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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 29, No 3, May/June 2018
AFRICA
169
Maximum precautions were taken not to inflate the balloon
in the left ventricular outflow tract. Inflation was first with the
syringe and then with the inflation device, since the total volume
frequently exceeded the capacity of the inflation device. A waist
formed and then disappeared (Fig. 2B, C). Inflations at increased
pressure were repeated if needed, with control for degree of
mitral regurgitation, mean transmitral diastolic gradient and
post-dilation mitral valve area on TEE.
Results
Mean fluoroscopy time was 22.6
±
6.4 min (18.5–30.0). Mean
transmitral gradient decreased from 24.1
±
5.9 (16–35) to 6.6
±
3.8 (3–14) mmHg, as measured on TEE. Mean mitral valve area
increased from 0.69
±
0.13 cm
2
(range 0.5–0.9) before dilation to
1.44
±
0.25 cm
2
(range 1.1–1.9) after dilation (
p
<
.001). Mean
estimated pulmonary artery systolic pressure decreased from
110.0
±
35 mmHg (range 75–170) before dilation to 28.0
±
14.4 mmHg (range 10–60) immediately after dilation on TEE.
Outcome variables after balloon dilation are shown in Table 3.
One patient developed severe mitral regurgitation due to a
tear on the anterior mitral valve leaflet and she underwent semi-
urgent valve replacement surgery. Another patient developed
moderate mitral regurgitation, which was well tolerated. No
complications were noted in the other patients either immediately
after the procedure or on subsequent follow up.
At the follow up, up to 20 months later, all the patients were
in NYHA functional class I–II. Mean mitral valve area remained
stable at 1.43
±
0.32 cm
2
(range 1.1–1.9). Transmitral mean
diastolic pressure gradient was 5.4
±
2.7 mmHg (range 2–7).
Estimated mean of the systolic pulmonary artery pressure was
40.1
±
8.4 mmHg (range 25–45).
Mitral regurgitation was mild in three patients while it was
trivial or none in the rest. Tricuspid regurgitation was graded
as mild in four patients and minimal in the rest. All the patients
were on monthly benzathine penicillin prophylaxis against
recurrence of rheumatic fever. None was on diuretics or any
other cardiac medications or has needed further intervention.
Discussion
Currently the Inoue balloon technique is the standard technique
for mitral valve dilation for treatment of mitral stenosis due to
rheumatic heart disease or calcific mitral stenosis. The technique
we describe here does not compare to the Inoue balloon
technique in terms of ease and safety of operation. We do not
imply that this technique is an alternative to the Inoue balloon
under circumstances where the Inoue balloon is available and the
operator is well versed with the technique. There is no doubt that
the Inoue balloon is superior, if it is available and the operator
is experienced with it.
Our technique is actually a modification of older single-
balloon techniques used for the treatment of mitral stenosis.
20,21
Compared to other single-balloon techniques, the Nucleus
balloon offers the advantage of asymmetric inflation of both
extremities before the central part of the balloon, thus ensuring
some degree of stabilisation over the stenotic orifice.
Our technique is significantly different from that in which
the Nucleus balloon has been used, in that it avoids placing a
stiff wire in the left ventricle, decreasing the risk of ventricular
arrhythmia, or hypotension from mitral interference. The use
of a very floppy Terumo wire in our technique preserves mitral
valve function until the arteriovenous loop is pulled for some
seconds during balloon inflation. Furthermore, the risk of apical
left ventricular rupture associated with the double balloon and
other similar techniques is less likely to be a problem with our
technique.
Establishment of an arteriovenous loop offers better balloon
stability and can potentially be used with any other type of
balloon available, especially in resource-limited settings. We felt
that stabilising the balloon in that manner would be a particular
advantage in our relatively young and small population of
patients.
Indeed the procedure was adopted in our first patient, after
initial inflation of the Nucleus balloon over a stiff wire placed
at the left ventricular apex proved unsuccessful, the balloon
being pushed back to the left atrium. The concern that applying
tension on both ends of the Terumo wire may result in aortic
injury may be overcome by placing a catheter over the wire,
although we have not done this in the patients treated thus far.
We used small balloons to dilate the septal puncture. Although
there may be a theoretical risk of creating an iatrogenic atrial
septal defect through the hole, this did not occur in any of our
patients.
In initial publications describing single-balloon over-the-
wire procedures,
18
Lock
et al.
positioned the exchange wire in
the descending aorta, thus increasing support and stability for
the balloon. The addition of the arteriovenous loop increases
stability by pulling both ends of the wire, while using a softer
Table 2. Nominal balloon diameter versus inflation pressures and
corresponding effective balloon diameters obtained
Balloon diameters
Applied pressure 18.0 mm 20.0 mm 22.0 mm 25.0 mm 28.0 mm 30.0 mm
1 atm
15.5
16.7
19.0
21.8
24.4
25.9
2 atm
16.1
17.3
19.6
22.9
27.4
29.7
3 atm
16.9
17.3
19.6
22.9
4 atm
17.9
19.9
Table 3. Outcome variables in patients treated for severe rheumatic
mitral stenosis using the modified Nucleus balloon technique
Variables
Before dilation
mean
±
SD
(range)
After dilation
mean
±
SD
(range)
p
-value
Mitral valve area (cm
2
) by
planimetry
0.69
±
0.13
(0.5–0.9)
1.44
±
0.25
(1.1–1.9)
<
0.001
Mean transmitral gradient
(mmHg)
24.1
±
5.9
(16–35)
6.6
±
3.8
(3–14)
<
0.001
Average estimated pulmonary
artery systolic pressure (mmHg)
110.0
±
35
(75–170)
28.0
±
14.4
(10–60)
<
0.001
Mitral regurgitation
Severe
–
1
Moderate
–
1
Mild
2
5
Trivial
5
2
None
4
1
Tricuspid regurgitation
Severe
–
–
Moderate
1
–
Mild
6
6
Trivial
4
3
None
–
1