Updated: Oct 2, 2008
Coarctation of the aorta is a narrowing of the aorta most commonly found just distal to the origin of the left subclavian artery. Most patients with coarctation have juxtaductal coarctation. Older terms, such as preductal (infantile-type) or postductal (adult-type), are often misleading.
The vascular malformation responsible for coarctation is a defect in the vessel media, giving rise to a prominent posterior infolding (the "posterior shelf"), which may extend around the entire circumference of the aorta. The gross pathology of coarctation varies considerably. The lesion is often discrete but may be long, segmental, or tortuous in nature.
Histology
The coarctated aortic segment reveals an intimal and medial lesion consisting of thickened ridges that protrude posteriorly and laterally into the aortic lumen. The ductus (ie, patent embryonic remnant) or ligamentum arteriosus (closed and fibrosed) inserts at the same level anteromedially. Intimal proliferation and disruption of elastic tissue may occur distal to the coarctation. At this site, infective endarteritis, intimal dissections, or aneurysms may occur. Cystic medial necrosis occurs commonly in the aorta adjacent to the coarctation site and acts as a substrate for late aneurysm formation or aortic dissection in some patients.
Embryology
Coarctation is due to an abnormality in development of the embryologic left fourth and sixth aortic arches that can be explained by 2 theories, the ductus tissue theory and the hemodynamic theory.
In the ductus tissue theory, coarctation develops as the result of migration of ductus smooth muscle cells into the periductal aorta, with subsequent constriction and narrowing of the aortic lumen. Commonly, coarctation becomes clinically evident with closure of the ductus arteriosus. This theory does not explain all cases of coarctation. Clinically, coarctation may occur in the presence of a widely patent ductus arteriosus, and it may occur quite distant from the insertion of the ductus arteriosus, such as in the transverse arch or abdominal aorta.
In the hemodynamic theory, coarctation results from reduced volume of blood flow through the fetal aortic arch and isthmus. In a normal fetus, the aortic isthmus receives a relatively low volume of blood flow. Most of the flow to the descending aorta is derived from the right ventricle through the ductus arteriosus. The left ventricle supplies blood to the ascending aorta and brachiocephalic arteries, and a small portion goes to the aortic isthmus. The aortic isthmus diameter is 70-80% of the diameter of the neonatal ascending aorta.
Based on this theory, lesions that diminish the volume of left ventricular outflow in the fetus also decrease flow across the aortic isthmus and promote development of coarctation. This helps to explain the common lesions associated with coarctation, such as ventricular septal defect, bicuspid aortic valve, left ventricular outflow obstruction, and tubular hypoplasia of the transverse aortic arch. This theory does not explain isolated coarctation without associated intracardiac lesions.
This condition represents 5-10% of all congenital cardiac lesions. It represents 7% of critically ill infants with heart disease.
Coarctation is 7 times more common in whites than Asian persons. It has a lower incidence among Native Americans than other population groups in Minnesota.
Male-to-female predominance is 1.3-2:1 in most series.
Age at detection of coarctation of the aorta is dependent on severity of obstruction and coexistence of other lesions.
The history of those with coarctation of the aorta includes the following.
The diagnosis of coarctation generally can be made on physical examination. Blood pressure differential and pulse delay are pathognomonic.
The exact etiology of coarctation of the aorta is not known.
No specific laboratory tests are necessary for coarctation of the aorta.
Catheter-based intervention is now the preferred therapy for recurrent coarctation when the anatomy permits and necessary skills are available. Its use in native or unoperated coarctation is less well established. Treatment may be with balloon angioplasty alone or with a stent. Outcomes are good in skilled hands, but residual or recurrent coarctation with resultant hypertension and repair site aneurysms can occur. Catheter-based treatment can cause death from aortic rupture and dissection, but mortality compares favorably with surgery if coarctation is recurrent, and perhaps for initial treatment.
