CHAPTER XII
Arterial Aneurysms and Arteriovenous Fistulas
Spontaneous Cures
Harris B. Shumacker, Jr., M. D.
For many years spontaneous cures of both arterial aneurysms and arteriovenous fistulas have been recorded in the medical literature. These accounts have appeared chiefly in the form of isolated case reports or as single examples in small series of cases. By 1907, according to Matas, l Boinet was able to collect 60 such cures in aortic aneurysms alone. Spontaneous cures of arteriovenous fistulas have been reported less frequently than cures of arterial aneurysms. The cures of aneurysms have included both saccular and fusiform types and the lesions have occurred in practically all arteries.The duration of the lesion before cure occurred has varied from a few months to many years.
Because of the character of the reports in the literature, it is almost impossible to determine anything concerning the frequency with which spontaneous cures occur. Winslow 2 found only 1 instance of spontaneous cure in 86 aneurysms of the internal carotid artery and none in 19 arteriovenous fistulas, while Callander 3 mentioned only 1 instance of cure among the 447 arteriovenous fistulas which he analyzed.A few other cases are described in which the lesion disappeared after treatment by compression.
The literature thus supplies little information concerning the frequency of spontaneous cures of arterial aneurysm and arteriovenous fistulas, the adequacy and permanency of these cures, and the therapeutic means by which they can be encouraged to take place.
Among the 119 aneurysms and 245 arteriovenous fistulas observed at the vascular center of Mayo General Hospital, there were 8 spontaneous cures of arterial aneurysms and 5 of arteriovenous fistulas. Two additional aneurysms became solidly clotted but lead to be excised because of associated nerve lesions, and 3 additional arteriovenous fistulas underwent spontaneous cure by thrombosis of the affected vein, but persistence of associated saccular aneurysms made surgery necessary in each of these cases. With 11 exceptions, 7 of which were of congenital origin, these 364 lesions were traumatic.
1 Matas, R.: Surgery of the vascular system. In Keen, William W., and DaCosta, John C.: Surgery: Its Principles and Practice. Philadelphia, W. B. Saunders Co.. 1909, vol 5, pp. 17-350.
2 Winslow, N.:Extracranial aneurysm of the internal carotid artery; history andanalysis of thecases registered up to August 1, 1925. Arch. Surg. 13: 689-729, Nov 1926.
3 Callander, L.: Study ofarteriovenous fistula with an analysis of 447 cases. Johns HopkinsHosp.Rep. 19: 347-362, 1921.
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It was possible to determine from notes made at the time of operation and from examination of excised specimens, the types of fistulas and the presence or absence of associated saccular aneurysms in 195 arteriovenous fistulas ob served at Mayo General Hospital during the course of World War II. In 78, 40 percent, no aneurysm was present; there was only a direct communication between artery and vein.In the other 117, 60 percent, one or more aneurysms were present, and these varied in size from a mass 1 cm. in diameter to an ovoid mass about 22 cm. long and 15 cm. in diameter.
SPONTANEOUSCURES OF ANEURYSMS
Analysis ofData
Of the 119 aneurysms observed at the vascular center of Mayo General Hospital in the course of World War II spontaneous clinical cure occurred in 10 instances.In 8 of these (6.7 percent of the total number) the end results were satisfactory without local treatment in that the mass disappeared.In the other 2, the thrombosed sac persisted and required surgical treatment because of associated nerve lesions, in 1 of these because of pressure of the thrombosed mass on the nerve rather than because of trauma to the nerve per se. In 3 of the 10, the aneurysms arose from relatively small arteries as, for example, the posterior tibial and the ulnar. In the 7 remaining, larger arteries such as the carotid, brachial, femoral, popliteal, and axillary were involved.
In the 10 patients in whom thrombosis occurred, the process began from 1.5 to 4.5 months following injury and was complete in from 2 to 15 months. These time intervals are to be compared with approximately 3.5 months, the average duration of the lesion at the time of operation in the 109 aneurysms in the series treated by surgical measures.
