Surgical Reconstruction of Occluded Pulmonary Arteries in Patients With Congenital Heart Disease
Effects on Pulmonary Artery Growth
Background— This study was undertaken to determine outcomes and best strategies for treatment of occluded pulmonary arteries in patients with congenital heart disease.
Methods and Results— Between 1998 and 2002, occlusion of a previously patent pulmonary artery was established in 23 patients. Data were obtained retrospectively. Diagnoses were pulmonary atresia and ventricular septal defect in 11, tetralogy of Fallot in 6, and other forms of pulmonary stenosis or atresia in 6. Median age and weight at diagnosis were 9 years (range, 6 days to 43 years) and 24 kg (range, 2.6 to 60 kg). Fourteen patients had had a previous surgery. The occluded pulmonary artery was visualized at angiography by wedge injection or injection into the collateral circulation. The left pulmonary artery was occluded in 20 patients and the right pulmonary artery in 3. Criteria for reconstruction were estimated duration of occlusion <6 months and ratio of occluded to contralateral artery >0.2. Twelve patients fulfilled these criteria and underwent pulmonary artery reconstruction at a mean interval of 2 months (range, 6 days to 6 months) from evidence of occlusion. Six patients had pericardial patch reconstruction, 3 terminoterminal anastomosis, 2 thrombectomy, and 1 a Blalock-Taussig shunt. There was 1 late death. At a median follow-up of 4 years (2 months to 5 years), all patients underwent cardiac catheterization: in 8 patients the reconstructed artery was patent, in 3 reoccluded. Hypoplasia of the occluded artery was reversed in 6 patients.
Conclusions— Our data show that in selected patients, reconstruction of an occluded pulmonary artery can restore pulmonary vascularization and reverse hypoplasia. Strict surveillance is mandatory to prevent pulmonary artery loss.
Received November 5, 2003; revision received February 6, 2004; accepted February 10, 2004.
In patients with conotruncal congenital heart disease and patent ductus arteriosus, abnormal extension of ductal tissue, implantation of a right ventricle–to–pulmonary artery conduit or of a Blalock-Taussig shunt can prompt obstruction of a pulmonary artery.1–3 Occlusion of a main pulmonary vessel occurring during the first month of life can lead to ipsilateral lung hypoplasia and impaired vascular growth and maturation.1,4 After the neonatal period, occlusion of a pulmonary artery leads to ventilation/perfusion mismatch and possibly to right ventricular hypertension.5 Absent perfusion can be complicated by thrombosis, can induce development of collateral circulation, and can eventually prevent surgical revascularization.
There is little information about the fate of occluded pulmonary arteries after surgical revascularization. No recommendations exist on timing and optimal surgical strategy for reconstruction of occluded pulmonary arteries.
In our institution, to prevent early and late complications of pulmonary artery occlusion, surgical revascularization of occluded arteries is performed in selected cases. We report our experience with 23 patients with secondary occlusion of a main pulmonary artery with regard to surgical approach, anatomic determinants, and mid-term follow-up.
From January 1, 1998, to January 1, 2003, we observed secondary occlusion of a main pulmonary artery in 23 patients with conotruncal malformations. Clinical characteristics and anatomic features are reported in Table 1. Median age and weight at diagnosis were 9 years (range, 6 days to 43 years) and 24 kg (range, 2.6 to 60 kg). Seven patients were ≤1 year old, and 4 were <3 months old. Chromosomal anomalies were found in 5 patients. Table 2 illustrates previous surgery, estimated duration of occlusion, and hemodynamic data. The left pulmonary artery was occluded in 20 patients (1 thrombosis) and the right pulmonary artery in 3 (2 thromboses). Fourteen patients had had a previous surgery aimed to feed the pulmonary arteries in a retrograde (10 systemic-to-pulmonary shunts) or antegrade manner (4 right ventricle–to–pulmonary artery conduits). Estimated duration of occlusion, when not coincident with time from last surgery to evidence of occlusion, was calculated on the basis of last echography or angiography showing patent pulmonary vessels. In patients followed up in our institution, occlusion of a main pulmonary artery was suspected on the basis of clinical and echocardiographic data during programmed evaluation. In 4 patients referred from other institutions (patients 13, 21, 22, and 23), pulmonary artery occlusion was a fortuitous finding.
