Coarctation of the Aorta
Chandni Patel, MD
Kurt Bjorkman, MD
Jeremy D. Asnes, MD
Key Points
Coarctation of the aorta may be first identified in adolescence or adulthood with hypertension often being the first presenting sign.
Intervention for coarctation should be approached cautiously and methodically.
For native coarctation, current recommendations suggest a multidisciplinary approach incorporating input from surgeons, cardiologists, and interventionalists with adult congenital heart disease expertise to determine surgical versus catheter-based intervention.
For recurrent discrete coarctation, guidelines favor percutaneous catheter intervention over surgery.
Stent angioplasty has been shown to have superior outcomes and lower complication rates as compared with both balloon angioplasty and surgery.
Covered stents should be available during interventional procedures in the event of serious aortic wall injury.
Given the risk of aortic wall injury with catheter-based intervention for coarctation, routine follow-up with either CT angiography or MR angiography should be performed.
I. Introduction
A. Coarctation of the aorta describes a wide variation of anatomic narrowing of the aorta, most commonly occurring as a discrete lesion in the proximal thoracic aorta opposite the insertion site of the ductus arteriosis.1 However, even when discrete, coarctation is considered to be part of a generalized arteriopathy.2 It is one of the more common congenital lesions, accounting for 5%-10% of all congenital heart disease. Genetic influences on coarctation have long been suspected with a well-documented male predominance of disease with an incidence ratio of 1.7:1.3 This genetic link is further evidenced by coarctation appearing in 35% of patients with Turner syndrome (45X). NOTCH1 and MCTP2 have recently been recognized as possible loci for disease.4,5
B. Permutations of this disease exist not only in location but also in length, severity, coexisting conditions, time of presentation, and complications.1 Rarely, coarctation involves the ascending or abdominal aorta.6 Although most often diagnosed in infancy or childhood, aortic coarctation may first be identified in adolescence or adulthood. Furthermore, with increasing survival and patient longevity, significant rates of residual coarctation, as well as recurrence postintervention, are seen well into adulthood.7,8,9,10
C. Hypertension of the aorta and its branches proximal to the obstructed aortic segment is the most obvious consequence of this disease. However, coarctation-associated hypertension is only one component of a complex arteriopathic disease. Moreover, although it is
tempting to consider treatment of coarctation as a simple procedure directed at relief of aortic obstruction and hypertension, the care of the patient with aortic coarctation requires a life-long, often multidisciplinary approach that should include experts in adult congenital heart disease.
II. Coexisting Disease
A. Occurrence
1. Coarctation most commonly occurs in conjunction with other congenital heart lesions including aortic arch hypoplasia, ventricular septal defects (VSDs), patent ductus arteriosus, transposition of the great arteries, atrioventricular canal defects, and left-sided obstructive lesions including abnormalities of the mitral valve and the subaortic region.11
B. Anomalies
Coarctation is also associated with extracardiac vascular anomalies including important variations in brachiocephalic artery anatomy, a robust collateral arterial circulation, and intracranial aneurysms.1,11,14
Arterial collaterals may arise from the internal thoracic and subclavian arteries, thyrocervical trunks, and vertebral and anterior spinal arteries and provide blood supply to the descending aorta, bypassing the obstruction caused by the coarctation itself.15 The aortic wall itself is abnormal and predisposed to dissection and rupture.16
III. Natural History
A. The natural history of uncorrected coarctation of the aorta was described by Campbell in 1970 after reviewing the records of 465 patients who had survived the first year of life.
1. Of these, there was a mean age of death at 34 years, and 75% of patients died by age 46 years, with the most common causes of death including congestive heart failure (26%), aortic rupture (21%), endocarditis (18%), and intracranial hemorrhage (12%).3
B. Life expectancy is significantly improved with intervention, but still notably reduced from nonaffected populations with survival rates of 72% at 30 years after operation in those operated on at median age of 16 years, and 81% survival at 50 years after surgery in those operated on before the age of 5 years.17,18
C. In patients who have had corrective intervention, the most common causes of late death are coronary artery disease, sudden cardiac death, heart failure, cerebrovascular accidents, and ruptured aortic aneurysm.17 Thus, intervention is essential to prevent significant morbidity and mortality.