In 6 of the 10 patients the thrombosis seemed to occur rather suddenly and to be complete immediately. In the other 4, it was a gradual and progressive process. In general, a marked contraction of the clotted sac took place, and in the 8 patients in whom cure was entirely satisfactory the mass either disappeared completely or became insignificant in size. One patient (Case 5) had had sympathectomy performed on the indication of poor collateral circulation prior to the time the thrombotic process began, and in another patient (Case 2) a traumatic sympathetic denervation had resulted from the same injury which produced the vascular lesion.
Brief abstracts of the 10 cases in which aneurysms cured spontaneously are presented herewith:
Case 1. A 27-year-old soldier received multiple penetrating wounds from fragments of an exploding shell. Thereafter there were present signs and symptoms of an aneurysm of the left common carotid artery including paralysis of the left vocal cord, vigorous pulsation of a palpable mass, a systolic bruit, and the subjective sensation of a short, swishing sound heard synchronously with. each. heart beat. In a hospital overseas an exploratory operation was carried out 1 month after injury but no attempt was made to correct the vascular lesion.
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Some 3 months later, while the patient was being evacuated by sea to the Zone of Interior, he observed that the swishing note had disappeared and that the mass was pulsating less forcefully. When examined a few weeks later in the vascular center of Mayo General Hospital a firm pulsating mass about 2 cm. in diameter was palpable in the region of the left common carotid artery. Proximal compression of the artery temporarily stilled the pulsation of the mass. Four months later (8 months after injury) examination revealed practically the same findings. At the end of another 4 months the mass was no longer palpable and there was no evidence of the thrill, bruit, or abnormal pulsation previously present. The left common carotid artery pulsated normally proximally and distally to the site of the original mass. It was concluded that the aneurysm had cured spontaneously and that the lumen of the artery had been preserved.
The first improvement was observed during the time the patient was at sea, but he had not been seasick and dehydration could not be regarded as initiating the chain of events leading to cure (see Case 18).
Case 2. A 25-year-old soldier was injured by a shell fragment 7 weeks before he was seen at this vascular center in the Zone of Interior.He had a pulsating mass about 3.5 by
5 cm. in the left side of the neck (Figs. 46Aand B).The mass was compressible and was associated with a loudsystolic bruit. It ceased to pulsate when the left common carotidartery was occluded proximally.There was alsoevidence of left cervical sympathetic and of left recurrent laryngealparalysis.
The soldier was granted a furlough and after his return an examination revealed that the mass was smaller, firmer, and pulsated less vigorously. In addition, the bruit had disappeared.At this time 4 months had elapsed since the date of injury.The mass con tinued to decrease rapidly in size and 6 weeks later it was only a firm, nonexpansible nodule about 1.5 by 0.7 cm. in size adherent to the carotid artery.Two months later (7½ months after injury), examination revealed the same findings.(Fig. 46C.) No signs of aneurysm were present and the carotid artery pulsated normally proximally and distally.
Case 3. A 30-year-old soldier was wounded by machinegun fire. A small arterial aneurysm of the midportion of the brachial artery developed, also paralysis of the right median nerve. The aneurysm measured about 2 by 1.5 centimeters. Examination revealed expansile pulsation of the mass and a systolic bruit.
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Six weeks after injury the mass became firmer and ceased to expand with pulsation. The changes were associated with definite local pain and tenderness. The mass continued to decrease in size and after several months had elapsed was no longer even palpable. The hand, however, showed evidence of persistent vasospasm and was sensitive to cold.
Seven months after injury, during operative neurolysis of the median nerve, it was possible to inspect the brachial vessels. Both the artery and the vein were thrombosed and were excised. A study of the specimen revealed a defect in the arterial wall which represented the former mouth of the aneurysm. No sac could be found. Return of median nerve function was satisfactory but sensitivity to cold continued and a dorsal sympathectomy was therefore carried out. The results were excellent.