The immediate improvement in hypertension and morbidity were similar across all groups. Surgical therapy was associated with a low risk of restenosis and recurrence, whereas endovascular therapy had much higher incidence of restenosis and need for repeat interventions.4 Endovascular therapy is highly promising in elderly and frail patients with multiple comorbidities who pose a high surgical risk. Overall, long-term outcome of endovascular approaches need to be evaluated.
See Surgical Care.
As with all aortopathies and aortic valve problems, significant and prolonged isometric activities are contraindicated. The risk of dissection, even in repaired coarctation, remains significant and may be increased with isometric activity.
No specific medications are used to treat coarctation of the aorta because it is a mechanical obstruction. In the neonate, management of concomitant congestive heart failure may include prostaglandin E1 to maintain patency of the ductus arteriosus. Beyond the neonatal period, management of congestive heart failure may include digoxin and diuretics.
This agent promotes vasodilatation by direct effect on the vasculature and smooth muscle of the ductus arteriosus.
Used to maintain patency of ductus arteriosus when cyanotic lesion or interrupted aortic arch presents in newborn. Most effective in premature infants.
Currently used as part of protocols; recommended dosages have yet to be established
For palliation: 0.05-0.1 mcg/kg/min continuous IV infusion; may be increased to 0.2 mcg/kg/min if necessary
None reported
Documented hypersensitivity; respiratory distress syndrome; persistent fetal circulation
X - Contraindicated; benefit does not outweigh risk
Because of potential risk of apnea, neonates are usually intubated prophylactically; caution in neonates with bleeding tendencies; prolonged use occasionally necessary (eg, in patients with hypoplastic left heart syndrome who are transplant candidates) and may be associated with third spacing of fluid
These agents increase the contractility of cardiac muscle in a dose-dependent manner (ie, positive inotropic effect).
Cardiac glycoside with direct inotropic effects in addition to indirect effects on cardiovascular system. Acts directly on cardiac muscle, increasing myocardial systolic contractions. Its indirect actions result in increased carotid sinus nerve activity and enhanced sympathetic withdrawal for any given increase in mean arterial pressure.
Loading dose: 1 mg (0.5 mg then 0.25 mg q6h X 2) PO/IV
Maintenance dose: 0.125-0.375 mg/d PO/IV
Dosing is age and weight based; total digitalizing dose (TDD) is administered in mcg/kg/d
Loading dose: 1/2 TDD followed by 1/4 TDD q8h X 2
Maintenance dose <10 years: Divided dose bid
Maintenance dose >10 years: Administered qd
Medications that may increase digoxin levels include alprazolam, benzodiazepines, bepridil, captopril, cyclosporine, propafenone, propantheline, quinidine, diltiazem, aminoglycosides, oral amiodarone, anticholinergics, diphenoxylate, erythromycin, felodipine, flecainide, hydroxychloroquine, itraconazole, nifedipine, omeprazole, quinine, ibuprofen, indomethacin, esmolol, tetracycline, tolbutamide, and verapamil; medications that may decrease serum digoxin levels include aminoglutethimide, antihistamines, cholestyramine, neomycin, penicillamine, aminoglycosides, oral colestipol, hydantoins, hypoglycemic agents, antineoplastic treatment combinations (including carmustine, bleomycin, methotrexate, cytarabine, doxorubicin, cyclophosphamide, vincristine, procarbazine), aluminum or magnesium antacids, rifampin, sucralfate, sulfasalazine, barbiturates, kaolin/pectin, and aminosalicylic acid
Documented hypersensitivity; beriberi heart disease; idiopathic hypertrophic subaortic stenosis; constrictive pericarditis; carotid sinus syndrome
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Hypokalemia may reduce positive inotropic effect of digitalis; IV calcium may produce arrhythmias in digitalized patients; hypercalcemia predisposes patient to digitalis toxicity, and hypocalcemia can make digoxin ineffective until serum calcium levels are normal; magnesium replacement therapy must be instituted in patients with hypomagnesemia to prevent digitalis toxicity; patients diagnosed with incomplete AV block may progress to complete block when treated with digoxin; exercise caution in hypothyroidism, hypoxia, and acute myocarditis
These agents inhibit electrolyte reabsorption in the thick ascending limb of the loop of Henle, thus promoting diuresis.