IV. Presentation and Examination Findings
A. Presentation
1. The most common presenting sign of disease in the patient with aortic coarctation is systolic hypertension, and perhaps the most easily identified finding is a differential between the upper extremity and lower extremity systolic blood pressure.19
Patients presenting with coarctation-associated hypertension fall into one of the three categories: those with “native” coarctation for which no prior intervention has been undertaken; those with residual or recurrent obstruction at or adjacent to a site of prior catheter or surgical intervention, so called recurrent coarctation; and those with well-repaired coarctation, no residual aortic arch obstruction, and persistent hypertension (Fig. 5A.1).
2. Not discussed in this chapter is the far more uncommon presentation of a patient with complications of aortic aneurysm related to a prior coarctation repair.
B. Examination Findings
1. Aside from hypertension, notable physical examination findings may include diminished and delayed femoral pulses as compared with the radial pulse (pulsus parvus et tardus) as well as a cardiac murmur.
2. A systolic ejection murmur from the coarctation may be heard in the left upper sternal border, at the base of the heart, and in the back. In addition, continuous murmurs may be heard over the anterior chest wall and back in patients with a robust collateral arterial system.
3. Associated lesions such as aortic valve stenosis, VSDs, or mitral stenosis will produce their own distinct murmurs as well.1
4. Surgery for coarctation may be performed from a left or right lateral thoracotomy, or from a median sternotomy (most often in the setting of concomitant cardiac disease or arch hypoplasia). Surgical scars will help guide an understanding of the approach taken in patients without a well-known history.
V. Evaluation
A. Testing and Imaging
1. Blood pressure assessment in all four extremities
2. Full physical examination including identification of scars related to prior surgery
3. Echocardiogram to assess associated congenital cardiac disease and/or surgical repairs and myocardial function
4. Thoracic CTA (CT angiography) or MRA (MR angiography) for detailed assessment of the entire thoracic aorta and its branches
FIGURE 5A.1: A, Native coarctation in a 40-year-old man who had previously undergone ascending aorta and aortic valve replacement (narrowest diameter 4.5 mm). B, 4.5-cm-long Cheatham Platinum Covered Stent premounted on 22 mm balloon-in-balloon catheter; deployment with inner balloon inflated. C, Outer balloon inflated at 3 atm. D, Final angiogram following covered stent angioplasty.
5. Imaging of the intracranial vasculature (CTA or MRA) is recommended to exclude coexisting aneurysms, which can be seen in up to 10% of patients with coarctation16,21
6. In the older adult or others at risk for peripheral vascular disease, consideration should be given to assessment of the femoral and iliac arteries (CTA or MRA)
B. Anatomic Considerations
1. Notably, 3%-4% of patients with coarctation will have an aberrant right subclavian artery arising from the descending aorta distal to the obstruction, complicating the assessment of a blood pressure differential.
2. Furthermore, in patients with a robust arterial collateral circulation, the blood pressure differential may be reduced, masking the severity of the aortic obstruction.
3. In addition, surgical approaches to coarctation may include sacrifice of the left subclavian artery as a component of the repair (subclavian flap technique).
In these patients, the blood pressure in the left arm is unreliable.
Owing to a combination of anatomic variation and/or surgical repair, there is no reliable, noninvasive means of assessing the systolic blood pressure proximal to a segment of narrowed aorta.
VI. Indications for Treatment
American and European guidelines for the treatment of adult patients with congenital heart disease include specific recommendations regarding the treatment of aortic coarctation.2,16 A summary of indications for intervention can be found in Table 5A.1.
