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SECTION VI - Coarctation of the Aorta
Part I - Background Information
Coarctation of the aorta is a stenosis, usually but not always, in the region of the ligamentum arteriosum. Rarely, it can occur in the ascending or abdominal aorta. It is usually discrete but may be associated with diffuse hypoplasia of the aortic arch and isthmus. The specific anatomy, severity and degree of hypoplasia proximal to the aortic coarctation is highly variable.
Simple aortic coarctation refers to discrete coarctation in the absence of other intracardiac lesions. It is the most common form detected de novo in adults. "'Complex' aortic coarctation is used to describe coarctation in the presence of other important intracardiac anomalies and is usually detected in infancy. The most common associated abnormalities are VSD, aortic stenosis, subaortic stenosis or a combination, accounting for 2/3 of cases of 'complex' aortic coarctation. The ratio of 'simple' to 'complex' aortic coarctation is approximately 1:1.
A significant aortic coarctation is usually one with right arm hypertension and a peak pull back gradient of more than 20 mmHg across the coarctation site at angiography. If there is extensive collateral circulation, a significant aortic coarctation may have minimal or no pressure gradient and even acquired aortic atresia.
Associated cardiovascular abnormalities include:
- Bicuspid aortic valve (up to 85%).
- Berry (intracranial) aneurysms of the circle of Willis (3-5%).
- Anomalies of the brachiocephalic circulation such as anomalous origin of the right subclavian artery (5%) or involvement of the left subclavian artery in the coarctation.
- Collateral circulation both anteriorly (involving the internal mammary arteries) and posteriorly (involving the intercostal arteries).
- Aortic medial disease in the para-coarctation aorta, and in the ascending aorta if a bicuspid aortic valve is present.
- VSD.
Non-cardiovascular abnormalities, involving the respiratory, gastrointestinal, genitourinary tracts or musculoskeletal system have been reported in up to 25% of cases. There is good evidence that coarctation is usually associated with a diffuse arteriopathy that persists even after repair of the coarctation itself.
Part II - Prevalence and Genetics
Coarctation of the aorta is more common in males, with a male to female ratio of 1.3-1.7:1. It is usually sporadic, but genetic influences can play a role (up to 35% of Turner syndrome (45,X) females have aortic coarctation). Very rarely, it may be autosomal dominant.
Part III - History and Management of Unoperated Patients
Presentation in adolescence/adulthood is usually with upper limb hypertension, differential arm-leg pulses, headaches, exertional leg fatigue or an incidental murmur. Symptoms are often absent. Rarely, presentation may be with an intracerebral hemorrhage. An occasional patient may be diagnosed from the typical x-ray appearance.
The mean survival (prior to widespread surgical repair and modern diagnostic methods) of patients with untreated aortic coarctation was 35 years, with 75% mortality by 46 years of age. Most developed systemic hypertension, typically during childhood, and ultimately, by the 5th decade, left ventricular failure.
Death in untreated aortic coarctation is usually due to:
- Heart failure, usually beyond 30 years of age (28%).
- Aortic rupture/dissection (21%).
- Infective endarteritis/endocarditis (18%).
- Cerebral hemorrhage (12%).
- Premature coronary artery disease.
- Concomitant aortic valve disease (usually involving a bicuspid aortic valve).
Part IV - Diagnostic Recommendations
An initial diagnostic workup should document:
- The location and type of aortic coarctation together with its severity.
- The presence (or absence) and severity of other intracardiac lesions (bicuspid aortic valve, mitral valve abnormalities, subaortic stenosis, VSD).
- Left ventricular function and the presence (or absence) of left ventricular hypertrophy.
- The presence (or absence) of other extracardiac cardiovascular anomalies such as collateral circulation, involvement of other vessels (subclavian/carotid stenoses) and associated aneurysms.
The diagnostic workup should include at a minimum:
- a thorough clinical assessment, including upper and lower limb blood pressure measurement, determination of radiofemoral pulse delay, palpation of femoral and distal pulses and auscultation for collaterals around the scapula.
- ECG which may show signs of left ventricular hypertrophy 'strain'.
- Chest x-ray which may show the '3 sign' (caused by indentation of the aorta at the site of the aortic coarctation, combined with dilation before and after the coarctation) or 'rib notching' (caused by erosion of the inferior border of the posterior ribs by enlarged intercostal arteries).
- Echo Doppler evaluation by an appropriately trained individual. The echo window, in particular the suprasternal arch view, may be difficult in adults.
- MRI to delineate the coarctation anatomy, possible aneurysm formation and with velocity mapping, assess the degree of restenosis. Contrast MR angiography may allow visualization of arch geometry and collaterals (76).
The diagnostic workup may require:
- Invasive angiography with hemodynamic measurements to assess the aortic coarctation gradient and nature of the obstruction and to determine the presence/absence of collaterals or aneurysm formation if appropriate information cannot be obtained by MRI, if MRI is not available, or if percutaneous intervention is not planned. If percutaneous intervention is planned, angiography can be performed at the time of procedure.
- Digital subtraction angiography (DSA) which provides good anatomical detail and may obviate the need for invasive arteriography.
- Complete heart catheterization with aortography if associated cardiovascular lesions are present.
- Coronary angiography because of the increased risk of premature coronary artery in these patients, if a clinical indication exists, if the patient is over 40 years (or younger if major coronary risk factors), or if there is any evidence of left ventricular failure.
