A N E W TECHNIQUE FOR THE CREATION OF A N ATRIAL SEPTAL DEFECT W I T H CLINICAL APPLICATION Samuel R. Schuster, M.D., Earl Kiernan, M.D., Jens Rosencranz,
M.D.,
and Achmed Bozer, M.D., Boston, Mass.
B
and Edwards of the Mayo Clinic suggested as early as 1947 that a surgically created atrial septal defect might be beneficial in certain patients who are suffering from congenital cardiac malformations. The work of Blalock and Hanlon 6 in 1950 and the more recent reports of Ash 2 and Ochsner 19 have clinically demonstrated that the surgical creation of an atrial septal defect can improve the condition of critically ill infants who are suffering from transposition of the great vessels. It has been the feeling of many that the creation of such a defect in these patients is less disturbing than other pro cedures designed to increase the systemic oxygen saturation. We have, in the past, had disappointing results whenever we attempted to do more than the simplest of procedures in young infants suffering from transposition of the great vessels. In these very sick babies, our early attempts involving the creation of an atrial septal defect with open-heart techniques with brief periods of in-flow occlusion met with poor results. Several attempts at establishment of an atrial septal defect were made with the use of a punch-type instrument without in-flow occlusion. These were likewise unsuccessful. For these reasons, we sought a method that would not require special instruments, would be technically easy, and would avoid even temporary interruption of any part of the circulation. URCHELL
THE ANATOMY OF THE INTERATRIAL SEPTUM
A popular image exists that the plane of the interatrial septum is vertical and faces to the left; that this is not so was appreciated over a half a century ago by Fetterolf and Gittings 12 in their wonderfully complete study in children of the thoracic cage and its contents. Fig. 1, A is a modified drawing of a sagittal section through the body of a newborn child viewed from the right as Prom the Surgical Service, The Children's Hospital Medical Center, and the Department of Surgery, Harvard Medical School, Boston, Mass. This work was supported by grants from the National Heart Institute, The American Heart Association, and the Massachusetts Heart Association. Received for publication March 29, 1963. 510
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seen at the operating table. This shows the relationship of the left atrium (LA) to the right atrium (RA). Pig. 1, B, which represents a magnification of the area of the atrial septum and adjacent atria, is magnified and oriented to portray the plane of the septum as seen by the operator. To complete the anatomical orientation, Pig. 2, A shows a horizontal section of the body of the newborn child while Fig. 2, B, a magnification of the region immediately around the atrial septum, demonstrates the relationship of the atria to each other and to the atrial septum and portrays the fact that the interatrial septum is directed approxi mately 35 degrees in an anterior direction from the horizontal when the subject is in the supine position.
"^MmM^ *,*- : 'I •"»
MJ.A.
■LA.
INTER ATRIAL SEPTUM tv, 0 r-Jlf;nh^TA1' i p ff aBS lA} t ^ 1 ■ s t. < l ti0 ? o f \ h e b ? d y o f a n e w b o r n child, viewed from t h e r i g h t . N o t e «V^i «1 l H S f l * u ( " g h t a t r i u m ) t o LA (left a t r i u m ) . T h e p l a n e of t h e s e p t u m is v e r t i c a l a n d p a r a l l e l t o t h e v e r t e b r a l column. ( F r o m G. P e t t e r o l f a n d J. C. G i t t i n g s . " ) „ „ . * ; E n l a r g e d d i a g r a m of a r e a w i t h i n b r o k e n lines in P i g . 1, A. N o t e s e p t a l p l a n e a s p r e sented to t h e o p e r a t o r w h e n t h e p a t i e n t is in t h e left l a t e r a l position.