To confirm occlusion, a right or left heart catheterization was performed, according to pathology. Right catheterization was preferred in patients with a right ventricle–to–pulmonary artery shunt and left catheterization in those with a systemic-to-pulmonary shunt and in nonoperated patients with tetralogy of Fallot and pulmonary atresia with ventricular septal defect.
The diameter of pulmonary vessels was measured using as a reference the diameter of the diagnostic catheter, corrected for magnification. Patients with an estimated duration of pulmonary artery occlusion >6 months, no collateral circulation, and a ratio of occluded versus contralateral pulmonary artery <0.2 were not considered for surgery. All other patients (patients 1 to 12) were operated on at a median interval of 3 days (range, 2 days to 3 months) from evidence of occlusion.
Patients 19 and 21, although fulfilling the inclusion criteria, were not operated on because of unfavorable social environment associated with chromosomal anomaly or complex underlying disease.
In 13 patients, a pulmonary artery stenosis or hypoplasia preexisted (Table 1). The development of occlusion was ipsilateral in 10 patients. The remaining 3 patients had bilateral hypoplasia of pulmonary arteries and developed unilateral occlusion, most likely because of ductal constriction in patient 13 and right ventricle–to–pulmonary artery conduit in patients 14 and 15. The median ratio of occluded/contralateral pulmonary artery was 0.5 (range, 0.1 to 1).
The presence of aortopulmonary collaterals did not prevent hypoplasia of the proximally occluded pulmonary artery.
Surgical data are illustrated in Table 3. All but 2 patients were operated on by the same surgeon. Continuity between pulmonary arteries was restored in 10 of 12 patients operated on. Associated surgery was performed in 6 patients.
One death, due to sepsis, occurred 2 months after surgery in 1 patient with multiple malformations and microcephaly.
At a median follow-up of 4 years (range, 2 months to 5 years) (Table 4), all patients operated on underwent cardiac catheterization. Eight patients had a patent pulmonary artery and 3 a reoccluded, nonvisualized artery. Hypoplasia of a previously occluded pulmonary artery was reversed in 6 patients, 5 of whom had an antegrade flow to the lungs, and persisted in 1 patient treated with a Blalock-Taussig shunt. The mean ratio of occluded/contralateral pulmonary artery increased from 0.71±0.19 to 0.92±0.09 (P=0.036, paired Student’s t test). After pulmonary artery reconstruction, patients 3 and 7 had a bidirectional cavopulmonary connection, patient 4 had percutaneous closure of a ventricular septal defect, patient 8 underwent heart transplantation because of biventricular failure, and patient 10 underwent percutaneous implantation of a valved stent. Patients 1 through 12 are in NYHA class I.
Among patients who did not fulfill criteria for pulmonary artery revascularization, patients 13 and 16 underwent balloon dilation of the pulmonary valve, and patient 17 had a right ventricle–to–right pulmonary artery conduit.
Complete occlusion of a main pulmonary artery can occur in patients with conotruncal congenital heart diseases. Obstruction of a main pulmonary artery secondary to ductal constriction is usually referred to as pulmonary artery coarctation.1,2 Embryology suggests a pathogenetic similarity between coarctation of the aorta and this type of stenosis. Indeed, both are caused by extension of the ductal tissue in the portion of the great artery facing the ductus, the aorta being involved in normal fetal circulation, and the pulmonary arteries being involved when there is a reverse ductal flow during fetal life.1,2 Coarctation of a main pulmonary artery can induce hypertensive changes in the contralateral lung and/or preclude neonatal decrease of pulmonary vascular resistances.4 Peripheral pulmonary arterial changes are age dependent and associated with asymmetrical blood flow between the right and left pulmonary arteries.4
Implantation of a right ventricle–to–pulmonary artery conduit or of a Blalock-Taussig shunt can also prompt obstruction of a pulmonary artery.1–3 The mechanism that causes juxtaductal obstruction of a pulmonary artery could be turbulent flow at the insertion of the shunt, with subsequent jet lesion on ductal tissue,3 or development of scar tissue in a low-pressure system with reduced driving pressure.1 Thrombosis can also cause pulmonary artery obstruction in the postoperative period.6
To prevent loss of a main pulmonary artery before lung maturation is completed, strict surveillance of these neonates is recommended; however, occlusion can develop rapidly or can be diagnosed fortuitously.
