Absent right pulmonary artery

Absent Right Pulmonary Artery* Problems in Diagnosis and Management ROBERT

C.

BAHLER, M .D .,t PETER CARSON, B .M ., M .R .C .P ., ELMERICE TRAKS, M .D ., ARTHUR LEVENE, M .D . and DAVID GILLESPIE, M .D .

Cleveland, Ohio Two cases of congenital absence of the right pulmonary artery and one case of probably acquired obstruction of the right pulmonary artery are discussed. Patients with congenital absence of the right pulmonary artery frequently present with pulmonary hypertension during infancy, particularly if there is an associated patent ductus arteriosus . Adults with absent right pulmonary artery may be asymptomatic . The diagnosis may be suspected from the chest roentgenogram and confirmed by pulmonary angiography . Aortography is essential for the recognition of the not infrequent anomalous origin of the right pulmonary artery . Previous surgical results and possible therapeutic approaches to the problem of absent right pulmonary artery are discussed . HE ABSENCE of a right pulmonary artery is an uncommon but not rare congenital anomaly. This defect was first reported by Fraentzel in 1868 [1] . Subsequently numerous case reports of an absent right or left pulmonary artery have appeared in the literature . In 1952 Madoff et al . [2] were the first to demonstrate an absent right pulmonary artery by angiography . Pool, Vogel and Blount [3] by 1962, collected ninety-eight cases of unilateral absence of a pulmonary artery. Their review emphasized the frequent occurrence of pulmonary hypertension when an absent pulmonary artery was associated with a left to right shunt . They also found that pulmonary hypertension was present in 19 per cent of the cases in which there was no evidence of a shunt . Unilateral absence of a pulmonary artery is frequently accompanied by other cardiac anomalies . Tetralogy of Fallot often occurs in association with absent left pulmonary artery whereas patent ductus arteriosus is a common companion of an absent right pulmonary artery . In these situations the symp-

T

toms are not primarily related to the absent pulmonary artery but to the dominant cardiac anomaly. In the following three cases we show that the diagnosis of absent right pulmonary artery may be difficult and that the approach to management may be even more perplexing. Case 1 indicates that although an isolated absent right pulmonary artery may be an incidental finding in an asymptomatic adult, it can present with hemoptysis . Case 2 shows that unilateral absence of a pulmonary artery is one of the many causes of pulmonary hypertension in infancy . Case 3 illustrates that acquired occlusion of a pulmonary artery may be erroneously interpreted as a congenitally absent pulmonary artery . CASE REPORTS CnsE 1 . A sixteen year old Negro woman (gravida 1, para 1) was admitted in November 1966 following an episode of hemoptysis . There were no associated symptoms and her past medical history was noncontributory. A routine chest roentgenogram obtained two years earlier was interpreted as

• From the Department of Medicine, Case Western Reserve University, School of Medicine at Cleveland Metropolitan General Hospital, Cleveland, Ohio 44109 . Manuscript received November 24, 1967 . Requests for reprints should be addressed to Robert C, Bahler, M .D . t Present address : Department of Cardiology, Veterans Administration Hospital, 10701 East Boulevard, Cleveland, Ohio 44106 . 64

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Absent Right Pulmonary Artery-Bahler et al .

FIG . 1 . Case 1 . Chest roentgenogram . The usual findings in absent right pulmonary artery are present. See text .

Fm, 2 . Case 1 . Pulmonary an . giogram . The right pulmonary artery is not opacified and the lung vessels are normal .

being consistent with an absent right pulmonary artery . On examination the blood pressure was 110/65 Turn . Hg, the pulse 88 per minute and respirations were 18 per minute . The patient appeared healthy . The right side of the chest was reduced in size, and breath sounds were diminished over the right lateral and posterior chest. There were no rales. The heart was not enlarged to palpation and the heart sounds were normal . A grade 1/6 systolic ejection murmur was present along the upper left sternal border. The remainder of the physical examination was within normal limits . The electrocardiogram showed no abnormalities . Previous and current chest roentgenograms showed the trachea and mediastinal structures to be deviated to the right, and the volume of the right hemithorax was diminished . The vascular markings in the right lung appeared irregular compared to the left . The right hilar comma was small, and the heart was normal (Fig . 1) . Bronchoscopy and bilateral bronchograms did not reveal any abnormalities of the tracheobronchial tree . Results of routine spirographic studies

