A the ascending aorta (AORPA) is a rare cardiac

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1 Anomalous Origin of the Right Pulmonary Artery From the Ascending Aorta Yuichirou Nakamura, MD, Hisataka Yasui, MD, Hideaki Kado, MD, Kunihiro Yonenaga, MD, Yuichi Shiokawa, MD, and Shigehiko Tokunaga, MD Departments of Cardiovascular Surgery, Fukuoka Children's Hospital Medical Center, Fukuoka, Japan Five cases of anomalous origin of the right pulmonary artery from the ascending aorta were seen at our hospital. Patients 1 and 2 had an intact right pulmonary artery originating from a right posterior aspect (proximal form), and primary anastomosis of the right pulmonary artery and main pulmonary trunk was performed. Patients 3 and 4 showed a narrowing right pulmonary artery originating from near the base of the innominate artery (distal form). The stenotic right pulmonary artery was reconstructed with an 8-mm graft in patient 3, whereas patient 4 became inoperable because complete obstruction had developed in the right pulmonary artery during the 3 months that the patient was waiting to undergo opera- tion. In patient 5, primary anastomosis was undertaken, but morphologically the anomalous origin was of the distal form, so the occurrence of stenosis in the reconstructed right pulmonary artery was a matter of concern. The morphological type was found to be related to the surgical options in this anomaly. Therefore, primary anastomosis was considered the best choice for a correction of the proximal form, whereas a graft interposition with a resection of the stenotic portion on the right pulmonary artery was deemed preferable in the distal form. (Ann Tkorac Surg 1991;52: ) nomalous origin of the right pulmonary artery from A the ascending aorta (AORPA) is a rare cardiac malformation. We operated on 5 cases of AORPA between 1983 and These could be divided into two morphological types (2 patients had the proximal form and 3, the distal form) [l], and 2 of the patients with the distal form had narrowing of the right pulmonary artery (PA). It seemed that an adequate evaluation of its pathogenesis was required for appropriate correction of the AORPA. Our purpose in the present report is to comment on the various surgical considerations of this disease. Summary of Cases The clinical conditions and data at admission of the 5 patients are summarized in Table 1. Two were neonates and 3 were infants at first admission. Patients 1, 2, and 4 were admitted with moderate to severe heart failure, whereas patients 3 and 5 had no prominent cardiac symptoms except for poor weight gain. In patient 4, the operation was postponed until the patient could achieve an adequate weight gain, because the patient's condition dramatically improved after admission. Two-dimensional echocardiography was able to detect the AORPA in 3 of the 5 patients. Preoperative Angiograplzy and Catheterization All patients underwent preoperative angiography. Typical features of the proximal form of AORPA were ob- Accepted for publication June 28, 1991 Address reprint requests to Dr Nakamura, Department of Cardiovascular Surgery, Medical Center for Sick Children, Fukuoka City, 2-5-1, Tohjinmachi, Cyuoku, Fukuoka, 810 Japan. served in patients 1 (Fig 1A) and 2 (Fig lb), that is, the right PA originating from the posterior aspect of the ascending aorta near the aortic valve. No narrowing site on the right PA was found in either case. Patients 3 (Fig 1C) and 4 (Fig 1D) had a narrowing site on the middle portion of the right PA, which originated from the right lateral aspect of the ascending aorta. Those features were compatible with the distal form of AORPA. Patient 5 (Fig 1E) showed no evidence of narrowing of the right PA, but the takeoff from the aorta was near the bifurcation of the innominate artery, so this case of AORPA seemed to belong to the distal form. Patients 1, 2, 3, and 5 also had patent ductus arteriosus. The pressure values at the first catheterization are given in Table 2. Severe pulmonary hypertension was demonstrated in all patients. Even in the patients with stenotic right PA (patients 3 and 4), pulmonary hypertension was found. Operative Findings and Surgical Procedures Surgical repair was performed several days after the first catheterization in patients 1, 2, 3, and 5. However, in patient 4, the operation was undertaken about 3 months after the first catheterization. In all patients, the correction was performed through a median sternotomy. Cardiopulmonary bypass was not used in patients 1, 3, 4, or 5 but was on standby. In patient 2, the most recent case, cardiopulmonary bypass was used. PATIENT 1. The main pulmonary artery was enlarged (11 mm) and the right PA (5 mm) originated from the right posterior aspect of the ascending aorta. A partial occluding clamp was placed across the right side of the aorta to by The Society of Thoracic Surgeons /91/$3.50

