Key words: coarctation of aorta, pregnancy,
anaesthesia
Introduction
Coarctation of thoracic aorta is present in approximately 5-7%
of patients with congenital heart disease [1].
Coarctation of aorta (CoA) is usually characterised by a
discrete narrowing of the aorta distal to the subclavian
artery. Diagnosis is made during infancy or childhood in 80%
of the cases and most of them survive into adulthood. Females
with previously corrected coarctation of aorta may present
with pregnancy. Uncorrected CoA may also present for the first
time during pregnancy as hypertension. Pregnancy with heart
disease presents unique challenges to the anaesthesiologist as
well as to the obstetrician.
We report the successful management of a parturient with CoA
undergoing lower segment Caesarian section.
Case report
A 21 year old primigravida at 38 weeks and 3 days of gestation
with regular antenatal checkup was posted for lower segment
Caesarian section. She was diagnosed to have CoA and bicuspid
aortic valve for which stenting was done at the age of 11
years. She was found to be free of any cardiac symptoms after
the procedure. When she became pregnant she was found to have
hypertension for which she was started on tablet labetalol 50
mg twice daily. On examination she was comfortable at rest
with dyspnoea only on severe exertion. Her heart rate was 85/
minute, regular, good volume and equal on both sides. Her
upper limb blood pressure was found to be 140/60 mm Hg on the
right side and 120/60 mmHg on the left. Blood pressure in her
lower limb was 116/58 mm Hg. A systolic murmur was present in
her left sternal border. ECG was normal and Echo showed CoA
post angioplasty with residual gradient of 40 mm Hg. In
addition bicuspid aortic valve was present. There was no
aneurysm. Left ventricular ejection fraction was 62%. As the
patient was term it was decided to do an elective lower
segment Caesarian section. The patient was fasted overnight.
Infective endocarditis prophylaxis was given as injection
Ampicillin 2 gram and Gentamicin 80 mg half hour before
surgery. Monitors included pulse oximetry, 5 lead ECG, end
tidal capnography and non invasive blood pressure in the upper
and lower limbs. Oxygen was administered at 4 litres/ minute
using a poly mask.
As the patient had a good left ventricular function with
normal coagulation profile we decided to provide graded
epidural anaesthesia which will maintain stable hemodynamics.
Under aseptic precautions epidural block was given at the
level of L3-L4. A 3 ml test dose of 2% lignocaine was given to
rule out intravascular and intrathecal block. After confirming
the position of the epidural catheter, 10 ml of 0.5%
bupivacaine was given in incremental doses till a sensory
level of T6 was obtained. A Caesarian section was
performed and a female infant with APGAR score of nine at one
minute was delivered within five minutes of incision.
Intravenous Oxytocin 20 units in 500 ml normal saline was
started slowly and given over 1 hour. A good uterine tone was
achieved. Haemodynamically the patient remained stable
intraoperatively. Vasopressors were not needed throughout the
perioperative period. Patient was shifted to post operative
ICU for monitoring. Post operative analgesia was provided by
epidural infusion of 0.2% ropivacaine at 4 to 6 ml/hr.
Patient was observed for 2 days in the postoperative ICU and
then shifted to the room.
Discussion
Coarctation of aorta was first described by Morgagni in 1760
[2]. CoA is the fifth most common congenital heart defect with
an estimated incidence of 1 in 2500 births with a higher
incidence in males. Mean life expectancy of untreated patients
is 35 years [3].
CoA is a discrete narrowing of the thoracic aorta at the
junction of the ductus arteriosus and the aortic arch, just
distal to the subclavian artery. CoA has been found to be
associated with other congenital cardiovascular abnormalities
including bicuspid aortic valve (85%), intracranial aneurysms
(3-10%), intrinsic abnormalities of the aorta, aortic arch
hypoplasia, ventricular septic defects, patent ductus
arteriosus, aortic stenosis at valvular, subvalvular and
supravalvular levels and mitral valve abnormalities. There is
an increased familial risk with increased prevalence in
Turners syndrome, maternal phenylketonuria syndrome and Kabuki
syndrome [4].
