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Solitary peripheral pulmonary artery aneurysms
Solitary peripheral pulmonary artery aneurysms Pathogenesis and surgical treatment The case of a solitary peripheral pulmonary artery aneurysm in a patient with congenital heart disease and secondary pulmonary hypertension is presented. The aneurysm appeared following an episode of bacterial endocarditis and was probably mycotic in origin. Resection was prompted by a recent increase in size. A successful aneurysmectomy was performed. Lobectomy was the procedure employed in seven other reported cases treated surgically. A brief review of the literature emphasizes the necessity for resection whenever the diagnosis is made to prevent a fatal outcome due to rupture. A classification of pulmonary artery aneurysms based on their etiology is proposed, together with a possible explanation for the pathogenesis of peripheral aneurysms of nonspecific etiology.
Ruben Ungaro, M . D . , Salim Saab, M . D . , Carl H. Almond, M . D . , and Surendra Kumar, M . D . , Columbia, Mo.
O ince aneurysms of the trunk and right and left main pulmonary arteries manifest some differences from those of the intrapulmonary portion of these arteries, we propose to describe the former as central and the latter as peripheral. Peripheral aneurysms thus include those of the lobar and segmental branches, and may be multiple or solitary. Untreated, the majority end fatally due to sudden rupture and exsanguination. 1 This emphasizes the need for surgical intervention whenever the diagnosis is made. Case report R. L., a 20-year-old white man, was diagnosed to have asymptomatic congenital heart diesase at 2 months of age, manifested by a heart murmur. At 9 years of age cardiac catheterization confirmed the presence of a ventricular septal defect and a septum secundum atrial defect with normal pulmonary artery pressure. Chest roentgenogram then showed moderate cardiomegaly and increased pulmonary vascularity. At 10 years of age (on Nov. 13, 1964) he was admitted with a febrile illness and blood cultures repeatedly grew Staphylococcus aureus, coagulase positive. The diagnosis of pneumonia, septicemia, and bacterial endocarditis was made. This was treated successfully with antibiotics. Two months later, in January of 1965, a roentgenogram of the chest From the Department of Surgery, University of Missouri Medical Center, Columbia, Mo. Received for publication Aug. 15, 1975. Address for reprints: Carl H. Almond, M.D., Professor of Surgery and Chief, Section of Thoracic and Cardiovascular Surgery, University of Missouri Medical Center, Columbia, Mo. 65201. 566
showed a round mass, 3 cm. in diameter, in the right perihilar region, which was not present previously. Another cardiac catheterization 1V4 years later demonstrated this mass to be an aneurysm of the intrapulmonary portion of the right pulmonary artery, and revealed the presence of pulmonary hypertension with a pulmonary arterial pressure of 110/50 mm. Hg. On Aug. 30, 1966, an open cardiotomy was performed and the atrial and ventricular septal defects were repaired. Resection of the pulmonary artery aneurysm was thought to require a pneumonectomy in view of its location in the major fissure, adjacent to the origin of the major lobar branches. This was not considered wise at this operation. Follow-up catheterization on Oct. 12, 1967 demonstrated a residual small ventricular septal defect with a pulmonary arterial pressure of 50/15 mm. Hg. An electrocardiogram then showed a right bundle branch block and atrial flutter that was controlled with digoxin. Cardiac catheterization was repeated on June 3, 1975 and showed the same findings but pulmonary angiography indicated an increase in the size of the aneurysm to 5 cm. in diameter and a chest roentgenogram showed calcification in its wall (Figs. 1 and 2). Surgical intervention was advised and a right posterolateral thoracotomy was performed on April 24, 1975. Fibrovascular adhesions were encountered between the lung and the chest wall, probably due to the previous operation and infection. These were dissected and the pulsatile peripheral aneurysm of the right pulmonary artery was identified in the oblique fissure distal but adjacent to the origin of the right middle lobe branch with the main mass projecting upward into the substance of the right upper lobe (Fig. 3). It felt like a cracked eggshell due to the diffuse calcification in its wall. Although it was embedded in the substance of the right upper lobe, there were no major vascular communications. It was hence dissected meticulously after proximal control of the right main pulmonary artery was obtained. A vascular clamp was applied to the neck of the aneurysm, which measured 2.5 cm.