2 1286 NAKAMURA ET AL AORTIC ORIGIN OF RlGHT PULMONARY ARTERY Ann Thorac Surg 1991;52: Table 1. Clinical Features at Admission Patient Weight No. Age Sex (g) History Murmur CTR ECG 1 16 d F 2,530 Tachypnea, mild cyanosis 2 2 mo M 3,900 Tachypnea 3 1y5mo F 7,400 Poor weight 4 22 d (4 mo)b F 4,900 gain Tachypnea, mild 5 7 mo F 4,200 cyanosis Poor weight gain a By chest roentgenogram. In patient 4, operation was postponed for 3 months after the first admission. Grade 111 SM, 3LSB 0.69, RAD, BVH Atelectasis Grade I1 SM, 2LSB; 0.64 NAD, RVH grade I1 MDM, Apex Grade I11 continuous, 0.59, PV (right RAD, RVH 2RSB < left) Grade I11 SM, 3-4LSB 0.64 NAD, BVH Grade 1-11 SM, 2LSB 0.60 NAD, RVH BVH = biventricular hypertrophy; CTR = cardiothoracic ratio; ECG = electrocardiogram; LSB = left sternal border; MDM = middiastolic murmur; NAD = normal axis deviation; PV= pulmonary vascularity; RAD = right axis deviation; RSB = right sternal border; RVH = right ventricular hypertrophy; SM = systolic murmur include the origin of the right PA. The right PA was divided, and the aorta was sutured with 5-0 polypropylene. The right PA was passed behind the ascending aorta, and the stump was anastomosed to the right lateral aspect of the side-clamped main pulmonary trunk in an end-toside fashion with 6-0 polypropylene continuous suture posteriorly and with an interrupted suture anteriorly. The patent ductus arteriosus was then doubly ligated. PATIENT 2. The right PA (6 mm in diameter) originated from the ascending aorta in the same fashion as in patient 1. A pansystolic thrill was palpable on the right atrial wall due to tricuspid regurgitation. Cardiopulmonary bypass was performed using aortic cannulation, which was done 5 mm distal to the takeoff of the innominate artery using a 2.4-mm metal cannula, and venous cannulation, which was selectively inserted in the superior and inferior venae cavae. Moderate hypothermia with high-flow cardiopulmonary bypass (2.5 L/min/BSA) was performed. After ligation of the patent ductus arteriosus, cardioplegic arrest was induced by crystalloid cardioplegia (glucose, 2.5 g/l; sodium chloride, 75 mmol/l; sodium bicarbonate, 10 mmovl; potassium chloride, 20 mmovl; calcium gluconate, 0.6 mmovl; xylocaine, 100 mg/l; albumin, 10 g/l; osmolarity, 340 mosm/l) combined with topical cooling using ice slush. After aortic cross-clamping and occlusion of the right PA, the right PA was divided at its origin and an end-to-side anastomosis was performed with absorbable sutures. The aortic cross-clamp time was 46 minutes. PATIENT 3. A right PA originated from the right lateral aspect of the ascending aorta near the takeoff of the innominate artery. The middle portion of the right PA was stenotic, with a luminal diameter of 1 mm. After division of the right PA, a longitudinal incision was made in the peripheral side through the stenotic portion. A shelf was found in the stenotic portion. Graft interposition was performed using an 8-mm polytetrafluoroethylene graft. The new right PA was reconstructed through the anterior side of the aorta. PATIENT 4 (INOPERABLE CASE). The right PA originated from the ascending aorta in the same fashion as in patient 3. However, at 10 mm distal to its origin, the right PA showed a complete obstruction. We dissected the obstructed peripheral right PA beyond its trifurcation, but atrophic change of the right PA extended to the intrapulmonary artery, which prevented any surgical repair. The stenotic lesion on the right PA was considered to have developed during the 3 months while waiting for the operation. The magnetic flowmeter indicated a flow of 0 ml/min in the right PA. Fortunately, the main pulmonary arterial pressure showed a normal value (33/8 mm Hg). PATIENT 5. The right PA (8 mm in diameter) originated from right lateral aspect of the ascending aorta just proximal to the takeoff of the innominate artery. No stenotic segment was observed in the right PA. Primary anastomosis was performed with a double ligation of the patent ductus arteriosus. We encountered severe hypotension and bradycardia during the anastomosis. This episode discouraged us from reconstructing the AORPA routinely without cardiopulmonary bypass. Postoperative Angiography, Catheterization, and Courses Postoperative angiographic and catheterization data are shown in Figure 2 and Table 3. Postoperatively, all patients had uneventful courses, and in the patients who were operated on, the symptoms of heart failure dramatically improved. Cardiac catheterization at 1 month after operation showed the tendency of residual moderate pulmonary hypertension (pulmonary to systemic pressure ratio, 0.5). In patients 1 and 2, neither evidence of stenosis nor progress of pulmonary hypertension had appeared at 6 years and 1 year after operation, respectively. In patient 1, a lung perfusion scintigram 18 months after operation showed no perfusion defect in the right lung (Fig 3). In the patient who received a graft (patient 3),

3 NAKAMURA ET AL A n n Thorac Surg 1991;52: A D B E 1287 Fig 1. Preoperative angiocardiography: ( A )patient 1, ( B ) patient 2, (C) patient 3, ( D ) patient 4, ( E ) patient 5. In patients 2 and 2, the C right pulmonary artery (RPA) originates from the ascending aorta (Ao) near the aortic valve. In patients 3 and 4, the right pulmonary artery arises from the midportiun of the ascending norta and a narrouing portion can be found (arrow). I I I patient 5, the RPA originates from near the innominate arfery, but there is no stcnotic portion. (Des A 0 = descending aorta.)