Sobotta and Mc Murrich 22 in 1914 noted in their Atlas and Textbook of Anatomy that the interatrial septum was posterior when viewed from in front and not medial as described classically. Eodriguez and Wofford20 have, in more recent times, reaffirmed the posterior position of the cardia septa. In addition, they have observed that the septum is roughly triangular in shape with the base located between the entrances of the venae cavae as they enter the right atrium; the apex of the triangle is near the prominence of the aorta. Sondergaard of Sweden, 23 ' 24 more than anyone else, has appreciated the anatomical relationships that exist between the right and left atria in the region of the interatrial groove. The interatrial septum, in its peripheral part, actually consists of the walls of the right and left atria separated by loose connective tissue and fat. The technique that we will describe has evolved from the appreciation of this natural surgical cleavage. It is only at the base of the interatrial sulcus, where the muscle fibers cross over from right to left, that the real atrial septum is formed. Our technique for a simple method for the safe creation of an interatrial septal defect has been developed through the appreciation of these fundamental anatomical facts.
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INTERATRIAL GROOVE »>..v
INTERATRIAL „ , SEPTUM' Pig. 2.—A, Horizontal section of the body of a newborn child. Note the relationship of RA (right atrium) to LA (left atrium). The view is from above. (G. Fetterolf and J. C. Gittings. 12 ) B, Enlarged diagram of area within broken lines in Fig. 2, A. Note the interatrial septum is directed approximately 3 5 degrees in an anterior direction from the horizontal when the sub ject is in the supine position.
METHODS
To determine the best method for the creation of an inter-auricular septal defect, several techniques were evaluated. All of these were performed through a right thoraeotomy in the fifth intercostal space in dogs that ranged in weight from 2 to 18 kilograms. All animals were anesthetized with intravenous Nembutal (30 mg. per kilogram of body weight) and an endotracheal tube was inserted and attached to an automatic respirator. Fig. 3 portrays the details of a technique which we finally adopted with good effect, both in the experimental laboratory and clinically. The heart is viewed as seen by the operator through a right thoraeotomy. Drawing 1 demonstrates the development of the interatrial groove after the
Pig. 3.—Technique for creation of interatrial septal defect. Drawing 1. Development of interatrial groove. Drawing 2 shows purse-string sutures encompassing interatrial groove at juncture of superior and inferior venae cavae and atrium ; it also shows the suture between the purse-strings which enters one atrium, transfixes the septum, and emerges from the other atrium. Drawing S shows a sharp and pointed scissors about to be thrust through the upper purse-string suture so that each blade will be in a different atrium. The inter-atrial septum will be encompassed by the blades of the scissors. Drawing h shows the atrial septum being cut with scissors placed within the lower purse-string. The superior cut has been completed and the purse-string tightened and tied. Drawing l,a is a cross section showing the relationship of the atrial septum and the scissors as the cut, noted in Drawing 4, is being made. Drawing^ 5 portrays the free atrial septal flap created after completion of both cuts in the septum. Drawing 6 shows the defect in the septum as septal transfixing suture retracts the free septal flap. Drawing 7 shows the outer appearance of heart at completion of procedure.
pericardium had been opened parallel and lateral to the phrenic nerve. This groove represents the lateral margin of the interatrial septum and is prepared by carefully dislodging the fat pad that exists therein. It is only necessary to develop a shallow groove between the right atrial wall and the right pul-