Volume 71 Number 4 April, 1976
Pulmonary artery aneurysms
567
Fig. 1. Preoperative roentgenograms of the chest showing the right perihilar "coin lesion" in the (A) posteroanterior and (B) lateral views. Note the calcine rim in the wall of the aneurysm. in length, parallel to the long axis of the pulmonary artery. The aneurysm was excised and the pulmonary arterial rent was closed with a continuous 4-0 Tevdek vascular suture. No pulmonary tissue was resected. The postoperative course was complicated by excessive bleeding through the chest tubes, for which the right chest was re-explored. The source of bleeding was found to be from the fibrovascular adhesions in the chest wall and diaphragm. Adequate hemostasis was achieved and the patient then had an uneventful recovery (Fig. 4). Pathological examination of the resected aneurysm sac revealed a cup-shaped piece of tan tissue measuring 4 cm. in diameter. This was smaller than the preoperative measurement, probably because of cessation of the pulsatile flow. The wall was calcine and varied in thickness from less than 1 to 2 mm. The internal surface was covered with irregularly distributed fibrous yellow-tan tissue and the external surface was hyperemic but otherwise unremarkable. Microscopically, the aneurysmal wall had calcification and consisted primarily of pink collagen with relatively few fibroblasts. There was no normal pulmonary artery component identified, and on elastic stain, only few coarse elastic fibers were located adjacent to the acellular intimal area. The attached lung parenchyma had delicate alveoli, some of whose lumens contained hemosiderin-laden macrophages and fresh red blood cells. There were also lymphocytic collections in the lung parenchyma. Discussion The rarity of pulmonary artery aneurysms has been emphasized by several reviews. 2 ' 3 In an excellent
analysis of necropsy material reported between 1848 and 1946, Deterling and Clagett 2 found one such aneurysm in every 13,696 necropsies. They collected a total of 198 cases of central aneurysm of the pulmonary arteries. Groedel 4 estimated the ratio of pulmonary to aortic aneurysm to be 1:250. Peripheral pulmonary aneurysms were more frequent in the past, when tuberculosis was rampant. "Rasmussen aneurysms," occurring in association with chronic tuberculous cavities, were present in 4 to 5 per cent of necropsies of patients who died of chronic pulmonary tuberculosis. 5 Although tuberculous and syphilitic aneurysms are caused by infectious organisms, they are specific enough to be classified separately from other infections. Etiologically, therefore, we propose the following classification for pulmonary artery aneurysms: A. Specific etiology 1. Tuberculous 2. Syphilitic 3. Traumatic B . Nonspecific etiology 1. Mycotic 2. In association with pulmonary hypertension 3. Congenital (a defect in the arterial wall) 6 4. Arteriosclerotic 2 Among reported cases of solitary peripheral pulmonary aneurysms, tuberculous ones are the commonest.
568
Ungaro et al.
Fig. 2. Pulmonary angiogram showing the tip of the catheter inside the aneurysm. Note the absence of vascular communications with the sac, and the segmentai branches of the right lower lobe distally. They occurred in 22 of 26 patients dying of pulmonary tuberculosis, of whom 17 deaths (78 per cent) were attributed to rupture.7 Although syphilis usually affects the central pulmonary arteries, there was one documented case of solitary syphilitic aneurysm in a peripheral pulmonary artery which also ended fatally due to rupture.8 Five cases of traumatic solitary peripheral pulmonary artery aneurysms have been reported; two of these patients died of rupture and two were treated successfully by lobectomy.9 Mycotic aneurysms mostly arise in the segmentai pulmonary arteries. They are usually multiple and often bilateral. However, of 22 cases collected by Kauffman, Lynfield, and Hennigar10 four were solitary. Of 20 deaths 13 (65 per cent) were due to rutpure of an aneurysm. The only survivors were two patients with solitary aneurysms treated by resection (lobectomy). Mycotic aneurysms have been particularly associated with bacterial endocarditis. Fourteen such cases have been described, in nine of which endocarditis complicated the course of congenital heart disease with left-to-right shunt.10 Another intersting relationship exists between peripheral pulmonary aneurysms and febrile illnesses characterized by recurrent thrombophlebitis and thromboembolism. Eight such cases have been described: The Hughes-Stovin11 syndrome.