4 ~ ~~ ~~ ~ 1288 NAKAMURA ET AL Ann Thorac Surg 1991;52128%91 Table 2. Preoperative Cardiac Catheterization Data Pressure (mm Hg) Patient No. MeanRA RV MPA MeanLA LV(Ao) I'p/Ps /6 67/ / /0 63/ / /0 47/27... (61130) /8 104/ / / (75/50) 1.06 LA = left atrial; LV (Ao) = left ventricular (aortic); MPA = main pulmonary artery; PplPs = pulmonary to systemic peak pressure ratio; RA = right atrial; RV = right ventricular. anticoagulant therapy (aspirin, 10 mg - kg-' * day-', and dipyridamole, 5 mg - kg-' - day-') has been continued. Although a chest roentgenogram showed no laterality of pulmonary vascularity, the systolic murmur increased at the right upper sternal border 2 years after operation. In the inoperable patient (patient 4), no pulmonary hypertension had developed by 3 years after operation. The patient has no particular complaints, but the laterality of the pulmonary vascularity is unchanged. We carefully followed up patient 5 in regard to the stenosis in the right PA. Neither laterality of pulmonary vascularity on chest roentgenograms nor a heart murmur has appeared in the recent outpatient check-ups. B Fig 2. Postoperative angiocardiography: (A) patient I, (B) patient 2, (0 patient 3, (D) patient 5. Direct anastomosis was performed in patients 1, 2, and 5, and a graft interposifion was undertaken in patient 3. D

5 Ann Thorac Surg 1991;52: NAKAMURA ET AL 1289 Comment Anomalous origin of the right pulmonary artery from the ascending aorta is a rare malformation. Since it was first reported by Fraentzel[2] in 1868, more than 80 cases have been documented in terms of its interesting embryological and physiological features. It is generally recognized that AORPA has two different formal types of genesis [l, 3,4], the proximal and distal form. In the proximal form, the anomalous right PA originates from the right posterior aspect of the proximal ascending aorta close to the aortic valve. The cumulative study by Kutsche and Van Mierop [l] showed that 85% of cases of AORPA were classified as this type. Schneiderman [5] and others [6] consider it to be the result of a lack of leftward migration of the right sixth aortic arch. Cucci and associates [7] and Richardson and co-workers [8] believe it to be due to an abnormal truncal septation. The abnormal right PA develops from the proximal portion of the right sixth arch in the same way a normal one does, and there is no narrowing site in this type. On the other hand, in the distal form, the anomalous right PA originates from the ascending aorta near the base of the innominate artery. Ode11 and Smith [9] explained that a fifth arch developed and the proximal and the distal part of the sixth arch disappeared. The dorsal portion of the sixth arch (which involved patent ductus arteriosus tissue) thus remains connected to the fifth arch and pulmonary artery. This is a plausible explanation for the fact that narrowing of the PA often occurs in this type of AORPA. The difference in the pathogenesis between the two types could also be suggested by the associated anomalies. Aorticopulmonary septa1 defect (15%) and the interruption of aortic arch type A (9%) are commonly associated anomalies in the proximal type (1, 101, whereas they are not common in the distal type. Patients 1 and 2 could be classified as having the proximal form, and the others, the distal form. Patients 3 and 4 had narrowing - of the PA, whereas patient 5 had none. We want to comment on the surgical considerations for this anomaly. There is no doubt that radical correction is life saving for this anomaly. Penkoske and associates [6] report that the mortality of this malformation with palliative operation including ligation of the anomalous RPA, ligation of the patent ductus arteriosus, or PA banding reached 82% (18/22), whereas it is 26% (6/23) in radical correction. Table 4 shows the reported radical correction and its results. Those include 28 cases of the proximal Table 3. Postoperative Cardiac Catheterization Data Pressure (mm Hg) Patient No. MeanRA RV MPA MeanLA LV (Ao) PplPs / Z-1 38/14... (73136) 0.52 LA = left atrial; LV (Ao) = left ventricular (aortic); MPA = main pulmonary artery; PplPs = pulmonary to systemic peak pressure