- Email: [email protected]
Patterns of pulmonary arterial supply in patients with truncus arteriosus
Patterns of pulmonary arterial supply in patients with truncus arteriosus Patients with anatomic discontinuity between the heart and pulmonary arterial system are now candidates for corrective surgical procedures. Differentiation between patients with pulmonary arteries (truncus arteriosus types I, II and Ill, and pseudotruncus) and those without pulmonary arteries (absent sixth aortic arch, truncus arteriosus type IV) is crucial. Anatomic classification, diagnostic criteria, and indications for surgical repair are still controversial. This paper presents four cases of truncus arteriosus that were managed surgically. Three of these had variants of type I anatomy, with hypoplasia or atresia of the connection to the ascending aorta. The fourth patient had a complicated type of truncus IV anatomy. Three points are emphasized: (I) Patients with type I truncus arteriosus can present with hypoplasia or atresia of the truncus-pulmonary connection. These patients may have suitable anatomy for full physiological correction, and their condition should not be confused with the type IV anatomy. (2) Ligation of collateral arterial supply is important. (3) We hypothesize that any patient with truncus arteriosus and continuous murmur has some kind of pulmonary arterial system which is surgically accessible. Currently, we perform an exploratory operation on any such patient. If reasonably large pulmonary arteries are found at operation, physiological correction with a valved conduit is performed. If the arteries are diminutive, a systemic-to-pulmonary shunt is constructed which it is hoped will stimulate dilation of the pulmonary arterial system and allow later physiological correction. Prolonged follow-up of a larger number of these patients is necessary.
Stephen J. Rossiter, M.D., James F. Silverman, M.D., and Norman E. Shumway, M.D.,
Stanford, Calif.
Patients with anatomic discontinuity between the heart and pulmonary arterial system are now condidates for corrective surgical procedures.":" Differentiation between patients with pulmonary arteries (truncus arteriosus types I, II, III, and pseudotruncuss- 9) and those without pulmonary arteries (absent sixth aortic arch.!? truncus arteriosus type IV8) is central to proper patient selection and surgical planning. Three cases presented herein are unusual in that they demonstrate hypoplasia or atresia of ascending aortic origins of pulmonary arterial supply in children who had truncus arteriosus type I at birth. A fourth patient had a complicated type of truncus type IV anatomy. Points emphasized are (I) the importance of differentiating truncus type I from truncus arteriosus type IV From the Departments of Cardiovascular Surgery and Radiology, Stanford University Medical Center, Stanford, Calif. 94305. Received for publication May 23, 1977. Accepted for publication July 26, 1977. Address for reprints: Stephen J. Rossiter, M.D., Department of Cardiovascular Surgery, Stanford University Medical Center, Stanford, Calif. 94305.
(absent sixth aortic arch), (2) the necessity of dealing with bronchial coliaterals, and (3) the significance of continuous murmurs.
Case reports CASE I. J. R. (50-41-98), a female child, was noted to have a heart murmur at birth and required treatment for congestive heart failure by the age of 6 months. In 1970, cardiac catheterization revealed an arterial oxygen saturation of 73 percent, and angiograms were believed to reveal origin of the pulmonary arteries from the ascending aorta. Between the ages of 6 and 18 months, the patient had repeated bouts of pneumonia and a poor growth pattern, but she participated in relatively normal activities. When she was 6 years old, repeat catheterization revealed an arterial oxygen saturation of 83 percent, Qp: Qs = 1: 1.5, and Rp: Rs = 0.7: I. Angiograms revealed a single trunk originating from the base of the heart and the origin of the left pulmonary artery from the ascending aorta. The right pulmonary artery filled later, but the site of its origin was not definitely demonstrated. The child was referred to Stanford University Hospital for operation. On physical examination the child was acyanotic. The point of maximal impulse was at the anterior axillary line in the sixth intercostal space. There was a right ventricular heave and a Grade 4/6 systolic ejection murmur at the right upper sternal
73
74 Rossiter, Silverman, Shumway
The Journal of Thoracic and Cardiovascular Surgery
Fig. 1. A, Preoperative angiogram. Selective catheterization (short arrow) passing up right-sided aorta into bronchial artery (bronchial vessel not seen in this phase of injection). Pulmonary arteries with normal proximal anatomy (long arrow) seen on later phase of injection. B, Postoperative angiogram. Contrast injection into right ventricle (block arrow). Conduit seen exiting from right ventricle (long arrow). Valve stent (smaller block arrow) within conduit. Good filling of peripheral pulmonary arteries (open arrow).
Fig. 2. Case 3. Systemic-to-pulmonary central shunt.
border. In addition, a continuous murmur was audible over both anterior and posterior lung fields, significantly greater on the right. On Oct. 21, 1975, a corrective operation was performed. The left pulmonary artery was seen to arise from the lateral ascending aorta. The right pulmonary artery originated from the same trunk but was extremely hypoplastic and was connected to the trunk by a fibrous band. This anatomy was interpreted to represent a type I truncus arteriosus with acquired atresia of the origin of the right pulmonary artery. The right pulmonary artery was 5 mm. in its greatest diameter. A large ventricular septal defect was closed through a right ventriculotomy. A 20 mm. knitted Dacron tube graft with a porcine valve was sutured to the right ventriculotomy proximally and to the left pulmonary artery distally after the pulmonary artery had been divided from the truncus. In addition, an 8 mm. Dacron graft sidearm was placed from the valved conduit to the right pulmonary artery under the superior vena cava. Throughout the procedure, copious bronchial return into the left atrium produced rather low perfusion pressure on cardiopulmonary bypass. Postoperatively, left-sided weakness and cortical blindness was noted but resolved completely after a few weeks. A continuous murmur was still present over the right side of the chest posteriorly. The patient was discharged 19 days postoperatively but was readmitted 5 days later with intractable congestive heart failure. Repeat cardiac catheterization revealed normal right-sided oxygen saturations with no stepup. Right ventricular pressure was 78/10 mm. Hg, left ventricular pressure 105/20, and aortic pressure 100/60.
Volume 75 Number 1
January, 1978
Truncus arteriosus
75
Fig. 3. Portable chest film showing bilateral hilar and upper zone infiltrates (arrows).
Fig. 4. Portable chest film showing rapid clearing of infiltrates after collateral vessel ligation.