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monary veins as they enter the left atrium. Little bleeding is encountered, although occasionally a small vessel must be tied to keep the area dry; this is an essential condition for operating in this area. In Drawing 2, two purse-string sutures have been placed in an elliptical manner encompassing the interatrial groove; one is at the juncture of the superior vena cava with the right atrium and the other at the juncture of the inferior vena cava with the right atrium. This was all that was done in the initial group of experimental animals subjected to this technique. However, in a second group, an additional single silk suture was placed midway between the superior and inferior venae cavae, directed through the left atrium ad jacent to the interatrial groove, then through the septum, and finally emerged through the right atrium opposite the point at which it had entered the left atrial wall. This suture can be seen between the purse-string sutures in Draw ing 2. None of these sutures are tied down at this time. Drawing 3 shows that sharp-angled scissors are being thrust in a medial direction through the upper of the two purse-string sutures. The blades of the scissors as they enter the walls of the atria are oriented so that one blade lies on top of the interatrial septum in the right atrium and the other beneath the interatrial septum in the left atrium. When the blades are approximated, a cut will be made through the interatrial septum. This cut in the interatrial septum through the upper purse-string is directed medially, inferiorly, and slightly anteriorly, while that through the lower one is directed medially, superiorly, and slightly anteriorly. The accomplishment of these cuts in the septum are shown in Drawing 4; they are gauged so that the distal (most medial) point of each would cross that of the other. As the cut is completed and the scissors withdrawn, the purse-string suture is speedily but gently tightened and tied down so that there is almost no blood loss. Drawing 4a shows, in detail, a horizontal view through the atrial septum; one can see the relationship of the scissors to the septum as the septal cut is being made in Drawing 4. These cuts have produced a triangular-shaped free flap of interatrial septum hinged at its base on the interatrial groove and free at its apex as seen in Drawing 5. This free triangular flap of interatrial septum was then secured to the base of the interatrial groove by tying the suture previously placed between the purse-strings. Drawing 5 demonstrates the completed creation of a free triangular septal flap and Drawing 6 shows the defect as it would appear through a window in the right atrial wall as the suture through the septal flap is tightened. The tight ening of this suture folds the septal flap up against the interatrial groove. Draw ing 7 demonstrates the outward appearance of the heart at the completion of the operation and suggests the appearance of the newly created interatrial septal defect. It is important for the operator to get the feel of the interatrial septum against the cutting edge of the lower blade of the scissors as it passes into the left atrium. Once this is felt, the scissors are thrust in the appropriate direction as described above and the cut is completed.
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RESULTS
Twenty-one animals had defects created in this manner; Table I shows the results obtained. All but 3 animals had a resultant atrial septal defect of con siderable size. These dogs were sacrificed on an average of 82.6 days after operation. TABLE I. INTERATRIAL
|
DOG
SEPTAL DEFECTS CREATED EXPERIMENTALLY U S E OF THE DESCRIBED TECHNIQUE
WEIGHT
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 •Greatest diameter
(KG.)
DAYS POSTOP.
ASD*
10 47 9 62 8 66 11 92 9 105 10 106 11 112 7 112 11 112 10 112 7 20 10 28 14 73 10 76 10 76 11 78 10 78 10 79 17 81 10 104 19 116 of a roughly circular defect.
IN 21 DOGS W I T H
(CM.)
THE
REMARKS
Excellent Excellent Healed Good Good Good Excellent Good Good Healed Healed Good Good Excellent Good Excellent Excellent Excellent Fair Good Excellent
1.0 1.45
—
0.7 0.75 0.8 1.0 0.75 0.65
— —
0.75 0.9 1.25 0.5 1.25 1.0 1.0 0.4 0.58 1.1
CLINICAL MATERIAL
The following are case reports of patients subjected to this procedure. These are summarized in Table II. CASE 1.—CHMC 52-42-76. An 8-month-old boy, weighing 13 pounds and 8 ounces, entered Children's Medical Center on Sept. 6, 1961, with cyanosis since the first weeks of life.
TABLE I I .
SUMMARY
OF CLINICAL DATA IN 3 P A T I E N T S HAVING HAD ATRIAL SEPTAL CREATED W I T H THE U S E OP T H I S TECHNIQUE
CREATION OF INTER-AURICULAR
SEPTAL DEFECT
(TRANSPOSITION
OF THE GREAT
PREOPERATIVE PA TIENT
ARTERIAL SATURATION
DEFECTS
VESSELS)
POSTOPERATIVE
CYANOSIS AT REST
GENERAL CONDITION
ARTERIAL SATURATION
(%)
CYANOSIS AT REST
AGE
(%)
1
8 mo.
34
4+
Poor
54
1+
1 yr.; much improved
2
1 wk.
41
4+
Poor
77
1+
1 yr.; much improved
3
4wk.
