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SURGICAL MANAGEMENT OF DISSECTING ANEURYSMS OF THE AORTA
SURGICAL M A N A G E M E N T OF DISSECTING ANEURYSMS OF THE AORTA Michael E. De Bakey, M.D., Walter S. Henly, M.D., Denton A. Cooley, George C. Morris, Jr., M.D., E. Stanley Crawford, M.D., Arthur C. Beall, Jr., M.D., Houston,
M.D.,
and
Texas
D
aneurysm has long been recognized as an ominous and highly lethal form of aortic disease, for which no effective therapy was avail able until about a decade ago. 3 ' 5 ' " ' 1 T More recently an increasing number of reports have appeared indicating that the natural course of the disease can be altered favorably by surgical treatment. 1 ' 2 ' 6 ' 8 ' 10> 12> 13 > 15 ' 16 ' 18 During the past decade, since our first successful operation for a dissecting aneurysm of the aorta, we have employed some form of surgical treatment in 179 patients with either acute or chronic types of the disease. As a consequence of this experience, a much better understanding of the anatomic and pathologic patterns of the disease has been obtained, leading to the development of specific and more effective methods of surgical treatment. Accordingly, this report is concerned with certain significant observations derived from an analysis of our expe rience, with particular reference to the specific methods of surgical treatment for each of the different patterns of the disease and the immediate and longterm results. In our early experience, two methods of surgical treatment were developed, and their application depended upon the location and extent of the dissecting process.5 The first method was employed for dissections which arose in the ascending aorta and extended for a varying distance into or beyond the descend ing thoracic aorta. This method consisted essentially in the creation of a re entry passage from the false to the true aortic lumen and was accomplished by dividing the descending thoracic aorta between occluding clamps, obliterat ing the false passage below by approximating the outer and inner layers, ex cising a small segment from the inner wall above to permit re-entry into the true lumen, and completing the procedure by end-to-end anastomosis. The second method was applied to dissections arising in the descending thoracic aorta and consisted essentially in excising this segment of the aorta, obliterating the false ISSECTING
From the Cora and Webb Mading Departments of Surgery, Baylor University College of Medicine, and the Methodist, St. Luke's Episcopal, Jefferson Davis, and Ben Taub General Hospitals, Houston, Texas. Supported in part by the U. S. Public Health Service (HE-03137) and (HE-05435). Presented a t the Forty-fourth Annual Meeting of the American Association for Thoracic Surgery, Montreal, Canada, April 29, 1964. 130
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lumen in the distal end by suture approximation of the inner and outer layers, and replacing the excised segment with a graft. Although the latter method proved to be satisfactory in achieving its ob jective of eliminating the origin and progression of the dissecting process, it soon became apparent that the first method was unsatisfactory in these terms. Indeed, it was based upon the concept of palliation rather than actual restora tion of normal aortic mural integrity and function and for this reason was abandoned subsequently. With increasing experience and a better understand ing of the anatomic and pathologic patterns of the disease, certain conceptual changes have evolved and have provided more effective methods of surgical treatment for the different forms of the disease. 8 - 10 ' 15 SURGICAL CLASSIFICATION OF DISSECTING ANEURYSM
Considerable variations in the anatomic and pathologic features of dis secting aneurysm have been found and described and various classifications have been proposed to designate them. 11 ' 17 On the basis of our experience and from the standpoint of surgical treatment, most, if not all, of the different patterns of the disease may be classified into three basic types 10 (Fig. 1) : TYPE I.—This pattern of the disease is characterized by the fact that the dissecting process, along with the intimal tear, arises in the ascending aorta and extends distally for a variable distance, but usually throughout the re maining aorta and not infrequently into its major terminal branches (Fig. 1). The dissecting process also varies in the extent of circumferential involvement but is usually incomplete. Aortic valve insufficiency is frequently present. TYPE II.—This form of the disease is characterized by the fact that the dissecting process is limited to the ascending aorta. There is usually a trans-
Fig. 1.—Drawing which illustrates surgical classification of dissecting aneurysm of aorta into three basic types in accordance with origin and extent of dissecting process.
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verse tear in the intima beginning just above the aortic valve, with separation of the intramural layers that terminates just proximal to the origin of the innominate artery (Fig. 1). It also is characterized by a relatively thin outer layer that usually assumes the appearance of a fusiform aneurysm and often is associated with incompetence of the aortic valve. This type is .more likely to be found in patients with certain stigmata of Marfan's disease. TYPE III.—This form of the disease is characterized by the fact that the dissecting process arises in the descending thoracic aorta usually at or just distal to the origin of the left subclavian artery and extends distally for a varying distance. In some instances the dissecting process is limited to the descending thoracic aorta (Fig. 1). Circumferentially there is also variation in the extent of the dissecting process, but it is usually incomplete. In most cases, however, progressive dilatation of the outer, layer and consequent enlargement of the false lumen with ultimate rupture is limited to the descending thoracic aorta. SURGICAL METHODS OF T R E A T M E N T
TYPE I.—Because of the tendency for this form of the disease to progress rapidly toward a fatal termination, surgical treatment should be applied as soon as possible after onset. The procedure consists essentially in transection of the ascending aorta with the use of temporary cardiopulmonary bypass and obliteration of the false lumen by approximation of the inner and outer walls of the dissecting process by means of a continuous suture both proximally and distally, followed by end-to-end anastomosis of the transected aorta (Fig. 2). Median sternotomy has been found to provide excellent exposure for this pur pose. The use of 5 per cent dextrose in distilled water for priming disposable plastic oxygenators not only prevents complications associated with the use of a pool of homologous blood, but also has the added advantage of facilitating emergency operation in these patients. 4 Once bypass is instituted, a special aortic occluding clamp is applied to the ascending aorta just proximal to the origin of the innominate artery and the ascending aorta is transected a few centimeters above the aortic valve. Special catheters for coronary perfusion then are inserted into the orifices of the coronary arteries (Fig. 2, a). The in ner and outer layers of the dissecting process are approximated by a continuous suture both proximally and distally, and the procedure is completed by end-toend anastomosis of the sutured edges of the transected aorta (Fig. 2, b—d). This method of repair is particularly applicable in the early stages of the dissecting process when there is minimal anatomical disruption and distortion of the aorta at the site of intimal laceration. The procedure is designed to restore mural integrity and normal blood flow into the true aortic lumen and by thus obliterating the false lumen to prevent further progression of the dis secting process (Fig. 3). Under some circumstances, usually in the later stages of the disease with more extensive mural disruption, it may be necessary to modify this method of repair by partial or complete excision of this diseased segment of aorta and restoration of vascular continuity by the use of a Dacron patch or tube graft.
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Although the aortic valve leaflets themselves are not diseased in most cases with this type of dissection, aortic insufficiency is not uncommon and usually is produced by some dilatation of the annulus or by lack of support or fixation of the intimal attachment of the valve commissures resulting from proximal dissection. The former factor is more likely to occur in the chronic forms of the disease, whereas the latter is predominant in the acute form and usually is corrected by restoring proper fixation of the aortic leaflet attachments during suture approximation of the inner and outer layers of the dissecting process. TYPE II.—Surgical treatment for these aneurysms consists essentially in resection and graft replacement of the entire ascending aorta using temporary cardiopulmonary bypass (Figs. 4 and 5). As in Type I cases, median sternotomy
Fig. '2.—Drawing which illustrates method of surgical treatment in Type I dissecting aneurysm with the use of cardiopulmonary bypass with coronary perfusion. a, After an occlud ing clamp is applied to the ascending aorta just proximal to innominate artery, the ascending aorta is transected through double-layer aortic wall produced by dissecting process, and special catheters for coronary perfusion are applied to orifices of coronary arteries, b, Inner and outer layers of dissecting process are approximated by continuous suture, both proximally and distally. c, Sutured edges of transected aorta are then approximated by end-to-end anas tomosis. d, After completion of end-to-end anastomosis, the proximal occluding clamp is re leased, permitting restoration of normal circulation.
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Pig-. 3.—Drawing (A) and preoperative aortogram (B) show extensive dissecting aneurysm arising in ascending aorta (Type I) in a 38-year-old white man. C, Drawing shows method of surgical treatment consisting of transection of ascending aorta, approximation of inner and outer layers, and end-to-end anastomosis. D, Aortogram made 1 year after operation shows restoration of normal aortic function.