65

FIG . 3 . Case 1 . Aortogram. The

right pulmonary artery arises from the ascending aorta.

were normal (Table I) . Bronchospirometry indicated that the right lung was perfused by arterialized blood since there was little oxygen uptake but significant carbon dioxide release (Table n) . Right heart catheterization showed normal rightsided pressures but the right pulmonary artery could not be entered . A pulmonary angiogram, with a right atrial injection, failed to show a right pulmonary artery (Fig . 2) . Later films in the series demonstrated normal pulmonary venous return from the left lung and suggested that a major vessel from the ascending aorta was perfusing the right lung . This was subsequently confirmed by an aortogram (Fig. 3) . A lateral cineangiogram showed this vessel to arise from the posterior aspect of the ascending aorta . No abnormal bronchial collateral circulation was noted . A second minor hemoptysis occurred on the third hospital day . No specific therapy was recommended, The patient continues to do well, although hemop . rysis recurred one year later . CASE 2 . A six and a half month old Negro boy was admitted in June 1962 because of cyanosis and

TABLE I

TABLE n

PULMONARY FUNCTION IN CASE 1

BRONCHOSPIROMETRY IN CASE 1

Study

Predicted

Vital capacity (L .) 3 .57 Forced expiratory volume (%) >75 1 sec . >90 3 sec . Maximum expiratory flow rate (L ./sec .) 5 .9 f 1 .2 Mid-maximum flow (L ./sec .) 4 .1 f 0 .8 Maximum breathing 100 capacity (L ./min .) VOL . 46, JANUARY 1969

Observed 3 .80

86 (3 .26 L .) 99 (3 .76 L .)

Study

Right Lung

Ventilation (air) (%) 02 uptake, room air (%) Os uptake, high Os` (%) CO s output, (air) (%) Vital capacity (%)

42 3

11 29 36

Left Lung 58 97 89 71 64

8 .4 3 .8 113

• Air was enriched with oxygen to approximately a 60 per cent oxygen concentration, thereby increasing the alveolar-arterial pO s gradient .

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Absent Right Pulmonary Artery-Bahler

respiratory distress . He was the product of a thirtysix week pregnancy and his birth weight was 2,200 gm . He was well when discharged thirty-two days after birth. Otitis media occurred at four months of age at which time his weight and length were below average . One week before admission rhinorrhea and cough developed and progressed to severe respiratory distress . Physical examination on admission revealed a poorly developed infant with marked respiratory distress and cyanosis . The pulse was 120 per minute and respirations were 60 per minute . The temperature was 36 .0°C . and the weight on admission was 3,800 gin . Rhonchi and rales were heard throughout both lung fields. The cardiac impulse was normal and there were no murmurs . The liver edge extended 6 cm . below the right costal margin . The chest film obtained on admission showed bilateral pulmonary infiltrates and pleural effusions. Subsequent films suggested some vascular asymmetry ; the heart was enlarged (Fig . 4) . The electrocardiogram and vectorcardiogram showed right ventricular hypertrophy . Urinalysis was normal . The white blood count was 13,350 cells per cu . Turn . and there was a shift to the left . The hematocrit was 55 per cent . Pleural fluid from each hemithorax appeared cloudy yellow and contained numerous polymorphonudear white blood cells. Bacterial cultures of the pleural fluid were sterile . Bilateral chest tubes were inserted because of the suspicion of empyema . Methicillin, chloramphenicol, digitalis, mercuhydrin and oxygen were given . The patient's condition improved during the first two weeks, and antibiotic therapy and chest tube drainage were discontinued . During the remaining three months of hospitalization the signs and symptoms of right heart failure persisted despite strict medical therapy . Right heart catheterization one month before the infant's death did not reveal any shunts, the main pulmonary artery pressure was 50/ 10 mm. Hg, and the wedge pressure was normal . The patient died of respiratory arrest at the age of ten months . The cause of the pulmonary hypertension remained unexplained during life, At postmortem examination the body weighed 3,600 gm . There were fine, easily lysed adhesions in both pleural cavities and the pleural surfaces were shiny . The right and left pulmonary veins were normal . The heart was enlarged . Both the right and left ventricular wall thicknesses were 0-6 cm . The right ventricle was dilated . There was no right pulmonary artery arising from the main pulmonary artery. A vessel, 2 mm . in external diameter, coursed from the ascending aorta to the right hilum (Fig . 5) . The bronchi of both lungs were normal . The pulmonary arterioles of the left lung showed intimal proliferation and medial thickening (Fig . 6A), whereas the arterioles of the right lung were thin walled (Fig. 6B) . There was a chronic infiam-

et al .