Case 4. A 23-year-old soldier was injured by the explosion of a land mine. He sustained fractures of the right radius and ulna and of the left femur, laceration of the mesentery of the ileum for which laparotomy was performed, and an injury to the right common femoral artery. When examined at the vascular center of Mayo General Hospital 6 weeks later, a pulsating mass about 3 cm. in diameter was found in the right groin over the junction of the external iliac and common femoral arteries. A systolic thrill and a bruit were present. Direct pressure over the mass or over the distal portion of the external iliac artery stilled the aneurysm.
Three months later the mass was smaller and firmer. It still expanded with pulsation and the bruit was still present but the thrill had disappeared. Examination a year after the injury showed that the original pulsating mass had been replaced by one that was small and indurated. This mass completely disappeared 3 months later. There was no other evidence of the presence of an aneurysm at either of these examinations.
Case 5. A 24-year-old soldier was injured by a shell fragment. When examined 2 months later a compressible dumbbell-shaped mass 6 cm. in diameter was present over the upper portion of the left femoral artery.Expansile pulsation was palpable and a systolic bruit heard. Both pulsation and bruit were abolished by compression of the common femoral artery. Tests revealed the collateral circulation to be inadequate and left lumbar sympathectomy was performed. The circulation was improved after this procedure but was still regarded as inadequate.
Two months later, while the patient was on furlough, the mass became firm and ceased to pulsate. Examination on his return a few weeks later showed that the 6-cm. pulsating mass had been replaced by a hard, nonexpansile mass 2 cm. in diameter and without any associated thrill or bruit.The mass continued to decrease in size and 9 months after the original injury an arteriogram revealed a sac only about 0.5 cm. in diameter.At the end of another month the mass was still smaller; only a tiny, firm nodule was palpable. Oscillometric readings showed that the circulation was normal in the thigh, calf, and ankle on the affected side.Appropriate tests showed that the patency of the artery had been maintained.
Case 6. A 26-year-old soldier was injured in the right popliteal area by a shell fragment. Soon afterward a pulsating mass developed in this area associated with a systolic bruit. About 6 weeks after injury the mass became smaller and firmer and ceased to pulsate.At the end of another 2 weeks it had disappeared entirely as had the bruit. The popliteal artery and its anterior and posterior tibial branches all pulsated normally.
Case 7. A 32-year-old soldier was injured by a shell fragment. Soon afterward a pulsating expansile mass appeared on the posteromedial aspect of the leg just above the internal malleolus. A diagnosis of a posterior tibial aneurysm was made. Two months after injury the pulsating mass became firm and did not pulsate. Examination revealed a solid mass about 1.5 cm. in diameter. No bruit or thrill was present. No posterior tibial pulse could be palpated distal to the mass. Examination 2 months later showed little change in the mass, but at the end of another 4 months it was neither visible nor palpable. The posterior tibial pulse distal to the site of injury was still absent.
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Case 8. A 26-year-old soldier received multiple penetrating wounds from shellfragments.A small pulsating mass,associated with a loud systolic murmur, developed in the middle thirdof the right calf. It was diagnosed as aposterior tibial aneurysm. During the third month after injury, whilethe patient was on furlough, the mass ceasedto pulsate and became firm and indurated. Examination revealed neitherthrill nor bruit. The induration graduallysubsided. An arteriogram 4 months after injury revealed anormal-appearing arterial tree. There was no suggestionof aneurysmal dilatation at the site of injury but in the roentgenogramthe site of the injury was marked by thepresence of a small shell fragment.
Case 9. A 23-year-old soldier was wounded in the right axilla by shell fragments. At the time of wounding there was considerable bleeding. No numbness or paralysis was noted. A pulsating mass soon developed in the axilla and a systolic bruit became audible. Six weeks after injury some loss of sensation was noted in the digits and a week later the extensor power of the wrist and forearm was lost and all movements of the hand became weak. These neurologic changes persisted.
