Discussion
Our team modified a novel approach of PmVSD closure via ultra-minimal
trans intercostal incision. Compared with the minimally invasive
inferior sternotomy approach, the operation trauma of novel approach is
much less (≤1 cm). This novel surgical incision avoids the need for a
sternal incision and blood transfusion. The pericardium hanging
technique
replaced
the tissue retractor devices for exposure that can avoid injury to the
ribs and the intercostal
tissue[12].
After the incision healing, it does not affect the appearance and the
postoperative mental health of patients. By using ultra-minimal skin
incisions and transintercostal incision , surgical trauma can be greatly
reduced, Particularly in the pediatric population.
Compared with the transcatheter PmVSD closure
approach, the novel approach is
simpler. This approach has a short operating pathway of and does not
require the establishment of an arteriovenous guidewire
loop[12], which can prevent inferior vena cava and
aorta injure. It provides an angle point toward the PmVSD,and the
guidewire is easier to pass through VSD. Moreover, clear TEE
image[12,13] can accurately and effectively assess
PmVSD and clearly show the guide wire, sheath and occluder to provide
real-time guidance that enables cardiac surgeons to operate smoothly.
The positions of the intercostal incision and the purse-string suture
should be selected very carefully and accurately because ultra-minimal
incisions (≤1 cm) limit the range over which the guidewire and sheath
can move. Our team used both TTE and TEE to select accurately location
of the incision and that of the purse-string suture, according to the
location of the PmVSDs and the main direction of blood flow. First, TTE
was used to determine the position of the incision. The PmVSDs is often
located behind the sternum. So the incision should be located next to
the left sternum, simultaneously, the blood vessels and nerve tissues
were avoided. Then, TEE was used to determine the purse-string position.
Under TEE guidance, the surgeon gently pulled the heart to the left, and
found out the position of purse-string suture through tweezer being
moved on the right ventricular anterior wall. It should be noted that
the surgeons should clamp gently the right ventricular surface using the
tweezers to avoid damage to the right ventricular surface when the
position of the purse-string suture is determined. When the tweezers was
pointed toward the orifice of the VSD or the direction of blood flow,
the position can be fine-tuned to ensure that the puncture site and
PmVSD had the best entry angle and lay the foundation for the wire to
smoothly pass through the VSD. The correct location of the incision and
the purse-string suture can greatly increase the success rate of device
closure and can reduce the operative time and surgical risk.
When multiple defects of AMS are very close together, it is easier to
occlude the PmVSD completely through unfolded disk. Nevertheless, when
the defects are divergent, PmVSD closure is a major
challenge[14]. Devendran
etc.[15] considered that closure of multistream
PmVSDs using a single device was not possible when the defects were far
apart. But there were a few cases of success in our study. For example,
we had one case with the two defects in the AMS far from each other. One
defect was near the tricuspid septal leaflet, the other was close to the
interventricular septum. The entry of guide wire into the VSD was
extremely difficult. The guidewire and sheath could not enter the defect
near the tricuspid septal leaflet. And only the defect close to the
interventricular septum could be selected. If the guide wire is
completely aligned with the direction of blood flow, entering the AMS is
not difficult, but turning the guidewire 90 degrees to enter the left
ventricle is very difficult. In this case, the purse-string can be
positioned at a certain angle to reduce the difficulty for the guidewire
to enter the left ventricle after it enters the AMS.
The reasons such as the defects of the multistream PmVSD being
divergent, retrosternal PmVSD forming an Angle with the incision, led to
that the procedure durations of PmVSDs closure via an ultra-minimal
trans intercostal incision were longer than thats of DCVSDs
closure[12]. So, the cooperation of the team and
the cumulation of experience is more important. All members of the team
should remain aware of the patient’s condition and know how to deal with
the situation changed during surgery. The surgeons and the
echocardiologist should work closely to make the operation smoothly.
Skillful surgical technique and proficient TEE guidance, wicth can
reduce the duration of surgery, are very important for a successful
procedure.
For AMS with a single stream, the left disk of the occluder can be all
or partly pulled into the aneurysm to close PmVSD easily. However, the
basilar part of the multistream PmVSD need be occluded through the left
disk of the occluder be anchored on the left ventricle side of PmVSD.
The surgical experience is summarized as follows. First, it is important
to assess carefully PmVSD through TEE before select the appropriate
occluders. Second, this challenge requires the surgeons and
echocardiologist to have great patience and tacit cooperation.
Third, when the guidewire enters the AMS, the surgeon can gently pull on
the heart to reduce the angle and make it easier to allow the guidewire
to enter the left ventricle.
Fourth,
a mild residual shunt (≤ 2 mm)[16]and low flowing
velocity do not significantly impact the patient and can heal by itself.
Scholars had reported that the estimated incidence of arrhythmia,
especially complete atrioventricular block, was 5.7–22 % after
transcatheter device closure[17,18].The use of an
oversized occluder is one of the main reasons for atrioventricular
conduction block and other arrhythmias. Therefore, the size of occluders
should be chosen as small as possible on the premise of success closure
in order to avoid arrhythmia. In this study, the size of the device is
approximately 1 (0.5-1.5 ) mm larger than the PmVSD diameter, and no
obvious arrhythmia or complete atrioventricular block occurred.
The complications such as
pericardial effusion, pleural
effusion and hyperpyrexia contributed to increased postoperative
hospital stay. These patients were not discharged until they had normal
temperature and pericardial and pleural effusion improved.
Among them, 2 patients transferred to ventricular septal defect repair
operation under direct visualization with a cardiopulmonary bypass. One
patient was overweight, so the surgeon must pull the heart leftwards
more than 3cm to locate the precise position of the purse-string suture.
Ventricular fibrillation occured when guide wire passed the PmVSD, which
may be associated with excessive traction. The other patient had so
large PmVSD that the device dislocated. The trans intercostal
ultra-minimal incision is difficult to set up cardiopulmonary bypass
quickly. PmVSD repair under visualization needs a new mid-sternum
incision. After surgical repair, the presence of both a long and a short
incision may affect the patient’s appearance. We suggested that large
PmVSD or obese children’s PmVSD should be occluded via the minimally
invasive inferior sternotomy approach. If closure fails, the incision
can be extended.