matory infiltrate in portions of the left lung and thickened alveolar walls in both lungs . A forty-four year old Negro woman CASE 3 . (gravida 1, pan 1) was admitted in August 1964 for control of hemoptysis. She had had pneumonia at age ten . Hemoptysis first occurred at age seventeen and thereafter she produced blood-tinged sputum during frequent respiratory tract infections . She had her first large hemoptysis in February 1964 and this recurred twice before her present admission . Each episode yielded I to 2 cups of blood . Systemic hypertension was first diagnosed at age twenty-seven . At age forty-one her blood pressure had risen to 230/130 mm . Hg. No cause was found for her hypertension. She was treated with a thiazide diuretic and reserpine . Left ventricular failure occurred one month before admission and responded to digitalis . On examination the patient appeared well . The blood pressure was 145/95 mm . Hg, respiratory rate 18 per minute and the pulse 80 per minute and regular. The chest was symmetric . Rhonchi were present over the right posterior chest . The left ventricular impulse was moderately increased and displaced 2 cm. lateral to the mid-clavicular lineThe heart sounds were normal . A grade 2/6 ejection murmur was present at the base. The chest film demonstrated an enlarged heart (Fig . 7). The right hemithorax was diminished and the vascularity of the right lung appeared diminished and had a reticular pattern . Rib notching was present on the right side. The electrocardiogram showed digitalis effect. A previous bronchoscopic examination was within normal limits . Repeat bronchoscopic examination revealed blood coming from the right main bronchus. Bilateral bronchograms were normal . Pulmonary function studies showed a reduced vital capacity and maximum breathing capacity (Table in) . Bronchospirometry data showed some oxygen uptake by the right lung (Table Iv) . On right heart catheterization the right ventricular pressure was 52/11 mm . Hg and the cardiac index 4 .26 L . per M 2 . A pulmonary capillary pressure could not be obtained . The right heart angiogram did not show a right pulmonary artery (Fig . 8) . A right retrobrachial arteriogram showed intercostal and right internal mammary artery collateral circulation to the right lung . Because of the repeated large hemoptyses a right pneumonectomy was performed. Hemorrhage from the collateral circulation was uncontrollable and the patient died during surgery despite transfusion of 29 units of blood . At postmortem examination the right pleural cavity contained 1,000 cc . of blood . The left pleural space was almost entirely obliterated by fibrous adhesions. The pericardium was normal . The heart weighed 600 gm . The left ventricular wall measured

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et al .

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LEFT RULM. RTERY AM RUL. ARTERY

Fm . 4. Case 2. Chest roentgenogram . Cardiomegaly and asymmetry of the pulmonary vasculature are present .

Ftc . 5 . Case 2 . Drawing based on autopsy photographs of the small Yes . sel arising from the ascending aorta and entering the right hilum .

FIG. 6 . Case 2 . A, photomicrograph of the left lung demonstrating the arteriolar changes of pulmonary hyperten . sion . B, photomicrograph of the normal right lung vasculature .

Ftc . 7 . Case 3 . Chest roentgenogram . Cardiomegaly, small right hemithorax and diminished, irregular vascularity of the right lung are present . The rib notching is seen in the fourth through eighth ribs . Fm. 8 . Case 3 . Pulmonary angiogram fails to visualize the right pulmonary artery . VOL .

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Absent Right Pulmonary Artery-Bahler et al .

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TABLE In PULMONARY FUNCTION IN CASE 3

Observed Study

Predicted

1962

1964

Vital capacity (L .) Forced expiratory volume (1 sec .) (L.) Maximum breathing response (L ./min .) Walking ventilation (L ./M2./min .) Physiologic dead space (cc.) Blood gases (mm . Hg) pCO 2 p0 s

