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