When the patient was examined at this vascular center some 5 months later he stated that pulsation in the mass had recently ceased. Examination showed a solidly thrombosed aneurysm in the right axilla (Fig. 47).The brachial, radial, and ulnar pulses were absent. Complete radial and partial ulnar and median paralysis was present, and the sequence of events left no doubt that nerve damage had resulted from pressure from the axillary aneurysm.
Figure 47. (Case 9.) Right axillaryaneurysm 3 months after injury.
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An exploratory operation was performed and an axillary aneurysm was found which measured between 5 and 6 cm. in diameter. The axillary artery was thrombosed distal to the lesion. The median, ulnar, and radial nerves lay in grooves in the wall of the aneurysmal sac (Fig. 48).The median nerve showed only a little damage and the u1nar nerve was only moderately thinned, but the radial nerve was thinned out to a fine thread for a distance of 3.5 cm.; strong faradic stimulation in this area yielded no response. The aneurysm was excised after which the damaged portion of the radial nerve was resected and the ends sutured. The postoperative course was smooth.
When the excised aneurysm was opened it was found to be completely filled with thrombus, most of the clot was old and well organized. Near the mouth of the sac, however, was a small portion which was fresher and less well organized.
Case 10. A 20-year-old soldier sustained a wound from a rifle bullet in his left hand. An ulnar aneurysm developed in the hypothenar space and there was some damage to the digital nerves. By the end of the third month after injury the aneurysm was completely thrombosed, but over the next 7 weeks it did not decrease in size and there was no improve-
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ment in the neurologic condition. Operation was therefore performed. The aneurysm, which was 1.5 cm. in diameter, was solidly clotted and the artery distal to it, thrombosed. The sac was evacuated and the injured nerves sutured. Recovery was uncomplicated.
SPONTANEOUSCURES OF ARTERIOVENOUS FISTULAS
Analysis of Data
Of the 245 arteriovenous fistulas observed at this vascular center during World War II, apparently spontaneous clinical cure occurred in 8 instances. In 5 (2 percent of the total number) the end results were satisfactory without further local treatment. A saccular aneurysm was known to be associated with the fistula in 2 of the 5. In the other 3, while the fistula was closed by spontaneous thrombosis of the vein, an associated saccular aneurysm persisted and operation was necessary. In all but 1 or 2 the artery involved was a large vessel such as the carotid, brachial, subclavian, or femoral.
In the 5 patients in whom the end result of spontaneous cure was entirely satisfactory, the process of obliteration began 1.5 and 5.5 months after onset of the lesion. In 4 of these patients the process began within 3 months or less. In all 4 the process occurred rather suddenly, leading one to infer that closure of the fistula was achieved by thrombosis rather than by scarring and fibrosis which is a more gradual process. In the remaining patient in this group the process occurred gradually, beginning within 2 months after injury and completed within the next 1.5 months.
In only 2 instances was the presumption concerning the method of cure established: In 1 instance (Case 11) by the presence of a palpable, thrombosed saccular aneurysm, and in the other (Case 12) by clinical observation of thrombosis of the vein, confirmed by later inspection of the involved vessels at operation. In the 3 patients in whom operation was necessary because of persistence of an associated aneurysm, the process of obliteration began, respectively 1.5, 3.9, and 4 months after injury. The time intervals in this group and in the preceding group of patients in whom completely successful spontaneous cure occurred should be compared with 5 months, the average interval between injury and operation in the 237 arteriovenous fistulas treated by surgical excision.
Another point of interest is the proportion of patients in whom cure occurred as the result of thrombosis. This is in contrast to the general experience that experimentally produced arteriovenous fistulas often close, when they do so spontaneously, by gradual scarring and contraction of the communication rather than by thrombosis.
One of the patients who had a completely satisfactory spontaneous cure, and 2 of the 3 who required further surgery, had undergone sympathectomy before the fistula became obliterated. In 1 of these patients (Case 18) thrombosis of the vein was obviously associated with dehydration and shock.