The Journal of Thoracic and Cardiovascular Surgery
The third observation worthy of mention is an apparent link between pulmonary hypertension and the pathogenesis of mycotic pulmonary artery aneurysms; the prevalence of congenital heart disease with left-to-right shunt and recurrent thrombophlebitis, two clinical entities that may produce secondary pulmonary hypertension, has already been mentioned. Furthermore, two patients have been described with mycotic pulmonary aneurysms, who also had primary pulmonary hypertension.10 In two other patients with solitary aneurysms who had systolic pulmonary hypertension only, history of a febrile illness was present in one12 but not mentioned in the other patient.13 Binding these observations together, plus the fact that aneurysms related to pulmonary hypertension alone are usually central and fusiform, rather than peripheral and saccular,14 we cannot escape the speculation that (1) infection, (2) pulmonary hypertension, and (3) a vascular defect, congenital or acquired, form the three apices of a triangle, and that the combination of any two of them in one patient places that individual patient in a likely situation for peripheral pulmonary aneurysm formation (Fig. 5). Thus, infection could lodge in the wall of a pulmonary vessel that is already weakened by a congenital or acquired defect, or that is already diseased by changes of pulmonary hypertension. This hypothesis would account for patients who develop mycotic pulmonary aneurysms and give a history of bacterial endocarditis, but have no left-to-right shunt and no pulmonary hypertension. It would also account for patients with the Hughes-Stovin11 syndrome, where it is postulated that degenerative changes in the bronchial arteries lead to poor nutrition of the pulmonary arteries, thus predisposing them to respond to the mildly septic emboli by aneurysm formation. It is implied here that the failure to demonstrate the infective organisms by histopathology or by culture is due to the infection being of "low virulence and the number of organisms small." 14 Our case fits in the category of infection (bacterial endocarditis) with pulmonary hypertension secondary to intracardiac septal defects with left-to-right shunt. This helps explain the pathogenesis, although the pathologist did not consider the microscopic findings to be characteristic of mycotic aneurysms. The histopathology of mycotic aneurysms typically consists of destruction of elastic tissue with a replacement by organized granulation tissue. Foci of calcified thrombi and infective organisms may be identified, while organized recanalized thrombi may be present in other arteries.10 However, the long interval that lapsed between the first
Volume 71 Number 4 April, 1976
Pulmonary artery aneurysms
5 69
Sup. Seg RLL
Fig. 3. Diagram illustrating the location of the saccular aneurysm in relation to the lobar and segmental pulmonary arterial branches. MPA, Main pulmonary artery; LPA, left pulmonary artery; RPA, right pulmonary artery; RUL, right upper lobe branch; RML, right middle lobe branch; RLL, right lower lobe branch; Sup. seg, superior segment. appearance of the aneurysm (immediately after the febrile illness) and the time of surgery (10 years later) could explain the lack of evidence of acute infection in its wall. Clinical course and management The symptoms of a solitary peripheral pulmonary aneurysm may be those of the predisposing or coexisting disease, and help draw attention to the "coin lesion" in the perihilar area. Hemoptysis, dyspnea, cough, and chest pain have been described. The differential diagnosis covers a wide spectrum of benign and malignant diseases. Unveiling the true nature basically requires a suspicion of the diagnosis by the physician, to be confirmed by pulmonary angiography. If the latter is done, as part of a right cardiac catheterization, then measurement of intracardic and pulmonary arterial oxygen saturation as well as pulmonary arterial pressure will indicate the presence or absence of intracardiac shunt and/or pulmonary hypertension. Of a total of 35 cases of solitary peripheral pulmonary aneurysms reported in the literature, 21 (60 per cent) died of rupture.1 This emphasizes the necessity for operation whenever the diagnosis is made, irrespective of the presence or absence of symptoms. The first successful lobectomy for a solitary peripheral pulmonary aneurysm was performed by
Hohlweg16 in 1948. Since then six more cases treated by lobectomy were reported.1, 9> 12_14- 17 In contradistinction to our case, none of them had calcification in the wall of the aneurysm. Our case, hence, brings the total to eight patients treated by resection, but is the first in which the patient was treated by an aneurysmectomy alone, thus preserving functional pulmonary tissue. It should be pointed out, however, that such a procedure was feasible only because of the accessible location of the aneurysm in the oblique fissure, and the demonstration of a well-defined neck by angiography, with no tributaries arising from the sac. The safety of the operation was further enhanced by obtaining proximal control of the right main pulmonary artery. The alternatives would have been ligation of the main pulmonary artery,15 or a pneumonectomy, because of the location of the aneurysm adjacent to the lobar arterial branches. However, we were reluctant to perform either of the two procedures in a young man. Finally, it is recommended that prophylactic antibiotics be given to patients with a history of bacterial endocarditis and congenital heart disease until the aneurysm is resected, to avoid recurrence of infection and its attending risk of acute necrosis with resultant rupture and sudden death.10 In conclusion, the following remarks may be made about solitary peripheral pulmonary artery aneurysms. (1) Trauma, infections (specific or nonspecific), pulmonary hypertension, and pulmonary vascular defects
570
The Journal of Thoracic and Cardiovascular Surgery
Ungaro et al.