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is the exposure most often used. After the patient is placed on cardiopulmonary bypass, the aorta is divided between occluding clamps applied just proximal to the innominate artery (Pig. 4, a ) . A woven Dacron graft of suitable size then is attached to the distal cut end of the aorta by end-to-end anastomosis (Fig. 4, b). During this portion of the procedure, relatively normal cardiac function may be maintained by continuing pulmonary ventilation and permitting the heart to perfuse itself with coronary sinus return and bronchial arterial flow. After the distal anastomosis has been completed, the proximal occluding clamp is removed and the outer layer of the aneurysm is incised to expose the aortic annulus. Catheters then are applied to provide coronary perfusion during the remainder of the procedure (Fig. 4, c). The aneurysm is excised, the graft is
Fig. 4.—Drawing which illustrates method of resection and graft replacement with the use of cardiopulmonary bypass in Type II dissecting aneurysm. a, After patient is placed on cardiopulmonary bypass, the ascending aorta is divided between occluding clamps applied Just proximal to innominate artery, b, A woven Dacron graft of suitable size is attached to distal end of aorta by end-to-end anastomosis. During performance of this procedure relatively nor mal cardiac function may be maintained by continuing pulmonary ventilation and thus permit ting heart to perfuse itself, c, Following completion of distal anastomosis of graft, proximal occluding clamp is removed and aneurysm is excised. Coronary perfusion catheters are then applied to provide coronary perfusion during remainder of procedure. Graft is tailored to fit excised segment of ascending aorta and is attached to proximal opening of aorta above aortic valves by end-to-end anastomosis, d, After completion of proximal anastomosis, occluding clamp is removed to permit restoration of normal circulation.
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Fig". 5.—Drawing (A) and preoperative aortogram (B) shown dissecting aneurysm of as cending aorta (Type I I ) . G, Drawing shows method of surgical treatment consisting of resection of entire ascending aorta and replacement with Dacron graft with the use of cardiopulmonary bypass. D, Postoperative aortogram shows restoration of normal aortic continuity and function.
cut to the proper length, and the proximal end-to-end anastomosis is performed. Associated valvular insufficiency more often is encountered in Type II than in the other types and, in most instances, can be corrected as described for Type I. In cases in which there is marked dilatation of the aortic annulus, however, annuloplasty, including bicuspidization, or even actual valve replace ment, may be necessary. Sometimes a Dacron graft can be used for annuloplasty
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permitting circumferential constriction of the annulus through performance of the end-to-end anastomosis of the graft. TYPE III.—The surgical procedure for this form of the disease consists essentially in excision with graft replacement of the segment of descending thoracic aorta in which the dissection arises (Fig. 6). Since the dissecting process in this form of the disease is limited proximally to the level of the origin of the left subclavian artery, the proximal occluding clamp usually can be applied just distal to this artery or to the left common carotid artery. In the latter circumstance it may be desirable to sacrifice the left subclavian artery by ligation or to restore continuity by a graft attached end-to-side to the graft replacement for the aorta. In any case, complete excision of the proximal extent of the dissecting process is possible, permitting the graft to be attached by end-to-end anastomosis to the single true lumen of the proximal cut end of the aorta. In some instances the distal extent of the dissecting process is limited to the descending thoracic aorta, and under these circumstances complete resection
Fig. 6.—a, Drawing which illustrates method of resection and graft replacement in Type III dissecting aneurysm with the use of left atrial to femoral artery pump bypass, b-d, Draw ings show method of resection and Dacron graft replacement in cases in which dissecting pro cess is limited to descending thoracic aorta, e-g, Drawings illustrate method of resection and Dacron graft replacement in cases in which there is some distal extension of dissecting process beyond the diaphragmatic hiatus. Before performing distal anastomosis, false lumen is obliter ated by approximating inner and outer layers of dissecting process.
Pig. 7.—Drawing (A) and preoperative aortogram (B) show dissecting aneurysm (Type III) arising in descending thoracic aorta just distal to origin of left subclavian artery. Dissecting process is limited to descending thoracic aorta. C, Drawing which shows method of treatment con sisting of complete resection of segment of descending thoracic aorta involved in dissecting process with replacement by Dacron graft D, Aorto gram made 5 years after operation shows restoration of normal aortic continuity and function. Patient has remained asymptomatic and normally active.
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„o„,. EW' 8 UTT Drawin f-, (A) anA Preoperative aortogram (B) show dissecting aneurysm (Type III) arising in descending thoracic aorta in a 45year-old white man. C, Drawing which shows method of treatment, consisting of resection of descending thoracic aorta and replacement with fa n pe f , ™ ? , ^ ? r t 0 5 , r a m - i a d e t y e a r s a f t e r ° P e r a t l P n * o w s restoration of normal aortic continuity and function. E, Drawing which shows dissecting " T y IS ot abdominal aorta, occurring approximately 5 years after operation on descending thoracic aorta. F, Drawing-whichshows: method of treatment consisting of resection of dissecting aneurysm of abdominal aorta and replacement with Dacron graft Patient hTs rremTin^dTsvlmDto emalne matic and normally active 7 years after first operation on thoracic aorta and 2 years after operation on abdominal aorta d asympto-
Fig. 9.—Drawing fA> and preoperative aortogram (B) show extensive dissecting aneurysm (Type III) involving entire descending thoracic and upper abdominal aorta in a 14-year-old Negro boy. C, Drawing shows method of surgical treatment consisting of resection of descending thor acic and upper abdominal aorta with bypass Dacron graft replacement. D, Postoperative angio-aortograni shows restoration of aortic function through Dacron graft. Patient has remained well 3 years after operation.
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of the dissecting aneurysm is possible (Fig. 6, b and d, and Fig. 7). More often, however, some distal extension of the dissecting process into the abdominal aorta occurs (Fig. 8). In most cases of this type the circumferential extent of the dissecting process becomes increasingly smaller as the descending thoracic aorta approaches the diaphragmatic hiatus. The false lumen in this lower area can be obliterated by approximating the inner and outer walls with a con tinuous suture before attaching the graft to the distal cut end of the aorta by end-to-end anastomosis (Fig. 6, e—g). During performance of this procedure, left atriofemoral pump bypass is employed to provide adequate circulation distal to the level of aortic occlusion and to prevent serious left ventricular strain by maintenance of blood pressure at near normal levels. In our experience this method has been found far su perior to our earlier use of hypothermia during descending thoracic aortic oc clusion.6 In still other cases of more extensive Type I I I dissecting aneurysms, ex tending well beyond the diaphragmatic hiatus and into the upper segment of the abdominal aorta, another type of procedure may be employed (Fig. 9). This consists essentially in first applying a temporary bypass graft from the thoracic aorta proximal to the dissecting process to the abdominal aorta distal to the dissecting process, following which the entire descending thoracic and upper abdominal aorta involved in the dissecting process is excised. The Dacron bypass graft is now allowed to remain as the permanent graft. ANALYSIS OP RESULTS
The age and sex incidence of this series of patients are similar to those previously recorded 8 (Fig. 10). Males predominated in a ratio of about 5 to 1, and age distribution showed a predominance in the fifth to seventh decades.
0-39
40-49 50-59 60-69 AGE GROUP
70-79
Fig. 10.—Graph which shows age and sex incidences.
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The youngest patient in this series was 14 and the oldest 78 years of age. Ten of the younger patients had definite characteristics of Marfan's disease; the highest incidence was in the Type II form of dissection. A somewhat higher operative mortality rate was seen among females than among males, the respective figures being 31 per cent and 19 per cent. This difference is not readily explained, and, owing to the relatively small propor tion of females in the series, perhaps is not significant. Particularly noteworthy and also not readily explainable is the fact that the operative mortality rate was significantly higher among patients in the younger age groups. Thus, among patients under 50 years of age the operative mortality rate was 29 per cent, whereas among those over 50 years of age it was 18 per cent. To some extent this was due to the fact that a much higher proportion of patients having Type I and Type I I dissecting aneurysms, in which there was a higher operative mortality rate, was found in the younger age groups. But even among the Type I I I dissecting aneurysms there was a higher operative mortality rate in pa tients under 50 years of age than in those over this age, the respective figures being 26 per cent and 17 per cent. 41%
_29_ DEATHS,-..,, 179 CASES U' M
o 2
1954-1957 1958-1960 1961-1964 YEARS Fig. 11.—Graph which shows operative mortality according to periods.
The total operative mortality rate in this series was 21 per cent. However, this figure has decreased steadily during the decade spanned by this surgical experience (Fig. 11). Thus, in the group of 97 patients operated upon since 1961 there were only 12 deaths. This is a reflection not only of technical re finement and improvements in surgical experience, but also of proper appli cation of specific methods of surgical treatment for the different patterns of the disease. As observed previously, 8 ' 9 hypertension and heart disease constitute sig nificant factors in the risk of operation, a fact that was confirmed in the present series. Among 116 patients who were hypertensive the operative mortality rate was 23 per cent, whereas among the remaining normotensive patients it was only 17 per cent. Similarly, among 119 patients with clinical evidence of heart disease the operative mortality rate was 24 per cent, as compared to 17 per cent in the remaining cases with no evidence of heart disease.