Brief abstracts of the 8 cases in which spontaneous cures of arteriovenous fistulas occurred are presented herewith:
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Case 11. A 34-year-old soldier received multiplepenetrating wounds from a land mine explosion. He developed 2arteriovenous fistulas, 1 involving the right common carotid artery andinternal jugular vein, 1 the right femoralartery and vein. The femoral fistula was excised about a month afterinjury. Two months later the buzzingsensation, which had been present in the right side of the neck sincethe arteriovenous fistula had developed,suddenly ceased. Examination revealed that the previously continuousthrill had disappeared while of thecontinuous bruit formerly present only a slight systolic component nowremained. A rubbery, nonexpansile masshad replaced the original carotid aneurysm. The carotid artery pulsatednormally both proximally and distally tothe lesion. Within another month the systolic bruit disappeared, andthe mass became progressively smaller so thatby 6 months after injury it was barely palpable.
Case 12. A 22-year-old soldier sustained a shell-fragment injury. A brachial arteriovenous fistula associated with a small saccular aneurysm developed, also a partial median paralysis. He was admitted to this vascular center 6 months after injury. A continuous thrill and bruit were present, and compression of the fistula resulted in bradycardia. Seven weeks after injury thrombosis of the dilated brachial vein became evident and signs of the arteriovenous fistula disappeared. Since steady improvement was apparent in median nerve function, operation was deferred. After the lapse of about 4½ months there was complete recovery of motor function, but anesthesia of the median nerve distribution persisted. A neurolysis was carried out. At this time the brachial artery and vein were inspected and were found completely thrombosed, adherent to each other. A tiny, solid mass was all that remained of the original saccular aneurysm.
Case 13. In a 26-year-old soldier an arteriovenous fistula of the femoral vessels developed in the midportion of the thigh following a wound from a rifle bullet. Two months after injury the continuous bruit and thrill which had been present since the fistula developed became much less prominent. A month later the thrill was barely palpable and the bruit, though still continuous, was very faint. Pulsations were good in the popliteal, dorsalis pedis, and posterior tibial arteries. Within the next 2 weeks all signs of the fistula disappeared and they did not reappear during an additional month of observation. Whether the lesion in this patient involved the femoral vessels or some of the smaller branches was not definitely established.
Case 14. A 25-year-old soldier was injured by a shell fragment. One month later clear-cut signs of an arteriovenous fistula in the left thigh below the inguinal region were present. These persisted for 2 months, then disappeared. When the patient was examined 4 months after injury no abnormal pulsation was present, no thrill could be palpated, and no bruit heard.
The notes were not sufficiently complete to permit accurate localization of the fistula, but the findings suggested that it involved branches of the profunda femoris vessels. The continuous bruit and thrill noted by several competent observers before the patient was seen in this vascular center left no doubt that an arteriovenous fistula had actually been present.
Case 15. A 24-year-old soldier received a penetrating shell-fragment wound of the left chest wall. There was transient paralysis of the left upper extremity and some numb ness which did not subside for several weeks. Soon after injury signs suggestive of a subclavian arteriovenous fistula appeared. When he was examined about 2½ months after injury, a strong and continuous thrill was palpable just above the inner third of the clavicle. An extremely loud and continuous bruit was transmitted into the mediastinum, up into the neck, and down the arm to the midforearm. The subclavian vessels could not be occluded by digital pressure nor could the thrill and bruit be eliminated. Minimal hyperesthesia was present in the ulnar distribution. A diagnosis of subclavian arteriovenous fistula was made.