Commonly used diuretic with moderate diuretic potency.
Usual dose: 20-80 mg PO/IV q6-12h; not to exceed 600 mg/d
Continuous IV infusion: 0.05 mg/kg/h; titrate to effect
Dosages are age and weight based
Usual dose: 0.5-2 mg/kg/dose PO/IV q6-12h
Maximum dose: 6 mg/kg/dose PO; 2 mg/kg/dose IV
Metformin decreases concentrations; interferes with hypoglycemic effect of antidiabetic agents and antagonizes muscle-relaxing effect of tubocurarine; increases auditory toxicity associated with aminoglycosides—hearing loss of varying degrees may occur; may increase anticoagulant activity of warfarin; may increase plasma lithium levels and toxicity
Documented hypersensitivity; hepatic coma; anuria; severe electrolyte depletion
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Perform frequent serum electrolyte, carbon dioxide, glucose, creatinine, uric acid, calcium, and BUN determinations during first few months of therapy and periodically thereafter
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aorta coarctation, coarctation of aorta, cardiac lesion, juxtaductal coarctation, preductal coarctation, postductal coarctation, vascular malformation, coarctated aortic segment, infective endarteritis, cystic medial necrosis, coarctation of the aorta, narrowing of the aorta, ductus tissue theory, hemodynamic theory, ventricular septal defect, bicuspid aortic valve, left ventricular outflow obstruction, tubular hypoplasia of the transverse aortic arch, congenital cardiac lesions, XO Turner syndrome, aortic arch hypoplasia, extracardiac vascular anomalies
Sandy N Shah, DO, MBA, Private Practice, Houston, Texas
Sandy N Shah, DO, MBA is a member of the following medical societies: American College of Cardiology, American Heart Association, and American Osteopathic Association
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Dawn M Calderon, DO, Co-Director of Center for Adults With Congenital Heart Disease, Clinical Associate Professor, Departments of Cardiology and Internal Medicine, Deborah Heart and Lung Center, Robert Wood Johnson School of Medicine
Dawn M Calderon, DO is a member of the following medical societies: American College of Cardiology and American Osteopathic Association
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Alan D Forker, MD, Professor of Medicine, Program Director of Cardiovascular Fellowship, University of Missouri at Kansas City School of Medicine; Director, Outpatient Lipid Diabetes Research Center, MidAmerica Heart Institute of St Luke's Hospital
Alan D Forker, MD is a member of the following medical societies: Alpha Omega Alpha, American College of Cardiology, American College of Physicians, American Heart Association, American Medical Association, American Society of Hypertension, and Phi Beta Kappa
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Frank M Sheridan, MD, Cardiology, Providence Everett Medical Center
Frank M Sheridan, MD is a member of the following medical societies: American College of Cardiology, American Heart Association, and Society for Cardiac Angiography and Interventions
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Amer Suleman, MD, Consultant in Electrophysiology and Cardiovascular Medicine, Department of Internal Medicine, Division of Cardiology, Medical City Dallas Hospital
Amer Suleman, MD is a member of the following medical societies: American College of Physicians, American Heart Association, American Institute of Stress, American Society of Hypertension, Federation of American Societies for Experimental Biology, Royal Society of Medicine, and Society of Cardiac Angiography and Interventions
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George A Stouffer III, MD, Henry A Foscue Distinguished Professor of Medicine and Cardiology, Director of Interventional Cardiology, Cardiac Catheterization Laboratory, Chief of Clinical Cardiology, Division of Cardiology, University of North Carolina Medical Center
George A Stouffer III, MD is a member of the following medical societies: Alpha Omega Alpha, American College of Cardiology, American College of Physicians, American Heart Association, Phi Beta Kappa, and Society for Cardiac Angiography and Interventions
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