Discussion
PDA is one of the most common congenital heart diseases. Excessive blood flow to the lungs caused by PDA results in pulmonary congestion, pulmonary edema and respiratory failure (10). This patency may also cause cerebral, renal or mesenteric hypoperfusion that leads to serious complications in intensive care unit (11). Medical management, surgical ligation or percutaneous closure of PDA are treatment methods used currently for preterm infants. Percutaneous closure of PDA has really limited place among the teatment methods although transcatheter technology advances (12-15).
Indomethacin or ibuprofen is used for the medical treatment of PDA. If medical treatment is unsuccessful surgical closure is performed. These drugs have various side effects and may cause thrombocytopenia, necrotizing enterocolitis, pulmonary edema and bleeding, renal failure (16). There are even publications suggesting early surgery instead of medical therapy to save the patients from complications of PDA and medications. (17,18)
In 1938, Gross was first to ligate PDA successfully (19). With the improvement in cardiovascular surgery better cosmetic results and less harm to lung tissue became more important. For this purpose, several minimally invasive techniques have been tried by surgeons instead of the conventional methods without affecting the operative results (19,20).
Another choice is transcatheter closure of PDA. With the rapid development of science and technology new occlusion devices serve to close PDA in appropriately selected preterms. However, it is still not routinely occluded in very small infants with birth weight ≤2 kg and still there is a lack of experience (12). As it is safe and successful transcathater closure of PDA receives more attention; but there are some concerns about vascular access, risk of residual shunt, providing the suitable device, possibility of device migration or embolization and contrast administration in preterm infants (21,22).
Lateral thoracotomy has been procedure of choice for PDA closure in preterm infants for over five decades; but it doesn’t have the qualities that left anterior mini-thoracotomy technique has. Lung injury and potential long-term spinal and chest wall deformities are potential risks of lateral thoracotomy (23,24)
Verhaegh et al compared lateral thoracotomy with sternotomy for PDA closure in preterm infants and they found that the postoperative pulmonary complication rate was significantly lower in the median sternotomy patients. This obviously shows that it is important not to touch lungs as much as possible during operation to avoid lung-related postoperative complications (23).
Technically, left anterior mini-thoracotomy technique requires short surgical times (< 20 minutes), offering direct visualization of the left recurrent laryngeal nerve, thus preventing complications secondary to its damage, guarantees good surgical exposure of the PDA (also in patients < 1.5 kg who are not routinely managed through catheterization). In addition, less trauma to lung tissue reduces the risk of pulmonary complications. This technique also has good aesthetical results. This is a simple technique and provides good exposure and the closest approach to the PDA when compared to the other thoracotomy incisions. The patient is in the supine position during the operation with the left chest elevated for anterior mini-thoracotomy. Supine position provides extra comfort for the surgeon and can be maintained easily in the operating room or in the intensive care unit. In case of emergency (for example; massive bleeding) you can easily convert to sternotomy.
We operated all of our patients in the operating room. Patient was under the heater till the start of the operation. Sometimes even gentle traction of pulmonary artery for PDA dissection for better view caused bradycardia and hypotension so adrenaline infusion was started all of the patients, preoperatively. Our operation time was generally under 20 minutes. Therefore, time under hypothermia was also not long. Our lightest baby was 480 g. Interestingly, we operated twins, two sisters, on the same day and discharged them to home one day apart.
In our study, we especially focused on advantages of the technique on time and lung related complications and possible surgical complications related with PDA closure. In our cohort, we didn’t have any intraoperative bleeding, chylothorax and chylomediastinum; but we had one left diaphragma elevation. Left diaphragma was plicated and the patient was successfully discharged. Dissection of PDA for beter view may be dangerous in some patients who have more fragile PDA tissue than the others. In these type of cases we prefer clip ligation. In these cases using a metallic vascular clip allows for limited dissection and safe occlusion. After the operation air was removed using the underwater drainage system, the thoracotomy was closed without placing a chest tube . This may have improved the comfort of the patient after the operation.
48% (13) of the patients were transferred to our center for PDA closure. After the operation we followed-up the patients for one day in our neonatal intensive care unit. The day after the operation all of the 13 patients were transferred back to their centers. Transfer of a preterm patient especially before the surgery is important. If the patient comes to the surgery in hypothermic condition with loss of intravenous lines or ventilation problems, this may increase the risk of the surgery.
Although there was no surgery related mortality, our hospital mortality rate was 29,6 %. This is higher than most of the prior studies related to PDA closure in preterms (23-25). As our cohort includes preterm patients with PDA and serious comorbidities these mortality rates are connected to complications associated with prematurity, infection and comorbidities. Five were due to sepsis, one was due to necrotizing enterocolitis, one was due to hydrops fetalis and one was due to renal failure with hepatoblastoma.
Of course we have several limitations. First of all a limited population was retrospectively studied. We only have early and mid-term results but not long term results. Also we can not compare the technique with another technique as we did not have another group operated by another surgical technique. All of these avoid us claiming the superiority of the technique over other techniques. Also, our short and mid term results with left anterior mini-thoracotomy technique in preterm infants are promising.
To conclude, PDA closure with the left anterior mini-thoracotomy method is advantageous in terms of reducing damage to the already congested lung, shortening the hypothermia time of the baby by shortening the procedure time, and has good cosmetic results, especially in very low birth weight preterm babies. Prospective randomised studies are needed to compare the technique’s safety and efficiency with other conventional techniques.
Declaration of conflicting interests: The authors declared no conflicts of interest with respect to the authorship and/or publication of this article.
Funding: The authors received no financial support for the research and/or authorship of this article.