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Because of a rather striking vasoconstriction in the left upper extremity and the inability to occlude the subclavian artery for testing the collateral circulation, a dorsal sympathectomy was performed about 4½ months after injury. Some days later the thrill previously felt over the lesion disappeared and the continuous bruit was replaced by a loud, short, systolic bruit. The subclavian vessels were explored shortly afterward in the belief that though the fistula had been obliterated a saccular aneurysm remained. The vessels were traced proximally to the point at which they emerged from the mediastinum. There was considerable scarring in this area but no aneurysm could be palpated. Since the remaining bruit could be explained by compression of the artery by scar tissue, exploration was discontinued. The short systolic bruit persisted, but became less intense, during the 6-week period of observation after operation
There was unmistakable evidence in this case of the presence of an arteriovenous fistula, and it seems likely that it involved the first portion of the subclavian vessels.
Case 16. A 24-year-old soldier was injured by fragments from a bazooka shell. Because of gas gangrene a right midthigh amputation was necessary. A large left femoral aneurysm developed. Three months after injury, examination revealed a very large pulsating mass in the left thigh, associated with a loud systolic bruit. The aneurysm could be stilled by proximal compression of the femoral artery. Testing showed the collateral circulation to be entirely inadequate. Left lumbar sympathectomy was performed and the circulation became satisfactory; aneurysmorrhaphy was carried out thereafter. The sac was huge and in addition to a large free cavity contained 2.5 liters of partially organized thrombus. The midportions of the femoral artery and vein each opened separately intothe sac through large rents. In this area the femoral vein wascompletely occluded by a well-organized thrombus.
When this patient was first examined at the vascular center only an arterial aneurysm was present. The previous records also contained no description of findings diagnostic of an arteriovenous fistula. The findings at operation, however, left no doubt that the original lesion was an arteriovenous fistula and that the artery and vein had communicated via the large sac described. Thrombosis of the vein had converted the fistula into an arterial aneurysm.
Case 17. A 22-year-old soldier was struck in theleft shoulder by a missile of unknown type. Immediately partialulnar and radial paralysis developed. Two weeks later a small pulsatingmass was noted in the upper portion of theleft arm. Four days later the mass began to increase rapidly in sizeand the radial pulse disappeared. Ulnar andradial paralysis then became complete and a partial median paralysisdeveloped. Causalgia which had appearedsoon after the injury became much worse.
When the patient was examined at this vascular center 6 weeks after injury, a tense pulsating mass was found in the left upper arm and shoulder area associated with a continuous thrill and bruit. Sympathetic block produced transient relief of pain, and sympathectomy was performed. This produced permanent relief from most of the pain. Four days after operation the aneurysm again began to increase in size and simultaneously the continuous bruit and thrill disappeared; only a short systolic bruit remained.
When exploration was carried out the following day, the brachial artery and vein were found to communicate independently with a large, poorly organized sac. The vein was completely occluded by a thrombus recently formed.
Case 18. A 33-year-old soldier was injured by amachinegun bullet. Partial paralysis of the right ulnar and mediannerves resulted. A brachial arteriovenous fistula and a small saccularaneurysm also developed. Three months afterinjury, since the collateral circulation appeared to be extremely poor,dorsal sympathectomy was performed. Thecollateral circulation showed gradual improvement and at the end of 5weeks it was thought to be adequate forsurgery.
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At this time, before the operation could be performed, the patient had a severe attack of food poisoning with so much vomiting and diarrhea that a profound degree of circulatory collapse resulted. The epidemic was widespread and available fluids for intravenous use became depleted so rapidly that they were reserved for those in the severest states of dehydration and shock. This patient therefore did not receive adequate parenteral fluid until he was badly dehydrated and in such a state of collapse that his pulse was imperceptible. He recovered rapidly, however, after appropriate therapy.
The day after this episode it was observed that the continuous thrill and bruit previously associated with the brachial arteriovenous fistula had disappeared. The brachial pulse distal to the lesion was good. At exploration a few days later the brachial artery and vein were found to have communicated through independent openings into a saccular aneurysm about 2 cm. in diameter. The artery still opened freely into this sac but the vein had become thrombosed. The ulnar and median nerves were adherent to and stretched over the aneurysm. They were freed from the aneurysm and it was excised. Recovery was uneventful.
