Subaortic Stenosis Diagnosed in the Course of a Twins Pregnancy: C

CASO CLÍNICO
Subaortic Stenosis Diagnosed
in the Course of a Twins Pregnancy:
A Controversial Management [33]
J. M. SOBRINO MARQUEZ, F. J. RODRIGUEZ-VERA, J. M. GARCÍA MORENO, R. GRAELL ESCOBAR, A. MATA
Hospital Juan Ramón Jiménez de Huelva, Spain
Rev Port Cardiol 2002; 21 (4) : 447-450
ABSTRACT
Fixed subaortic stenosis, commonly
associated with other congenital cardiac defects,
is the cause of 10 per cent of cases of congenital
obstruction of the left ventricular outflow.
Corrective surgery is frequently a successful
treatment, recommendations being based on the
transaortic gradient in Europe while in the USA
the most prevalent opinion is surgical repair
independently of the gradient. We present a case
of adult clinical onset of a fixed subaortic
stenosis during pregnancy, in which
hemodynamic changes are significant, that was
medically treated and followed in the outpatient
clinic of our hospital, and review the state of the
art of the management and surgical indications of
this condition.
Key words
Subaortic stenosis; Surgery indication; Pregnancy
BACKGROUND
F
ixed subaortic stenosis accounts for 8 to 10
per cent of all cases of congenital obstruction of the left ventricular outflow (1, 2). Thirteen
per cent have familial presentation (3), and between 25% and 45% of association with other
congenital cardiac defects have been reported (4).
The presence of a tunnel or ridge type obstruction (ridge) is the cause of almost 10 % of
all cases of fixed subaortic stenosis, the membranous form being the most frequent. In this,
a diaphragm or ring structure occludes the outflow tract near the aortic valve. In other cases,
RESUMO
Estenose Aórtica Diagnóstica no
Decurso de uma Gravidez Gemelar:
Abordagem Controversa
A estenose subaórtica fixa, frequentemente
associada a outras cardiopatias congénitas,
representa cerca de 10% dos casos de obstrução
congénita do tracto de saída do ventrículo
esquerdo. A cirurgia correctiva é frequentemente
um tratamento eficaz, sendo as recomendações
para a sua realização na Europa baseadas no
gradiente transaórtico, enquanto dos EUA a
opinião mais prevalente é a de intervir sempre,
independentemente do gradiente. Apresentamos
um caso clínico duma estenose subaórtica fixa
com manifestação clínica inicial na fase adulta,
durante a gravidez, altura em que as alterações
hemodinâmicas são significativas, tendo a doente
sido tratada medicamente e seguida na consulta
de ambulatório do nosso hospital. Faz-se uma
revisão sobre a abordagem e indicações
cirúrgicas desta situação clínica.
Palavras-chave
Estenose subaórtica fixa; Correcção cirúrgica; Gravidez
a fibromuscular narrowing is the cause of the
obstruction (shelf) (5).
Surgical treatment of this condition is
usually curative, its morbidity and mortality
being low, although dependent on the associated defects (4). A recurrence of the stenosis has
been found in 27% of cases within five years
of surgery (6). The moment at which surgical
treatment should be performed is the subject
of controversy, especially in cases of mild to
moderate obstruction.
We present the case of a 23-year-old
woman who was diagnosed with subaortic
Recebido para publicação: Julho de 2001 • Aceite para publicação: Março de 2002
Received for publication: July 2001 • Accepted for publication: March 2002
447
membranous stenosis in the 24th week of a
twin pregnancy and review the management
and surgical indications for the treatment of
this condition.
CLINICAL CASE
A 23-year-old woman, with a “cardiac murmur” diagnosed in childhood but not studied,
mother of a 2-year-old son whose pregnancy
had been uneventful, and with no physical
limitations in her daily activity, having been
diagnosed with a twin pregnancy, was admitted
to the Gynecology Department in the 24th
week for a threatened premature delivery that
receded with ritodrine, and was discharged
home after the clinical event was controlled.
Twenty-four hours after discharge, she
returned to the Emergency Department with
severe oppressive central chest pain irradiating
to the left arm diagnosed as typically anginous
by the clinician responsible for her admission,
together with slight dyspnea. Her blood pressure at admission was 120/70 mmHg. In the
physical examination, a IV/VI systolic ejection
murmur with no signs of cardiac failure was
found. Chest X-ray, biochemistry and hematological analysis showed no relevant abnormalities. The electrocardiogram revealed sinus
tachycardia at 125 bpm, with no signs of
hypertrophy of the chambers and a slight depression of the ST segment in V4-V6.
The pain was treated with magnesium metamizol, and beta-blockers were prescribed (propranolol 40 mg/8h) to slow the tachycardia.