There was an extremely large bronchial flow to the right pulmonary artery. Because of the congestive heart fail ure and pulmonary overcirculation, the chest was explored through a right thoracotomy on Dec. 8, 1975. Three 4 mm. diameter bronchial arteries to the right pulmonary artery were ligated. The continuous pulmonary artery thrill disappeared after ligation of the vessels. On the postoperative chest x-ray films, pulmonary vascularity was markedly decreased as compared to the preoperative film. On follow-up I year later, the child is growing, extremely active, and asymptomatic. She continues to take digoxin and furosemide. CASE 2. L. L. (53-47-68), a female child, was born on July 19, 1960 and was noted to be cyanotic at birth. Cardiac catheterization on Nov. I, 1961, at another institution revealed a single vessel arising from both ventricles and the presence of pulmonary arteries. It was believed that the pulmonary arteries most likely had origins from the ascending aorta, but this could not be definitely ascertained. Arterial oxygen saturation was 74 percent. Repeat cardiac catheterization in 1968 was interpreted as showing truncus arteriosus type II with an absent left pulmonary artery. Oxygen saturation at that time was 65 percent. Cardiac catheterization in 1976 revealed a right atrial pressure of 8 mm. Hg, right ventricular pressure of 110/15, left ventricular pressure of I 12/15, and aortic pressure of 112/65 with an arterial oxygen saturation of 94 percent. The patient was noted to have significant bronchial circulation to both pulmonary arteries, but no communication with the ascending aorta was seen on angiograms (Fig.
I, A). The diagnosis of pseudotruncus was made and the patient was referred to Stanford University Hospital for surgical therapy. On physical examination the child was noted to be cyanotic. There were continuous murmurs bilaterally in the subclavicular areas and a Grade 3/4 systolic murmur in the right third intercostal space. On Sept. 23, 1976, corrective surgery was performed. Several large bronchial arteries were noted supplying the pulmonary artery. After ligation of these arteries and just before cardiopulmonary bypass was started, the arterial P0 2 fell to 28 mm. Hg. Truncus arteriosus type I anatomy was defined with an extremely small remnant of main pulmonary artery originating from the ascending aorta. The right and left pulmonary arteries were confluent intrapericardially. The ventricular septal defect was closed through a right ventriculotomy. A 25 mm. Dacron valved conduit was anastomosed to the right ventricle proximally and to the pulmonary artery bifurcation distally. It was noted that there was no pulmonic valve remnant. The truncal valve was a dysplastic tricuspid valve with prolapsing of one cusp. The postoperative course was uneventful. Repeat anagiographic studies on Oct. I, 1976, revealed a right ventricular pressure of 70 mm. Hg systolic. Good pulmonary artery filling was seen from the valved pulmonary conduit (Fig. I, B). The patient continues to do well 4 months postoperatively. 'CASE 3. R. C. (54-35-50), a 22-year-old man, had been noted to have a heart murmur at the age of 3 months in 1954. Cardiac catheterization was performed at the age of 3 months,
The Journal of Thoracic and Cardiovascular Surgery
76 Rossiter, Silverman, Shumway
Fig. 5. Case 4. Stenotic aortic collateral (arrow) feeding pulmonary vessels at hilus of left lung. 6 years, and 22 years. The patient had dyspnea on exertion but could perform normal daily activities. On physical examination, moderate cyanosis was present, in addition to pectus carinatum and digital clubbing. Continuous murmurs were audible bilaterally. Cardiac catheterization on Dec. 20, 1976, revealed the following: Qp: Qs = 2.3: I, right ventricular pressure and left ventricular pressure were equal to systemic pressure, and arterial oxygen saturation was 86 percent. Angiograms revealed a ventricular septal defect and two ventricles with a single great vessel arising from the heart. There was a right aortic arch and a left-sided descending aorta. No central pulmonary arteries were seen, but peripheral pulmonary arteries, filled by extensive collaterals from the descending aorta, were described. A diagnosis of truncus arteriosus was made. On Dec. 22, 1976, the chest was explored via a median sternotomy. Truncus type I anatomy was found with an atretic band connecting the truncus to the pulmonary artery bifurcation. The pulmonary arteries were retropericardial, confluent, and diminutive (4 mm. in diameter) with low pressure to palpation. Because of the small size of the pulmonary arteries, a right ventricular-pulmonary conduit was not used. Instead, a systemic-pulmonary shunt was created by connecting the truncus to the pulmonary artery bifurcation with a 10 mm. Dacron graft (Fig. 2). Postoperatively, pulmonary edema, progressive in nature, developed in the upper lobes of both lungs. An aortogram revealed a patent graft, perfusing mainly the upper lobes, plus a plethora of collateral vessels to the upper lobes which resulted in marked hyperperfusion. Aortic pressure was 110/60 mm. Hg and graft pressure was 34/20. On Dec. 28, 1976, the collaterals were ligated via a left thoracotomy. There was immediate clinical improvement, and radiographic clearing of the lungs followed (Figs. 3 and 4). The patient required a tracheostomy but recovered and was discharged on Jan. 20, 1977. At follow-up approximately I month after discharge, the patient was subjectively improved, but catheterization and angiography have been deferred.
CASE 4. C. T. (24-72-76), an 8-year-old boy, had been cyanotic at birth and had required digitalis for congestive heart failure at the age of 2V2 years. The patient had increasing fatigue, headaches, dyspnea on exertion, and cyanosis. Cardiac catheterizations at the ages of 4 months and 2V2 years revealed truncus arteriosus type IV. Repeat study on April 5, 1976, revealed Qp: Qs = 0.9/ I with right ventricular pressure equal to systemic pressure and a large ventricular septal defect. Angiographic studies revealed truncus arteriosus type IV with peripheral pulmonary arteries on the left filled by a stenotic collateral from the descending aorta: pressure in the left peripheral pulmonary artery was 35/15 mm. Hg. No pulmonary artery was seen centrally or in the peripheral right lung. The right lung was fed by aortic collaterals, with systemic pressure. Physical examination revealed a small cyanotic boy with mild clubbing and a continuous murmur over the left hemithorax but not on the right. On June 3, 1976, the chest was explored through a median sternotomy. Extensive dissection revealed no central pulmonary artery and no hilar pulmonary artery on the right. In February, 1977, a left thoractomy was performed. A lowpressure pulmonary arterial system was found at the hilus of the lung, fed by a stenotic collateral from the descending aorta (Fig. 5). A modified Blalock/Taussig anastomosisinterposing a 10 mm. Dacron graft between the subclavian artery and pulmonary artery-was performed. The postoperative course was uneventful and repeat study is planned in 6 to 12 months.
