- Email: [email protected]
Failure of free spleen grafts to vascularize myocardium
Failure
of Free
Spleen
Vascularize
Grafts
to
Myocardium
DONALD J. GLOTZER, M.D., ALAN L. POHL, M.D., AND PHILLIP A. STONE, B.S.,
Boston, Massachusetts
From the Departments of Surgery, Tufts University School of Medicine and the New England Medical Center Hospitals, Boston, Masmchusetts. This work was aided by grant No. 782 from the Massachusetts Heart Association and an institutional U.S.P.H.S. research grant.
S
PLEEN
has
been
revascularize
used
splenocardiopexy
[1-31
using the known
ability
to implant (splenosis). ability plant and
We
have
and
to carry tested
either
or as free grafts of fragments
and reconstitute
of free grafts
have
experimentally
the myocardium
blood
[2,4-61 spleens
evaluated
on the pericardium
the
to as a
of spleen
into small
further
ventricular cavity, theoretically providing a pathway for blood from the ventricle to enter the myocardium. To challenge the hearts with intracavitary spleen with coronary ischemia, ameroid constrictors 2.77 mm. in internal diameter previously placed in sterile Vaseline for twenty minutes were placed on the anterior descending coronary or on both anterior descending and left circumflex arteries [7]. Control animals had either one or two ameroids placed without spleen strips. In these animals the ameroids were placed as closely to the origins of the two vessels as possible by ligating and dividing small branches hindering application at the origin; however, larger branches were left in situ. After death or after the animals had been killed with an overdose of a barbiturate, coronary angiography was performed by the injection of sodium diatrizoate under hand syringe pressure through a cannula which was tied into the root of the aorta after the branches had been ligated.
the to im-
to the myocardium
ability
of
graft placed into the left ventricle
a free
spleen
to carry blood
from the lumen of the heart to the myocardium. METHODS In mongrel dogs the spleen was removed through
RESULTS
a laparotomy incision which was then closed. The heart was exposed through a left anterolateral fourth interspace incision. The pericardium was opened anterior to the phrenic nerve. In the first group of experiments the spleen was minced into bits 1 to 2 mm. in diameter and then 2 to 3 ml. of this minced spleen was injected into the myocardium through a No. 14 gauge needle through several tracts which avoided the coronary vessels. An additional 4 to G ml. of spleen was placed in the pericardial sac which was closed tightly to contain the spleen. In most instances prior to placement of the pericardial spleen, the epicardium and pericardium were treated with a 10 per cent solution of formalin. We visualized that an epicardial frosting of vascular spleen with pericardial connections and with branches extending into the myocardium might result from this preparation. In the second group of experiments the spleen was cut into strips measuring 2 to 3 mm. in diameter and the strips were placed in stab wounds made through two walls of the ventricle traversing the
Implantation of Spleen on and in the Heart. Minced
spleen was placed in the pericardial cavity of ten dogs and the hearts studied nine days to two years thereafter. Although some spleen was implanted in each animal, only a small fraction of the amount placed in the pericardial cavity “took” and remained viable. Much of the pericardial spleen in the first days after operation remained as a mixture of blood and necrotic spleen. If the animal survived for a longer period of time, only scattered foci of viable spleen were seen. There were variable degrees of pericardial adhesion. Frequently this type of preparation, which required tight closure of pericardium to contain the spleen, particularly when combined with formalinization of the pericardium, produeed a picture of constrictive pericarditis with marked anasarca, ascites, and hydrothorax leading to death of the 28
The .4 merican Journal of Surgery
Myocardial
Revascularization
This occurred in six of the nine dogs tvhich had pericardial spleen, five of which had bcleri treated with formalin in addition to spleen. In seven of these dogs spleen was injected into the myocardium via a No. 14 gauge needle in addition to that implanted in the pericardial cavity. The myocardial spleen was found more likely to “take” than that in the pericardium. If the bits of spleen were sufficiently small, they apparently did not undergo necrosis before forming a viable splenulus. Larger pieces of spleen became necrotic particularly in their central portions before being absorbed and reconstituted. The spleen strips placed to traverse the ventricular cavity in fifteen dogs were readily implanted. (Fig. 1.) Bleeding fram the ventricle via the tract was not a problem since the spleen strip plugged the tract. Since the animals generally survived this type of implantation, the earlier stages of implantation were not well studied. In one animal that died at seven days, both viable and necrotic spleen were present. Histologically there usually was myocytolysis and later some fibrous tissue reaction about the spleen strips. In contrast to the viable spleen seen in the myocardium, the portion of spleen strip traversing the ventricular cavity ultimately became a fibrous band looking not un-
mitnal~.
like a chorda tendinea. (Fig. 2.) On tissue section these bands were covered by endothelium and contained very little splenic tissue. being composed of fibrous tissue frequently containing cartilage and on occasion even bone marrow. Ameroid constriction of the coronaries with resultant &hernia did not favor growth of spleen. Blood-Glrrying C@ucity. On microscopic examination the spleen usually contained small blood vessels in which variable numbers of erythrocytes could be seen. Although occasional large vascular channels were seen, the vessels usually were of appropriate size to supply the spleen present, and no other function of these vessels was suggested on morphologic grounds. In only two animals did angiograms show a “blush” that represented filling of the spleen grafts by the contrast material. (Fig. 3.) In most angiograms only the normal vessel pattern was seen or, as in some instances, there would be an actual dearth of vessels in the region of the grafts suggesting devascularization by the tract and the graft. (Fig. 4.) Spleen grafts were found abutting myocardial infarcts produced by ameroid coronary constriction, suggesting a lack of blood-carrying role. In fact, the spleen in infarcted areas frequently also became necrotic.