60
4+
Poor
73
0
5 mo.; much improved
FOLLOW-UP
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Cardiac catheterization confirmed the diagnosis of transposition of the great vessels with inadequate mixing at the ventricular level. The oxygen saturation was 34 per cent in the aorta. I t was decided t h a t the creation of an atrial septal defect would be beneficial and on Sept. 8, 1961, an atrial septal defect was created with the use of the above tech nique. E a r oximetry performed on the third postoperative day was 54 per cent. Clinically the patient showed an immediate color improvement; subsequently the patient has gained weight and has continued to do well. One year following operation t h e patient has mild cyanosis, is active, and is beginning to walk.
The 20 per cent increase in oxygen saturation in the systemic circulation has provided striking clinical improvement. The sustained improvement suggests that the atrial septal defect created has remained open. CASE 2.—CHMC 52-52-31. This 7-day-old girl entered the Children's Medical Center with the complaint of cyanosis since birth. The patient was a well-developed, well-nourished, cyanotic female in no acute distress. Cardiac catheterization established the diagnosis of transposition of the great vessels with a small shunt at the atrial level. The right atrial saturation was 41 per cent. I t was believed t h a t the patient would benefit from an enlargement of the atrial septal defect and, therefore, on Oct. 5, 1961, an atrial septal defect was created. Immedi ately afterward the oxygen saturation in the right atrium was determined and found to be 82 per cent. Clinically the patient has done well since operation. E a r oximetry carried out on Nov. 14, 1961, revealed a peripheral oxygen saturation of 80 per cent. One year following operation the patient is active, has ver} - mild cyanosis a t rest, and is beginning to walk.
The 41 per cent increase in oxygen saturation within the right atrium associated with the immediate clinical improvement indicates that a large atrial septal defect has been created. The sustained elevation of the peripheral oxygen saturation and clinical improvement indicates that the atrial defect has remained open. CASE 3.—CHMC 53-67-32. This 4-week-old male infant entered the Children's Medical Center with a chief complaint of cyanosis and respiratory difficulty since birth. Cardiac catheterization and cineangiogram established a diagnosis of transposition of the great vessels, a small ventricular septal defect, and suspected pulmonary artery hypertension. I t was believed t h a t the patient would benefit from an enlargement of the atrial septal defect and therefore, on J u n e 6, 1962, an- atrial septal defect was created. Immedi ately after the creation of the defect, the heart became pinker; the patient's postoperative course was marked by an immediate improvement in systemic arterial saturation. E a r oximetry revealed a saturation of 73 per cent on the seventh postoperative day. Following a stormy late hospital stay as a result of severe pulmonary infection the patient was dis charged in an improved condition. Five months following operation the patient is cyanotic only when crying, is active and is beginning to walk.
Table II summarizes the clinical results obtained with the use of this technique. All 3 patients were desperately ill, cyanotic infants who withstood the operative procedure very well. Each had a significant and lasting increase in oxygen saturation which resulted in striking clinical improvement. In addition to the 3 patients in whom a defect was created, one other pa tient died during the operative procedure as a result of too vigorous dissection in the interatrial groove that resulted in severe and uncontrollable hemor rhage. This demonstrated that it is not necessary or desirable to carry out ex tensive dissection of this groove.