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This is reflected further by the fact that the most common cause of early deaths, occurring during or immediately after operation, was heart disease, in the form of congestive failure or myocardial infarction. Indeed, these forms of heart disease accounted for about one third of the total operative mortality (Table I ) . The next most common cause of death, accounting for approximately a fourth of the operative mortality, was progression of the aortic disease or dissecting process. Most of these deaths occurred in our early experience before the development of the proper specific surgical procedures for the appropriate type of dissecting aneurysm. Three of the four deaths from renal insufficiency also occurred in our early experience and prior to the development of left atriofemoral pump bypass. 14 TABLE I. CAUSES OF 38
OPERATIVE D E A T H S I N A U T H O R S '
1
CAUSE OF DEATH
Congestive heart failure or myocardial infarction Progression of aortic disease: External rupture Intrapericardial rupture Progression of dissection (mesenteric occlusion) Cardiac arrest during operation Renal insufficiency Pulmonary insufficiency Cerebral infarction Peritonitis (Perforated stress ulcer) Total deaths (operative)
SERIES NO. CASES
13 10
7 2 1
4 4 3 3 1 38
Among the 20 patients in this series classified as Type I, 6 were treated in accordance with our early experience utilizing the concept of a re-entry pro cedure with obliteration of the distal false lumen in the descending thoracic aorta (Table I I ) . Three patients in this group may be considered long-term survivors; 1 died of coronary thrombosis 5 years after operation, 1 died of complications of paraplegia 3 years after operation, and one is still alive 3 years after operation. Despite the fact that a few of these patients survived several years after the operation, increasing experience and a better under standing of the pathologic features of this form of the disease lead to the con-
TABLE I I . SURGICAL PROCEDURES PERFORMED FOR E A C H T Y P E OF DISSECTING ANEURYSM A U T H O R S ' SERIES, ALONG W I T H OPERATIVE D E A T H S OCCURRING IN E A C H PROCEDURE
TYPE OF ANEURYSM
SURGICAL
PROCEDURE
NO. OF PATIENTS
PER CENT
I
Re-entry descending thoracic aorta Repair ascending aorta
6 14
2 4
33 29
II
Excision and graft
replacement
17
5
29
III
Distal re-entry Excision and graft All procedures
replacement
3 139
1 26
33 19
179
38
21
Totals
IN
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elusion that such a procedure was at best palliative. Although distal progres sion of the dissecting process might be arrested by this procedure, proximal mural integrity was not restored and the process thus could progress with con sequent fatal rupture of the outer wall. This was indeed the cause of death in 1 of these patients. For this reason a more direct surgical approach designed to repair the dissecting process at its origin and achieve complete restoration of normal aortic mural integrity and function was developed. This method, as described above (see Fig. 2), first was applied in 1959 s - 10 and was used in the remaining 14 cases of this group. In 4 of these cases the dissecting process in the ascending aorta had produced sufficient mural destruction to require resection and graft replacement. There were two operative deaths in this group, one from uncon trollable hemorrhage, presumably due to hemorrhagic diathesis of undetermined cause, and the other from heart failure. The two remaining deaths in this series of 14 cases resulted in 1 patient, from complications of a congenital diaphrag matic hernia which required resection of a segment of the ileum and colon on the fourth postoperative day and, in the other patient, from sudden hemothorax. In this group of 20 patients with Type I dissecting aneurysms, 10 were ad mitted to the hospital with an acute onset of the dissecting process while the onset in the remaining 10 patients was of sufficient duration to be classified as chronic. Although the operative mortality rate in the former group was significantly greater than in the latter (Table I I I ) , it should be recognized that the prognosis without operation in this form of the disease is extremely grave, with a fatal termination in the great majority of these patients in a matter of hours or days after onset. More significant, therefore, is the fact that in 60 per cent of these patients the highly lethal natural course of the disease was favorably altered. For this reason we believe that operative intervention is indicated in this form of the disease. All patients with Type II dissecting aneurysm were considered to have the chronic type of disease (Table I I I ) . While in some patients there was a history of an acute episode suggesting the onset several months to several years previous to admission to the hospital, in most of them the onset was so insidious
TABLE I I I . ACUTE AND CHRONIC DISSECTING A N E U R Y S M S IN A U T H O R ' S SERIES, LISTED BY T Y P E , AND NUMBER OF OPERATIVE D E A T H S OCCURRING UNDER E A C H HEADING DEATHS TYPE
NO. CASES
1
PER CENT
10 10
4 2
Chronic
17
5
29
Acute Chronic Acute Chronic All
48 94
9 18 13 25 38
19 19 23 20 21
I
Acute Chronic
II III Totals
NO. CASES
58 121 179
40 20
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that it was not possible to determine the duration of the disease. All of these patients had moderate to severe aortic valve insufficiency. The surgical procedure of excision and graft replacement, as described above (see Fig. 4), was used for all patients in this group. The first of these patients was operated upon in January, 1958, but died of uncontrollable hemor rhage presumably due to hemorrhagic diathesis. The four subsequent opera tive deaths were caused respectively by renal failure, pneumonia and cardiorespiratory failure, heart failure, and rupture of the iliac artery during retro grade perfusion. In all of the patients who survived operation, the associated aortic valve insufficiency was corrected, although this required bicuspidization of the valve in 2 patients. All but 3 of the patients having Type I I I dissecting aneurysms were treated by the method of excision and graft replacement described above (see Pig. 6 and Table I I ) . The progressive improvement in operative mortality in this group is well demonstrated by the fact that among the 48 patients operated upon during the first 5 years of this 10-year series there was an operative mortality rate of 31 per cent, whereas among the 94 operated upon during the last 5 years this figure was only 12 per cent. This is undoubtedly a reflection of increasing experience in the surgical management of these patients, including, particu larly, refinements in operative technique resulting in more expeditious per formance of the operative procedure and the abandonment of hypothermia in favor of left atriofemoral pump bypass. Furthermore, while homografts and many types of synthetic arterial grafts were employed in the early years of this series, Dacron grafts have been used exclusively since 1957.7 This refinement in operative technique has improved results not only in patients with Type I I and Type I I I forms of the disease, but also in the occasional patient with Type I dissection in whom a patch or tubu lar graft was required. Use of these grafts has both simplified operative pro cedures and reduced incidence of operative complications. Particularly noteworthy is the fact that the operative mortality rate was not significantly greater among patients operated upon with an acute dissect ing process than among those with chronic dissections (see Table I I I ) . This fact supports our current conviction that all patients with dissecting aneurysms should be considered for surgical treatment as soon as possible after the onset of the disease. Of special interest also is the fact that 6 patients in this series subsequently had resection of an aneurysm of the abdominal aorta (see Fig. 8). One of these patients died of renal failure. With few exceptions, results in the 141 patients surviving operation have been most gratifying. Follow-up studies, often including angiography (Figs. 3, 5, 7, and 8), have been made on all patients in this series, providing infor mation on their current status. Observations up to 9 years after operation re veal that most of these patients have resumed normal activity. Many are retired but active, while others engage in hard manual activity. One patient under went operation 10 years ago and currently is on an around-the-world cruise. One patient is a semi-invalid, and 2 are paraplegic. The favorable alteration of the generally grave prognosis of dissecting
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aneurysm by operation is well illustrated by a comparison of the long-term survival rates of our operative series with those of a nonoperative series of 425 cases reported by Hirst 11 (Pig. 12). Thus, in striking contrast to the fact that only 7 per cent of the nonoperative cases were alive 1 year after diagnosis, 70 per cent of our operative cases were alive at the end of this period (Fig. 12). Even more impressive is the fact that at the end of 5 years 50 per cent of our operative cases were still alive while less than 1 per cent of the nonoperative cases had survived this long (Fig. 12). The fact, too, that the operative mor tality has been progressively reduced in recent years to approximately a third of the earlier figure will be reflected in a further improvement in these longterm survival rates. These results thus provide good evidence in support of the concept of surgical intervention for this grave disease. 100-5
179 OPERATIVE CASES (Authors' series)
80-
60
> DC
40Z UJ
o LJ O-
425 NON-OPERATIVE CASES (After Hirst)
20
10-
5i
N
ONE MO. I
17%
^ ^ ^ . ^ r f »
AFTER ONSET PERIOD OF SURVIVAL YEARS
Fig. 12.-—Graph which shows survival rates in authors' series of surgically treated dissecting aneurysm of aorta and in nonoperative cases, as reported by Hirst."
