To investigate if bronchial blocker is more suitable for one-lung ventilation during thoracoscope assisted mitral valve replacement surgery with Cardiopulmonary Bypass than the double-lumen endobronchial tube.

Postoperative hoarseness, sore throat, and vocal cord injuries are common complications after general anesthesia. The incidence of postoperative hoarseness is as frequent as 50% after short-term tracheal intubation. In the past, several risk factors for postoperative hoarseness and laryngeal injury have been identified, including demographic factors, quality of tracheal intubation and technical factors such as endotracheal tube size. One-lung ventilation during thoracotomy can be achieved via two basic techniques: (1) use of a double-lumen endotracheal tube (DLT) consisting of an endotracheal and an endobronchial lumen allowing independent single-lung ventilation ; or (2) use of an endobronchial blocker such as the Arndt blocker, which allows lung collapse distal to the occlusion. It has been recently demonstrated that DLT and endobronchial blocker are similar in their efficacy to achieve lung isolation for elective thoracic surgery. No data are available yet about the influence of the chosen technique on postoperative hoarseness, vocal cord injuries, sore throat, and bronchial injuries. Published data of Stout et al. imply that the incidence of postoperative hoarseness and vocal cord injury might be directly correlated with size of the used endotracheal tube. During thoracoscope assisted mitral valve replacement cardiac surgery, excellent lung isolated was not required. One-lung ventilation with the other lung collapsed is used to achieve a better exposure and assist the surgery. During the cardiac surgery under cardiopulmonary bypass, heparinization will lead to uncontrolled hemorrhage if there is endotracheal tube insertion associated injury. In addition, DLTs need to be exchanged for a single-lumen tube before the patient transferring to cardiac care unit for postoperative ventilatory support. This may result in second time injury. Investigators hypothesized that using a bronchial blocker to achieve one-lung ventilation may result in a lower incidence of clinically relevant laryngeal and bronchial morbidity after thoracoscope assisted mitral valve replacement cardiac surgery compared with a control group intubated with a DLT.

Inclusion Criteria:

1. New York Heart Association (NYHA)I-III level.
2. scheduled for thoracoscope assisted mitral valve surgery under surgery
3. provide with informed consent.

Exclusion Criteria:

1. emergency surgery.
2. preoperative pulmonary diseases, such as chronic obstructive pulmonary disease, atelectasis.
3. preoperative voice hoarse or sore throat.
4. involved in other clinical trials within 3 months .
5. Cannot cooperate with language understanding disorders or psychological problems.