Presentation of Infantile Aortic Coarctation in an Adult

Abstract

Rarely, the initial presentation of aortic coarctation, a congenital anomaly, occurs in adults. Surgical repair is indicated for symptomatic patients. We report the case of a 68-year-old woman who underwent successful surgical repair of the infantile (preductal) type of aortic coarctation with use of an interposition graft. (Tex Heart Inst J 2001;28:304–7)

Coarctation of the aorta is a congenital narrowing of the thoracic aorta that usually occurs just before or after the insertion of the ductus arteriosus remnant. This lesion, which is seen primarily in the infantile (preductal) form, is the 8th most common congenital heart defect but rarely presents for the 1st time in an adult. ^1,2 Herein, we report the case of a symptomatic adult in whom infantile aortic coarctation was successfully repaired with an interposition Dacron graft.

Case Report

In January 1999, a 68-year-old woman presented with symptoms of headache, chest pain, and fatigue when walking. Her long-standing hypertension, which had recently become more difficult to control, was being treated with triple-drug therapy (amlodipine, losartan, and clonidine). In 1970, cardiac evaluation had revealed a 22-mmHg difference in brachial pressure between the right and left arms (146/90 vs 124/90 mmHg, respectively). Aortic angiography at that time revealed kinking of the aortic arch between the left carotid and subclavian arteries without narrowing, and the diagnosis of pseudocoarctation was made.

In January 1999, the patient was re-evaluated after her symptoms became more severe. Physical examination revealed a 65-mmHg difference in brachial pressure between the right and left arms (200/90 vs 135/90 mmHg, respectively). A harsh bruit, which was transmitted to both carotid arteries, was heard at the base of the neck (left side) and in the intrascapular region. Weak left brachial and femoral pulses were palpated bilaterally. Laboratory evaluation revealed blood count and chemistry results within normal limits, except for an elevated blood urea nitrogen (BUN) level of 25 mg/dL. Cardiac catheterization revealed normal coronary anatomy, a hyperdynamic left ventricle, and an elevated left ventricular end- diastolic pressure of 19 mmHg. Angiography showed kinking and stenosis of the distal aortic arch. The recorded mean gradient across the coarctation was 30 mmHg. Magnetic resonance angiography further clarified the pathologic changes, revealing elongation and narrowing of the distal aortic arch between the left carotid and left subclavian arteries. The transverse diameter of the proximal aortic arch (25 mm) narrowed to 8 mm at the coarctation before enlarging to 26 mm at the descending thoracic aorta (Fig. 1). The left subclavian artery, small and tortuous, entered the aorta distal to the coarctation. The patient was referred for surgical repair.

Fig. 1 Magnetic resonance angiogram (left anterior oblique projection) shows infantile (preductal) coarctation of the aorta. The distal aortic arch is tortuous and elongated, and the diminutive left subclavian artery arises distal to the coarctation.

After induction of general anesthesia and dual-lumen intubation of the trachea, a spinal drainage catheter was placed. Right brachial and femoral artery catheters were placed in order to monitor the arterial pressure. A left thoracotomy was performed to expose the distal aortic arch. The phrenic and vagus nerves were carefully dissected and preserved. The distal aortic arch beyond the origin of the left carotid artery was found to be tortuous, elongated, and heavily calcified. The ligamentum arteriosum was divided and oversewn. Heparin was administered, after which the left atrium and distal descending thoracic aorta were cannulated for partial left-heart bypass. The aortic arch was cross-clamped just distal to the left common carotid artery and at the level of the mid-descending thoracic aorta. The left subclavian artery was occluded with a vessel loop. Upon application of the aortic cross-clamp, the patient's femoral artery pressure fell abruptly to 30 mmHg. Bypass flow was adjusted to a rate between 500 and 1000 cc per minute in order to maintain a mean distal aortic pressure greater than 50 mmHg.

The coarctation was partially excised, with care taken to preserve the recurrent laryngeal nerve. Aortic continuity was restored with an 18-mm Dacron graft (Hemashield®; Boston Scientific Corporation; Natick, Mass). The left subclavian artery was incorporated in the distal anastomosis. Upon completion of the repair, pulses in all 4 extremities were found to be equal. Antihypertensive treatment was required only during the first 24 hours postoperatively. There were no postoperative complications. The patient was extubated on postoperative day 1, transferred from the intensive care unit on day 2, and discharged from the hospital on day 6. When seen 10 months postoperatively, the patient was doing well clinically with improved control of her blood pressure (110/60 mmHg bilaterally) on losartan and amlodipine.