ratio; RA = right atrial; RV = right venhicular. Ant R Ant 30' R4b Rm Post L Ant30O 6. L Lpt 4Q Fig 3. Lung perfusion scintigrarn in patient 1 at 18 months after operation shows no perfusion defect in the right lung. (Ant = anterior; L = left; Iat = lateral; post = posterior; R = right.) form and 3 of the distal form. In the cases of proximal form, 70% had primary anastomosis performed either with or without cardiopulmonary bypass. The origins of the right PA (posterior aspect of ascending aorta) and the main PA are not distant in this form, so the right PA could easily be reanastomosed through the posterior side of the ascending aorta. Technically, adequate dissection of both PAS beyond their first bifurcation may be a point for providing an easy anastomosis. Few reports of the reconstruction of right PA with a stenotic portion can be found [ll], but we encountered 2 cases of this type. Complete resection of the narrowing portion and graft interposition would be a preferable means of reconstruction in this form. The stenosis in the right PA seems to be sometimes progressive [4], so surgical intervention should not be delayed. In patient 4, complete obstruction of the stenotic right PA, which interfered with the radical correction, had developed during the 3-month waiting period. Fortunately, the pulmonary hypertension and the clinical symptoms were relieved by the disappearance of shunt flow. However, there is no doubt that two lungs are superior to one lung from the standpoint of pulmonary function. Hemoptysis

6 1290 NAKAMURA ET AL Ann Thorac Surg 1991;52: Table 4. Reported Cases of Radical Correction Procedure Use of CPB or Morphological Type No. of Cases Primary Anastomosis Graft Circulatory Arrest Proximal form 28 (5)" VSD closure 2 +ASD closure 2 +repair of cor triatriatum 1 Distal form 3 (0) With stenosis Without stenosis TOF correction 1 Unclear 4 (0) 3 1 No description Total 35 (5) a Numbers in parentheses are operative deaths. ASD = atrial septal defect; CPB = cardiopulmonary bypass; TOF = tetralogy of Fallot; VSD = ventricular septal defect. due to a hemorrhage into the disused lung supplied by the anomalous systemic vessels [12] is a serious complication. These disadvantages would not permit us any delay in surgical intervention in the case of a distal form of AORPA. Although patient 5 had no evidence of narrowing lesions in the right PA, she was considered to have a distal form. The surgical problems must focus on the distal form of AORPA without a narrowing right PA. Descriptions of the microscopic structure of the right PA have seldom been given, so it is not possible to find out how often tissue of ductal origin is present in this form of AORPA. If patent ductus arteriosus tissue is contained in the right PA, then a resection of the midportion of the AORPA and reconstruction using a synthetic graft may be the best choice. A different pathogenesis might be taken into consideration for patient 5, however, such as explained by Ambrus [13]; a right fifth arch developed whereas a sixth did not. If this hypothesis is true in this case, then primary anastomosis may be the best choice. We are now carefully following up this patient. We did not routinely use cardiopulmonary bypass to avoid its several postoperative adverse effects. Now, however, its use might be taken into consideration depending on the details of each case, because anastomosis with a side clamp would not be so easy and safe in all cases. The development of a cardiopulmonary bypass technique for neonates or small infants would be one reason for using it [14]. There are some explanations for the cause of the bilateral pulmonary hypertension caused by different blood supply to each lung [12, 151. In the right lung, the increased pulmonary blood flow at systemic levels of pressure would affect the pulmonary vasculature like a large patent ductus arteriosus or ventricular septal defect. The left lung is perfused with the entire right ventricular output, but it is unlikely that the flow alone is responsible for the changes in this lung. The vasoconstrictive reaction due to the abnormal state of the vascular bed on the right lung is considered to be responsible for the