Pulmonary thromboendarterectomy
2 Alias for pulmonary thromboendarterectomyPulmonary thromboendarterectomy; Pulmonary thromboendarterectomy; Pulmonary thromboendarterectomy
3 ClassificationCardiovascular surgery / Surgery for pulmonary embolism / Surgical treatment of chronic pulmonary embolism
4 ICD codes38.1501
5 OverviewChronic pulmonary embolism, also known as chronic thromboembolic pulmonary hypertcnsion, is clinically Chronic thromboembolic pulmonary hypertcnsion, also known as chronic thromboembolic pulmonary hypertcnsion (CPH), is a rare clinical condition characterized by progressive dyspnea after activity and death from respiratory failure, with surgery as the only cure. The occurrence of this disease is due to a small number (only about 0.5% to 4%) of patients with acute pulmonary embolism, the embolus fails to autolyze and remains mechanized, and secondary thrombosis or recurrent multiple small emboli resulting in widespread obstruction of the pulmonary vascular bed to form pulmonary arterial hypertension, hypoxemia and right heart failure. It has also been suggested that the underlying cause is damage to the pulmonary endothelium itself, which affects the production of tPA inhibitors and exposes the subendothelial structures to thrombosis. more than 90% of the lesions are bilateral, and the extent of the obstruction is usually more than 50%. Thrombus emboli are located in the main pulmonary artery, lobar or segmental arteries and are white, fibrous material tightly adherent to the pulmonary artery, often with a fresher red secondary thrombus proximal to it. The wall of the damaged pulmonary artery is thin, and the pulmonary artery is often fibrotic and difficult to separate from the bronchus, and the bronchial artery is dilated. Unlike acute pulmonary embolism, pulmonary hypertension is the basic pathophysiologic change of the disease, and in 48 cases by Sebastian et al, the mean pulmonary arterial pressure was 42 ± 5 mm Hg, which is proportional to the extent of the obstruction and correlates with prognosis. Hypoxemia appeared only after activity in the early stages, with a progressive decrease in partial pressure of oxygen with the progression of the disease, mostly in the range of 55-60 mmHg, PaCO 230 mmHg, pH 7.5 or so, showing chronic respiratory alkalosis. Its clinical manifestations are also characterized by dyspnea after progressive activity, ventilation may be mildly impaired, and diffusion function may appear normal due to the presence of bronchial artery collateral circulation. Dead space ventilation following pulmonary arterial blood flow obstruction with a disproportionate ventilation/blood flow ratio is the underlying cause of hypoxemia. Diagnosis is based on lung ventilation/perfusion scanning as the basic step and initial screening of patients for surgery, CT, MRI and ultrasound to confirm the diagnosis and pulmonary arteriography for precise localization and surgery.
6 Indications
Pulmonary thromboendarterectomy is indicated for:
1. Significant symptoms of chronic progressive respiratory failure, hypoxemia and hypocapnia, failure of anticoagulant therapy for 6 months, and cardiac function (NYHA) class III and IV.
2. Mean pulmonary artery pressure of 30 mmHg or more, pulmonary circulation resistance ≥ 300 dyne/(s.cm5).
3. Pulmonary arteriography showing >50% of the extent of obstruction, located in arteries above the lung segments that can be reached by surgery, located in the main branches of the pulmonary arteries or the proximal parts of the lobar arteries is particularly suitable.
7 Contraindications1. Obstruction farther than the pulmonary segmental arteries, extensive small arterial embolization that cannot be removed.
2. Severe right heart failure.
3. Combination of serious diseases of other organs and other conditions that are not suitable for surgery.
8 Preoperative preparation1. Sebastein, Lyerly et al. believe that preoperative bronchial arteriography should be done, only if there is abundant dilatation of the bronchial artery collateral circulation in the area of pulmonary artery obstruction, showing the opening of the pulmonary blood vessels on the distal side of the obstruction, the efficacy of the surgery is accurate and conducive to the implementation of the operation. However, Rich et al. held the opposite opinion, that it is not necessary, and have not seen the bronchial arteriography did not show collateral circulation and surgical failure.
2. There is a difference of opinion as to whether a preoperative (postoperative) inferior vena cava filter should be placed, with Daily routinely placing one, and Rich suggesting that postoperative anticoagulation is sufficient to prevent recurrence and to keep the pulmonary arterial bed clear, and that prophylactic placement is not necessary.
