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.