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DISCUSSION
Attempts to improve markedly cyanotic patients suffering from trans position of the great vessels have been made by both direct attack upon the great vessels themselves and by rearrangement of the venous and pulmonary inflow tracts. The direct approach on the great vessels has been attempted by Bailey, 4 Mustard, 18 Bjork, 5 and Idriss, 13 without success. The technical difficulties in managing the coronary arteries, together with the matching of low pressure chambers to high pressure systems and high pressure chambers to low pressure systems, have been the chief obstacle with this approach. Senning 21 and Kirklin 14 have reported complete intra-atrial correction in transposition of the great vessels with a mortality rate exceeding 50 per cent. Baffes3 has reported on a large number of cases (145) in which a partial palliative repair has been carried out. An increase in oxygen saturation of 22.8 per cent was measured in 6 eases. In patients younger than 3 months of age, the mortality was 29 per cent. In the classic report of Blalock and Hanlon," 36 patients were treated by extracardiac shunts, atrial septal defects, and a combination of these two methods. Improvement was achieved but their mortality rate in this experience was 30 per cent. Ochsner 19 and co-workers have reported treating 45 patients suffering from transposition of the great vessels by creating an atrial septal defect utilizing a modified version of the Blalock-Hanlon technique. An aver age increase of 17.37 per cent oxygen saturation was determined in 13 cases. Thirteen (29 per cent) succumbed in the immediate postoperative period. The need for a simple and safe technique for the creation of an atrial septal defect is apparent. A review of the literature from 1947 to the present revealed eleven dif ferent methods for producing atrial septal defects. 8-11 ' ir " 17'25_27 Most of these techniques were related to the intense interest of the cardiovascular surgeons at that time in developing techniques for closure of atrial septal defects. Several reports were of particular interest to us. Tcmpleton and Gibbon 26 re ported the disadvantages inherent in any technique in which interruption of the circulation is necessary. Swan and colleagues 25 produced elliptical incisions blindly with a knife, via the auricular wall. These atrial septal defects healed completely within a period of 3 weeks. This same group tried several other tech niques, one which utilized a rotary punch via the right atrial wall. This created a 1.0 cm. ragged defect that apparently healed within 2 weeks. Another method of this group utilized a special forceps. This technique produced a roughly circular defect, 1.0 cm. in diameter. Spontaneous healing occurred in 4 to 8 weeks. This same group removed 2.0 cm. circular pieces of tissue from the interatrial septum, under direct vision. Again, healing was common in 2 to 3 months. Martin and Essex, 17 in their report, stated that they used both blind and open techniques. They noted the tendency of artifically created atrial septal defects to close spontaneously. It was their opinion that closure was more pronounced in the smaller defects. In larger defects there was less tendency toward closure.
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Leeds, 15 in discussing Swan's paper, reported the creation of an atrial septal defect (using a modified nasal-septal punch), measuring 1.4 cm. in diameter, 162 days after operation. From these reports it appeared that atrial septal defects which consist of slits, regardless of length, heal within 2 to 3 weeks. Even defects created by removal of septal tissue, with a freshly cut margin left behind tend to heal. This conforms with our results when we used comparable techniques in the laboratory. Defects, 0.1 to 1.5 cm. in diameter, with ragged raw edges, generally healed within 2 to 3 months. The healing of defects greater than 1.5 cm. in diameter remained an open question.
Fig. 4.—Photograph of a newly created atrial septal defect in a dog which demonstrates that defects involving almost the entire septum can be established by means of this method.
The basic considerations given to our present investigation were to confirm the findings of others and to devise a method of creating an atrial septal defect that would, at the end of the healing period, remain open. This opening would have to be large enough to allow mixing of the two circulations with a result ing net increase in peripheral oxygen saturation which would approach 20 per cent or better. Alexis Carrel, 7 investigating the healing of wounds in dogs, noted a dif ference in the rate of reparation and the size of the wound. In a wound, 30 to 40 mm. in width or smaller, the retraction of the "granulations" was very efficient; it quickly brought the edges of the wound to a distance of 10 to 15 mm. This distance was very favorable to "epidermization." If a wound was 60 to 70 mm. or larger in size, the "retracting granulations" could not bring the edges to the minimum distance. Epidermization could not take place and rep-
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aration was brought to a standstill. This work supports the importance of the initial size of the wound on the ultimate dimensions of the atrial septal defect. Abercrombie, Flint, and James, 1 working with rats, removed small squares of skin within standard tattoo marks and measured the amount of wound con traction over various periods of time. Contraction occurred, was very active between 5 and 10 days after operation, and did not proceed after 10 days. They concluded that the wounded area exerts a contractile force on the wound edge. Watts, Grillo, and Gross28 removed 2 cm. squares of skin from guinea pigs, analyzed the wounds for collagen and degree of contraction, and con cluded that wound contraction is produced by activity in a narrow zone along the wound edges.
