Coarctation and PDA closure

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.

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.

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.

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.