COMMENT
Incomplete notes unfortunately do not permit statistical statements concerning either the presence or the extent of intrasaccular thrombosis in the arterial aneurysms and arteriovenous fistulas observed at Mayo General Hospital. Certain general statements may, however, be made: Extensive intrasaccular thrombosis was the rule in large aneurysms with small mouths, and generally no thrombus was present in small aneurysms with relatively large openings into the parent artery. In some instances the thrombus was well organized and, ordinarily, the older the lesion the more complete was the process of organization. In some instances (Fig. 49) there was both a well organized thrombus adherent to the wall of the sac, and a poorly organized red thrombus only loosely attached. In other instances only a poorly organized clot was present (Fig. 50). The size and extent of the thrombus varied widely. Several femoral aneurysms contained from 2 to 2.5 liters of recent and old clot. The progressive deposition of thrombus within the sac was often apparent clinically from the decrease in pulsation of the sac, a palpable increase in its firmness, and sometimes by a diminution in the thrill and bruit. Indeed, in one patient, a large aneurysm of the profunda femoris became so firm and so completely lost its pulsatile character and its bruit that, until arteriography revealed a persistent large cavity, it was thought to have undergone spontaneous cure.
It is a matter of considerable interest that in 6 of the 10 aneurysms in which spontaneous cures occurred, the continuity of the parent artery was preserved. In this connection, Ballance and Edmunds 4 cited Scarpa, who wrote:
It is a certain and incontrovertible fact in practical surgery that a complete and radical cure of an aneurysm cannot be obtained in whatever part of the body this tumor is situated unless the ulcerated, lacerated, or wounded artery from which the aneurysm is derived is by the assistance of nature, or of nature combined with art, obliterated and converted into a perfectly solid ligamentous substance, for a certain space above and below the place of the ulceration, laceration, or wound.
4 Ballance, C. A., and Edmunds,W.: A Treatise on the Ligation of the Great Arteries in Continuity withObservations on the Nature, Progress and Treatment of Aneurysms.London, Macmillan and Co., 1891.
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Figure 49. Traumatic aneurysm excised 11 years after its origin. A. Intact specimen B. Transected specimen showing well-organized thrombus. Some poorly organized red thrombus can be seen along the margin of the cavity and between the organized thrombus and the sac wall in that area where the old thrombus is not fixed to the wall. The sac in this view is smaller because it has been fixed and shrunken in formalin solution.
This "truth," according to Ballance and Edmunds, writing in 1891, had never been disproved; they had been unable to find the record of a single cure which had occurred in any other way. The experience of the vascular center of Mayo General Hospital, however, indicates that apparently complete cures may occur with preservation of the artery.
In discussing the possible factors involved in the spontaneous cure of arterial aneurysms, Matas 5 wrote as follows:
The conditions which provoke or favor this occurrence may be classified under three heads: (1) Those which favor clotting in the sac by retardation or arrest of the current through it; (2) those which increase the coagulability of the blood; (3) those which provoke coagulation through changes in or about the walls of the sac (Stimson). All these may be briefly summarized as follows: Spontaneous recovery takes place by (1) gradual deposit of fibrin from the blood in a laminated manner on the walls of the sac, so that the
6 See footnote 1, p. 361.
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aneurysm is completely consolidated and subsequently, by condensation and shrinking, becomes converted into a small, nodular mass of fibrous tissue. The artery, under such circumstances, may remain pervious or become converted into a fibrous cord as far as the first collateral branch above and below the seat of the aneurysm. Such a favorable termination may be brought about by retardation of the blood-current induced by (a) the lowering of the heart's action; (b) the pressure of the aneurysm upon the artery above its opening into the sac; (c) partial blocking of the mouth of the sac with a piece of detached coagulum; (d) the impaction of a piece of clot in the artery below the mouth of the sac; (e) the pressure of another aneurysm or a tumor upon the artery above the sac or on the sac itself; (f) the aneurysm rupturing and the effused blood compressing the artery leading to the aneurysm. (2) By filling of the sac with recent ordinary coagulum as distinguished from the deposit of old-standing laminated fibrin. The coagulation of the blood in the sac may be brought about by: (a) the complete blocking of the mouth of the sac by a piece of detached clot; or (b) the complete plugging of the artery above and below the aneurysm. The clot may thus become organized and transformed into a fibrous cord. (3) The inflammation and sloughing of the sac and the plugging of the artery above and below the clot.
