Coarctation of the aorta – what it means and how it’s treated
Coarctation of the aorta is an extracardiac (literally, outside of the heart) condition which is congenital, and which affects the body’s main systemic artery – the aorta – usually around the level of the aortic arch.
Coarctation simply means “narrowing”, so a coarctation of the aorta is a narrowing of the aorta. As above, that narrowing usually occurs around the level of the aortic arch, and often in the vicinity of the ductus arteriosus (a communication between the pulmonary and systemic arterial circulation that is always present before birth, and usually closes shortly after birth).
The length of tissue affected and the degree of narrowing present will vary from patient to patient, and the coarctation of the aorta may present with one or more other structural anomalies. There is some observed association between this lesion and other lesions affecting the left side of the heart.
The effects of coarctation of the aorta
The narrowing in the aorta imposes a significant degree of extra stress on the left ventricle (the chamber in the heart that pumps oxygenated blood around the body). This is because the left ventricle has to pump harder to get oxygenated blood past the narrowed area and towards the body below this point. There is also likely to be an observable pressure differential in bloodflow before and after the coarctation (the differential is in direct proportion to the degree of the narrowing).
Children with a severe degree of this condition typically exhibit symptoms of high blood pressure in their upper body, and low pressure in their lower body: for this reason, one way to test for this condition is to measure blood pressure above and below the level of the aortic arch: a significant differential between the two measurements would strongly imply the presence of an anomaly (probably a narrowing) at the aortic arch.
A large proportion of children who suffer from this condition will be diagnosed within the first year of life: they will have a more severe degree of narrowing and the type and severity of symptoms manifested will reflect that (hence it is picked up more quickly). However, diagnosis can occur very late – it is not unheard of for this to occur during the patient’s teens.
Parents may find that:
- if the narrowing is mild, then symptoms may be barely noticeable or actually absent.
- if present, symptoms characteristically include breathing difficulties, problems with feeding and failure to thrive.
- if the condition goes undetected, then symptoms including dizziness, fainting and shortness of breath may arise. These are associated with the extra strain the condition imposes upon the heart.
- the likelihood of higher blood pressure in the upper body can lead to fatigue, headaches and nosebleeds. The corresponding likelihood of lower blood pressure in the lower limbs can lead to sensations of coldness in the patient’s feet and/or legs, and/or pain upon exercise.
How coarctation of the aorta can be diagnosed and treated
If the child’s symptoms are severe, it is probable that echocardiography (a form of ultrasound) would be sufficient to make a diagnosis. Echocardiography is very good at detecting anomalies of flow, and it is correspondingly likely that a narrowing which significantly impeded the flow of blood would be visible on echocardiography.
In older children and teenagers, other diagnostic imaging might be required to confirm the diagnosis (possibly MRI or angiography).
Once the diagnosis has been made and clarified, it might be appropriate to do nothing if the symptoms are either mild or non-existent. Surgical treatment is likely to be indicated if the symptoms are more severe.
Surgery typically involves the dissection and excision of the narrowed portion of the aorta, and either joining (anastomosing) the two ends of the aorta, or alternatively placing a surgical stent (a length of tubing) in position.
A less invasive alternative would be to perform angioplasty. This involves the insertion of a device into the arterial circulation. It is guided to the site of the narrowing and once in position, a balloon is inflated, thus widening the artery. There is some evidence of coarctation recurrence after balloon dilatation. It is therefore not unknown for more than one corrective procedure to be required.
In order to place a stent, the two ends of the aorta on either side of the narrowed section must be clamped. The narrowed section is then cut out, and the stent is stiched into place. There is a limited amount of time within which to complete the surgical manoeuvres relating to this. The risks of this surgery are related primarily to the manoeuvres and the clamping of the aorta.
Whenever an operation on the aortic arch occurs, there is also a risk of stroke. This is because an interruption of blood supply to the brain is likely to occur. It is possible to mitigate this risk and, unsurprisingly, the research literature suggests that meticulous pre-operative planning is highly advisable.
If the lower body is deprived of oxygenated blood for a sufficiently lengthy period of time, then a range of issues can ensue. In one case we are aware of, the surgical stent was fitted and blood was let back into the aorta. At this point, the stent shot off the repair site on the arc of a jet of blood, and the surgical team lost it. The aorta was re-clamped and there was a desperate hunt around the operating theatre for the stent. It was eventually retrieved and reinserted. The patient was left paraplegic.