SUMMARY
1. Experience with surgical management of 179 patients with dissecting aneurysms of the aorta during the past decade has allowed development of certain conceptual changes and new methods of operative treatment based on a better understanding of the anatomic and pathologic patterns of the disease. On the basis of these conceptual developments, dissecting aneurysms may be classified into three basic types: Type I, in which the dissecting process along with its intimal tear arises in the ascending aorta and not infrequently extends into its major terminal branches; Type II, in which the dissecting process is limited to the ascending aorta; and Type III, in which the dissecting process arises in the descending thoracic aorta, usually at or just distal to the origin
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of the left subclavian artery, and extends distally for a varying distance. Not infrequently, the first two types of dissection are associated with aortic valve regurgitation, due either to annular dilatation or to loss of support for the valve commissural attachments. 2. Also based upon these conceptual developments, specific and definitive surgical approaches have evolved for each type of dissecting process. Type I dissections are managed by transection of the ascending aorta with the use of temporary cardiopulmonary bypass and obliteration of the false lumen by approximation of the inner and outer walls of the dissecting process by con tinuous suture both proximally and distally, followed by end-to-end anasto mosis of the transected aorta. Surgical treatment of Type II dissections consists essentially in resection and graft replacement of the entire ascending aorta using cardiopulmonary bypass. When present in these two types of dissection, aortic valve regurgitation is corrected concomitantly by annuloplasty, including annular constriction, bicuspidization or resupport of the valve, or by prosthetic replacement of the valve. Type I I I dissections are managed by excision with graft replacement of the segment of descending thoracic aorta in which the dissection arises, using pump bypass from the left atrium to the femoral artery. 3. These procedures have been found applicable to both acute and chronic forms of the disease, and results have been increasingly gratifying in altering the generally grave prognosis of these patients. This is reflected by the fact that the operative mortality has been steadily reduced from 41 per cent in the first 4 years of this surgical experience to only 12 per cent in a series of 97 patients operated upon during the last 4 years. This is further reflected in the long-term survival rates based upon follow-up observations on all patients in the series extending up to 10 years. Thus, the 5-year survival rate of 50 per cent in this surgically treated series of patients, most of whom have resumed normal activities, is in sharp contrast to the less than 1 per cent figure previ ously reported for nonoperative cases. On the basis of this experience, surgical intervention is now considered the treatment of choice in all instances, and emergency operation is often indicated. REFERENCES
1. Bahnson, H. T., and Spencer, F . C.: Excision of Aneurysm of Ascending Aorta With Pros thetic Replacement During Cardiopulmonary Bypass, Ann. Surg. 151: 879, 1960. 2. Beckwith, J . R., Muller, W. H., Warren, W. S., and Wood, J . E . : Acute Dissecting Aneurysm of the Aorta, Arch. Int. Med. 104: 217, 1959. 3. Burchell, H. B . : Aortic Dissection (Dissecting Hematoma; Dissecting Aneurysm of the A o r t a ) , Circulation 12: 1068, 1955. i. Cooley, D. A., Beall, A. C , Jr., and Grondin, P . : Open Heart Operations Using Disposable Oxygenators, 5 Per Cent Dextrose Prime and Normothermia, Surgery 52: 713, 1962. 5. De Bakey, M. E., Cooley, D. A., and Creech, O., J r . : Surgical Considerations of Dis secting Aneurysm of the Aorta, Ann. Surg. 142: 586, 1955. 6. De Bakey, M. E., Cooley, D. A., Crawford, E. S., and Morris, G. C , J r . : Aneurysms of the Thoracic Aorta: Analysis of 179 Patients Treated by Resection, J . THORACIC SURG. 36: 393,
1958.
7. De Bakey, M. E., Cooley, D. A., Crawford, E. S., and Morris, G. C , J r . : The Clinical Application of a New Flexible Knitted Dacron Arterial Substitute, Am. Surgeon 24: 862, 1958. 8. De Bakey, M. E., Henly, W. S., Cooley, D. A., Crawford, E. S., and Morris, G. C , J r . : Surgical Treatment of Dissecting Aneurysm of the A o r t a : Analysis of 72 Cases, Circulation 24: 290, 1961.
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9. De Bakey, M. E., Henly, W. S., Cooley, D. A., Crawford, E . S., Morris, G. C , Jr., and Beall, A. C , J r . : Aneurysms of tlie Aortic Arch: Factors Influencing Operative Risk, S. Clin. North America 42: 1543, 1962. 10. De Bakey, M. E., Henly, W. S., Cooley, D. A., Morris, G. C , J r . , Crawford, E. S., and Beall, A. C , J r . : Surgical Management of Dissecting Aneurysm Involving the Ascending Aorta, J . Cardiovas. Surg. 5: 200, 1964. 11. Hirst, A. E., Jr., Johns, V. J., Jr., and Kime, 8. W., J r . : Dissecting Aneurysms of the A o r t a : A Review of 505 Cases, Medicine 37: 217, 1958. 12. Hufnagel, C. A., and Conrad, P . W.: Dissecting Aneurysms of Ascending Aorta: Direct Approach Repair, Surgery 5 1 : 84, 1962. 13. Hume, D. M., and Porter, R. R.: Acute Dissecting Aortic Aneurysms, Surgery 5 3 : 122, 1963. 14. Morris, G. C , Jr., Witt, R. R., Cooley, D. A., Moyer, J . H., and De Bakey, M. E . : Al terations in Renal Hemodynamics During Controlled Extracorporeal Circulation in the Surgical Treatment of Aortic Aneurysm, J . THORACIC SUKG. 34: 590, 1957. 15. Morris, G. C , Jr., Henly, W. S., and De Bakey, M. E . : Correction of Acute Dissecting Aneurysm of Aorta With Valvular Insufficiency, J . A. M. A. 184: 63, 1963. 16. Muller, W. H., J r . , Damman, F . J., J r . , and Warren, W. D . : Surgical Correction of Car diovascular Deformities in M a r f a n ' s Syndrome, Ann. Surg. 152: 506, 1960. 17. Shennan, T . : Dissecting Aneurysms (Med. Res. Council, Spec. Rep. Series No. 193), London, H. M. S. O., 1934. 18. Spencer, F . C , and Blake, H . : Report of Successful Surgical Treatment of Aortic Regurgitation From Dissecting Aortic Aneurysm in Patient With Marfan Syndrome, J . THORACIC & CARDIOVAS. SURG. 44:
238,
1962.
DISCUSSION DR. P E T E R J . FERRATO, Lorain, Ohio.—I would like to present some interesting roentgenographic findings of a patient with a dissecting aneurysm. This is a 59-year-old white woman, a known hypertensive, who was admitted to a small hospital in Oberlin, Ohio, with a 2 day history of back pain and dyspnea. I first saw her 2 days later because of per sistence of severe upper back pain. The pulse was 86 and blood pressure 110/80, but she did not appear to be in distress. [Slide] The posteroanterior chest film shows slight prominence of the aortic knob and slight cardiac enlargement. The peripheral pulses were excellent. However, because of the persistence of back pain, I submitted her to angiocardiography. [Slide] This is the first film taken 5 seconds after I had injected the dye. The aorta is not yet filled. [Slide] The aorta is now beginning to fill, and dye is seen outside its lumen. [Slide] The aorta is now well filled, and dye can be seen on both sides outside the lu men. The arrows show the probable points of dissection and re-entry. [Slide] Dye still flows in the aorta and in the plane of dissection 12 seconds after injection. [Slide] Dye is beginning to fade from the anterior surface of the aorta. [Slide] Seventeen seconds after injection, there is no dye in or out of the aortic lumen, indicating that there was free flow of blood in the dissecting plane of the aorta. Except for recognizing the aneurysm, I had not interpreted these films correctly, and therefore transferred her to the pump-oxygenator team a t Cleveland Metropolitan General Hospital. There, she would have been operated upon had not their radiologist interpreted the films as above presented. She is now doing well 2 % months later, with no widening of the mediastinal shadow. I had wanted to ask Dr. De Bakey if he would agree with this method of management, or whether he would have operated upon her immediately; but after having heard his paper, I feel quite certain he would have operated upon her then, and now also. DR. ROBERT E . GROSS, Boston, Mass.—Dr. De Bakey, have you had any spinal cord problems after extensive removal of the intercostal arteries?
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DR. DE B A K E Y (Closing).—In answer to Dr. F e r r a t o ' s question about the patient, I would have operated upon the patient if I were convinced the patient had a dissecting aneurysm; and on the basis of the films seen, I am so convinced. In answer to your question, Dr. Gross, we have. Our experience with neurologic disturbances, particularly spinal cord disturbances, following resection of the descending thoracic aorta leaves us completely puzzled as to the basic reasons why they occur. I n our experience with both dissecting aneurysms and other forms of aneurysms involving the descending thoracic aorta, there have been somewhere in the neighborhood of 2 per cent of patients developing disturbances of the spinal cord. Fortunately not all of these have been permanent, but they have occurred, and we are unable to correlate them with the degree of resection. As a matter of fact, in a great majority of patients in whom there has been extensive resection of the entire descending thoracic aorta, there have been no disturbances of any kind. Indeed, the disturbances have occurred in patients in whom only a small amount of descending thoracic aorta has been resected. Why that is, I don't know; but I am inclined to believe it is related to the anatomic nature of the circulation to the spinal eord in the individual cases.