Discussion
Considerable confusion exists regarding the classification of patients with anatomic discontinuity between the pulmonary arterial system and the heart. 11, 12 Truncus arteriosus is a rare condition'< P in which a single great artery arises from the base of the heart, with coronary arteries, pulmonary arteries, and sys-
Volume 75 Number 1
January. 1978
temic arteries ansmg from this vessel. 8. 12. 16 The majority of cases have an associated ventricular septal defect, but Van Praagh's'" classification includes a group with intact ventricular septum. The most widely used classification is that of Collett and Edwards''; type I, main pulmonary artery arises from the truncus; type II, both pulmonary arteries arise posteriorly from the truncus; type III, both pulmonary arteries arise from sides of the truncus; and type IV, no pulmonary arteries exist; arterial circulation to the lungs is from bronchial arteries. Type IV truncus arteriosus is embryologically distinct from types I, II, and III, and it is more correctly identified as "absent sixth aortic arch." In this situation, derivatives of the sixth aortic arch (the right and left pulmonary arteries and the ductus arteriosus) plus the main pulmonary artery, the right ventricular infundibulum, and the pulmonary valve all are absent.l''- 17 Peripheral pulmonary arteries which develop, along with the lung bud, as separate entities from the sixth aortic arch may be present.!" Arterial supply to the lungs is from the bronchial or collateral arteries. (Actually, these arteries probably are not bronchials but are other aortic collaterals.!") These vessels may be large and mistaken for pulmonary arteries.P" Although surgical repair of this anomaly has been performed, continuity being established between the right ventricle and bronchial artery or peripheral pulmonary artery.! operative results to date have been generally unfavorable. The complete absence of a true pulmonary arterial system, the tortuosity and multiplicity of the bronchial vessels, and the elevated pulmonary vascular resistance account for the technical and physiological failures when repair has been attempted in truncus type IV.I7· 20-22 Pseudotruncus arteriosus is in reality the most severe form of tetralogy of Fallot with pulmonary valvular atresia and ventricular septal defect. 10 True pulmonary arteries are present (either confluent or nonconfluent) and are connected to the blind right ventricular infundibulum by a fibrotic remnant. Pulmonary blood flow comes from the ductus arteriosus, coronary-topulmonary artery fistulas, nonspecific aorta-pulmonary collaterals, or bronchial arteries.P" Surgical repair is often feasible'": 22 in pseudotruncus, and differentiation from truncus arteriosus type IV is of great import. 14. 17.23 The first three cases presented represent forms of truncus arteriosus type I. Patient I and Patient 2 had angiograms at other institutions during infancy, and in both the studies were reported as showing "probable origin of pulmonary arteries from the ascending aorta." At surgical exploration, origin of the pulmo-
Truncus arteriosus
77
Fig. 6. Contrast injected into aorta showing narrowings at juxta-aortic (open arrow) and intrahilar (block arrow) communications. nary arteries from a common pulmonary trunk connected to a truncus arteriosus was found in all three cases. In Case I there was stenosis of the right pulmonary artery at its origin with hypoplasia of the right pulmonary artery. Large aortic collaterals supplied blood to the right lung. The left pulmonary artery communicated with the truncus arteriosus as in most type I situations. The pulmonary vascular resistance was elevated (0.7 of systemic) and the pulmonary-tosystemic flow ratio was decreased (I: 1.5)-a situation which has been said to contraindicate surgery. 20 In Case 2, type I anatomy again was confirmed at operation, but there was severe stenosis of the pulmonary arterial takeoff and hypoplasia of the main pulmonary trunk. Preoperative angiograms failed to demonstrate any communication of the pulmonary vessels with the ascending aorta or with the right ventricle. Virtually all pulmonary flow arose from the aortic collaterals. Selective injection of these bronchial collaterals revealed the presence of central pulmonary arteries and thereby ruled out a diagnosis of truncus arteriosus type IV (absent sixth aortic arch). Preoperative assessment was indicative of pseudotruncus except for the history of type I anatomy seen on angiography 15 years earlier and the absence of a right ventricular infundibulum.!? Early postoperative study revealed persistent right ventricular hypertension (systolic pressure 70 mm. Hg), and the eventual outcome depends on the reversibility of the pulmonary hypertension. We have previously observed a significant decrease in pulmonary
The Journal of
7 8 Rossiter, Silverman, Shumway
arterial resistance in a patient with truncus arteriosus type 11.24 Case 3 is similar in that it represents a type I anatomy, with atresia of the truncus-pulmonary co~ nections; pulmonary blood flow was derived solely from descending aorta collaterals, as in type IV truncus. This patient, however, had derivatives of the sixth aortic arch, albeit diminutive, with confluent pulmonary arteries clearly differentiating his condition from that of a patient with type IV truncus. Case 4 represents a true truncus arteriosus type IV, with no derivatives of the sixth aortic arch present. On the left side a small pulmonary artery was present at the hilus of the lung. Extensive dissection of the right hilus failed to reveal any true pulmonary artery. In both Cases 3 and 4 the diminutive nature of the pulmonary vascular system precluded a physiological correction, and systemic-to-pulmonary shunts were constructed. The therapeutic benefits of such shunts and the possibility of dilatation of the pulmonary vascular system with later correction remain conjectural, and prolonged follow-up is necessary. Gill, Moodie, and McGoon 25 have reported several cases of pulmonary atresia with diminutive pulmonary arteries that were managed by palliative reconstruction of the right ventricular outflow tract with a valveless patch. Early results are encouraging, indicating significant pulmonary arterial dilatation. Continuous murmurs were heard in all of these patients. This physical sign has been reported in patients with pseudotruncus and in those with truncus arteriosus type IV.10. 