Reports on reconstruction of occluded pulmonary arteries are scanty. No specific publications on this topic exist.
Stamm et al6 reported 9 cases of occlusion of a main pulmonary artery after reconstitution of pulmonary artery continuity. However, all cases were a result of thrombosis, and only 3 patients needed surgical treatment. In the setting of pulmonary atresia and ventricular septal defect, Ishizaka et al7 reported 5 patients in whom thrombectomy allowed repermeabilization of a central pulmonary artery.
Our data show that in selected patients, reconstruction of an occluded pulmonary artery offers good results. The patients included had neither severe hypoplasia of the occluded pulmonary artery nor a prolonged duration of occlusion. A prolonged duration of occlusion was associated with very hypoplastic artery, except when the occluded vessel was perfused by collateral circulation. Indeed, the risk of thrombosis is reduced when collateral vessels are present, except in the segments in which there is a competition between flow from different origins.
In patients scheduled for single-ventricle repair, it is of primary importance to obtain patency of both pulmonary arteries. In 3 patients of our series with single ventricle, it was possible to restore pulmonary artery continuity. Stamm et al6 showed a good survival of patients with single ventricle and repaired discontinuity of pulmonary arteries.
A second finding of our study was regression of pulmonary artery hypoplasia in 6 patients, 5 of whom had anterograde perfusion of the pulmonary arteries.
Most authors agree that antegrade pulmonary blood supply is the best strategy to promote pulmonary artery growth and to avoid the development of pulmonary vascular disease.6 Indeed, the antegrade pulsatile flow pattern may have beneficial effects on pulmonary artery development compared with shunt perfusion.8,9
However, a bias could have been introduced in our results when we measured the ratio of the occluded to the contralateral pulmonary artery in nonperfused and perfused arteries.
We could not identify any factor explaining definitive loss of a pulmonary artery in patients in whom revascularization failed. Larger series of patients and multicenter studies should be encouraged.
Limitations of the Study
Data were collected retrospectively, and selection of patients for surgery was established on the basis of institutional criteria, because no recommendations about reconstruction of occluded pulmonary arteries exist. Two eligible patients were not operated on because of an association of chromosomal disease or unfavorable social environment. Even if it is logical to think that a longstanding occlusion of a very hypoplastic pulmonary artery will prevent its revascularization, this has not been proved.
Momma K, Takao A, Imai Y, et al. Obstruction of the central pulmonary artery after shunt operations in patients with pulmonary atresia. Br Heart J. 1987; 57: 534–542.
Tscholl D, Langer F, Wendler O, et al. Pulmonary thromboendarterectomy: risk factors for early survival and hemodynamic improvement. Eur J Cardiothorac Surg. 2001; 19: 771–776.
Ishizaka T, Yagihara T, Yamamoto F, et al. Results of unifocalization for pulmonary atresia, ventricular septal defect and major aortopulmonary collateral arteries: patency of pulmonary vascular segments. Eur J Cardiothorac Surg. 1996; 10: 331–337.
Reddy VM, McElhinney DB, Amin Z, et al. Early and intermediate outcome after repair of pulmonary atresia with ventricular septal defect and major aortopulmonary collateral arteries: experience with 85 patients. Circulation. 2000; 101: 1826–1832.