M.D.,
and
Texas
D
aneurysm has long been recognized as an ominous and highly lethal form of aortic disease, for which no effective therapy was avail able until about a decade ago. 3 ' 5 ' " ' 1 T More recently an increasing number of reports have appeared indicating that the natural course of the disease can be altered favorably by surgical treatment. 1 ' 2 ' 6 ' 8 ' 10> 12> 13 > 15 ' 16 ' 18 During the past decade, since our first successful operation for a dissecting aneurysm of the aorta, we have employed some form of surgical treatment in 179 patients with either acute or chronic types of the disease. As a consequence of this experience, a much better understanding of the anatomic and pathologic patterns of the disease has been obtained, leading to the development of specific and more effective methods of surgical treatment. Accordingly, this report is concerned with certain significant observations derived from an analysis of our expe rience, with particular reference to the specific methods of surgical treatment for each of the different patterns of the disease and the immediate and longterm results. In our early experience, two methods of surgical treatment were developed, and their application depended upon the location and extent of the dissecting process.5 The first method was employed for dissections which arose in the ascending aorta and extended for a varying distance into or beyond the descend ing thoracic aorta. This method consisted essentially in the creation of a re entry passage from the false to the true aortic lumen and was accomplished by dividing the descending thoracic aorta between occluding clamps, obliterat ing the false passage below by approximating the outer and inner layers, ex cising a small segment from the inner wall above to permit re-entry into the true lumen, and completing the procedure by end-to-end anastomosis. The second method was applied to dissections arising in the descending thoracic aorta and consisted essentially in excising this segment of the aorta, obliterating the false ISSECTING
From the Cora and Webb Mading Departments of Surgery, Baylor University College of Medicine, and the Methodist, St. Luke's Episcopal, Jefferson Davis, and Ben Taub General Hospitals, Houston, Texas. Supported in part by the U. S. Public Health Service (HE-03137) and (HE-05435). Presented a t the Forty-fourth Annual Meeting of the American Association for Thoracic Surgery, Montreal, Canada, April 29, 1964. 130
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lumen in the distal end by suture approximation of the inner and outer layers, and replacing the excised segment with a graft. Although the latter method proved to be satisfactory in achieving its ob jective of eliminating the origin and progression of the dissecting process, it soon became apparent that the first method was unsatisfactory in these terms. Indeed, it was based upon the concept of palliation rather than actual restora tion of normal aortic mural integrity and function and for this reason was abandoned subsequently. With increasing experience and a better understand ing of the anatomic and pathologic patterns of the disease, certain conceptual changes have evolved and have provided more effective methods of surgical treatment for the different forms of the disease. 8 - 10 ' 15 SURGICAL CLASSIFICATION OF DISSECTING ANEURYSM
Considerable variations in the anatomic and pathologic features of dis secting aneurysm have been found and described and various classifications have been proposed to designate them. 11 ' 17 On the basis of our experience and from the standpoint of surgical treatment, most, if not all, of the different patterns of the disease may be classified into three basic types 10 (Fig. 1) : TYPE I.—This pattern of the disease is characterized by the fact that the dissecting process, along with the intimal tear, arises in the ascending aorta and extends distally for a variable distance, but usually throughout the re maining aorta and not infrequently into its major terminal branches (Fig. 1). The dissecting process also varies in the extent of circumferential involvement but is usually incomplete. Aortic valve insufficiency is frequently present. TYPE II.—This form of the disease is characterized by the fact that the dissecting process is limited to the ascending aorta. There is usually a trans-
Fig. 1.—Drawing which illustrates surgical classification of dissecting aneurysm of aorta into three basic types in accordance with origin and extent of dissecting process.
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verse tear in the intima beginning just above the aortic valve, with separation of the intramural layers that terminates just proximal to the origin of the innominate artery (Fig. 1). It also is characterized by a relatively thin outer layer that usually assumes the appearance of a fusiform aneurysm and often is associated with incompetence of the aortic valve. This type is .more likely to be found in patients with certain stigmata of Marfan's disease. TYPE III.—This form of the disease is characterized by the fact that the dissecting process arises in the descending thoracic aorta usually at or just distal to the origin of the left subclavian artery and extends distally for a varying distance. In some instances the dissecting process is limited to the descending thoracic aorta (Fig. 1). Circumferentially there is also variation in the extent of the dissecting process, but it is usually incomplete. In most cases, however, progressive dilatation of the outer, layer and consequent enlargement of the false lumen with ultimate rupture is limited to the descending thoracic aorta. SURGICAL METHODS OF T R E A T M E N T
TYPE I.—Because of the tendency for this form of the disease to progress rapidly toward a fatal termination, surgical treatment should be applied as soon as possible after onset. The procedure consists essentially in transection of the ascending aorta with the use of temporary cardiopulmonary bypass and obliteration of the false lumen by approximation of the inner and outer walls of the dissecting process by means of a continuous suture both proximally and distally, followed by end-to-end anastomosis of the transected aorta (Fig. 2). Median sternotomy has been found to provide excellent exposure for this pur pose. The use of 5 per cent dextrose in distilled water for priming disposable plastic oxygenators not only prevents complications associated with the use of a pool of homologous blood, but also has the added advantage of facilitating emergency operation in these patients. 4 Once bypass is instituted, a special aortic occluding clamp is applied to the ascending aorta just proximal to the origin of the innominate artery and the ascending aorta is transected a few centimeters above the aortic valve. Special catheters for coronary perfusion then are inserted into the orifices of the coronary arteries (Fig. 2, a). The in ner and outer layers of the dissecting process are approximated by a continuous suture both proximally and distally, and the procedure is completed by end-toend anastomosis of the sutured edges of the transected aorta (Fig. 2, b—d). This method of repair is particularly applicable in the early stages of the dissecting process when there is minimal anatomical disruption and distortion of the aorta at the site of intimal laceration. The procedure is designed to restore mural integrity and normal blood flow into the true aortic lumen and by thus obliterating the false lumen to prevent further progression of the dis secting process (Fig. 3). Under some circumstances, usually in the later stages of the disease with more extensive mural disruption, it may be necessary to modify this method of repair by partial or complete excision of this diseased segment of aorta and restoration of vascular continuity by the use of a Dacron patch or tube graft.
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Although the aortic valve leaflets themselves are not diseased in most cases with this type of dissection, aortic insufficiency is not uncommon and usually is produced by some dilatation of the annulus or by lack of support or fixation of the intimal attachment of the valve commissures resulting from proximal dissection. The former factor is more likely to occur in the chronic forms of the disease, whereas the latter is predominant in the acute form and usually is corrected by restoring proper fixation of the aortic leaflet attachments during suture approximation of the inner and outer layers of the dissecting process. TYPE II.—Surgical treatment for these aneurysms consists essentially in resection and graft replacement of the entire ascending aorta using temporary cardiopulmonary bypass (Figs. 4 and 5). As in Type I cases, median sternotomy
Fig. '2.—Drawing which illustrates method of surgical treatment in Type I dissecting aneurysm with the use of cardiopulmonary bypass with coronary perfusion. a, After an occlud ing clamp is applied to the ascending aorta just proximal to innominate artery, the ascending aorta is transected through double-layer aortic wall produced by dissecting process, and special catheters for coronary perfusion are applied to orifices of coronary arteries, b, Inner and outer layers of dissecting process are approximated by continuous suture, both proximally and distally. c, Sutured edges of transected aorta are then approximated by end-to-end anas tomosis. d, After completion of end-to-end anastomosis, the proximal occluding clamp is re leased, permitting restoration of normal circulation.
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Pig-. 3.—Drawing (A) and preoperative aortogram (B) show extensive dissecting aneurysm arising in ascending aorta (Type I) in a 38-year-old white man. C, Drawing shows method of surgical treatment consisting of transection of ascending aorta, approximation of inner and outer layers, and end-to-end anastomosis. D, Aortogram made 1 year after operation shows restoration of normal aortic function.