Discussion

Coarctation of the aorta, a congenital narrowing of the aorta that usually occurs near the site of insertion of the ductus arteriosus, is classified anatomically as preductal (infantile) or postductal (adult). Aortic coarctation has an incidence of 0.2 to 0.6 per 100 live births and accounts for 5% to 8% of all cases of congenital heart disease. ^1,2 The clinical presentation varies from cardiovascular collapse in infancy to asymptomatic hypertension in older children and in adults. Adults who have coarctation tend to present with proximal systemic hypertension that manifests as headaches, epistaxis, or cerebral aneurysm rupture. Left untreated, such patients have a much lower-than-average survival rate. ³ Because there is essentially no medical treatment for older children or adults with coarctation, they are usually referred for surgical repair.

Over time, surgical repair of aortic coarctation has expanded to include resection with end-to-end anastomosis, ⁴ prosthetic patch aortoplasty, ⁵ subclavian flap aortoplasty, ⁶ and aortic resection with graft replacement. Since further aortic growth is not a concern in adults, graft replacement or bypass is often used and produces the best results. ^7–9 Recently, angioplasty with or without stenting has been used successfully to treat lesions in both children and adults, primarily in those patients with recurrent coarctation. ^10,11 In view of the medial degeneration and calcification often found in histologic specimens from adult patients with coarctation, surgical resection and graft replacement is the preferred method to avoid rupture, aneurysm formation, or recurrent coarctation. Recoarctation is more common after balloon angioplasty than it is after graft replacement. After successful angioplasty, up to 25% of patients develop restenosis, and another 20% form aneurysms. ^12–14

Complications of surgical repair of aortic coarctation include hemorrhage, paradoxical postoperative hypertension, aneurysm formation, paraplegia, and re-coarctation. Paradoxical postoperative hypertension, if present, is usually secondary to increased sympathetic activity in the first 24 hours postoperatively ^15,16 and to increased renin-angiotensin activity thereafter. ^17,18 Surgically treated patients older than 21 years should receive close follow-up, because they are more likely than younger patients to experience persistent hypertension and cardiovascular complications. The most severe of these complications is an aneurysm or pseudoaneurysm occurring either distal to or at the site of coarctation. ^19,20

Paraplegia remains a serious complication after surgical repair of the descending thoracic aorta. In general, children with coarctation are considered to be at lower risk of spinal cord injury due to their bodies' ability to develop extensive intercostal collateral circulation to the distal aorta. In a review of 12,532 coarctation repairs, Brewer and colleagues ²¹ found postoperative neurologic deficits in only 0.41%. However, adults with coarctation may not have the abundant collateral circulation found in children, because later in life, segmental arteries may not develop at all, may atrophy, or may develop atherosclerotic occlusive disease. ²² In an earlier report on simple aortic cross-clamping for repair of the proximal descending thoracic aorta, we noted a 3% risk of paraplegia after the procedure. We also noted that the risk of spinal cord injury varied with aortic cross-clamping time (3% if ≤30 min vs 8% if > 30 min). ²³ Partial left-heart bypass provides a convenient method of distal aortic perfusion, which reduces the risk of ischemic injury to the spinal cord, kidney, and abdominal viscera. Distal aortic perfusion also helps control proximal aortic hypertension, which in turn decreases the workload of the heart, lowers the risk of stroke and myocardial infarction, and averts visceral ischemia, acidosis, and declamping hypotension. ²⁴ Some authors ^25,26 have suggested that distal aortic perfusion pressures should be maintained above 50 to 60 mmHg, since pressures below this level may increase the risk of paraplegia. Cerebrospinal fluid drainage has also been reported to provide a measure of spinal cord protection. ²⁷

In conclusion, the presentation of infantile aortic coarctation for the 1st time in an adult is unusual. We performed successful surgical repair in a 68-year-old woman who had severe symptoms and uncontrolled hypertension caused by infantile coarctation of the aorta.