Estenose Subaortica severa

Severe Subaortic Stenosis
Marie-Eve Nepveu, MD*
Jennifer Cogan, MD, FRCPC*
Raymond Cartier, MD, FRCSC†
Andre´ Y. Denault, MD, FRCPC*
A61-year-old woman (with a body surface area of
1.63 m2) presented for aortic valve (AV) replacement
secondary to moderately severe aortic insufficiency
because of aortic valvular and subvalvular stenosis.
Preoperative transthoracic echocardiography demonstrated
a peak pressure gradient of 108 mm Hg. Her
medical and surgical history was significant for hypertension,
hypercholesterolemia, and surgical repair
of a patent ductus arteriosus with excision of a subaortic
web approximately 40 years previously. No
preoperative cardiac output was available.
The intraoperative transesophageal echocardiograph
(TEE) midesophageal long axis image of the AV
and left ventricular outflow tract (LVOT) revealed a
web-like structure attached to the ventricular side of
the base of the anterior mitral leaflet (Fig. 1, please see
video clip available at www.anesthesia-analgesia.org).
The aortic annular and LVOT dimensions were 16 and
12 mm, respectively (Fig. 2). AV planimetry was 1.2
cm2. Color flow Doppler demonstrated severe aortic
insufficiency, with acceleration of flow at the level of
the LVOT in systole (Fig. 3). The peak and mean LVOT
gradients were 42 and 16 mm Hg, respectively.
Because of the small dimension of the aortic root
and severe narrowing of the LVOT, the surgeons
elected to perform a Konno procedure. This procedure
is used to palliate tunnel type subaortic stenosis. It
involves full thickness resection of the ventricular
septum, patch enlargement of the LVOT with concomitant
AV replacement (1). A Carbo Medics Inc 23
model R500 (Sorin Group, Austin, TX) with an effective
orifice area of 1.63 cm2 was implanted.
The mean gradient by continuous wave Doppler
across the revised LVOT and prosthetic AV was 8.95
mm Hg. Her cardiac index was 3.1 L
min
1
m
2.
The revised LVOT diameter could not be measured
using either a midesophageal or deep transgastric
view because of poor image quality and perivalvular
edema. Other than a high degree atrioventricular
block which required a permanent pacemaker, her
perioperative course was uneventful.
Fixed subvalvular aortic stenosis is a congenital
disease which encompases a spectrum of anomalies
ranging from a localized fibrous web of the LVOT
1–1.5 cm below the AV to a long fibrous tunnel with
hypoplasia of the aortic annulus. Ventricular hypertrophy
can also occur, predisposing to dynamic
obstruction of the LVOT (1,2). AV insufficiency is a
common associated condition, occurring in about
25% of patients (1). More than half of these patients
have additional cardiac malformations, most frequently
patent ductus arteriosus, ventricular septal
defect, and coarctation of the aorta. The disease is
progressive and recurrent, with re-obstruction after
surgery in 6%–30% of patients (1,2). Permanent or
transient complete heart block is a complication of
subaortic obstruction repair, and may occur in up to
15% of patients (3). It appears to be related to the
magnitude of the corrective procedure performed
(1). In a recent study involving 53 patients undergoing
a Konno procedure over a 24-year period, Suri
et al. observed a 10-year survival of 86% (4). The risk
factors for mortality were the duration of cardiopulmonary
bypass (CPB) (hazard ratio of 1.93/h P
0.04. and the NY Heart Association grade (hazard
ratio 2.2, P 0.04).
This case report illustrates the important role of
TEE before, during, and after AV surgery. Nowrangi
et al. published the results of the impact of intraoperative
TEE in 383 patients undergoing AV surgery for
aortic stenosis at the Mayo clinic (5). In their study,
intraoperative TEE modified the proposed surgery in
13% of cases. In a single-center 417-patient study in
This article has supplementary material on the Web site:
www.anesthesia-analgesia.org.
From the Departments of *Anesthesiology and †Cardiothoracic
Surgery, Montreal Heart Institute and Universite´ de Montre´al,
Montreal, Quebec, Canada.
Accepted for publication March 19, 2007.
Address correspondence and reprint requests to Andre´ Y.
Denault, MD, Department of Anesthesiology, Montreal Heart Institute,
5000 Belanger Street, Montreal, Quebec, H1T 1C8, Canada.
Address e-mail to denault@videotron.ca.
Copyright © 2007 International Anesthesia Research Society
DOI: 10.1213/01.ane.0000265543.67722.71
Vol. 105, No. 1, July 2007 34
Israel, the impact of TEE was reported for 221 patients
undergoing AV replacement (6). Immediate surgical
corrections were required for perivalvular leak in four
patients and coronary obstruction by the aortic bioprosthesis
in two patients. Prolonged removal of air
was necessary in 45 patients (10.8%) and in 47 patients
(11.3%) TEE after CPB was pivotal in evaluating the
causes of difficult separation from CPB. There are
some limitations, however, in the use of TEE before
AV surgery. As observed in our patient, the intraoperative
gradients were lower than those reported by
the transthoracic examination. This may be explained
by the effect of general anesthesia on cardiac performance
similar to that which has been shown in
patients undergoing mitral valve surgery (7).
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Figure 2. Transesophageal echocardiographic mid-esophageal
long axis view of the aortic valve (AV) at a multiplane angle of
125 degree. The measurement of the AV diameter, aortic (Ao)
diameter (diam) of the sinus of Valsalva (SVals), the aortic
sinotubular (st) junction (junct), and the ascending (asc) aorta
are shown.
Figure 3. Transesophageal echocardiographic midesophageal
long axis view of the aortic valve at a multiplane
angle of 125 degree. The color Doppler acceleration in the
left ventricular outflow tract is shown.
Figure 1. Transesophageal echocardiographic
midesophageal long axis view
of the aortic valve at a multiplane
angle of 125 degrees in mid systole.
There is a ridge attached to the anterior
aspect of the mitral valve. The left
ventricular outflow tract is narrowed
on all its length.