Part V - Indications for Intervention
| All patients with significant aortic coarctation or recoarctation, including those with proximal systemic hypertension (regardless of age) whether symptomatic or asymptomatic, warrant intervention. | ||
Patients with significant aortic valve stenosis may also require valve surgery, which may or may not be done at the same time as aortic coarctation repair. If operated upon separately, the sequence depends upon the severity of each of the lesions, the more severe one being dealt with first.
Part VI - Surgical/Interventional Options
For aortic coarctation or recoarctation, intervention may be either surgical or percutaneous (78). Surgical repair remains the gold standard against which newer therapies must be compared.
| Surgical repair of aortic coarctation in adults is more hazardous than in children. It should be performed by congenital heart surgeons. | ||
Surgical repair may involve:
- Interposition graft.
- End-to-end anastomosis (usually the preferred method for initial repair).
- Patch aortoplasty.
- Arch augmentation.
- Jump graft by-passing the aortic coarctation segment.
- Subclavian flap aortoplasty (may be used in children, but not recommended in adults because of concern about the arterial supply to the arm).
| Balloon dilation and/or stent insertion is being used increasingly as an alternative to surgery and, in some centres, has replaced surgery as the primary management strategy, unless additional problems coexist. It is not an appropriate therapy if there is an interposition graft or important concomitant arch hypoplasia involving the origin of the left common carotid or in the proximal arch. It should only be performed in centres and by individuals with a commitment to the technique and to its clinical evaluation. | ||
If there is aortic stenosis, and the aortic coarctation is relieved first, re-evaluation of the aortic gradient is needed after the procedure. This is usually accomplished with echo Doppler.
Part VII - Surgical/Interventional Outcomes
Following surgical repair of simple aortic coarctation, the obstruction is usually relieved with minimal mortality (< 1%). Mortality is higher for re-operation (5 - 15%). Recurrent coarctation is more common when initially repaired in infancy.
Complications of surgical repair include:
- Paraplegia due to spinal cord ischemia. It is uncommon but recognized, particularly in patients who do not have well developed collateral circulation.
- Rebound paradoxical hypertension in the early post-operative phase. It may be due to rebound sympathetic activation and activation of the renin-angiotensin system. It usually responds to beta blockade.
- Recurrent laryngeal nerve palsy.
- Phrenic nerve injury with diaphragmatic paralysis.
- Aneurysm formation following patch aortoplasty (particularly Dacron). It occurs opposite the patch.
- Late dissection at the repair site is a rare complication but false aneurysms may occur.
- Arm claudication (rare) if subclavian flap aortoplasty has been used.
Balloon dilation and/or intravascular stenting for native aortic coarctation or recoarctation can be as effective as surgical repair in relieving stenoses, with similar mortality (81-83). Long-term outcomes are unknown.
Complications of balloon dilation and/or intravascular stenting include:
- Recoarctation. The rate is higher for balloon dilation without stenting compared to surgery, particularly for younger patients.
- Aneurysm formation (6-12% with native aortic coarctation) although this is substantially less with stent utilization.
- Femoral artery injury/thrombosis.
- Stroke (rare).
- Aortic rupture (rare).
Hemoptysis from a leaking/ruptured aneurysm is a life-threatening complication and requires immediate investigation and treatment. MRI or DSA are optimal because of the risk of rupture with aortography and also, at times, failure to visualize the aneurysm.
Long-term follow up after surgical repair has shown an increased incidence of premature cardiovascular disease and death (84).
Prior hypertension resolves in many patients but this may depend on the length of follow up and age at repair. If it fails to resolve, it is generally responsive to standard therapy. Systolic hypertension is common with exercise, the significance of which is unknown. It may be related to residual arch hypoplasia. Persistent exercise-induced upper limb hypertension may occur, even in the absence of any significant residual gradient.
Heart failure usually resolves.
Late strokes may occur, notably in those repaired as adults and in those with residual hypertension. Cerebral hemorrhage due to a ruptured berry aneurysm can occur late after repair, even in the absence of systemic hypertension.
Endocarditis/endarteritis can occur at the aortic coarctation site or involving associated lesions. If at the coarctation site, embolic manifestations are usually restricted to the abdominal viscera and legs.
Part VIII - Pregnancy
| Females with aortic coarctation contemplating pregnancy should have repair prior to pregnancy. Management of hypertension in the unoperated pregnant patient may be problematic because too low a pressure below the coarctation site may result in abortion or death of the fetus. The risk of aortic dissection or aneurysm rupture during pregnancy is low, but death is likely if one of these occurs. | ||
Part IX - Follow Up
All patients require periodic follow up by an ACHD cardiologist.
All patients should have a periodic MRI or angiogram following repair of the aortic coarctation to document the post-repair anatomy and mechanical complications (restenosis or aneurysm formation).
Particular attention should be directed towards:
- Residual hypertension, heart failure, coronary artery disease or other cardiac disease.
- Associated bicuspid aortic valve, which may develop stenosis or regurgitation later in life.
- Recurrent aortic coarctation or significant arm-leg blood pressure gradient at rest.
- Ascending aortopathy especially in the presence of bicuspid aortic valve.
- New or unusual headaches because of the possibility of berry aneurysms.
- Late dissection proximal or distal to the repair site.
- Aneurysm formation at the site of aortic coarctation repair, especially if either a Dacron patch or if balloon angioplasty has been used.
| Endocarditis prophylaxis is recommended for 6 months following coarctation repair or for life if any residual gradient or associated indications persist. | ||