Fig. 4. Roentgenograms of the chest taken 2 months postoperatively, in the (A) posteroanterior and (B) lateral views. Note the pleural reaction at the right base.
INFECTION
PULMONARY HYPERTENSION
WALL DEFECT (CONGENITAL OR ACQUIRED)
Fig. 5. Diagram illustrating factors related to the pathogenesis of peripheral pulmonary artery aneurysms.
(congenital or acquired) are all factors that could predispose, alone or in combination, to the development of solitary peripheral pulmonary artery aneurysms. (2) History of the above, followed by the appearance of a perihilar coin lesion on chest roentgenogram in a patient, should draw attention to the diagnosis, which then should be confirmed or ruled out by pulmonary angiography. (3) Surgical resection is mandatory as soon as the diagnosis is made, to prevent rupture and death. This usually consists of lobectomy but aneurysmectomy may be attempted in
an effort to save functional pulmonary tissue and is feasible in selected cases. REFERENCES 1 Monchik, J., and Wilkins, E. W., Jr.: Solitary Aneurysms of the Middle Lobe Artery: A Case Report and Review of Solitary Peripheral Pulmonary Artery Aneurysms, Ann. Thorac Surg. 17: 496, 1974. 2 Deterling, R. A., and Clagget, O. T.: Aneurysm of the Pulmonary Artery: Review of the Literature and Report of a Case, Am. Heart J. 34: 471, 1947. 3 Boyd, L. J., and McGavack, T. H.: Aneurysm of the Pulmonary Artery: A Review of the Literature and Report of Two Cases, Am. Heart J. 18: 562, 1939. 4 Groedel, F. M.: Aneurysm of the Pulmonary Artery, Radiology 33: 219,1939. 5 Auerbach, Oscar: Pathology and Pathogenesis of Pulmonary Arterial Aneurysm in Tuberculous Cavities, Am. Rev. Tuberc. 39: 99, 1939. 6 Brenner, O.: Pathology of the Vessels of the Pulmonary Circulation, Part V, Arch. Intern. Med. 56: 1189, 1935. 7 Kidd, P.: Unusual Cases of Pulmonary Aneurysms, Trans. Pathol. Soc. Lond. 35: 98, 1884. 8 Warthin, A. S., Syphilis of the Pulmonary Artery, Am. J. Syph. 1: 693, 1917. 9 Symbas, P. N., and Scott, H. W., Jr.: Traumatic Aneurysm of the Pulmonary Artery, J. THORAC. CARDIOVASC. SURG. 45: 645,
1963.
10 Kauffman, S. L., Lynfield, J., and Hennigar, G. R.:
Volume 71 Number 4 April, 1976
Mycotic Aneurysms of the Intrapulmonary Arteries, Circulation 35: 90, 1967. 11 Hughes, J. P., and Stovin, P. G.: Segmental Pulmonary Artery Aneurysm With Peripheral Venous Thrombosis, Br. J. Dis. Chest 53: 19, 1959. 12 Sancetta, S. M., Driscol, T., and Hackel, D. B.: Primary Pulmonary Systolic Hypertension Associated with Aneurysm of the Pulmonary Artery, Am. Heart J. 55: 607, 1958. 13 Mackenzie, D. A., and Clagett, O. T.: Unusual Aneurysm of a Pulmonary Artery: Report of a Case in Which Treatment Was Surgical, J. THORAC. SURG. 25: 524, 1953.
Pulmonary artery aneurysms
571
14 Frater, R. W., Beck, W., and Schrire, V.: Syndrome of Pulmonary Artery Thrombi and Peripheral Venous Thrombi, J.
THORAC. CARDIOVASC.