After her angina was treated, the patient remained asymptomatic and was examined by
448
Fig. 1 A non dilated LV with
signs of moderate hypertrophy is
shown. Measures: Wall thickness
13.7 mm, LV mass 265.
the Echocardiography and the Cardiology Outpatients services. Echocardiography showed a
non-dilated left ventricle with signs of wall
hypertrophy (wall thickness 13.7 mm, LV mass
265) (Fig. 1) and a thin subaortic shelf membrane located 13 mm from the aortic valve
(Figs. 2 and 3). The septal veil of the mitral
valve was preserved. The aortic valve had no
structural abnormalities, an output tract peak
systolic instantaneous gradient of 55 mmHg
being measured by Doppler. No aortic valve
regurgitation or other associated abnormalities
were found.
The patient was followed by the Cardiology
Department during the subsequent months of
pregnancy, with no new episodes of thoracic
pain or other symptoms reported. Beta-blockers were not withdrawn after the diagnosis of
aortic stenosis, on the basis of the predominant
tachycardia of the patient, the mild gradient of
the obstruction and the safety of this product
during pregnancy (7), the treatment being changed to atenolol 50 mg/24 h for its safer pharmacological profile (8) and more convenient posology. Two other echocardiograms were done
during this period, with no increase in the aortic subvalvular gradient detected.
In the 36th week of pregnancy a cesarean
section with intradural anesthesia was performed because of metrorrhagia, no complications
being reported during the procedure.
After the delivery, the woman was discharged with atenolol 50 mg/24h as the only cardiological medication. After the first year of follow-up she has not complained of any kind of
symptoms and an echocardiogram showed a
decrease in the gradient to 35 mmHg measur-
Fig. 2 A thin subaortic membrane is shown 13 mm from the
aortic valve.
ed by Doppler. Our management of the patient
at present is limited to the performance of periodic echocardiographic checks, since the patient refused the option of surgical repair.
DISCUSSION
Congenital subaortic stenosis makes up 8 to
10 % of all cases of aortic stenosis. Its prevalence is higher in males (2:1) (9). Obstruction is
usually absent in the early stages of life and
becomes more evident in late childhood and
young adulthood. It is uncommon to detect the
disease in people older than 30, which suggests that survival after this age without surgical treatment is exceptional (10). Several reports
show that its progression is faster than aortic
stenosis (3). The aortic regurgitation that is usually associated is probably caused by valve thickening due to subvalvular turbulence, which
may also be the predisposing factor for endocarditis even after the excision of the membrane. On the basis of the progression of obstruction and aortic regurgitation, even a low
grade of obstruction is an indication for elective surgery (3, 4).
The classical recommendations for the surgical repair of discrete subaortic stenosis depend on the angiographic visualization of a
subvalvular membrane or diaphragm and a
pressure gradient higher than 40 mmHg (1, 3).
These recommendations are based on the potential progression of the condition (scarcely
tested in these studies) and the intention of
preserving the valve from damage caused by
the high-pressure flow. The Guidelines of some
cardiological associations, including the SEC
(Sociedad Española de Cardiología), are for
surgical repair in the above circumstances (11).
Recent relevant studies also support this option (12), given that patients with a low gradient
rarely have significant progression of the obstruction or develop aortic valvular regurgitation.
These standards, by contrast, go against the
opinion of researchers at UCLA (4), who consider early surgery necessary independently of
the gradient when diagnosed, reporting in a
case-control study that surgical resection of fixed subaortic stenosis before the development
of a significant (>40 mmHg) gradient might
prevent recurrence, reoperation and secondary
progressive aortic valve disease.
The case of our patient, aside from the singularity of onset, shows the need for a dynamic
and thorough consideration of the individual
circumstances, because in our case the
hemodynamic changes induced by the twin
pregnancy were the cause of the changes
observed in the gradient. The absence of progression of gradient and symptoms during the
third trimester of pregnancy supports our conservative attitude in the management of the
condition. Besides, the application of the American guidelines for the management of other
kinds of left ventricular output obstruction in
the course of pregnancy supported our management approach (13).
Recently, an echocardiographic model to
predict which individuals will develop progression of the stenosis has been proposed and validated. This model takes into account three
449
parameters: the gradient at the time of diagnosis, the distance from the membrane to the aortic valve, and whether there is involvement of
the anterior leaflet of the mitral valve (14). Using
this standard, our patient probably has nonprogressive discrete subaortic stenosis. Nevertheless, it will be the progression of her clinical and echocardiographical parameters,
together with her personal decision, that will
determine our attitude in the long term.
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Address for reprints:
450
F. JAVIER RODRIGUEZ-VERA
C/ Arjona, n.º 12 Esc 2-1º A
41001 SEVILLA
SPAIN
tel: +34670724998
e-mail: [email protected]