Relationship Between Tracheal and Left Pulmonary Artery Stenosis Index and Prognosis of PA Sling With Tracheal Stenosis
Condition: Anomalies of Pulmonary Artery, Congenital
MeSH terms: Tracheal Stenosis; Stenosis, Pulmonary Artery; Constriction, Pathologic
Study type: Observational

Summary: 
      Pulmonary artery sling is a rare congenital pulmonary vascular malformation, often associated
      with tracheal or bronchial stenosis. Surgical treatment of pulmonary artery sling with
      tracheal stenosis has a high risk and a relatively poor prognosis. This article aims to
      explore the relationship between the index of tracheal and left pulmonary artery stenosis and
      the surgical effect of pulmonary artery sling with tracheal stenosis. Methods: Retrospective
      analysis of the cases of pulmonary artery sling surgery in our center from January 2010 to
      December 2018. Before operation, routine cardiac enhancement CT examination was performed,
      and the diameter of the left pulmonary artery and the tracheal stenosis were measured on the
      CT tomogram respectively, and the ratio of the degree of tracheal stenosis / left pulmonary
      artery stenosis (T / P) was calculated, combining the surgical method and clinical prognosis
      analyzed and discussed.
    

Detailed description: 
      Pulmonary artery sling is a rare congenital pulmonary vascular malformation. The abnormality
      of the left pulmonary artery originates from the right pulmonary artery instead of the trunk
      of the pulmonary artery. It passes around the trachea, passes between the trachea and the
      esophagus, and forms a vascular ring with the arterial ligament. Compression of the trachea
      and esophagus, especially the symptoms of tracheal stenosis caused by the compression of the
      trachea, can be manifested as serious symptoms such as respiratory infections, wheezing, and
      even respiratory distress, which can be life-threatening in severe cases. Therefore, the key
      to the surgical treatment of pulmonary artery sling is to relieve tracheal compression and
      correct tracheal stenosis, which is also the difficulty. At present, the overall survival
      rate of surgical treatment of pulmonary artery sling around the world is about 78% to 93%
      [1], but the mortality rate for patients with severe tracheal stenosis is also high, reaching
      about 24% [1], mainly due to pre-operative or post-operative respiratory failure caused by
      narrowed trachea. At present, the selection and intervention of pulmonary artery sling
      combined with tracheal stenosis is still a difficult problem. On the one hand, if
      tracheoplasty is performed, anastomotic scar hyperplasia after surgery may lead to local
      tracheal stenosis again [2], and long-term care is also quite difficult; If tracheoplasty is
      not performed, tracheal stenosis may not be completely relieved, and obstructive ventilation
      disorder and respiratory failure may occur after surgery [1]. At present, there is basically
      no objection to the preoperative assessment methods of pulmonary artery sling. CCTA is
      generally considered to be an effective method for diagnosing pulmonary artery sling with
      tracheal stenosis. It can display abnormally deformed pulmonary arteries and narrowed
      trachea, and it can also detect intracardiac malformations. The important means of
      preoperative evaluation can also be used for postoperative evaluation [3].

      There is currently no consensus on the indications for tracheal intervention with pulmonary
      artery sling combined with tracheal stenosis. Some researchers believe that tracheoplasty
      should be performed for tracheal diameters less than 3mm, or the prognosis is poor [4]. Some
      researchers have suggested that the diameter / length percentage of tracheal stenosis can be
      used as a reference index for intervention of tracheal stenosis [5]. Brouns et al. found that
      the square of the cross-sectional area of the tracheal stenosis has a significant
      proportional relationship with the air flow, so they believe that the cross-sectional area of
      the tracheal stenosis is the main factor affecting the ventilation effect [6]. When I
      reviewed the imaging data of children with tracheal stenosis in our center, the most severe
      tracheal stenosis is usually located in the vascular ring formed by the right pulmonary
      artery starting segment, the left pulmonary artery starting segment, and the left pulmonary
      artery bypass segment. Not only was the trachea compressed and significantly narrowed, but
      the left pulmonary artery was also significantly narrowed, that is, the trachea and the left
      pulmonary artery were squeezed together in a limited space, causing both of them to be
      compressed and narrowed. This study was the first to investigate the interaction and
      morphological changes of the trachea and the left pulmonary artery, and the ratio of the
      degree of tracheal stenosis / left pulmonary artery stenosis (T / P) was used to indicate the
      degree of interaction between the two. A larger T / P ratio indicates that the left pulmonary
      artery is more dominant in tracheal compression, and tracheal stenosis is usually more
      serious. On the contrary, a smaller T / P ratio indicates that the trachea is more dominant
      in compression of the left pulmonary artery, and the tracheal stenosis is usually relatively
      lighter. This article retrospectively analyzes the cases in our center and discusses the
      effects of surgical treatment.
    

Intervention name(s): tracheoplasty
Intervention type(s): Procedure
Intervention description(s): tracheoplasty and only left pulmonary artery transplantation
Observational model: Cohort
Time perspective: Retrospective
Sampling method: Probability Sample
Study population: 
        patients with tracheoplasty and left pulmonary artery transplantation at the same time, and
        only with left pulmonary artery transplantation