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With a single exception, no factors were evident in these cases which could be singled out as possibly having contributed to the spontaneous cure either of arterial aneurysms or of arteriovenous fistulas. In this exceptional case (Case 18) a fistula was obliterated by thrombosis of the vein during a period of extreme dehydration and circulatory collapse due to fluid loss from diarrhea and vomiting. In some the process occurred while the patients were confined to bed; in none was there a coincident history of local trauma.
As already mentioned, in 1 patient in whom an arterial aneurysm underwent spontaneous cure, sympathectomy had been performed before the process of thrombosis began, while in another patient a traumatic sympathetic denervation had occurred. Sympathectomy had also been performed upon 1 patient with an arteriovenous fistula in whom an entirely satisfactory spontaneous cure occurred, and upon 3 other patients in whom a saccular aneurysm persisted.
Altogether, therefore, spontaneous cure occurred in 6 of 77 patients in whom sympathetic denervation had been produced by operation or trauma, and in 12 of 274 patients (presenting a total of 287 lesions) in whom sympathetic function of the part was intact. Clinically satisfactory spontaneous cures requiring no further treatment occurred in 2 patients submitted to sympathetic denervation, in 1 with traumatic sympathetic denervation, and in 10 with intact sympathetic function. In 1 patient only did the process leading to the spontaneous cure become evident soon enough after sympathectomy for a causal relationship to be considered a possibility.
In nearly all 18 instances of spontaneous cure the fistula or aneurysm had been temporarily stilled by digital compression once or several times, but the cure could hardly be said to have resulted from treatment by compression if only because compression had been employed in most of the patients in whom the lesion persisted until it was treated surgically.
Several cases are described in the literature in which aneurysms and arteriovenous fistulas disappeared after deliberate prolonged compression. Lyle, 6 for instance, collected a number of cases in which aneurysms of the pal mar arches were deliberately treated by this method. It hardly seems a desirable mode of treatment. For one thing, one could not be certain that thrombosis would be limited to the desired area, indeed it is quite possible that it might involve an uncontrolled extent of the affected artery and even of its collateral channels. The use of internal wiring to promote the development of a thick mural thrombosis in patients with inoperable aneurysm is often, of course, a palliative measure of great usefulness, but it was not employed in any instance in this series.
6 Lyle, H. H. M.: Aneurism of thepalmar arches; with a report of an aneurism of the deep arch cured byexcision.Ann. Surg. 80: 347-362, Sep 1924.
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A number of observers, notably Reid,7 have suggestedthat the possibility of a spontaneous cureof an arteriovenous fistula might constitute a valid reason to delaysurgical intervention for somemonths. If signs are observed which suggest the possible progressivespontaneous obliteration ofeither an aneurysm or an arteriovenous fistula, it would naturally bewise to follow this advice.The experience at the vascular center of Mayo General Hospitalindicates, however, that theincidence of such satisfactory cures of arteriovenous fistulas, atleast during the first few monthsafter injury, is so low (2 percent), as to make this possibility afactor of little or no significance indeciding upon the proper time for surgical attack. The incidence ofsatisfactory spontaneous curesof arterial aneurysms was somewhat higher (6.7 percent), but again theoccurrence seems sounlikely that the possibility is not a very important consideration inthe selection of the propertime for the operative treatment of aneurysms.
7 Reid, M. R.: Abnormalarteriovenous communications, acquired and congenital; treatment ofabnormalarteriovenous communications. Arch. Surg. 11: 237-253, Aug 1925.