VII. Goals of Therapy
A. The primary goal of any interventional therapy for aortic coarctation is to normalize the luminal diameter of the narrowed segment of the aorta and thereby eliminate the pressure gradient across the coarctation. In most but not all patients, this will lead to improvement in hypertension and a decrease in the need for antihypertensive medication.
B. Determining the appropriate or “normal” target diameter of the aorta in a patient with coarctation requires assessment of that individual’s aortic dimensions from the transverse arch to the distal thoracic aorta at the level of the diaphragm. There is often aneurysmal dilation of the ascending aorta, particularly when a bicuspid aortic valve is present. There may also be associated transverse arch hypoplasia, which in and of itself can lead to hypertension in the proximal arch and ascending aorta even after successful treatment of a discrete coarctation. Typically, there is aneurysmal dilation of the aorta just distal to the coarctation, but the dimensions of aorta at the level of the diaphragm are preserved. Thus, the diameter of the aorta at the diaphragm is often used as a therapeutic target.
C. Garcier et al. reported aortic lumen dimensions measured by MRI in 66 healthy adults with a mean age of 44.5 years (range 19.3-82.4 y).22 The mean diameter from the distal aortic arch to the midthoracic aorta ranged from 25 mm (range 16.4-35 mm) at the distal arch to 22.7 mm (range 13.8-32 mm) at the level of the left ventricle.22 Because of the coexisting aortopathy, these dimensions may not apply to individuals with aortic coarctation. However, when considering therapy in a young patient with growth potential, they must be kept in mind.
TABLE 5A.1. Indications for Intervention in Patients With Aortic Coarctation | |
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VIII. Treatment Options
A. Measures of Success
1. The successful treatment of aortic coarctation must be measured across multiple domains. In the hypertensive patient with native or recurrent coarctation, the overarching goal is reduction of systolic blood pressure.
However, it is well known that resting and exercise hypertension is common in this population, even in the absence of persistent aortic obstruction.
Furthermore, hypertension can be partially mitigated with pharmacologic therapies in some patients with aortic obstruction.
Thus, measures of therapeutic success may include not only angiographic improvement in aortic lumen size but also reduction in gradient, reduction in blood pressure at rest and/or with exercise, reduction in symptoms (when present), and reduction in antihypertensive medication requirements.
2. Measures of procedural success include not only therapeutic success but also the absence of significant procedure-related morbidity and mortality including aortic wall injury and aneurysm formation.
B. Surgery
1. Surgical repair of aortic coarctation may be accomplished through several different approaches including coarctectomy with direct end-to-end anastomosis or extended end-to-end anastomosis, interposition graft placement, bypass graft placement, and subclavian flap or patch aortoplasty. In patients with recurrent coarctation, understanding the initial surgical approach is critical to understanding the cause of recurrent obstruction and how to best manage it.
2. Current guidelines recommend surgical intervention for long-segment recoarctation and coarctation in the setting of aortic arch hypoplasia.16
Furthermore, these guidelines recommend that surgery be performed by surgeons with expertise in congenital heart surgery.
With regard to discrete native coarctation, guidelines do not specify a preference for surgery or transcatheter approach, but rather recommend a multidisciplinary approach incorporating input from surgeons, cardiologists, and interventionalists with adult congenital heart disease expertise.
For recurrent discrete coarctation, guidelines favor percutaneous catheter intervention over surgery.
C. Intervention Recommendations Surgery carries up to a 10% reintervention risk for older children and adults23 and in one study spanning several decades was associated with a perioperative mortality of 4.5%.17 Thus, there has been a shift recently toward percutaneous approaches (balloon angioplasty or stent placement) for primary intervention in adults with uncomplicated native coarctation.16,23,24 In patients with recoarctation, the general consensus favors, with rare exception, the transcatheter approach regardless of the age. In particular, stent angioplasty has come into favor as the intervention of choice
in adults with native or recurrent coarctation because of its superior outcomes and lower complication rates as compared with both balloon angioplasty and surgery.25 We describe in the sections that follow the available percutaneous options for treatment of coarctation of the aorta.
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