17. 23 In our experience, a truly continuous murmur in these patients always indicates the presence of a low-pressure pulmonary vascular bed communicating with systemic vessels and consequently suggests an operable situation. The murmurs ostensibly arise from sites of juxta-aortic or intrahilar stenosis where pathological systemic collaterals anastomose with true pulmonary arteries-a situation often observed angiographically (Fig. 6). Systolic and diastolic murmurs not wholly continuous are more often associated with advanced pulmonary hypertension or truncus arteriosus type IV (absent sixth aortic arch) without true pulmonary arteries. The differentiation is crucial and often can be made by selective angiography of bronchial or pulmonary arteries plus right ventriculography.F: 22, 23 Angiography, however, may fail to delineate central or hilar pulmonary arteries, especially if they are diminutive as in Case 3. The unequivocal radiographic identification of a right ventricular outflow tract effectively rules out a truncus arteriosus type IV, but this angiographic diagnosis can be very difficult. Currently, we undertake surgical exploration of any patient in this
Thoracic and Cardiovascular Surgery
clinical setting who has continuous murmurs. If reasonably large pulmonary arteries are found, either confluent and intrapericardial or nonconfluent and hilar, a valved conduit between the right ventricle and pulmonary arteries is constructed. If the pulmonary arteries are diminutive, a systemic-to-pulmonary artery shunt is performed. Hopefully, dilatation of the pulmonary artery will occur and allow subsequent total correction with a valved conduit. As mentioned previously, prolonged follow-up of a larger series of such patients is necessary to validate our thesis. The importance of controlling and ligating bronchial collaterals prior to cardiopulmonary bypass is illustrgted by Cases I and 3. With a large bronchial flow, a significant percentage of pump perfusate will be shunted to the pulmonary system, flood the operative field, and render intracardiac manipulations technically difficult. The shunting steals flow from the systemic system, possibly producing ischemic damage in other organs (the presumed cause of neurologic difficulties in Case I). Residual bronchial flow, added to the pulmonary flow supplied by the new right ventricularpulmonary artery conduit, may cause congestive heart failure postoperatively. The ligation of bronchial collaterals at the second operation produced a dramatic clinical and radiographic improvement with amelioration of the marked pulmonary overcirculation in both Cases I and 3. Ligation of bronchial vessels in Case 2 was easily accomplished from a median sternotomy in the patient with a right-sided descending thoracic aorta. We have generally been able to ligate the bronchials arising from a left-sided aorta with this approach. Others have recommended a separate thoractomy incision.t"- 22 REFERENCES McGoon, D. C., Rastelli, G. D., and Ongley, P. A.: An Operation for the Correction of Truncus Arteriosus, J. A.
M. A. 205: 69, 1968.
2 McGoon, D. c., Wallace, R. B., and Danielson, G. K.: The Rastelli Operation: Its Indications and Results, J. THORAc. CARDIOVASC. SURG. 65: 65, 1973. 3 Behrendt, D. M., Kirsh, M. M., Stem, A., et al.: The Surgical Therapy for Pulmonary Artery-Right Ventricular Discontinuity, Ann. Thorac. Surgery 18: 22,
1974. 4 Poirier, R. A., Berman, M. A., and Stansel, H., Jr.: Current Status of the Surgical Treatment of Truncus Arteriosus, J. THoRAc. CARDIOVASC. SURG. 69: 169, 1975. 5 Moore, C. A., Martelli, V., and Ross, D. N.: Reconstruction of Right Ventricular Outflow Tract With a Valved Conduit in 75 Cases of Congenital Heart Disease, J. THORAC. CARDIOVASC. SURG. 71: 11, 1976. 6 Appelbaum, A., Bargeron, L. M., Pacifico, A. D., et al.:
Volume 75 Number 1
January, 1978
Surgical Treatment of Truncus Arteriosus With Emphasis on Infants and Small Children, J. THoRAc. CARDIOVASe. SURG. 71: 436, 1976. 7 Bailey, L. L., Takeuchi, Y., Williams, W. G., et al.: Surgical Management of Congenital Cardiovascular Anomalies With the Use of Profound Hypothermia and Circulatory Arrest, 1. THORAe. CARDIOV ASC. SURG. 71:
485, 1976. 8 Collett, R. W., and Edwards, J. E.: Persistent Truncus Arteriosus: A Classification According to Anatomic Types, Surg. Clin. North Am. 29: 1245, 1949. 9 Taussig, H. B.: Congenital Malformations of the Heart, New York, 1947, The Commonwealth Fund, pp. 134,
248,257,259,270. 10 Stuckey, D., Bowdler, J. B., and Reye, R. D. K.: Absent
II
12
13
14
15
16
Sixth Aortic Arch: A Form of Pulmonary Atresia, Br. Heart 1. 30: 258, 1968. Somerville, J.: Management of Pulmonary Atresia, Br. Heart J. 32: 641,1970. Van Praagh, R., and Van Praagh, S.: The Anatomy of Common Aorticopulmonary Trunk (Truncus Arteriosus Communis) and Its Embryologic Implications, Am. J. Cardiol. 16: 406, 1965. McCue, C. M., Lester, R. G., Bosher, L. H., et al.: Persistent Truncus Arteriosus: A Clinical Correlation With the Pathologic Anatomy, Chest 46: 507, 1964. Fontana, R. S., and Edwards, J. E.: Congenital Cardiac Disease, Philadelphia, 1962, W. B. Saunders Company, pp. 93, 96. Keith, J. D., Rowe, R. D., and Vlad, P.: Heart Disease in Infancy and Childhood, New York, 1958, Macmillon Publishing Co., Inc., p. 770. Lev, M., and Saphir, 0.: Truncus Arteriosus Communis Persistens, J. Pediatr. 20: 74, 1942.
Truncus arteriosus
79
17 Chesler, E., Matisonn, R., and Beck, W.: The Assessment of the Arterial Supply to the Lungs in Pseudotruncus Arteriosus and Truncus Arteriosus Type IV in Relation to Surgical Repair, Am. Heart J. 88: 542, 1974. 18 Cudkowicz, L.: The Human Bronchial Circulation in Health and Disease, Baltimore, 1968, The Williams & Wilkins Company, p. 138. 19 Jefferson, K., Rees, S., and Somerville, J.: Systemic Arterial Supply to the Lungs in Pulmonary Atresia and Its Relation to Pulmonary Artery Development, Br. Heart J.
