Coarctation of the aorta occurs in approximately 5% of patients with congenital heart disease, and may occur as an isolated lesion or in association with other cardiovascular defects. Preductal coarctation is associated with patent ductus arteriosus, ventricular septal defect, bicuspid aortic valve and (in about 10% of cases) transposition of the great vessels. The majority of cases of preductal coarctation present with congestive cardiac failure in the neonatal period and are diagnosed and corrected surgically in infancy.
Postductal coarctation of the aorta may not be diagnosed until adolescence or adult life. There are associated berry aneurysms of the circle of Willis in approximately 10% of cases, and bicuspid aortic valve in 50% of patients.
Problems and special considerations
Corrected coarctation is considered a relatively low-risk lesion in pregnancy, unless there are associated abnormalities such as those described above. However, pregnancy in women with an uncorrected aortic coarctation or with residual hypertension, coarctation or aortic aneurysm is associated with a maternal mortality of 3-9%, and a fetal mortality of up to 20%.
Undiagnosed coarctation may present for the first time in pregnancy. There is invariably hypertension, and this may be accompanied by congestive cardiac failure, caused by inability to compensate for the increased blood volume and cardiac output of pregnancy. The generalised peripheral vasodilatation and consequent reduction in systemic vascular resistance that occur in pregnancy may also precipitate cardiac failure.
In uncorrected or undiagnosed aortic coarctation, there is a risk of aortic rupture or dissection or rupture of a cerebral aneurysm if blood pressure increases acutely, for example because of severe pain or following use of certain drugs (e.g. ergometrine, vasopressors). Increased shearing forces associated with swings in blood pressure may also be dangerous. Fetal mortality is increased because of decreased uteroplacental flow.
Hypertension is limited to the arms, and blood pressure may be reduced in the legs; palpation of the peripheral pulses frequently reveals absent foot pulses and radiofemoral delay. An aortic systolic murmur is heard on auscultation of the chest, and there may also be audible bruits over the intercostal and internal mammary vessels, which carry collateral flow to the lower limbs. A chest x-ray may show rib notching caused by the collateral vessels, and left ventricular hypertrophy.
Management options
Women with corrected coarctation should be assessed both before and early in pregnancy, and any associated abnormalities noted. Changes to usual obstetric and anaesthetic management are not generally indicated in the absence of complications or other pathology, although epidural analgesia will often be advised, particularly in the presence of hypertension.
In uncorrected coarctation, blood pressure should be controlled throughout pregnancy, even though this may further hinder uteroplacental flow, and regular monitoring of the fetus is required. There is no proven benefit of operative delivery for women with uncorrected coarctation, although anxiety about undiagnosed aneurysms of the circle of Willis may lead to recommendations for epidural analgesia and elective instrumental delivery. There is also no evidence that allowing the woman to labour increases her risks of aortic dissection or rupture, but again, epidural analgesia is usually recommended. Minimising haemodynamic disturbance is the main aim of management of delivery. Cardiac output is relatively fixed; tachycardia secondary to uncontrolled pain may precipitate cardiac failure, but bradycardia and acute reduction in systemic vascular resistance are also hazardous. Hypovolaemia leads to compromised left ventricular filling.
Invasive systemic arterial pressure monitoring allows close attention to changes in blood pressure and facilitates analgesic and anaesthetic management, although this may not be necessary in repaired coarctation with no residual obstruction or other problems. Postductal pressures (left radial) give the best indication of uteroplacental blood flow. Central venous pressure monitoring may also be useful. Epidural or combined epidural-spinal techniques can provide safe and effective pain relief in labour. Although the main risk is from hypertension, it is also important to avoid hypotension.
For caesarean section, both regional and general anaesthesia may be suitable, although many practitioners would avoid single-shot spinal anaesthesia because of the risk of uncontrolled hypotension. Combined spinal-epidural, continuous spinal or epidural techniques allow gradual extension of the anaesthetic level cephalad and minimise the risks of rapid onset of profound hypotension. If general anaesthesia is used, steps should be taken to prevent the hypertensive response to tracheal intubation.
Postoperative management in a high-dependency environment is essential; invasive monitoring should be continued postoperatively, and adequate analgesia should be ensured by using either the epidural route or patient-controlled intravenous analgesia.
Key points
• Women with corrected coarctation do not usually pose any particular problem in pregnancy, although there may be other associated cardiovascular abnormalities.
• Uncorrected coarctation may be associated with aortic dissection or rupture.
• Both general and regional anaesthesia are acceptable options but both may be hazardous in uncorrected or unstable cases.
• Invasive arterial ± central venous pressure monitoring is recommended in uncorrected coarctation or corrected cases with complications.
Further reading
European Society of Cardiology. ESC guidelines on the management of cardiovascular diseases during pregnancy: the Task Force on the Management of Cardiovascular Diseases during Pregnancy of the European Society of Cardiology (ESC). Eur Heart J 2011; 32: 3147-97.
van Hagen IM, Roos-Hesselink JW. Aorta pathology and pregnancy. Best Pract Res Clin Obstet Gynaecol 2014; 28: 537-50.