SURG. 49:
330,
1965. 15 Blades, B., Ford, W., and Clark, P.: Pulmonary Artery Aneurysms: Report of a Case Treated by Surgical Intervention, Circulation 2: 565, 1950. 16 Hohlweg, E.: Operative Geheiltes Traumatisches Aneurysma einer Lungarterie, Chirurg 19: 373, 1948. 17 Konhaus, C. H., and Kunkel, P. A., Jr.: Aneurysm of a Pulmonary Artery: Report of a Case in which Treatment Was Surgical. Ann. Surg. 142: 997, 1955.
Ruben Ungaro, M . D . , Salim Saab, M . D . , Carl H. Almond, M . D . , and Surendra Kumar, M . D . , Columbia, Mo.
O ince aneurysms of the trunk and right and left main pulmonary arteries manifest some differences from those of the intrapulmonary portion of these arteries, we propose to describe the former as central and the latter as peripheral. Peripheral aneurysms thus include those of the lobar and segmental branches, and may be multiple or solitary. Untreated, the majority end fatally due to sudden rupture and exsanguination. 1 This emphasizes the need for surgical intervention whenever the diagnosis is made. Case report R. L., a 20-year-old white man, was diagnosed to have asymptomatic congenital heart diesase at 2 months of age, manifested by a heart murmur. At 9 years of age cardiac catheterization confirmed the presence of a ventricular septal defect and a septum secundum atrial defect with normal pulmonary artery pressure. Chest roentgenogram then showed moderate cardiomegaly and increased pulmonary vascularity. At 10 years of age (on Nov. 13, 1964) he was admitted with a febrile illness and blood cultures repeatedly grew Staphylococcus aureus, coagulase positive. The diagnosis of pneumonia, septicemia, and bacterial endocarditis was made. This was treated successfully with antibiotics. Two months later, in January of 1965, a roentgenogram of the chest From the Department of Surgery, University of Missouri Medical Center, Columbia, Mo. Received for publication Aug. 15, 1975. Address for reprints: Carl H. Almond, M.D., Professor of Surgery and Chief, Section of Thoracic and Cardiovascular Surgery, University of Missouri Medical Center, Columbia, Mo. 65201. 566
showed a round mass, 3 cm. in diameter, in the right perihilar region, which was not present previously. Another cardiac catheterization 1V4 years later demonstrated this mass to be an aneurysm of the intrapulmonary portion of the right pulmonary artery, and revealed the presence of pulmonary hypertension with a pulmonary arterial pressure of 110/50 mm. Hg. On Aug. 30, 1966, an open cardiotomy was performed and the atrial and ventricular septal defects were repaired. Resection of the pulmonary artery aneurysm was thought to require a pneumonectomy in view of its location in the major fissure, adjacent to the origin of the major lobar branches. This was not considered wise at this operation. Follow-up catheterization on Oct. 12, 1967 demonstrated a residual small ventricular septal defect with a pulmonary arterial pressure of 50/15 mm. Hg. An electrocardiogram then showed a right bundle branch block and atrial flutter that was controlled with digoxin. Cardiac catheterization was repeated on June 3, 1975 and showed the same findings but pulmonary angiography indicated an increase in the size of the aneurysm to 5 cm. in diameter and a chest roentgenogram showed calcification in its wall (Figs. 1 and 2). Surgical intervention was advised and a right posterolateral thoracotomy was performed on April 24, 1975. Fibrovascular adhesions were encountered between the lung and the chest wall, probably due to the previous operation and infection. These were dissected and the pulsatile peripheral aneurysm of the right pulmonary artery was identified in the oblique fissure distal but adjacent to the origin of the right middle lobe branch with the main mass projecting upward into the substance of the right upper lobe (Fig. 3). It felt like a cracked eggshell due to the diffuse calcification in its wall. Although it was embedded in the substance of the right upper lobe, there were no major vascular communications. It was hence dissected meticulously after proximal control of the right main pulmonary artery was obtained. A vascular clamp was applied to the neck of the aneurysm, which measured 2.5 cm.