34: 418, 1972. 20 Doty, D. B., Kouchoukos, N. T., Kirklin, J. W., et al.: Surgery for Pseudotruncus Arteriosus With Pulmonary Blood Flow Originating From Upper Descending Thoracic Aorta, Circulation 45, 46: 121, 1972 (Suppl. I). 22 Pacifico, A. T., Kirklin, J. W., Bargeron, L. M., Jr., et al.: Surgical Treatment of Common Arterial Trunk With Pseudotruncus Arteriosus, Circulation 49, 50: 20, 1974 (Suppl. II). 23 Chesler, E., Beck, W., and Schrire, V.: Selective Catherization of Pulmonary or Bronchial Arteries in the Preoperative Assessment of Pseudotruncus Arteriosus and Truncus Arteriosus Type IV, Am. J. Cardiol. 26: 20,
1970. 24 Griepp, R. B., Stinson, E. B., and Shumway, N. E.: Surgical Correction of Types II and III Truncus Arteriosus, J. THoRAe. CARDIOVASe. SURG. 73: 345, 1977. 25 Gill, C. c., Moodie, D. S., and McGoon, D. C.: Staged Surgical Management of Pulmonary Atresia With Diminutive Pulmonary Arteries, J. THoRAc. CARDIOVASe. SURG. 73: 436, 1977.
Stephen J. Rossiter, M.D., James F. Silverman, M.D., and Norman E. Shumway, M.D.,
Stanford, Calif.
Patients with anatomic discontinuity between the heart and pulmonary arterial system are now condidates for corrective surgical procedures.":" Differentiation between patients with pulmonary arteries (truncus arteriosus types I, II, III, and pseudotruncuss- 9) and those without pulmonary arteries (absent sixth aortic arch.!? truncus arteriosus type IV8) is central to proper patient selection and surgical planning. Three cases presented herein are unusual in that they demonstrate hypoplasia or atresia of ascending aortic origins of pulmonary arterial supply in children who had truncus arteriosus type I at birth. A fourth patient had a complicated type of truncus type IV anatomy. Points emphasized are (I) the importance of differentiating truncus type I from truncus arteriosus type IV From the Departments of Cardiovascular Surgery and Radiology, Stanford University Medical Center, Stanford, Calif. 94305. Received for publication May 23, 1977. Accepted for publication July 26, 1977. Address for reprints: Stephen J. Rossiter, M.D., Department of Cardiovascular Surgery, Stanford University Medical Center, Stanford, Calif. 94305.
(absent sixth aortic arch), (2) the necessity of dealing with bronchial coliaterals, and (3) the significance of continuous murmurs.
Case reports CASE I. J. R. (50-41-98), a female child, was noted to have a heart murmur at birth and required treatment for congestive heart failure by the age of 6 months. In 1970, cardiac catheterization revealed an arterial oxygen saturation of 73 percent, and angiograms were believed to reveal origin of the pulmonary arteries from the ascending aorta. Between the ages of 6 and 18 months, the patient had repeated bouts of pneumonia and a poor growth pattern, but she participated in relatively normal activities. When she was 6 years old, repeat catheterization revealed an arterial oxygen saturation of 83 percent, Qp: Qs = 1: 1.5, and Rp: Rs = 0.7: I. Angiograms revealed a single trunk originating from the base of the heart and the origin of the left pulmonary artery from the ascending aorta. The right pulmonary artery filled later, but the site of its origin was not definitely demonstrated. The child was referred to Stanford University Hospital for operation. On physical examination the child was acyanotic. The point of maximal impulse was at the anterior axillary line in the sixth intercostal space. There was a right ventricular heave and a Grade 4/6 systolic ejection murmur at the right upper sternal
73
74 Rossiter, Silverman, Shumway
The Journal of Thoracic and Cardiovascular Surgery
Fig. 1. A, Preoperative angiogram. Selective catheterization (short arrow) passing up right-sided aorta into bronchial artery (bronchial vessel not seen in this phase of injection). Pulmonary arteries with normal proximal anatomy (long arrow) seen on later phase of injection. B, Postoperative angiogram. Contrast injection into right ventricle (block arrow). Conduit seen exiting from right ventricle (long arrow). Valve stent (smaller block arrow) within conduit. Good filling of peripheral pulmonary arteries (open arrow).
Fig. 2. Case 3. Systemic-to-pulmonary central shunt.
border. In addition, a continuous murmur was audible over both anterior and posterior lung fields, significantly greater on the right. On Oct. 21, 1975, a corrective operation was performed. The left pulmonary artery was seen to arise from the lateral ascending aorta. The right pulmonary artery originated from the same trunk but was extremely hypoplastic and was connected to the trunk by a fibrous band. This anatomy was interpreted to represent a type I truncus arteriosus with acquired atresia of the origin of the right pulmonary artery. The right pulmonary artery was 5 mm. in its greatest diameter. A large ventricular septal defect was closed through a right ventriculotomy. A 20 mm. knitted Dacron tube graft with a porcine valve was sutured to the right ventriculotomy proximally and to the left pulmonary artery distally after the pulmonary artery had been divided from the truncus. In addition, an 8 mm. Dacron graft sidearm was placed from the valved conduit to the right pulmonary artery under the superior vena cava. Throughout the procedure, copious bronchial return into the left atrium produced rather low perfusion pressure on cardiopulmonary bypass. Postoperatively, left-sided weakness and cortical blindness was noted but resolved completely after a few weeks. A continuous murmur was still present over the right side of the chest posteriorly. The patient was discharged 19 days postoperatively but was readmitted 5 days later with intractable congestive heart failure. Repeat cardiac catheterization revealed normal right-sided oxygen saturations with no stepup. Right ventricular pressure was 78/10 mm. Hg, left ventricular pressure 105/20, and aortic pressure 100/60.
Volume 75 Number 1
January, 1978
Truncus arteriosus
75
Fig. 3. Portable chest film showing bilateral hilar and upper zone infiltrates (arrows).
Fig. 4. Portable chest film showing rapid clearing of infiltrates after collateral vessel ligation.
There was an extremely large bronchial flow to the right pulmonary artery. Because of the congestive heart fail ure and pulmonary overcirculation, the chest was explored through a right thoracotomy on Dec. 8, 1975. Three 4 mm. diameter bronchial arteries to the right pulmonary artery were ligated. The continuous pulmonary artery thrill disappeared after ligation of the vessels. On the postoperative chest x-ray films, pulmonary vascularity was markedly decreased as compared to the preoperative film. On follow-up I year later, the child is growing, extremely active, and asymptomatic. She continues to take digoxin and furosemide. CASE 2. L. L. (53-47-68), a female child, was born on July 19, 1960 and was noted to be cyanotic at birth. Cardiac catheterization on Nov. I, 1961, at another institution revealed a single vessel arising from both ventricles and the presence of pulmonary arteries. It was believed that the pulmonary arteries most likely had origins from the ascending aorta, but this could not be definitely ascertained. Arterial oxygen saturation was 74 percent. Repeat cardiac catheterization in 1968 was interpreted as showing truncus arteriosus type II with an absent left pulmonary artery. Oxygen saturation at that time was 65 percent. Cardiac catheterization in 1976 revealed a right atrial pressure of 8 mm. Hg, right ventricular pressure of 110/15, left ventricular pressure of I 12/15, and aortic pressure of 112/65 with an arterial oxygen saturation of 94 percent. The patient was noted to have significant bronchial circulation to both pulmonary arteries, but no communication with the ascending aorta was seen on angiograms (Fig.