development of pulmonary hypertension. The differential development of pulmonary obstructive disease in each lung has been also reported. Yamaki and colleagues [16] hypothesized that the increased blood flow with highly saturated blood is a cause of highly progressive vascular disease in the right lung. In the present study, all 4 patients who were operated on, which included 1 neonate and 3 infants, showed moderate pulmonary hypertension (pulmonary to systemic pressure ratio >0.5) after reconstruction of the right PA. These facts would support early surgical intervention in this anomaly. Recently, some reports have emphasized the usefulness of echocardiography to determine the diagnosis and operative indications in this anomaly [17]. Echocardiography, however, seems unable to define the morphological type and presence of stenosis. We believe that cineangiography is necessary for determining the morphological diagnosis and surgical method. Therefore, an early definitive diagnosis by angiocardiography and prompt surgical intervention is our recommended surgical strategy for this anomaly. In summary, 5 cases of AORPA were operated on in our hospital over a 7-year period. Two were of the proximal form and the others were of the distal form. A narrowing right PA was seen in 2 of the 3 cases of distal form of AORPA. In 1 of them, complete obstruction developed during the 3-month period before surgical intervention. The morphological type is considered to be related to the surgical therapy in this anomaly. Primary anastomosis is the choice for the proximal form of AORPA, whereas a graft interposition would be preferable for the distal form with a narrowing right PA. References 1. Kutsche LM, Van Mierop LHS. Anomalous origin of a pulmonary artery from the ascending aorta: associated anomalies and pathogenesis. Am J Cardiol 1988;61:85&6.

7 Ann Thorac Surg 1991; NAKAMURA ET AL Fraentzel 0. Ein Fall von abnormer Communication der Aorta mit der Arteria pulmonalis. Virchows Arch[A] 1868;43: 42M. Rosenberg HS, Hallman GI, Wolfe RR, Latson JR. Origin of the right pulmonary artery from the aorta. Am Heart J 1966;72: Kauffman SL, Yao AC, Webber CB, Lynfield J. Origin of the right pulmonary artery from the aorta. A clinical-pathologic study of two types based on caliber of the pulmonary artery. Am J Cardiol 1967;19: Schneiderman LJ. Isolated congenital absence of the right pulmonary artery: a caution as to its diagnosis and a proposal for its embryogenesis. Report of a case with review. Am Heart J 1958;55: Penkoske PA, Castafieda AR, Fyler DC, Van Praagh R. Origin of pulmonary artery branch from ascending aorta. Primary surgical repair in infancy. J Thorac Cardiovasc Surg 1983;85: Cucci CE, Doyle EF, Lewis EW. Absence of a primary division of the pulmonary trunk. An ontogenic theory. Circulation 1964;29: Richardson JV, Doty DB, Rossi NP, Ehrenhaft J. The spectrum of anomalies of aortopulmonary septation. J Thorac Cardiovasc Surg 1979; Ode11 JE, Smith JC. Right pulmonary artery arising from ascending aorta. Am J Dis Child 1963;105: Berry TE, Bharati S, Muster AJ, et al. Distal aortopulmonary septa1 defect, aortic origin of the right pulmonary artery, intact ventricular septum, patent ductus arteriosus and hypoplasia of the aortic isthmus: a newly recognized syndrome. Am J Cardiol 1982;49: Car0 C, Lermanda VC, Lyons HA. Aortic origin of the right pulmonary artery. Br Heart J 1957;19: Griffiths SP, Levine OR, Andersen DH. Aortic origin of the right pulmonary artery. Circulation 1962;25:7W. 13. Ambrus G. Congenital absence of the right pulmonary artery with bleeding into the nght lung. J Tech Methods 1936; Yasui H, Yonenaga K, Kado H, et al. Open-heart surgery in infants using pulsatile hight-flow cardiopulmonary bypass. J Cardiovasc Surg 1989;30: Cumming GR, Ferguson CC, Sanchez J. Aortic origin of the right pulmonary artery. Am J Cardiol 1972; Yamaki S, Suzuki Y, Ishizawa E, Kagawa Y, Horiuchi T, Sat0 T. Isolated aortic origin of right pulmonary artery. Chest 1983;3: Lo RNS, Mok C, Leung MP, Lau C, Cheung DLC. Crosssectional and pulse Doppler echocardiographic features of anomalous origin of right pulmonary artery from the ascending aorta. Am J Cardiol 1987;60:9214.