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is the exposure most often used. After the patient is placed on cardiopulmonary bypass, the aorta is divided between occluding clamps applied just proximal to the innominate artery (Pig. 4, a ) . A woven Dacron graft of suitable size then is attached to the distal cut end of the aorta by end-to-end anastomosis (Fig. 4, b). During this portion of the procedure, relatively normal cardiac function may be maintained by continuing pulmonary ventilation and permitting the heart to perfuse itself with coronary sinus return and bronchial arterial flow. After the distal anastomosis has been completed, the proximal occluding clamp is removed and the outer layer of the aneurysm is incised to expose the aortic annulus. Catheters then are applied to provide coronary perfusion during the remainder of the procedure (Fig. 4, c). The aneurysm is excised, the graft is
Fig. 4.—Drawing which illustrates method of resection and graft replacement with the use of cardiopulmonary bypass in Type II dissecting aneurysm. a, After patient is placed on cardiopulmonary bypass, the ascending aorta is divided between occluding clamps applied Just proximal to innominate artery, b, A woven Dacron graft of suitable size is attached to distal end of aorta by end-to-end anastomosis. During performance of this procedure relatively nor mal cardiac function may be maintained by continuing pulmonary ventilation and thus permit ting heart to perfuse itself, c, Following completion of distal anastomosis of graft, proximal occluding clamp is removed and aneurysm is excised. Coronary perfusion catheters are then applied to provide coronary perfusion during remainder of procedure. Graft is tailored to fit excised segment of ascending aorta and is attached to proximal opening of aorta above aortic valves by end-to-end anastomosis, d, After completion of proximal anastomosis, occluding clamp is removed to permit restoration of normal circulation.
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Fig". 5.—Drawing (A) and preoperative aortogram (B) shown dissecting aneurysm of as cending aorta (Type I I ) . G, Drawing shows method of surgical treatment consisting of resection of entire ascending aorta and replacement with Dacron graft with the use of cardiopulmonary bypass. D, Postoperative aortogram shows restoration of normal aortic continuity and function.
cut to the proper length, and the proximal end-to-end anastomosis is performed. Associated valvular insufficiency more often is encountered in Type II than in the other types and, in most instances, can be corrected as described for Type I. In cases in which there is marked dilatation of the aortic annulus, however, annuloplasty, including bicuspidization, or even actual valve replace ment, may be necessary. Sometimes a Dacron graft can be used for annuloplasty
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permitting circumferential constriction of the annulus through performance of the end-to-end anastomosis of the graft. TYPE III.—The surgical procedure for this form of the disease consists essentially in excision with graft replacement of the segment of descending thoracic aorta in which the dissection arises (Fig. 6). Since the dissecting process in this form of the disease is limited proximally to the level of the origin of the left subclavian artery, the proximal occluding clamp usually can be applied just distal to this artery or to the left common carotid artery. In the latter circumstance it may be desirable to sacrifice the left subclavian artery by ligation or to restore continuity by a graft attached end-to-side to the graft replacement for the aorta. In any case, complete excision of the proximal extent of the dissecting process is possible, permitting the graft to be attached by end-to-end anastomosis to the single true lumen of the proximal cut end of the aorta. In some instances the distal extent of the dissecting process is limited to the descending thoracic aorta, and under these circumstances complete resection
Fig. 6.—a, Drawing which illustrates method of resection and graft replacement in Type III dissecting aneurysm with the use of left atrial to femoral artery pump bypass, b-d, Draw ings show method of resection and Dacron graft replacement in cases in which dissecting pro cess is limited to descending thoracic aorta, e-g, Drawings illustrate method of resection and Dacron graft replacement in cases in which there is some distal extension of dissecting process beyond the diaphragmatic hiatus. Before performing distal anastomosis, false lumen is obliter ated by approximating inner and outer layers of dissecting process.
Pig. 7.—Drawing (A) and preoperative aortogram (B) show dissecting aneurysm (Type III) arising in descending thoracic aorta just distal to origin of left subclavian artery. Dissecting process is limited to descending thoracic aorta. C, Drawing which shows method of treatment con sisting of complete resection of segment of descending thoracic aorta involved in dissecting process with replacement by Dacron graft D, Aorto gram made 5 years after operation shows restoration of normal aortic continuity and function. Patient has remained asymptomatic and normally active.
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„o„,. EW' 8 UTT Drawin f-, (A) anA Preoperative aortogram (B) show dissecting aneurysm (Type III) arising in descending thoracic aorta in a 45year-old white man. C, Drawing which shows method of treatment, consisting of resection of descending thoracic aorta and replacement with fa n pe f , ™ ? , ^ ? r t 0 5 , r a m - i a d e t y e a r s a f t e r ° P e r a t l P n * o w s restoration of normal aortic continuity and function. E, Drawing which shows dissecting " T y IS ot abdominal aorta, occurring approximately 5 years after operation on descending thoracic aorta. F, Drawing-whichshows: method of treatment consisting of resection of dissecting aneurysm of abdominal aorta and replacement with Dacron graft Patient hTs rremTin^dTsvlmDto emalne matic and normally active 7 years after first operation on thoracic aorta and 2 years after operation on abdominal aorta d asympto-
Fig. 9.—Drawing fA> and preoperative aortogram (B) show extensive dissecting aneurysm (Type III) involving entire descending thoracic and upper abdominal aorta in a 14-year-old Negro boy. C, Drawing shows method of surgical treatment consisting of resection of descending thor acic and upper abdominal aorta with bypass Dacron graft replacement. D, Postoperative angio-aortograni shows restoration of aortic function through Dacron graft. Patient has remained well 3 years after operation.
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of the dissecting aneurysm is possible (Fig. 6, b and d, and Fig. 7). More often, however, some distal extension of the dissecting process into the abdominal aorta occurs (Fig. 8). In most cases of this type the circumferential extent of the dissecting process becomes increasingly smaller as the descending thoracic aorta approaches the diaphragmatic hiatus. The false lumen in this lower area can be obliterated by approximating the inner and outer walls with a con tinuous suture before attaching the graft to the distal cut end of the aorta by end-to-end anastomosis (Fig. 6, e—g). During performance of this procedure, left atriofemoral pump bypass is employed to provide adequate circulation distal to the level of aortic occlusion and to prevent serious left ventricular strain by maintenance of blood pressure at near normal levels. In our experience this method has been found far su perior to our earlier use of hypothermia during descending thoracic aortic oc clusion.6 In still other cases of more extensive Type I I I dissecting aneurysms, ex tending well beyond the diaphragmatic hiatus and into the upper segment of the abdominal aorta, another type of procedure may be employed (Fig. 9). This consists essentially in first applying a temporary bypass graft from the thoracic aorta proximal to the dissecting process to the abdominal aorta distal to the dissecting process, following which the entire descending thoracic and upper abdominal aorta involved in the dissecting process is excised. The Dacron bypass graft is now allowed to remain as the permanent graft. ANALYSIS OP RESULTS
The age and sex incidence of this series of patients are similar to those previously recorded 8 (Fig. 10). Males predominated in a ratio of about 5 to 1, and age distribution showed a predominance in the fifth to seventh decades.
0-39
40-49 50-59 60-69 AGE GROUP
70-79
Fig. 10.—Graph which shows age and sex incidences.
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The youngest patient in this series was 14 and the oldest 78 years of age. Ten of the younger patients had definite characteristics of Marfan's disease; the highest incidence was in the Type II form of dissection. A somewhat higher operative mortality rate was seen among females than among males, the respective figures being 31 per cent and 19 per cent. This difference is not readily explained, and, owing to the relatively small propor tion of females in the series, perhaps is not significant. Particularly noteworthy and also not readily explainable is the fact that the operative mortality rate was significantly higher among patients in the younger age groups. Thus, among patients under 50 years of age the operative mortality rate was 29 per cent, whereas among those over 50 years of age it was 18 per cent. To some extent this was due to the fact that a much higher proportion of patients having Type I and Type I I dissecting aneurysms, in which there was a higher operative mortality rate, was found in the younger age groups. But even among the Type I I I dissecting aneurysms there was a higher operative mortality rate in pa tients under 50 years of age than in those over this age, the respective figures being 26 per cent and 17 per cent. 41%
_29_ DEATHS,-..,, 179 CASES U' M
o 2
1954-1957 1958-1960 1961-1964 YEARS Fig. 11.—Graph which shows operative mortality according to periods.
The total operative mortality rate in this series was 21 per cent. However, this figure has decreased steadily during the decade spanned by this surgical experience (Fig. 11). Thus, in the group of 97 patients operated upon since 1961 there were only 12 deaths. This is a reflection not only of technical re finement and improvements in surgical experience, but also of proper appli cation of specific methods of surgical treatment for the different patterns of the disease. As observed previously, 8 ' 9 hypertension and heart disease constitute sig nificant factors in the risk of operation, a fact that was confirmed in the present series. Among 116 patients who were hypertensive the operative mortality rate was 23 per cent, whereas among the remaining normotensive patients it was only 17 per cent. Similarly, among 119 patients with clinical evidence of heart disease the operative mortality rate was 24 per cent, as compared to 17 per cent in the remaining cases with no evidence of heart disease.
