In massive PE, RV/LV ratio and azygos vein
diameter are the best predictors of survival, enabling correct prediction of survival in 89% of patients.
In the chest there are numerous lympho-venous connections between the azygos veins
and the thoracic duct (3).
1), the stenosis was classified according to the Stanford classification  system into 4 types: (i) type I describes a partial obstruction of the SVC (up to 90%) with remaining patency and antegrade perfusion of the azygos vein
; (ii) type II shows increasing obstruction (90-100%); (iii) type III is complete obstruction with reverse circulation in the azygos vein
; and (iv) type IV is characterised by complete obstruction of the SVC and the azygos vein
, with the development of collateral circulations via the chest wall and the internal mammary veins.
On the right side, the azygos vein
and the anterior branch of the right pulmonary artery are at risk of injury.
The distended mediastinal pleura was opened over the azygos vein
up to the thoracic inlet and the purulent material was drained and the necrotized tissues were completely removed.
Surrounding tissues around superior vena cava were dissected up to azygos vein
in order to examine presence of partial anormal pulmonary venosus connection and high PAPVC small-medium size was observed.
Intravenous reflux into the azygos vein
and the inferior vena cava to the level of the hepatic venous system (Figure 2) was seen.
In order to avoid such a complication, the azygos vein
should be transected and the sac incised.
Some reported complications include injury to the spleen, azygos vein
laceration, chylothorax, recurrent laryngeal nerve paralysis, anastomotic leaks, cardiac abnormalities, pleural injury, and tears to the posterior tracheal wall.
sup] For example, the azygos vein
would act as the bypass collateral to the right atrium during the insertion under the condition that SVC obstruction lies below the azygos vein
The upper azygos vein
was distended and not opacified as compared to the opacified inferior part.