3 .53

2 .12

1 .84

>75%

1 .91

1 .42

100

70

73

7-11 <150

10 185

36-44 >85 7 .38-7 .42 96-9817, <18

37 78 .5 7 .38 94 .5% 23

pH O s Saturation

P(A-a)O s

1 .5 cm . and the right ventricular wall 0 .6 cm . The left pulmonary artery was normal . The right pulmonary artery also appeared normal at its origin from the main pulmonary artery, but it then tapered into a cord-like structure which bifurcated at the hilum (Fig. 9) . (The funnel-shaped protrusion to the right of the main pulmonary artery visible in Figure 8 may represent the origin of the right pulmonary artery.) There was marked thickening and fibrosis of the intima prior to the bifurcation and the two branches were obstructed by old, partially recanalized, thrombus (Fig . 10) . The left pulmonary artery also had some intimal thickening . Pulmonary edema was present in the left lung. The right lung showed multiple areas of focal fibrosis, chronic passive hyperemia and recent focal hemorrhage and atelectasis . COMMENTS

Patients with an absent right pulmonary artery may be divided into three groups : Group i-those with an associated left to right shunt, usually a patent ductus arteriosus. Group tt-patients with an isolated absent right TABLE Iv BRONCHOSPIROMETRY IN CASE 3

Study

Right Lung

Left Lung

Ventilation (%) 0s uptake, air (°fo ) Vital capacity (%)

41 13 46

59 87 54

pulmonary artery and pulmonary hypertension . Group u1-patients with an isolated absent right pulmonary artery without pulmonary hypertension . Group i patients usually present with congestive heart failure and/or associated respiratory problems during infancy [3-11,16] . Only a few patients have survived beyond age two [12-15] . The right pulmonary artery arises from the ascending aorta or less frequently from the right innominate or right subclavian artery . Its total absence, in patients with a patent ductus, has not been described in the English literature. A patent ductus arteriosus is thereby complicated by an additional aortic run-off lesion . Another likely contributing factor to their dismal prognosis is the presence of pulmonary hypertension in the left lung . With the usual distribution of pulmonary blood flow a 2 :1 shunt might be well tolerated but with an absent right pulmonary artery the left pulmonary artery flow is equivalent to a 4 :1 shunt. Group a patients present with pulmonary hypertension in infancy and usually die within the first eighteen months [8,17-20] . In half of the cases the right pulmonary artery arises from either the ascending aorta or the first vessel off the aortic arch . In the remaining cases the right lung receives its arterial supply from numerous small collateral vessels . These patients demonstrate that augmented pulmonary flow, prior to regression of the fetal pulmonary vascular pattern, may result in pulmonary hypertension . Group in patients do not have overt pulmonary hypertension in infancy and they may present in adult life with hemoptysis, or for evaluation of an abnormal routine chest roentgenogram [2,13,21-28] . The blood supply to the right lung has not been defined in many of the cases . Tomography suggested the aortic origin of the right pulmonary artery in the case reported by Madoff et al . [2] . We believe that our Case 1 is the first in which the anomalous aortic origin of the right pulmonary artery as an isolated abnormality was demonstrated in an adult by angiography . The blood supply to the right lung has more frequently been shown to be via collaterals [13,21,25] . Previous investigators have suspected that angiographic nonvisualization of a pulmonary artery is not synonymous with an absent pulAMERICAN JOURNAL OF MEDICINE

Absent Right Pulmonary monary artery [5,13] . Our Case 3 illustrates that either surgical or postmortem examination is needed for the definitive diagnosis of an absent right pulmonary artery. The diagnosis of an "absent" or anomalous right pulmonary artery is clearly established if the "right pulmonary artery" is shown to arise from the ascending aorta . If the right lung arterial supply is via multiple collaterals, an acquired or a congenital lesion may be present . Perhaps some of the adults with only angiographic evidence of an absent right pulmonary artery really have acquired lesions . In our Case 3 the thrombosis of the right pulmonary artery may have followed the childhood pneumonia or may have been superimposed on a congenital stenotic or hypoplastic right pulmonary artery . Aortography is therefore indicated in the evaluation of patients with an apparent absent right pulmonary artery . The anomalous origin of the "right pulmonary artery" from the ascending aorta probably represents a septation error of the primiarch [3] . This leads to persistence of the right pulmonary artery with bronchial vessels supplying the right lung is presumably a developmental failure of the ventral sixth branchial arch [3] . This leads to persistence of the right sixth dorsal branchial arch which communicates with the pulmonary plexus, thereby providing the blood supply to the right lung [301 . The right lung is usually normal on histologic examination despite an absent pulmonary artery. Medial hypertrophy and intimal proliferation are frequently noted in the left pulmonary arterioles of the patients with elevated pulmonary artery pressure, and may also be present in the right lung if it is perfused with a large vessel at systemic pressure [3] . The pulmonary function and bronchospirometry data in Case 1 are typical of those reported by other investigators [2,13,23,24] . The volume of the right lung may be moderately reduced but the combined vital capacity and airway resistance are usually normal . When the combined vital capacity is significantly reduced, as in our Case 3, a pulmonary parenchyrnal lesion and acquired obstruction of the right pulmonary artery should be the main consideration in the differential diagnosis . Carbon dioxide is expired in significant quantities from the right lung and oxygen uptake occurs VUL .46,JANUARY 1969