I, A). The diagnosis of pseudotruncus was made and the patient was referred to Stanford University Hospital for surgical therapy. On physical examination the child was noted to be cyanotic. There were continuous murmurs bilaterally in the subclavicular areas and a Grade 3/4 systolic murmur in the right third intercostal space. On Sept. 23, 1976, corrective surgery was performed. Several large bronchial arteries were noted supplying the pulmonary artery. After ligation of these arteries and just before cardiopulmonary bypass was started, the arterial P0 2 fell to 28 mm. Hg. Truncus arteriosus type I anatomy was defined with an extremely small remnant of main pulmonary artery originating from the ascending aorta. The right and left pulmonary arteries were confluent intrapericardially. The ventricular septal defect was closed through a right ventriculotomy. A 25 mm. Dacron valved conduit was anastomosed to the right ventricle proximally and to the pulmonary artery bifurcation distally. It was noted that there was no pulmonic valve remnant. The truncal valve was a dysplastic tricuspid valve with prolapsing of one cusp. The postoperative course was uneventful. Repeat anagiographic studies on Oct. I, 1976, revealed a right ventricular pressure of 70 mm. Hg systolic. Good pulmonary artery filling was seen from the valved pulmonary conduit (Fig. I, B). The patient continues to do well 4 months postoperatively. 'CASE 3. R. C. (54-35-50), a 22-year-old man, had been noted to have a heart murmur at the age of 3 months in 1954. Cardiac catheterization was performed at the age of 3 months,
The Journal of Thoracic and Cardiovascular Surgery
76 Rossiter, Silverman, Shumway
Fig. 5. Case 4. Stenotic aortic collateral (arrow) feeding pulmonary vessels at hilus of left lung. 6 years, and 22 years. The patient had dyspnea on exertion but could perform normal daily activities. On physical examination, moderate cyanosis was present, in addition to pectus carinatum and digital clubbing. Continuous murmurs were audible bilaterally. Cardiac catheterization on Dec. 20, 1976, revealed the following: Qp: Qs = 2.3: I, right ventricular pressure and left ventricular pressure were equal to systemic pressure, and arterial oxygen saturation was 86 percent. Angiograms revealed a ventricular septal defect and two ventricles with a single great vessel arising from the heart. There was a right aortic arch and a left-sided descending aorta. No central pulmonary arteries were seen, but peripheral pulmonary arteries, filled by extensive collaterals from the descending aorta, were described. A diagnosis of truncus arteriosus was made. On Dec. 22, 1976, the chest was explored via a median sternotomy. Truncus type I anatomy was found with an atretic band connecting the truncus to the pulmonary artery bifurcation. The pulmonary arteries were retropericardial, confluent, and diminutive (4 mm. in diameter) with low pressure to palpation. Because of the small size of the pulmonary arteries, a right ventricular-pulmonary conduit was not used. Instead, a systemic-pulmonary shunt was created by connecting the truncus to the pulmonary artery bifurcation with a 10 mm. Dacron graft (Fig. 2). Postoperatively, pulmonary edema, progressive in nature, developed in the upper lobes of both lungs. An aortogram revealed a patent graft, perfusing mainly the upper lobes, plus a plethora of collateral vessels to the upper lobes which resulted in marked hyperperfusion. Aortic pressure was 110/60 mm. Hg and graft pressure was 34/20. On Dec. 28, 1976, the collaterals were ligated via a left thoracotomy. There was immediate clinical improvement, and radiographic clearing of the lungs followed (Figs. 3 and 4). The patient required a tracheostomy but recovered and was discharged on Jan. 20, 1977. At follow-up approximately I month after discharge, the patient was subjectively improved, but catheterization and angiography have been deferred.
CASE 4. C. T. (24-72-76), an 8-year-old boy, had been cyanotic at birth and had required digitalis for congestive heart failure at the age of 2V2 years. The patient had increasing fatigue, headaches, dyspnea on exertion, and cyanosis. Cardiac catheterizations at the ages of 4 months and 2V2 years revealed truncus arteriosus type IV. Repeat study on April 5, 1976, revealed Qp: Qs = 0.9/ I with right ventricular pressure equal to systemic pressure and a large ventricular septal defect. Angiographic studies revealed truncus arteriosus type IV with peripheral pulmonary arteries on the left filled by a stenotic collateral from the descending aorta: pressure in the left peripheral pulmonary artery was 35/15 mm. Hg. No pulmonary artery was seen centrally or in the peripheral right lung. The right lung was fed by aortic collaterals, with systemic pressure. Physical examination revealed a small cyanotic boy with mild clubbing and a continuous murmur over the left hemithorax but not on the right. On June 3, 1976, the chest was explored through a median sternotomy. Extensive dissection revealed no central pulmonary artery and no hilar pulmonary artery on the right. In February, 1977, a left thoractomy was performed. A lowpressure pulmonary arterial system was found at the hilus of the lung, fed by a stenotic collateral from the descending aorta (Fig. 5). A modified Blalock/Taussig anastomosisinterposing a 10 mm. Dacron graft between the subclavian artery and pulmonary artery-was performed. The postoperative course was uneventful and repeat study is planned in 6 to 12 months.