Volume 71 Number 4 April, 1976
Pulmonary artery aneurysms
567
Fig. 1. Preoperative roentgenograms of the chest showing the right perihilar "coin lesion" in the (A) posteroanterior and (B) lateral views. Note the calcine rim in the wall of the aneurysm. in length, parallel to the long axis of the pulmonary artery. The aneurysm was excised and the pulmonary arterial rent was closed with a continuous 4-0 Tevdek vascular suture. No pulmonary tissue was resected. The postoperative course was complicated by excessive bleeding through the chest tubes, for which the right chest was re-explored. The source of bleeding was found to be from the fibrovascular adhesions in the chest wall and diaphragm. Adequate hemostasis was achieved and the patient then had an uneventful recovery (Fig. 4). Pathological examination of the resected aneurysm sac revealed a cup-shaped piece of tan tissue measuring 4 cm. in diameter. This was smaller than the preoperative measurement, probably because of cessation of the pulsatile flow. The wall was calcine and varied in thickness from less than 1 to 2 mm. The internal surface was covered with irregularly distributed fibrous yellow-tan tissue and the external surface was hyperemic but otherwise unremarkable. Microscopically, the aneurysmal wall had calcification and consisted primarily of pink collagen with relatively few fibroblasts. There was no normal pulmonary artery component identified, and on elastic stain, only few coarse elastic fibers were located adjacent to the acellular intimal area. The attached lung parenchyma had delicate alveoli, some of whose lumens contained hemosiderin-laden macrophages and fresh red blood cells. There were also lymphocytic collections in the lung parenchyma. Discussion The rarity of pulmonary artery aneurysms has been emphasized by several reviews. 2 ' 3 In an excellent
analysis of necropsy material reported between 1848 and 1946, Deterling and Clagett 2 found one such aneurysm in every 13,696 necropsies. They collected a total of 198 cases of central aneurysm of the pulmonary arteries. Groedel 4 estimated the ratio of pulmonary to aortic aneurysm to be 1:250. Peripheral pulmonary aneurysms were more frequent in the past, when tuberculosis was rampant. "Rasmussen aneurysms," occurring in association with chronic tuberculous cavities, were present in 4 to 5 per cent of necropsies of patients who died of chronic pulmonary tuberculosis. 5 Although tuberculous and syphilitic aneurysms are caused by infectious organisms, they are specific enough to be classified separately from other infections. Etiologically, therefore, we propose the following classification for pulmonary artery aneurysms: A. Specific etiology 1. Tuberculous 2. Syphilitic 3. Traumatic B . Nonspecific etiology 1. Mycotic 2. In association with pulmonary hypertension 3. Congenital (a defect in the arterial wall) 6 4. Arteriosclerotic 2 Among reported cases of solitary peripheral pulmonary aneurysms, tuberculous ones are the commonest.
568
Ungaro et al.
Fig. 2. Pulmonary angiogram showing the tip of the catheter inside the aneurysm. Note the absence of vascular communications with the sac, and the segmentai branches of the right lower lobe distally. They occurred in 22 of 26 patients dying of pulmonary tuberculosis, of whom 17 deaths (78 per cent) were attributed to rupture.7 Although syphilis usually affects the central pulmonary arteries, there was one documented case of solitary syphilitic aneurysm in a peripheral pulmonary artery which also ended fatally due to rupture.8 Five cases of traumatic solitary peripheral pulmonary artery aneurysms have been reported; two of these patients died of rupture and two were treated successfully by lobectomy.9 Mycotic aneurysms mostly arise in the segmentai pulmonary arteries. They are usually multiple and often bilateral. However, of 22 cases collected by Kauffman, Lynfield, and Hennigar10 four were solitary. Of 20 deaths 13 (65 per cent) were due to rutpure of an aneurysm. The only survivors were two patients with solitary aneurysms treated by resection (lobectomy). Mycotic aneurysms have been particularly associated with bacterial endocarditis. Fourteen such cases have been described, in nine of which endocarditis complicated the course of congenital heart disease with left-to-right shunt.10 Another intersting relationship exists between peripheral pulmonary aneurysms and febrile illnesses characterized by recurrent thrombophlebitis and thromboembolism. Eight such cases have been described: The Hughes-Stovin11 syndrome.