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FIG 9 . Case 8 . Drawing based on the autopsy photographs of the great vessels .

when the alveolar pO 2 exceeds the arteria pO2 . These data suggest that the right lung would be capable of greater gas exchange if i were perfused with venous blood . Bronchoscopy and bronchograms are usuall normal but may show crowding of the bronch on the right side . These studies may also b normal in acquired "absent right pulmonar artery" as shown in our Case 3 . The typical chest film of absent right pul monary artery shows a diminished volume o the right hemithorax, absent hilar comma, shift of the mediastinunt to the right and at asymmetric vascular pattern of the two lun! fields [3] . These findings are almost alway present in both children and adults, but it infants in group r and group it these roent genologic changes may be either absent or se subtle as to escape antemortem recognition Angiographic study is therefore essential fir

Case 3 . Photomicrograph of thrombosed right pulmonary artery .

Fic . 10 .

he

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Absent Right Pulmonary Artery-Bakler et al .

recognition of an absent right pulmonary artery as one of the causes of pulmonary hypertension in infancy . Patients with absent right pulmonary artery and a patent ductus arteriosus (group i) are usually critically ill . Their poor condition has led to a high surgical mortality. In three cases of patent ductus arteriosus and anomalous aortic origin of the right pulmonary artery death occurred following ligation of the duetus [65,15] . The ductus was successfully ligated in a fourth case but the child died suddenly nine weeks after ligation [311 . Caro et al . [12] described a patient who died after ductal ligation and anastomosis of the right pulmonary artery to the main pulmonary artery . Armer and his associates [101 reported a successful repair in a ten month old boy in whom the ductus was ligated and a Dacron® graft was used to anastomose the right pulmonary artery to the main pulmonary artery . Patency of this graft was later demonstrated by angiography . Redo et al . [32] reported a similar case of ductus ligation and a right pulmonary artery-main pulmonary artery anastomosis without a graft in a four and a half year old child . Pool et al . [301 reported ligation of a right-sided patent ductus in two cases of absent left pulmonary artery with right aortic arch . Despite the prior difficulties in the surgical treatment of patent ductus arteriosus associated with an anomalous right pulmonary artery, congestive heart failure in these patients still requires early ligation of the ductus. Consideration should also be given to an anomalous right pulmonary artery-main pulmonary artery anastomosis, which may also reduce pulmonary pressure, although this additional procedure may well increase the immediate surgical risk . Group it patients represent a most difficult problem in management . When there is a sizable pulmonary artery arising from the aorta or its major branches, anastomosis of this vessel to the main pulmonary artery would appear to be a logical approach since clinically recognized pulmonary hypertension in this group is not known to regress spontaneously. However, to date no attempts at this procedure have been reported . The natural history of group tit patients is not known . Surgery has not usually been warranted since symptoms have been mild or ab-

sent . If surgical intervention is deemed necessary because of recurrent hemoptysis there are two possible approaches . The pulmonary artery arising from the aorta could be anastomosed to the main pulmonary artery, as was suggested with groups i and it, and presumably the pressure reduction in the right pulmonary artery would prevent recurrent hemoptysis . Secondly pneumonectomy can be performed. Although no attempts at anastomosis have been reported, one nine year old boy with an isolated absent right pulmonary artery underwent a successful pneumonectomy for repeated hemoptysis and pneumonia [25] . When the chest film shows rib notching, extensive collateral circulation can be assumed and should be a relative contraindication to pneumonectomy. ADDENDUM

Kirkpatrick et al . [33] have recently reported a case of right ventricular failure in a seven month old boy with anomalous aortic origin of the right pulmonary artery . The severe pulmonary hypertension and failure were relieved by a direct anastomosis of the right pulmonary artery to the main pulmonary artery . This represents the first surgical correction of pulmonary hypertension in group n patients . Acknowledgment : We are indebted to Miss Gladys Heckman for the medical illustrations and to the Department of Radiology for their cooperation in these studies . REFERENCES

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