Discussion
Considerable confusion exists regarding the classification of patients with anatomic discontinuity between the pulmonary arterial system and the heart. 11, 12 Truncus arteriosus is a rare condition'< P in which a single great artery arises from the base of the heart, with coronary arteries, pulmonary arteries, and sys-
Volume 75 Number 1
January. 1978
temic arteries ansmg from this vessel. 8. 12. 16 The majority of cases have an associated ventricular septal defect, but Van Praagh's'" classification includes a group with intact ventricular septum. The most widely used classification is that of Collett and Edwards''; type I, main pulmonary artery arises from the truncus; type II, both pulmonary arteries arise posteriorly from the truncus; type III, both pulmonary arteries arise from sides of the truncus; and type IV, no pulmonary arteries exist; arterial circulation to the lungs is from bronchial arteries. Type IV truncus arteriosus is embryologically distinct from types I, II, and III, and it is more correctly identified as "absent sixth aortic arch." In this situation, derivatives of the sixth aortic arch (the right and left pulmonary arteries and the ductus arteriosus) plus the main pulmonary artery, the right ventricular infundibulum, and the pulmonary valve all are absent.l''- 17 Peripheral pulmonary arteries which develop, along with the lung bud, as separate entities from the sixth aortic arch may be present.!" Arterial supply to the lungs is from the bronchial or collateral arteries. (Actually, these arteries probably are not bronchials but are other aortic collaterals.!") These vessels may be large and mistaken for pulmonary arteries.P" Although surgical repair of this anomaly has been performed, continuity being established between the right ventricle and bronchial artery or peripheral pulmonary artery.! operative results to date have been generally unfavorable. The complete absence of a true pulmonary arterial system, the tortuosity and multiplicity of the bronchial vessels, and the elevated pulmonary vascular resistance account for the technical and physiological failures when repair has been attempted in truncus type IV.I7· 20-22 Pseudotruncus arteriosus is in reality the most severe form of tetralogy of Fallot with pulmonary valvular atresia and ventricular septal defect. 10 True pulmonary arteries are present (either confluent or nonconfluent) and are connected to the blind right ventricular infundibulum by a fibrotic remnant. Pulmonary blood flow comes from the ductus arteriosus, coronary-topulmonary artery fistulas, nonspecific aorta-pulmonary collaterals, or bronchial arteries.P" Surgical repair is often feasible'": 22 in pseudotruncus, and differentiation from truncus arteriosus type IV is of great import. 14. 17.23 The first three cases presented represent forms of truncus arteriosus type I. Patient I and Patient 2 had angiograms at other institutions during infancy, and in both the studies were reported as showing "probable origin of pulmonary arteries from the ascending aorta." At surgical exploration, origin of the pulmo-
Truncus arteriosus
77
Fig. 6. Contrast injected into aorta showing narrowings at juxta-aortic (open arrow) and intrahilar (block arrow) communications. nary arteries from a common pulmonary trunk connected to a truncus arteriosus was found in all three cases. In Case I there was stenosis of the right pulmonary artery at its origin with hypoplasia of the right pulmonary artery. Large aortic collaterals supplied blood to the right lung. The left pulmonary artery communicated with the truncus arteriosus as in most type I situations. The pulmonary vascular resistance was elevated (0.7 of systemic) and the pulmonary-tosystemic flow ratio was decreased (I: 1.5)-a situation which has been said to contraindicate surgery. 20 In Case 2, type I anatomy again was confirmed at operation, but there was severe stenosis of the pulmonary arterial takeoff and hypoplasia of the main pulmonary trunk. Preoperative angiograms failed to demonstrate any communication of the pulmonary vessels with the ascending aorta or with the right ventricle. Virtually all pulmonary flow arose from the aortic collaterals. Selective injection of these bronchial collaterals revealed the presence of central pulmonary arteries and thereby ruled out a diagnosis of truncus arteriosus type IV (absent sixth aortic arch). Preoperative assessment was indicative of pseudotruncus except for the history of type I anatomy seen on angiography 15 years earlier and the absence of a right ventricular infundibulum.!? Early postoperative study revealed persistent right ventricular hypertension (systolic pressure 70 mm. Hg), and the eventual outcome depends on the reversibility of the pulmonary hypertension. We have previously observed a significant decrease in pulmonary
The Journal of
7 8 Rossiter, Silverman, Shumway
arterial resistance in a patient with truncus arteriosus type 11.24 Case 3 is similar in that it represents a type I anatomy, with atresia of the truncus-pulmonary co~ nections; pulmonary blood flow was derived solely from descending aorta collaterals, as in type IV truncus. This patient, however, had derivatives of the sixth aortic arch, albeit diminutive, with confluent pulmonary arteries clearly differentiating his condition from that of a patient with type IV truncus. Case 4 represents a true truncus arteriosus type IV, with no derivatives of the sixth aortic arch present. On the left side a small pulmonary artery was present at the hilus of the lung. Extensive dissection of the right hilus failed to reveal any true pulmonary artery. In both Cases 3 and 4 the diminutive nature of the pulmonary vascular system precluded a physiological correction, and systemic-to-pulmonary shunts were constructed. The therapeutic benefits of such shunts and the possibility of dilatation of the pulmonary vascular system with later correction remain conjectural, and prolonged follow-up is necessary. Gill, Moodie, and McGoon 25 have reported several cases of pulmonary atresia with diminutive pulmonary arteries that were managed by palliative reconstruction of the right ventricular outflow tract with a valveless patch. Early results are encouraging, indicating significant pulmonary arterial dilatation. Continuous murmurs were heard in all of these patients. This physical sign has been reported in patients with pseudotruncus and in those with truncus arteriosus type IV.10. 17. 23 In our experience, a truly continuous murmur in these patients always indicates the presence of a low-pressure pulmonary vascular bed communicating with systemic vessels and consequently suggests an operable situation. The murmurs ostensibly arise from sites of juxta-aortic or intrahilar stenosis where pathological systemic collaterals anastomose with true pulmonary arteries-a situation often observed angiographically (Fig. 6). Systolic and diastolic murmurs not wholly continuous are more often associated with advanced pulmonary hypertension or truncus arteriosus type IV (absent sixth aortic arch) without true pulmonary arteries. The differentiation is crucial and often can be made by selective angiography of bronchial or pulmonary arteries plus right ventriculography.F: 22, 23 Angiography, however, may fail to delineate central or hilar pulmonary arteries, especially if they are diminutive as in Case 3. The unequivocal radiographic identification of a right ventricular outflow tract effectively rules out a truncus arteriosus type IV, but this angiographic diagnosis can be very difficult. Currently, we undertake surgical exploration of any patient in this
Thoracic and Cardiovascular Surgery
clinical setting who has continuous murmurs. If reasonably large pulmonary arteries are found, either confluent and intrapericardial or nonconfluent and hilar, a valved conduit between the right ventricle and pulmonary arteries is constructed. If the pulmonary arteries are diminutive, a systemic-to-pulmonary artery shunt is performed. Hopefully, dilatation of the pulmonary artery will occur and allow subsequent total correction with a valved conduit. As mentioned previously, prolonged follow-up of a larger series of such patients is necessary to validate our thesis. The importance of controlling and ligating bronchial collaterals prior to cardiopulmonary bypass is illustrgted by Cases I and 3. With a large bronchial flow, a significant percentage of pump perfusate will be shunted to the pulmonary system, flood the operative field, and render intracardiac manipulations technically difficult. The shunting steals flow from the systemic system, possibly producing ischemic damage in other organs (the presumed cause of neurologic difficulties in Case I). Residual bronchial flow, added to the pulmonary flow supplied by the new right ventricularpulmonary artery conduit, may cause congestive heart failure postoperatively. The ligation of bronchial collaterals at the second operation produced a dramatic clinical and radiographic improvement with amelioration of the marked pulmonary overcirculation in both Cases I and 3. Ligation of bronchial vessels in Case 2 was easily accomplished from a median sternotomy in the patient with a right-sided descending thoracic aorta. We have generally been able to ligate the bronchials arising from a left-sided aorta with this approach. Others have recommended a separate thoractomy incision.t"- 22 REFERENCES McGoon, D. C., Rastelli, G. D., and Ongley, P. A.: An Operation for the Correction of Truncus Arteriosus, J. A.