The Journal of Thoracic and Cardiovascular Surgery
The third observation worthy of mention is an apparent link between pulmonary hypertension and the pathogenesis of mycotic pulmonary artery aneurysms; the prevalence of congenital heart disease with left-to-right shunt and recurrent thrombophlebitis, two clinical entities that may produce secondary pulmonary hypertension, has already been mentioned. Furthermore, two patients have been described with mycotic pulmonary aneurysms, who also had primary pulmonary hypertension.10 In two other patients with solitary aneurysms who had systolic pulmonary hypertension only, history of a febrile illness was present in one12 but not mentioned in the other patient.13 Binding these observations together, plus the fact that aneurysms related to pulmonary hypertension alone are usually central and fusiform, rather than peripheral and saccular,14 we cannot escape the speculation that (1) infection, (2) pulmonary hypertension, and (3) a vascular defect, congenital or acquired, form the three apices of a triangle, and that the combination of any two of them in one patient places that individual patient in a likely situation for peripheral pulmonary aneurysm formation (Fig. 5). Thus, infection could lodge in the wall of a pulmonary vessel that is already weakened by a congenital or acquired defect, or that is already diseased by changes of pulmonary hypertension. This hypothesis would account for patients who develop mycotic pulmonary aneurysms and give a history of bacterial endocarditis, but have no left-to-right shunt and no pulmonary hypertension. It would also account for patients with the Hughes-Stovin11 syndrome, where it is postulated that degenerative changes in the bronchial arteries lead to poor nutrition of the pulmonary arteries, thus predisposing them to respond to the mildly septic emboli by aneurysm formation. It is implied here that the failure to demonstrate the infective organisms by histopathology or by culture is due to the infection being of "low virulence and the number of organisms small." 14 Our case fits in the category of infection (bacterial endocarditis) with pulmonary hypertension secondary to intracardiac septal defects with left-to-right shunt. This helps explain the pathogenesis, although the pathologist did not consider the microscopic findings to be characteristic of mycotic aneurysms. The histopathology of mycotic aneurysms typically consists of destruction of elastic tissue with a replacement by organized granulation tissue. Foci of calcified thrombi and infective organisms may be identified, while organized recanalized thrombi may be present in other arteries.10 However, the long interval that lapsed between the first
Volume 71 Number 4 April, 1976
Pulmonary artery aneurysms
5 69
Sup. Seg RLL
Fig. 3. Diagram illustrating the location of the saccular aneurysm in relation to the lobar and segmental pulmonary arterial branches. MPA, Main pulmonary artery; LPA, left pulmonary artery; RPA, right pulmonary artery; RUL, right upper lobe branch; RML, right middle lobe branch; RLL, right lower lobe branch; Sup. seg, superior segment. appearance of the aneurysm (immediately after the febrile illness) and the time of surgery (10 years later) could explain the lack of evidence of acute infection in its wall. Clinical course and management The symptoms of a solitary peripheral pulmonary aneurysm may be those of the predisposing or coexisting disease, and help draw attention to the "coin lesion" in the perihilar area. Hemoptysis, dyspnea, cough, and chest pain have been described. The differential diagnosis covers a wide spectrum of benign and malignant diseases. Unveiling the true nature basically requires a suspicion of the diagnosis by the physician, to be confirmed by pulmonary angiography. If the latter is done, as part of a right cardiac catheterization, then measurement of intracardic and pulmonary arterial oxygen saturation as well as pulmonary arterial pressure will indicate the presence or absence of intracardiac shunt and/or pulmonary hypertension. Of a total of 35 cases of solitary peripheral pulmonary aneurysms reported in the literature, 21 (60 per cent) died of rupture.1 This emphasizes the necessity for operation whenever the diagnosis is made, irrespective of the presence or absence of symptoms. The first successful lobectomy for a solitary peripheral pulmonary aneurysm was performed by
Hohlweg16 in 1948. Since then six more cases treated by lobectomy were reported.1, 9> 12_14- 17 In contradistinction to our case, none of them had calcification in the wall of the aneurysm. Our case, hence, brings the total to eight patients treated by resection, but is the first in which the patient was treated by an aneurysmectomy alone, thus preserving functional pulmonary tissue. It should be pointed out, however, that such a procedure was feasible only because of the accessible location of the aneurysm in the oblique fissure, and the demonstration of a well-defined neck by angiography, with no tributaries arising from the sac. The safety of the operation was further enhanced by obtaining proximal control of the right main pulmonary artery. The alternatives would have been ligation of the main pulmonary artery,15 or a pneumonectomy, because of the location of the aneurysm adjacent to the lobar arterial branches. However, we were reluctant to perform either of the two procedures in a young man. Finally, it is recommended that prophylactic antibiotics be given to patients with a history of bacterial endocarditis and congenital heart disease until the aneurysm is resected, to avoid recurrence of infection and its attending risk of acute necrosis with resultant rupture and sudden death.10 In conclusion, the following remarks may be made about solitary peripheral pulmonary artery aneurysms. (1) Trauma, infections (specific or nonspecific), pulmonary hypertension, and pulmonary vascular defects
570
The Journal of Thoracic and Cardiovascular Surgery
Ungaro et al.