There are infantile and adult types of CoA. The infantile
type, which presents in infancy and is associated with other
serious defects. This requires a patent ductus arteriosus for
survival. Unless corrected early in life, it is not
combatible to survival to adult life. Girls diagnosed with CoA
should be screened for Turner's syndrome due to the frequent
association between the two.
Patients with less severe coarctation may go unrecognised till
late childhood when a cardiac murmur is heard or hypertension
is detected. In such cases, there are collaterals that develop
from internal thoracic and subclavian arteries, thyrocervical
trunk, vertebral and the anterior spinal arteries to the
descending thoracic aorta. Undiagnosed adults with coarctation
may present with hypertension, headaches or claudication in
the lower extremities with exertion. These patients may
present with reduced lower extremity pulses and a systolic
pressure gradient between the upper and the lower extremities.
In the presence of extensive collaterals, femoral pulses and
the lower extremity blood pressures may be only minimally
reduced.
The delayed complications of CoA include persistent
hypertension (30% at 10 years and 66% at 40 years), premature
coronary artery disease (25%) and Berry aneurysms (2-3%).
Restenosis of the coarctation site may also occur in upto 35%
of the patients who have undergone repair [5].
Pregnancy is associated with normal physiological changes like
increase in the plasma volume, heart rate, stroke volume and
cardiac output and a decrease in the systemic vascular
resistance. There is a fear that the cardiac decompensation
may occur in patients with cardiac disease during pregnancy.
Although major cardiovascular complications are not very
frequent in pregnant patients with coarctation of aorta,
maternal and neonatal outcomes remain a source of concern.
Histological changes in the wall of ascending aorta together
with the physiological and hormonal changes during pregnancy
predispose these patients to increased risk of aortic
dilatation, rupture or dissection of aorta. There is also
increased chance for restenosis which can be assessed by
echocardiography and MRI.
Adults with CoA should have a lifelong follow-up by a
cardiologist. Patients who have had surgical or interventional
correction of the coarctation should be assessed annually with
echocardiography to rule out complications like aortic
dilatation and aneurysm formation. In a CoA patient with
systemic arterial hypertension brachial and femoral pulses
should be palpated simultaneously. This will help to determine
the timing and amplitude of both the pulses and to detect
radiofemoral delay. The differential pressures in the brachial
arteries of the upper limbs and the popliteal arteries in the
lower limbs should also be evaluated. Initial imaging and
hemodynamic evaluation by transthoracic echocardiography is
recommended in cases of suspected coarctation of aorta.
Thiazides diuretics and angiotensin converting enzyme
inhibitors are contra indicated in pregnancy. Labetalol is an
alpha blocker with non selective beta blocking properties. It
does not have any effect on the uteroplacental blood flow and
results in good and sustained control of blood pressure. It is
the preferred antihypertensive in CoA.
Our anaesthetic plan was graded epidural anaesthesia with
continuous hemodynamic monitoring. Titrated epidural drug
administration is a safe and effective alternative to general
anaesthesia in this case, though we should be prepared to deal
with an occasional fall in blood pressure. So the goals of
anaesthesia were the maintenance of an adequate intra vascular
volume, avoiding any compromise on the maternal
myocardium, maintaining the uteroplacental circulation and
finally to provide adequate perioperative analgesia to prevent
any further stress on the cardiovascular system.
Through a multidisciplinary approach, we were able to
successfully manage a challenging case of coarctation of aorta
in pregnancy. In this case, we opted for elective Caesarian
section. This was to avoid the second stage of labour and also
to reduce the need for Valsalva manoeuvre. These mechanisms
with their associated increase in the blood pressure runs the
risk of rupture of berry aneurysm.
Conclusion
Successful management of a parturient with coarctation of
aorta involves a team approach involving the cardiologist,
obstetrician and the anaesthesiologist. Also here there is an
increased risk of infective endocarditis. So it is mandatory
that antibiotics are prescribed at the time of surgery. These
patients are often hypertensive. So it is essential to
maintain proper blood pressure control to ensure maternal well
being as well as adequate fetal growth.
References
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