9 Anesthesia and ***General anesthesia by tracheal intubation, except for a few cases in which the pulmonary artery obstruction is limited to one side, the pulmonary artery can be dissected by a lateral thoracotomy (anterior thoracic or posterior posterolateral incision) without extracorporeal circulation, and the procedure is carried out after the proximal part of the pulmonary artery has been blocked. The surgery is usually performed in the supine position under a median incision with extracorporeal circulation.
10 Surgical steps1. Median incision, routine intubation and diversion, deep hypothermia (18 ℃) to block the circulation, cold blood cardiac arrest fluid coronary perfusion as the basic method.
2. Sufficiently free the superior vena cava to the innominate vein in order to retract and expose the right pulmonary artery.
Separate the two pulmonary arteries distally along their anterior walls within the pericardium, retracting anteriorly to protect the phrenic nerve, dissecting the pulmonary arteries within the pericardial reflexes and extending distally beyond the reflexes for several centimeters until the opening of the segmental pulmonary arteries is revealed (Figs. 6.54.2.11, 6.54.2.12). The above maneuver should be completed before the blood is cooled (18°C) to the point of cessation of circulation.
3. After cessation of circulation, the site of the pulmonary artery incision is determined on the basis of imaging and intraoperative examination, and a longitudinal dissection is made up to the bifurcation of the lobar artery.
4. Careful separation with a peeler to find the gap between the mechanized embolus and the wall, the correct plane to keep the middle layer intact, the inner surface of the first 360 ° separation, followed by distal dissection until all the thrombus endothelium stripped out of the whole piece, the blood can be seen to come out of the incision countercurrent.
5. Stopping the circulation is limited to 20 min, at which time the operation on one side can be completed, and the circulation is resumed for 8-10 min to restore the SvO2 to 90%-93%, and then the circulation is stopped for the operation on the opposite side.
6. The pulmonary artery incision is closed with continuous 60 polypropylene sutures, and when there is a possibility of stenosis, it is repaired with a singular vein sheet or pericardial sheet.
7. Rewarming, repacing, draining, placing the pacing lead, and suturing the incision.
11 Intraoperative points of attention1. The pulmonary artery has a lot of adhesions with the surrounding tissues, which must be carefully separated, and the dissection must be limited to the pericardium, mediastinum, and hilar region, and try not to enter the pleural cavity.
2. Pay attention to protect the bilateral phrenic nerve from mechanical and local hypothermia.
3. Patiently separate the embolus from the correct plane between the tube wall, fully stripping the embolus circumference and then extend, from the upper lobe to the lower lobe, so that all the embolus removed in one piece without breaking, pay attention to prevent the peeling of too deep to cause damage to the pulmonary artery.
4. The proximal side of the mechanized embolus can have fresh thrombus formation, do not mistakenly think that all the emboli will be removed and left behind the real mechanized thrombus.
12 Complications 12.1 1. Right heart failurePreoperative right heart function is impaired for a long time, due to the insufficient protection of the myocardium during the operation, the postoperative pulmonary vascular bed reperfusion after the reactive vasoconstriction and the pulmonary artery pressure can not be quickly decreased, for the main reason leading to postoperative right heart failure. Therefore, intraoperative myocardial protection and postoperative hemodynamic monitoring are necessary to take timely measures. Commonly used drugs for lowering pulmonary arterial pressure have the concern of lowering peripheral arterial pressure. Selective lowering of pulmonary hypertension drugs nitric oxide has been used in recent years, with a special device inhalation of nitric oxide concentration of 20 ~ 40 ppm, safe, effective and easy to control.
12.2 2. Reperfusion pulmonary edemaAlso known as "localized ARDS", "pulmonary hemorrhage syndrome", manifested in the postoperative obvious hypoxemia, can be in the immediate postoperative period or 3 ~ 5d after the emergence of the incidence of about 20%, the need to carry out mechanical ventilation. If necessary, supplemented with PEEP, can be gradually recovered after a few days, static injection of corticosteroids at the end of the operation, and then used once the next day can reduce its occurrence, severe cases may have a large amount of endobronchial hemorrhage, can be stopped by Carlen catheter obstruction of the side of the airway in order to temporarily fill the coagulation.
12.3 3. Bilateral phrenic nerve paralysisDue to intraoperative anatomical tension, ischemia, local hypothermia, and other factors, respiratory support is required for natural recovery.
12.4 4. Prevention of reformation and recurrence of thromboembolism