Coarctation of aorta

Coarctation of the aorta, or aortic coarctation, is a congenital condition whereby the aorta narrows in the area where the ductus arteriosus (ligamentum arteriosum after regression) inserts. Aortic coarctation is considered when a section of the aorta is narrowed to an abnormal width. The word “coarctation” means narrowing. Coarctations are most common where the aorta — the major artery leading away from the heart — arches toward the abdomen and legs. The aortic arch may be small in babies with coarctations. Other cardiac defects may also occur when coarctation is present, typically occurring on the left side of the heart. When a patient has a coarctation, the left ventricle has to work harder. Since the aorta is narrowed, the left ventricle must generate a much higher pressure than normal in order to force enough blood through the aorta to deliver blood to the lower part of the body. If the narrowing is severe enough, the left ventricle may not be strong enough to push blood through the coarctation, thus resulting in lack of blood to the lower half of the body. Physiologically its complete form is manifested as Interrupted aortic arch.

Types: There are three types:

1. Preductal coarctation: The narrowing is proximal to the ductus arteriosus. Blood flow to the aorta that is distal to the narrowing is dependent on the ductus arteriosus; therefore severe coarctation can be life-threatening. Preductal coarctation results when an intracardiac anomaly during fetal life decreases blood flow through the left side of the heart, leading to hypoplastic development of the aorta. This is the type seen in approximately 5% of infants with Turner Syndrome.
2. Ductal coarctation: The narrowing occurs at the insertion of the ductus arteriosus. This kind usually appears when the ductus arteriosus closes.
3. Postductal coarctation: The narrowing is distal to the insertion of the ductus arteriosus. Even with an open ductus arteriosus, blood flow to the lower body can be impaired. This type is most common in adults. It is associated with notching of the ribs (because of collateral circulation), hypertension in the upper extremities, and weak pulses in the lower extremities. Postductal coarctation is most likely the result of the extension of a muscular artery (ductus arteriosus) into an elastic artery (aorta) during fetal life, where the contraction and fibrosis of the ductus arteriosus upon birth subsequently narrows the aortic lumen.

Clinical features:

1.      Headache.

2.      Weakness and cramp in the legs.

3.      Pulse: Radio-femoral delay, weak femoral pulse, collaterial pulsation around scapula and intercostals ribs posteriorly.

4.      Blood pressure:

·         Raised in upper limbs.

·         Normal or low in lower limbs.

5.      Murmurs:

·         Systolic murmur posteriorly at the level of 4^th inter costal space ( due to turbulent flow through coarctation)

·         Continuous murmur over collaterals.

·         Systolic murmur over aortic area due to associated bicuspid aortic valve.

Investigations:

1.      Chest X-ray: 3 signs (indentation of descending aorta), rib notching from collaterals.

2.      ECG findings: Left ventricular hypertrophy (LVH)

3.      Aortography.

4.      MRI: Ideal for demonstrating the lesion.

Management:

1.      Surgical resection of coarctation & end-to-end anastomosis of the aorta.

2.      If recur: Balloon dilatation.

Prevention: Unfortunately, coarctations cannot be prevented because they are usually present at birth. The best thing for patients who are affected by coarctations is early detection. Some signs that can lead to a coarctation have been linked to things like Turner syndrome, bicuspid aortic valve, and other family heart conditions.

Reference:

1.      Davidson’s Principles and Practice of Medicine, 21^st edition.

2.      Wikipedia the free encyclopedia.