Figs. 5 and 6.—Atrial septal defects in dogs which had been created over 6 weeks prior to the sacrifice of the animals.
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Initial studies on the hearts of dogs used for acute experiments revealed that it was both possible and probable with our technique to create a defect involving 70 to 80 per cent of the inter-auricular septum. Fig. 4 demonstrates such a defect immediately after its creation. This entire atrial septum measured approximately 2.4 by 2.3 cm. whereas the defect created with this method measured 2.2 by 2.1 em. Long-term follow-up of dogs subjected to these tech niques indicated that permanent defects of significant size could be created in the hearts of dogs; Figs. 5 and 6 show defects which were created over a period of 6 weeks prior to the time that the animals were sacrificed. A defect created in the manner described herein contains an uncut and epithelized base made up of the triangular septal flap which represents an absence of contrac tile healing force in approximately one third of the total rim of the defect and has definite advantage in establishing a septal defect which does not heal. An interesting observation was made upon examination of the defects produced by the creation of the triangular flap. Evidence of the healing pro cess was not found on one third of the circumference of the defect. Approxi mately 60 per cent of the circumference of the defect had a rim consisting of firm, white, fibrous tissue characteristic of the final cicatrix. One third of the rim consists of normal, nonfibrous tissue. This portion of the rim represented the uncut base of the absorbed triangular flap of septal tissue. A review of the literature on mechanisms of wound healing led us to believe that this observa tion is an important one in the success of this technique. On the basis of both our experimental and clinical results, therefore, it appears that this operative technique conforms to our original requirements of a desirable method for creating inter-auricular septal defect in critically ill newborn infants. It is a simple, rapidly performed, and effective method of creating a sizable inter-auricular defect without the use of special equipment. SUMMARY
1. A simple and safe technique for the surgical creation of an atrial septal defect is described. 2. The anatomical facts which form the basis for this operation have been reviewed. 3. Three cases of transposition of the great vessels in which an interauricular septal defect has been established with the use of this technique are presented. We wish to express our thanks to Mrs. Denise P a v , supervisor of technical services in our laboratory, for her invaluable assistance in the completion of this work. REFERENCES
1. Abercrombie, M. H., Flint, M. H., and James, D. W.: Collagen Formation and Wound Contraction During Repair of Small Excised Wounds in the Skin of Rats, J . Embryol. Exper. Morph. 2: 264-274, 1954. 2. Ash, R., Johnson, J., Koop, C. E., Friedman, S., and Rashkind, W.: Cardiovascular Surgery in Children's Hospital. I I . Cyanotic Lesions: A Review of 193 Opera tions, J. Pediat. 54: 348-362, 1959.
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3. Baffes, T. G.: A N e w Method for Surgical Correction of Transposition of t h e Aorta and Pulmonary Artery, Surg. Gynec. & Obst. 102: 227-233, 1956. 4. Bailey, C. P., Cookson, B. A., Downing, D. F . , a n d Neptune, W. B . : Cardiac Surgery Under Hypothermia, J . THORACIC SURG. 27: 73-95, 1954. 5. Bjork, V. O., and Bouckaert, L.: Complete Transposition of t h e Aorta and t h e Pul monary A r t e r y : An Experimental Study of the Surgical Possibilities for I t s Treat ment, J . THORACIC SURG. 28: 632-635, 1954.