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This is reflected further by the fact that the most common cause of early deaths, occurring during or immediately after operation, was heart disease, in the form of congestive failure or myocardial infarction. Indeed, these forms of heart disease accounted for about one third of the total operative mortality (Table I ) . The next most common cause of death, accounting for approximately a fourth of the operative mortality, was progression of the aortic disease or dissecting process. Most of these deaths occurred in our early experience before the development of the proper specific surgical procedures for the appropriate type of dissecting aneurysm. Three of the four deaths from renal insufficiency also occurred in our early experience and prior to the development of left atriofemoral pump bypass. 14 TABLE I. CAUSES OF 38
OPERATIVE D E A T H S I N A U T H O R S '
1
CAUSE OF DEATH
Congestive heart failure or myocardial infarction Progression of aortic disease: External rupture Intrapericardial rupture Progression of dissection (mesenteric occlusion) Cardiac arrest during operation Renal insufficiency Pulmonary insufficiency Cerebral infarction Peritonitis (Perforated stress ulcer) Total deaths (operative)
SERIES NO. CASES
13 10
7 2 1
4 4 3 3 1 38
Among the 20 patients in this series classified as Type I, 6 were treated in accordance with our early experience utilizing the concept of a re-entry pro cedure with obliteration of the distal false lumen in the descending thoracic aorta (Table I I ) . Three patients in this group may be considered long-term survivors; 1 died of coronary thrombosis 5 years after operation, 1 died of complications of paraplegia 3 years after operation, and one is still alive 3 years after operation. Despite the fact that a few of these patients survived several years after the operation, increasing experience and a better under standing of the pathologic features of this form of the disease lead to the con-
TABLE I I . SURGICAL PROCEDURES PERFORMED FOR E A C H T Y P E OF DISSECTING ANEURYSM A U T H O R S ' SERIES, ALONG W I T H OPERATIVE D E A T H S OCCURRING IN E A C H PROCEDURE
TYPE OF ANEURYSM
SURGICAL
PROCEDURE
NO. OF PATIENTS
PER CENT
I
Re-entry descending thoracic aorta Repair ascending aorta
6 14
2 4
33 29
II
Excision and graft
replacement
17
5
29
III
Distal re-entry Excision and graft All procedures
replacement
3 139
1 26
33 19
179
38
21
Totals
IN
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elusion that such a procedure was at best palliative. Although distal progres sion of the dissecting process might be arrested by this procedure, proximal mural integrity was not restored and the process thus could progress with con sequent fatal rupture of the outer wall. This was indeed the cause of death in 1 of these patients. For this reason a more direct surgical approach designed to repair the dissecting process at its origin and achieve complete restoration of normal aortic mural integrity and function was developed. This method, as described above (see Fig. 2), first was applied in 1959 s - 10 and was used in the remaining 14 cases of this group. In 4 of these cases the dissecting process in the ascending aorta had produced sufficient mural destruction to require resection and graft replacement. There were two operative deaths in this group, one from uncon trollable hemorrhage, presumably due to hemorrhagic diathesis of undetermined cause, and the other from heart failure. The two remaining deaths in this series of 14 cases resulted in 1 patient, from complications of a congenital diaphrag matic hernia which required resection of a segment of the ileum and colon on the fourth postoperative day and, in the other patient, from sudden hemothorax. In this group of 20 patients with Type I dissecting aneurysms, 10 were ad mitted to the hospital with an acute onset of the dissecting process while the onset in the remaining 10 patients was of sufficient duration to be classified as chronic. Although the operative mortality rate in the former group was significantly greater than in the latter (Table I I I ) , it should be recognized that the prognosis without operation in this form of the disease is extremely grave, with a fatal termination in the great majority of these patients in a matter of hours or days after onset. More significant, therefore, is the fact that in 60 per cent of these patients the highly lethal natural course of the disease was favorably altered. For this reason we believe that operative intervention is indicated in this form of the disease. All patients with Type II dissecting aneurysm were considered to have the chronic type of disease (Table I I I ) . While in some patients there was a history of an acute episode suggesting the onset several months to several years previous to admission to the hospital, in most of them the onset was so insidious
TABLE I I I . ACUTE AND CHRONIC DISSECTING A N E U R Y S M S IN A U T H O R ' S SERIES, LISTED BY T Y P E , AND NUMBER OF OPERATIVE D E A T H S OCCURRING UNDER E A C H HEADING DEATHS TYPE
NO. CASES
1
PER CENT
10 10
4 2
Chronic
17
5
29
Acute Chronic Acute Chronic All
48 94
9 18 13 25 38
19 19 23 20 21
I
Acute Chronic
II III Totals
NO. CASES
58 121 179
40 20
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that it was not possible to determine the duration of the disease. All of these patients had moderate to severe aortic valve insufficiency. The surgical procedure of excision and graft replacement, as described above (see Fig. 4), was used for all patients in this group. The first of these patients was operated upon in January, 1958, but died of uncontrollable hemor rhage presumably due to hemorrhagic diathesis. The four subsequent opera tive deaths were caused respectively by renal failure, pneumonia and cardiorespiratory failure, heart failure, and rupture of the iliac artery during retro grade perfusion. In all of the patients who survived operation, the associated aortic valve insufficiency was corrected, although this required bicuspidization of the valve in 2 patients. All but 3 of the patients having Type I I I dissecting aneurysms were treated by the method of excision and graft replacement described above (see Pig. 6 and Table I I ) . The progressive improvement in operative mortality in this group is well demonstrated by the fact that among the 48 patients operated upon during the first 5 years of this 10-year series there was an operative mortality rate of 31 per cent, whereas among the 94 operated upon during the last 5 years this figure was only 12 per cent. This is undoubtedly a reflection of increasing experience in the surgical management of these patients, including, particu larly, refinements in operative technique resulting in more expeditious per formance of the operative procedure and the abandonment of hypothermia in favor of left atriofemoral pump bypass. Furthermore, while homografts and many types of synthetic arterial grafts were employed in the early years of this series, Dacron grafts have been used exclusively since 1957.7 This refinement in operative technique has improved results not only in patients with Type I I and Type I I I forms of the disease, but also in the occasional patient with Type I dissection in whom a patch or tubu lar graft was required. Use of these grafts has both simplified operative pro cedures and reduced incidence of operative complications. Particularly noteworthy is the fact that the operative mortality rate was not significantly greater among patients operated upon with an acute dissect ing process than among those with chronic dissections (see Table I I I ) . This fact supports our current conviction that all patients with dissecting aneurysms should be considered for surgical treatment as soon as possible after the onset of the disease. Of special interest also is the fact that 6 patients in this series subsequently had resection of an aneurysm of the abdominal aorta (see Fig. 8). One of these patients died of renal failure. With few exceptions, results in the 141 patients surviving operation have been most gratifying. Follow-up studies, often including angiography (Figs. 3, 5, 7, and 8), have been made on all patients in this series, providing infor mation on their current status. Observations up to 9 years after operation re veal that most of these patients have resumed normal activity. Many are retired but active, while others engage in hard manual activity. One patient under went operation 10 years ago and currently is on an around-the-world cruise. One patient is a semi-invalid, and 2 are paraplegic. The favorable alteration of the generally grave prognosis of dissecting
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aneurysm by operation is well illustrated by a comparison of the long-term survival rates of our operative series with those of a nonoperative series of 425 cases reported by Hirst 11 (Pig. 12). Thus, in striking contrast to the fact that only 7 per cent of the nonoperative cases were alive 1 year after diagnosis, 70 per cent of our operative cases were alive at the end of this period (Fig. 12). Even more impressive is the fact that at the end of 5 years 50 per cent of our operative cases were still alive while less than 1 per cent of the nonoperative cases had survived this long (Fig. 12). The fact, too, that the operative mor tality has been progressively reduced in recent years to approximately a third of the earlier figure will be reflected in a further improvement in these longterm survival rates. These results thus provide good evidence in support of the concept of surgical intervention for this grave disease. 100-5
179 OPERATIVE CASES (Authors' series)
80-
60
> DC
40Z UJ
o LJ O-
425 NON-OPERATIVE CASES (After Hirst)
20
10-
5i
N
ONE MO. I
17%
^ ^ ^ . ^ r f »
AFTER ONSET PERIOD OF SURVIVAL YEARS
Fig. 12.-—Graph which shows survival rates in authors' series of surgically treated dissecting aneurysm of aorta and in nonoperative cases, as reported by Hirst."
