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Medical > Therapy > Operative treatments

Surgical treatment of chronic thromboembolic pulmonary hypertension

Surgery is an effective and potentially curative therapeutic option for severe pulmonary hypertension. The procedure of choice for patients with chronic thromboembolic hypertension (CTEPH) is pulmonary thrombendarterectomy (1, 2). Lung perfusion scanning is used for screening. Multiple segemental or lobar perfusion defects can be easily distinguished from the pattern with diffuse patchy peripheral distribution of perfusion seen in primary pulmonary hypertension (PPH). However, the perfusion scan may underestimate the degree of vascular obstruction. Pulmonary angiography still remains the gold standard for diagnosis of CTEPH and the assessment of surgical accessibility (3). The interpretation of angiogramms can be difficult and requires specific experience. The classical signs include irregularities of the arterial wall, luminal narrowing or occlusion of central, lobar and segmental arteries caused by thrombus masses or webs and bands, sometimes accompanied by poststenotic dilatation. Helical CT scanning may give additional important information on operability and the risk of endarterectomy (4). In the future, magnetic resonance imaging might become a helpful non-invasive investigational tool in these patients.

Patients considered for endarterectomy are usually in NYHA functional class III or IV and severely incapacitated in their daily activities, and have a pulmonary vasculary resistance over 300-400 dyn x sec x cm-5. Chronic thrombotic lesions must be located at least as proximal as the origins of the segmental pulmonary artery branches or at the level of lobar or main arteries. With growing surgical experience endarterectomy may be performed in patients with more peripheral disease at an increased operative risk.

The operation is performed by the median sternotomy on cardiopulmonary bypass using profound hypothermia and periods of complete circulatory arrest, because the often excessive bronchial arterial flow otherwise makes it impossible to carry out the necessary delicate dissection, which in fact is a true thrombendarterectomy and not an embolectomy. Indeed, if only the proximal reddish material is removed, the patient will not be improved. It is essential that the whitish fibrotic material be dissected so that the lobar and segmental branches are opened. The most important complications are pulmonary reperfusion edema, bleeding, reversible acute renal failure and postcardiotomy syndrome. Meanwhile, experienced centers obtain an overall mortality as low as 5 per cent for "good" cases and 10-15 per cent for "difficult" cases (5). Most patients return to NYHA functional class II or lower and their pulmonary hemodynamics is nearly normal. Optimal live-long anticoagulation is crucial with respect to long-term results.

Lung transplantation remains the therapeutic option of choice in patients with CTEPH not accessible for thrombendarterectomy. Whereas in the early era more than 20 years ago heart-lung transplantation was the preferred operation (6), the increasing experience in isolated lung transplantation has shown that right ventricular dysfunction normalizes rapidly after reduction of the pulmonary vascular resistance. Increasing organ shortage and the problem of the coronary graft arteriopathy resulted in a sharp rise in isolated lung transplant procedures performed for severe pulmonary hypertension. A normal left ventricular function, normal coronary angiography and the absence of uncorrectable cardiac anomalies, however, are a prerequisite. Although single lung transplantation may be performed successfully in pulmonary hypertension (7), morbidity and mortality associated with severe ventilation perfusion mismatch either early preoperatively due to reperfusion injury or later due to obliterative bronchiolitis may be substantial. Thus, bilateral lung transplantation has become the procedure of choice at most centers (8, 9). Transplantation should be considered in patients with severe functional impairment of NYHA class III, or IV if there is evidence of right ventricular failure, right atrial pressure > 15 mmHg, low cardiac index < 2.0 L/min/m2 and low mixed-venous saturation < 60 % despite treatment with an intravenous continuous infusion of prostanoids. The prognosis after lung transplantation performed for pulmonary hypertension is somewhat worse than for operations performed for other indications. Especially, the immediate postoperative course may be complicated by circulatory problems. Therefore, the median time spent in the ICU postoperatively is about 20 days in patients transplanted for pulmonary hypertension compared to 3 days in patients transplanted for other indications (10). One- and 5-year-survival is about 70 and 60 per cent, respectively (11). The most important long-term complications include infectious diseases as a result of immunosuppressive treatment (12), adverse drug effects such as chronic renal failure due to cyclosporine and obliterative bronchiolitis (13). The latter still attains about 30 to 50 per cent of the patients within 5 years after transplantation and carries a significant morbidity and mortality.


References:

1. Daily PO, Dembitsky WP, Jamieson SW. The evolution and the current state of the art of pulmonary thrombendarterectomy. Semin Thorac Cardiovasc Surg 1999; 11:152-63.

2. Mayer E, Kramm T, Dahm M, Guth S, Oelert H. Surgical treatment of chronic thromboembolic pulmonary hypertension. Acta Chir Austriaca 1999; 31:308-13.

3. Auger WR, Channick RN, Kerr KM, Fedullo PF. Evaluation of patients with suspected chronic thromboembolic pulmonary hypertension. Semin Thorac Cardiovasc Surg 1999; 11:179-90.

4. Bergin CJ, Sirlin C, Deutsch R, Fedullo P, Hauschildt J, Huynh T, Auger W, Brown M. Predictors of patient response to pulmonary thromboendarterectomy. AJR Am J Roentgenol 2000; 174:509-15.

5. Archibald CJ, Auger WR, Fedullo PF. Outcome after pulmonary thrombendarterectomy. Semin Thorac Cardiovasc Surg 1999; 11:164-71.

6. Reitz BA, Wallwork JL, Sharon CB, Pennock JL, Billingham ME, Oyer PE, et al. Heart-lung transplantation. Successful therapy for patients with pulmonary vascular disease. N Engl J Med 1982; 306:557-64.

7. Levine SM, Gibbons WJ, Bryan CL, Walling AD, Brown RW, Bailey SR, et al. Single lung transplantation for primary pulmonary hypertension. Chest 1990; 98:1107-15.

8. Weder W, Speich R, Boehler A, Zollinger A, Stocker R, Lang T, Largiadèr F. Die isolierte Lungentransplantation. Schweiz Med Wschr 1995; 125:475-82.

9. Bando K, Armitage JM, Paradis IL, Keenan RJ, Hardesty RL, Konishi H, Komatsu K, Stein KL, Shah AN, Bahnson HT, et al. Indications for and results of single, bilateral, and heart-lung transplantation for pulmonary hypertension. J Thorac Cardiovasc Surg 1994; 108:1056-65.

10. Lee KH, Martich GD, Boujoukos AJ, Keenan RJ, Griffith BP. Predicting ICU lenght of stay following single lung transplantation. Chest 1996; 110:1014-7.

11. Speich R, Boehler A, Zalunardo M, Stocker R, Russi EW, Weder W. Improved results after lung transplantation - analysis of factors. Swiss Med Wkly 2001; 131:238-45.

12. Speich R, van der Bij W. Epidemiology and management of infections after lung transplantation. Clin Infect Dis 2001; 33:S58-S65.

13. Boehler A, Kesten S, Weder W, Speich R. Bronchiolitis obliterans after lung transplantation: a review. Chest 1998; 114:1411-26.

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