Fig. 4. Roentgenograms of the chest taken 2 months postoperatively, in the (A) posteroanterior and (B) lateral views. Note the pleural reaction at the right base.
INFECTION
PULMONARY HYPERTENSION
WALL DEFECT (CONGENITAL OR ACQUIRED)
Fig. 5. Diagram illustrating factors related to the pathogenesis of peripheral pulmonary artery aneurysms.
(congenital or acquired) are all factors that could predispose, alone or in combination, to the development of solitary peripheral pulmonary artery aneurysms. (2) History of the above, followed by the appearance of a perihilar coin lesion on chest roentgenogram in a patient, should draw attention to the diagnosis, which then should be confirmed or ruled out by pulmonary angiography. (3) Surgical resection is mandatory as soon as the diagnosis is made, to prevent rupture and death. This usually consists of lobectomy but aneurysmectomy may be attempted in
an effort to save functional pulmonary tissue and is feasible in selected cases. REFERENCES 1 Monchik, J., and Wilkins, E. W., Jr.: Solitary Aneurysms of the Middle Lobe Artery: A Case Report and Review of Solitary Peripheral Pulmonary Artery Aneurysms, Ann. Thorac Surg. 17: 496, 1974. 2 Deterling, R. A., and Clagget, O. T.: Aneurysm of the Pulmonary Artery: Review of the Literature and Report of a Case, Am. Heart J. 34: 471, 1947. 3 Boyd, L. J., and McGavack, T. H.: Aneurysm of the Pulmonary Artery: A Review of the Literature and Report of Two Cases, Am. Heart J. 18: 562, 1939. 4 Groedel, F. M.: Aneurysm of the Pulmonary Artery, Radiology 33: 219,1939. 5 Auerbach, Oscar: Pathology and Pathogenesis of Pulmonary Arterial Aneurysm in Tuberculous Cavities, Am. Rev. Tuberc. 39: 99, 1939. 6 Brenner, O.: Pathology of the Vessels of the Pulmonary Circulation, Part V, Arch. Intern. Med. 56: 1189, 1935. 7 Kidd, P.: Unusual Cases of Pulmonary Aneurysms, Trans. Pathol. Soc. Lond. 35: 98, 1884. 8 Warthin, A. S., Syphilis of the Pulmonary Artery, Am. J. Syph. 1: 693, 1917. 9 Symbas, P. N., and Scott, H. W., Jr.: Traumatic Aneurysm of the Pulmonary Artery, J. THORAC. CARDIOVASC. SURG. 45: 645,
1963.
10 Kauffman, S. L., Lynfield, J., and Hennigar, G. R.:
Volume 71 Number 4 April, 1976
Mycotic Aneurysms of the Intrapulmonary Arteries, Circulation 35: 90, 1967. 11 Hughes, J. P., and Stovin, P. G.: Segmental Pulmonary Artery Aneurysm With Peripheral Venous Thrombosis, Br. J. Dis. Chest 53: 19, 1959. 12 Sancetta, S. M., Driscol, T., and Hackel, D. B.: Primary Pulmonary Systolic Hypertension Associated with Aneurysm of the Pulmonary Artery, Am. Heart J. 55: 607, 1958. 13 Mackenzie, D. A., and Clagett, O. T.: Unusual Aneurysm of a Pulmonary Artery: Report of a Case in Which Treatment Was Surgical, J. THORAC. SURG. 25: 524, 1953.
Pulmonary artery aneurysms
571
14 Frater, R. W., Beck, W., and Schrire, V.: Syndrome of Pulmonary Artery Thrombi and Peripheral Venous Thrombi, J.
THORAC. CARDIOVASC.
SURG. 49:
330,
1965. 15 Blades, B., Ford, W., and Clark, P.: Pulmonary Artery Aneurysms: Report of a Case Treated by Surgical Intervention, Circulation 2: 565, 1950. 16 Hohlweg, E.: Operative Geheiltes Traumatisches Aneurysma einer Lungarterie, Chirurg 19: 373, 1948. 17 Konhaus, C. H., and Kunkel, P. A., Jr.: Aneurysm of a Pulmonary Artery: Report of a Case in which Treatment Was Surgical. Ann. Surg. 142: 997, 1955.