SUMMARY
1. Experience with surgical management of 179 patients with dissecting aneurysms of the aorta during the past decade has allowed development of certain conceptual changes and new methods of operative treatment based on a better understanding of the anatomic and pathologic patterns of the disease. On the basis of these conceptual developments, dissecting aneurysms may be classified into three basic types: Type I, in which the dissecting process along with its intimal tear arises in the ascending aorta and not infrequently extends into its major terminal branches; Type II, in which the dissecting process is limited to the ascending aorta; and Type III, in which the dissecting process arises in the descending thoracic aorta, usually at or just distal to the origin
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of the left subclavian artery, and extends distally for a varying distance. Not infrequently, the first two types of dissection are associated with aortic valve regurgitation, due either to annular dilatation or to loss of support for the valve commissural attachments. 2. Also based upon these conceptual developments, specific and definitive surgical approaches have evolved for each type of dissecting process. Type I dissections are managed by transection of the ascending aorta with the use of temporary cardiopulmonary bypass and obliteration of the false lumen by approximation of the inner and outer walls of the dissecting process by con tinuous suture both proximally and distally, followed by end-to-end anasto mosis of the transected aorta. Surgical treatment of Type II dissections consists essentially in resection and graft replacement of the entire ascending aorta using cardiopulmonary bypass. When present in these two types of dissection, aortic valve regurgitation is corrected concomitantly by annuloplasty, including annular constriction, bicuspidization or resupport of the valve, or by prosthetic replacement of the valve. Type I I I dissections are managed by excision with graft replacement of the segment of descending thoracic aorta in which the dissection arises, using pump bypass from the left atrium to the femoral artery. 3. These procedures have been found applicable to both acute and chronic forms of the disease, and results have been increasingly gratifying in altering the generally grave prognosis of these patients. This is reflected by the fact that the operative mortality has been steadily reduced from 41 per cent in the first 4 years of this surgical experience to only 12 per cent in a series of 97 patients operated upon during the last 4 years. This is further reflected in the long-term survival rates based upon follow-up observations on all patients in the series extending up to 10 years. Thus, the 5-year survival rate of 50 per cent in this surgically treated series of patients, most of whom have resumed normal activities, is in sharp contrast to the less than 1 per cent figure previ ously reported for nonoperative cases. On the basis of this experience, surgical intervention is now considered the treatment of choice in all instances, and emergency operation is often indicated. REFERENCES
1. Bahnson, H. T., and Spencer, F . C.: Excision of Aneurysm of Ascending Aorta With Pros thetic Replacement During Cardiopulmonary Bypass, Ann. Surg. 151: 879, 1960. 2. Beckwith, J . R., Muller, W. H., Warren, W. S., and Wood, J . E . : Acute Dissecting Aneurysm of the Aorta, Arch. Int. Med. 104: 217, 1959. 3. Burchell, H. B . : Aortic Dissection (Dissecting Hematoma; Dissecting Aneurysm of the A o r t a ) , Circulation 12: 1068, 1955. i. Cooley, D. A., Beall, A. C , Jr., and Grondin, P . : Open Heart Operations Using Disposable Oxygenators, 5 Per Cent Dextrose Prime and Normothermia, Surgery 52: 713, 1962. 5. De Bakey, M. E., Cooley, D. A., and Creech, O., J r . : Surgical Considerations of Dis secting Aneurysm of the Aorta, Ann. Surg. 142: 586, 1955. 6. De Bakey, M. E., Cooley, D. A., Crawford, E. S., and Morris, G. C , J r . : Aneurysms of the Thoracic Aorta: Analysis of 179 Patients Treated by Resection, J . THORACIC SURG. 36: 393,
1958.
7. De Bakey, M. E., Cooley, D. A., Crawford, E. S., and Morris, G. C , J r . : The Clinical Application of a New Flexible Knitted Dacron Arterial Substitute, Am. Surgeon 24: 862, 1958. 8. De Bakey, M. E., Henly, W. S., Cooley, D. A., Crawford, E. S., and Morris, G. C , J r . : Surgical Treatment of Dissecting Aneurysm of the A o r t a : Analysis of 72 Cases, Circulation 24: 290, 1961.
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9. De Bakey, M. E., Henly, W. S., Cooley, D. A., Crawford, E . S., Morris, G. C , Jr., and Beall, A. C , J r . : Aneurysms of tlie Aortic Arch: Factors Influencing Operative Risk, S. Clin. North America 42: 1543, 1962. 10. De Bakey, M. E., Henly, W. S., Cooley, D. A., Morris, G. C , J r . , Crawford, E. S., and Beall, A. C , J r . : Surgical Management of Dissecting Aneurysm Involving the Ascending Aorta, J . Cardiovas. Surg. 5: 200, 1964. 11. Hirst, A. E., Jr., Johns, V. J., Jr., and Kime, 8. W., J r . : Dissecting Aneurysms of the A o r t a : A Review of 505 Cases, Medicine 37: 217, 1958. 12. Hufnagel, C. A., and Conrad, P . W.: Dissecting Aneurysms of Ascending Aorta: Direct Approach Repair, Surgery 5 1 : 84, 1962. 13. Hume, D. M., and Porter, R. R.: Acute Dissecting Aortic Aneurysms, Surgery 5 3 : 122, 1963. 14. Morris, G. C , Jr., Witt, R. R., Cooley, D. A., Moyer, J . H., and De Bakey, M. E . : Al terations in Renal Hemodynamics During Controlled Extracorporeal Circulation in the Surgical Treatment of Aortic Aneurysm, J . THORACIC SUKG. 34: 590, 1957. 15. Morris, G. C , Jr., Henly, W. S., and De Bakey, M. E . : Correction of Acute Dissecting Aneurysm of Aorta With Valvular Insufficiency, J . A. M. A. 184: 63, 1963. 16. Muller, W. H., J r . , Damman, F . J., J r . , and Warren, W. D . : Surgical Correction of Car diovascular Deformities in M a r f a n ' s Syndrome, Ann. Surg. 152: 506, 1960. 17. Shennan, T . : Dissecting Aneurysms (Med. Res. Council, Spec. Rep. Series No. 193), London, H. M. S. O., 1934. 18. Spencer, F . C , and Blake, H . : Report of Successful Surgical Treatment of Aortic Regurgitation From Dissecting Aortic Aneurysm in Patient With Marfan Syndrome, J . THORACIC & CARDIOVAS. SURG. 44:
238,
1962.
DISCUSSION DR. P E T E R J . FERRATO, Lorain, Ohio.—I would like to present some interesting roentgenographic findings of a patient with a dissecting aneurysm. This is a 59-year-old white woman, a known hypertensive, who was admitted to a small hospital in Oberlin, Ohio, with a 2 day history of back pain and dyspnea. I first saw her 2 days later because of per sistence of severe upper back pain. The pulse was 86 and blood pressure 110/80, but she did not appear to be in distress. [Slide] The posteroanterior chest film shows slight prominence of the aortic knob and slight cardiac enlargement. The peripheral pulses were excellent. However, because of the persistence of back pain, I submitted her to angiocardiography. [Slide] This is the first film taken 5 seconds after I had injected the dye. The aorta is not yet filled. [Slide] The aorta is now beginning to fill, and dye is seen outside its lumen. [Slide] The aorta is now well filled, and dye can be seen on both sides outside the lu men. The arrows show the probable points of dissection and re-entry. [Slide] Dye still flows in the aorta and in the plane of dissection 12 seconds after injection. [Slide] Dye is beginning to fade from the anterior surface of the aorta. [Slide] Seventeen seconds after injection, there is no dye in or out of the aortic lumen, indicating that there was free flow of blood in the dissecting plane of the aorta. Except for recognizing the aneurysm, I had not interpreted these films correctly, and therefore transferred her to the pump-oxygenator team a t Cleveland Metropolitan General Hospital. There, she would have been operated upon had not their radiologist interpreted the films as above presented. She is now doing well 2 % months later, with no widening of the mediastinal shadow. I had wanted to ask Dr. De Bakey if he would agree with this method of management, or whether he would have operated upon her immediately; but after having heard his paper, I feel quite certain he would have operated upon her then, and now also. DR. ROBERT E . GROSS, Boston, Mass.—Dr. De Bakey, have you had any spinal cord problems after extensive removal of the intercostal arteries?
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DR. DE B A K E Y (Closing).—In answer to Dr. F e r r a t o ' s question about the patient, I would have operated upon the patient if I were convinced the patient had a dissecting aneurysm; and on the basis of the films seen, I am so convinced. In answer to your question, Dr. Gross, we have. Our experience with neurologic disturbances, particularly spinal cord disturbances, following resection of the descending thoracic aorta leaves us completely puzzled as to the basic reasons why they occur. I n our experience with both dissecting aneurysms and other forms of aneurysms involving the descending thoracic aorta, there have been somewhere in the neighborhood of 2 per cent of patients developing disturbances of the spinal cord. Fortunately not all of these have been permanent, but they have occurred, and we are unable to correlate them with the degree of resection. As a matter of fact, in a great majority of patients in whom there has been extensive resection of the entire descending thoracic aorta, there have been no disturbances of any kind. Indeed, the disturbances have occurred in patients in whom only a small amount of descending thoracic aorta has been resected. Why that is, I don't know; but I am inclined to believe it is related to the anatomic nature of the circulation to the spinal eord in the individual cases.