M. A. 205: 69, 1968.
2 McGoon, D. c., Wallace, R. B., and Danielson, G. K.: The Rastelli Operation: Its Indications and Results, J. THORAc. CARDIOVASC. SURG. 65: 65, 1973. 3 Behrendt, D. M., Kirsh, M. M., Stem, A., et al.: The Surgical Therapy for Pulmonary Artery-Right Ventricular Discontinuity, Ann. Thorac. Surgery 18: 22,
1974. 4 Poirier, R. A., Berman, M. A., and Stansel, H., Jr.: Current Status of the Surgical Treatment of Truncus Arteriosus, J. THoRAc. CARDIOVASC. SURG. 69: 169, 1975. 5 Moore, C. A., Martelli, V., and Ross, D. N.: Reconstruction of Right Ventricular Outflow Tract With a Valved Conduit in 75 Cases of Congenital Heart Disease, J. THORAC. CARDIOVASC. SURG. 71: 11, 1976. 6 Appelbaum, A., Bargeron, L. M., Pacifico, A. D., et al.:
Volume 75 Number 1
January, 1978
Surgical Treatment of Truncus Arteriosus With Emphasis on Infants and Small Children, J. THoRAc. CARDIOVASe. SURG. 71: 436, 1976. 7 Bailey, L. L., Takeuchi, Y., Williams, W. G., et al.: Surgical Management of Congenital Cardiovascular Anomalies With the Use of Profound Hypothermia and Circulatory Arrest, 1. THORAe. CARDIOV ASC. SURG. 71:
485, 1976. 8 Collett, R. W., and Edwards, J. E.: Persistent Truncus Arteriosus: A Classification According to Anatomic Types, Surg. Clin. North Am. 29: 1245, 1949. 9 Taussig, H. B.: Congenital Malformations of the Heart, New York, 1947, The Commonwealth Fund, pp. 134,
248,257,259,270. 10 Stuckey, D., Bowdler, J. B., and Reye, R. D. K.: Absent
II
12
13
14
15
16
Sixth Aortic Arch: A Form of Pulmonary Atresia, Br. Heart 1. 30: 258, 1968. Somerville, J.: Management of Pulmonary Atresia, Br. Heart J. 32: 641,1970. Van Praagh, R., and Van Praagh, S.: The Anatomy of Common Aorticopulmonary Trunk (Truncus Arteriosus Communis) and Its Embryologic Implications, Am. J. Cardiol. 16: 406, 1965. McCue, C. M., Lester, R. G., Bosher, L. H., et al.: Persistent Truncus Arteriosus: A Clinical Correlation With the Pathologic Anatomy, Chest 46: 507, 1964. Fontana, R. S., and Edwards, J. E.: Congenital Cardiac Disease, Philadelphia, 1962, W. B. Saunders Company, pp. 93, 96. Keith, J. D., Rowe, R. D., and Vlad, P.: Heart Disease in Infancy and Childhood, New York, 1958, Macmillon Publishing Co., Inc., p. 770. Lev, M., and Saphir, 0.: Truncus Arteriosus Communis Persistens, J. Pediatr. 20: 74, 1942.
Truncus arteriosus
79
17 Chesler, E., Matisonn, R., and Beck, W.: The Assessment of the Arterial Supply to the Lungs in Pseudotruncus Arteriosus and Truncus Arteriosus Type IV in Relation to Surgical Repair, Am. Heart J. 88: 542, 1974. 18 Cudkowicz, L.: The Human Bronchial Circulation in Health and Disease, Baltimore, 1968, The Williams & Wilkins Company, p. 138. 19 Jefferson, K., Rees, S., and Somerville, J.: Systemic Arterial Supply to the Lungs in Pulmonary Atresia and Its Relation to Pulmonary Artery Development, Br. Heart J.
34: 418, 1972. 20 Doty, D. B., Kouchoukos, N. T., Kirklin, J. W., et al.: Surgery for Pseudotruncus Arteriosus With Pulmonary Blood Flow Originating From Upper Descending Thoracic Aorta, Circulation 45, 46: 121, 1972 (Suppl. I). 22 Pacifico, A. T., Kirklin, J. W., Bargeron, L. M., Jr., et al.: Surgical Treatment of Common Arterial Trunk With Pseudotruncus Arteriosus, Circulation 49, 50: 20, 1974 (Suppl. II). 23 Chesler, E., Beck, W., and Schrire, V.: Selective Catherization of Pulmonary or Bronchial Arteries in the Preoperative Assessment of Pseudotruncus Arteriosus and Truncus Arteriosus Type IV, Am. J. Cardiol. 26: 20,
1970. 24 Griepp, R. B., Stinson, E. B., and Shumway, N. E.: Surgical Correction of Types II and III Truncus Arteriosus, J. THoRAe. CARDIOVASe. SURG. 73: 345, 1977. 25 Gill, C. c., Moodie, D. S., and McGoon, D. C.: Staged Surgical Management of Pulmonary Atresia With Diminutive Pulmonary Arteries, J. THoRAc. CARDIOVASe. SURG. 73: 436, 1977.