6. Blalock, A., and Hanlon, C. E . : Surgical Treatment of Complete Transposition of A o r t a and Pulmonary Artery, Surg. Gynec. & Obst. 90: 1-15, 1950. 7. Carrel, A.: The Treatment of Wounds, J . A. M. A. 55: 2148-2150, 1910. 8. Cohn, R.: An Experimental Method for t h e Closure of Inter-atrial Septal Defects in Dogs, Am. H e a r t J . 3 3 : 453-457, 1947. 9. Dodrill, F . D.: A Method for Exposure of the Cardia Septa, J . THORACIC SURG. 18: 652-660, 1949. 10. Donald, D. E. Kirklin, J . W., a n d Grindlay, J . H . : The Use of Poly vinyl Sponge Plugs in the Closure of Large Atrial Septal Defects Created Experimentally, Proc. Staff Meet. Mayo Clin. 28: 288-295 1953. 11. Donald, D. E., Kirklin, J . W., Ellis, F . H., and Grindlay, J . H . : Methods of Closure of Experimentally Produced Atrial Septal Defects, S. Forum 4 : 41-46, 1953. 12. Fetterolf, G., and Gittings, J . C : Some Anatomic Features of t h e Child's Thorax and Their Practical Application in Physiological Diagnosis, Am. J . Dis. Child. 1: 6-25, 1911. 13. Idriss, F . S., Goldstein, I . E., Granal, F . D., a n d P o t t s , W. J . : A N e w Technique for Complete Correction of Transposition of t h e Great Vessels. An Experimental Study With a Preliminary Clinical Report, Circulation 24: 5-11, 1961. 14. Kirklin, J . W., Devloo, E . A., a n d Weidman, W. H . : Open Intra-cardiac Eepair for Transposition of t h e Great Vessels, 11 Cases, Surgery 50: 58-66, 1961. 15. Leeds, S. E . : Discussion of Swan et al. 2 5 16. Martin, W. B., and Essex, H . E . : Experimental Production a n d Closure of Atrial Septal Defects W i t h Observations of Physiological Effects, Surgery 30: 283-297, 1951. 17. Martin, W. B., a n d Essex, H . E.: Production and Closure of Atrial Septal Defects in the Dogs, Observations on Atrial Pressures, Am. J . Physiol. 155: 453 1948. 18. Mustard, W. T., Chute, A .L., Keith, J . D., Sirek, A., Rowe, E . D., a n d Vlad, P . : A Surgical Approach to Transposition of the Great Vessels W i t h Extracorporeal Circuit, Surgery 36: 39-51, 1954. 19. Ochsner, J . L., Cooley, D. A., Harris, L. C , and McNamara, D. G.: Treatment of Com plete Transposition of t h e Great Vessels W i t h t h e Blalock-Hanlon Operation, Circulation 24: 51-54, 1961. 20. Eodriguez, J . A., a n d Wofford, J . L . : Surgical Anatomy of the Cardiac Septa, S. Forum 8: 274-277, 1957. 21. Senning, A.: Surgical Correction of Transposition of the Great Vessels, Surgery 4 5 : 966-980, 1959. 22. Sobotta and Mc Murrich: Atlas and Textbook of Human Anatomy, Philadelphia, 1914, W. B . Saunders Company, p. 143. 23. Sondergaard, T., Eahbeck Sorensen, H., Thue Poulsen, and Anderson, I . : Closure of Experimentally Produced A t r i a l Septal Defects, Acta chir. scandinav. 107: 485491, 1954. < 24. Sondergaard, T., Gotzsche, H., Ottosen, P., and Schultz, J . : Surgical Closure of I n t r a Atrial Septal Defects b y Circumclusion, Acta chir. scandinav. 109: 188-196, 1955. 25. Swan, H., Maresh, G., Johnson, M. D., a n d Warner, G.: Experimental Creation and Closure of Auricular Septal Defects, J . THORACIC SURG. 20: 542-551, 1950. 26. Templeton, J . Y., a n d Gibbon, J . H . : Experimental Reconstruction of Cardiac Valves by Venous and Pericardial Grafts, Ann. Surg. 129: 161-176, 1949. 27. Watkins, E., J r . , Pomeranz A. A., and Gross, R. E . : Healing P a t t e r n s Following Closure of Experimental Defects of t h e Atrial Septum, S. Forum 4 : 46-51, 1953. 28. W a t t s , G. T., Grillo, H . C , and Gross, J . : Studies in Wound Healing: The Role of Granulation Tissue in Contraction, Ann. Surg. 148: 153-160, 1958.