FIG. 1. Photomicrograph of transmyocardial spleen strip at four and a half months. Kate well preserved architecture and minimal surrounding fibrosis.
FIG. 2. Typical intraventricular portion of spleen strip; these became fibrotic cords which were well endotheliaiized on tissue section.
Vol. II/j.
July 196X
?!I
Glotzer,
30
Pohl, and Stone
3
4
FIG. 3. Best example of angiographic communication of spleen graft with coronary circulation. Arrow points to rectangular piece of spleen which filled from coronary circulation. FIG. 4. Usually the spleen tracts did not fill Ath contrast. In this example there was an actual lack of vessels in the region of implant at the apex (arrow).
Protection against Ameroid Constriction. Six control dogs had 2.77 ml. of ameroids placed on the left anterior descending coronary artery. One of these animals died at eleven days with pleural etIusions and atelectasis, but not myocardial infarct; the remaining animals in this group were sacrificed five to seven months later at which time well organized myocardial infarcts were found in two animals. Six experimental dogs had anterior descending ameroids placed and at the same time had transcavitary spleen strips placed. Although none of these animals died, two dogs had healed myocardial infarcts at the time of sacrifice at five and a half and seven months. Four dogs had spleen strips placed without constrictors and in none did myocardial infarcts develop. Six dogs had ameroids placed on both left anterior descending and left circumflex coronary arteries. Two of these animals died at fifteen and nineteen days, respectively, both with acute myocardial infarcts. An additional animal had a healed infarct at the time of the sacrifice six months later. Five experimental dogs had double ameroids plus spleen placed. In this group there were three deaths, all early and all due to myocardial infarcts. The hearts of the
remaining two dogs in this group showed no evidence of infarct at sacrifice. Thus, with both single and double ameroid constriction there was no apparent protection against ischemia by the implantation of spleen strips. COMMENTS
Splenosis is a term used to describe the phenomenon of autoimplantation of bits of splenic tissue after traumatic rupture or surgery. These bits of tissue are reconstituted to form splenculi with a microscopic structure almost indistinguishable from normal splenic tissue. This phenomenon can be produced experimentally and the steps that take place in so doing have been well described by Perla [8]. It seemed possible to us, as it had to others previously, that the spleen might be a rich source of vessels to supply the ischemic myocardium. Borow [I], Leighninger et al. [Z], and Seltzer and Maddock [3] all used spleen as a pedicle graft to the epicardium for this purpose. Garamella and Hay (PI, Movitz 151, and Sewall and Koth [6] used the phenomenon of splenosis as we had envisioned. Most of these investigators believed that there was some flow from the grafts to the heart by indirect means of The American
Journal of Swr~ery
Myocardial
Revascularization
nleasuremt’nt, but direct evidence of blood flow through the grafts was meager. Actually Sewall and Koth [S] demonstrated that the vascular connections \zere primarily venous. Our experiments confirmed the previous work insofar as \W axail demonstrated that free splenic grafts \~uld implant on the epicardium and pericardium. However, as in previous work, there \IYLSa disappointing lack of a tendency of the grafts to penetrate deeper into the heart even when the spleen was injected into myocardial tracts. IVe therefore attempted to assure that a continuous strip of spleen would penetrate from the epicardium into the myocardium and 50 began to place spleen strips into the myocardium This did not improve vascular connections between pericardial vessels and the myocardium. When one of these spleen strips was inadvertently introduced into the ventricle, it recalled experiments of Goldman et al. [9], 1Iassimo and Boffi [IO], and Vineberg, Baichwal. and Myers [II] who attempted to bring oxygenated blood from the ventricle into the myocardium by using vessel grafts, polyethylene tubes, or endocardial resections. Although these previous efforts failed because of obliteration of the ventricular openings, it seemed possible that spleen might provide a better type of tract since it already contained blood vessels and was not a foreign body. Initially it seemed that our dogs were being protected against double ameroid constriction, but final analysis of the results indicates that the control animals had equal survival to the experimental ones. The apparent protection in the early experiments proved to be due to the fact that coronary branches close to the origins of the left circumflex and left anterior descending coronary arteries were spared when the ameroid constrictors were applied. Furthermore at autopsy the ventricular portion of these spleen tracts invariably was well endothelialized and therefore protected from the blood stream. This was true whether or not the heart was challenged lvith ischemia. The most telling evidence against any major blood-carrying role of the spleen in these animals was the infrequent and meager angiographic filling of the experimentally implanted spleen. Therefore, although one might hypothesize that spleen as a vascular and perhaps somewhat primitive tissue capable of growing blood
I,‘ol. 110. July
1968
:
vessels might be a useful IINWI~ of InI-ocartlial vascularization, these cxprriment~ XII(I the rcsults of others reported UUIM ~nakr it appear that spleen, although readilv implat~tablc in or about the heart, is not a &ful meant of mvocardial revascularization. 1. An attempt has been made to use free grafts of spleen as a means of myocardial revascularization both as pericardial and n~vocardial grafts and as a means of carrvinx blood from the ventricle to the myocardiun;. 2. Although free spleen grafts become readily implanted in the myocardium. they arc not a useful means of carrying blood from either pericardial vessels or the ventricular cavity. RFFERENCFS i ,. 1. BOROW, hf. The use of cardiosplenopexy
to rev:~scularize the myocardiun~. .-1))I. .I ~‘/PoIv,-~,-.S’Z~J*:‘.1: 683, 1965. 2. LEIGHNIS(;ER, D. S., BECK, C. S., KVE(;EK. K. and I+XCHI, S. Spleen gK$ftS upon the heart. Fffect upon intercoronary blood flow. .i. T’horcr,-i~ $ cu/diowsc-. .shrg., 45: 412, 1Rtx~. 3. SELTZER. E. I. and MADDOCK, S. J. ‘l‘wllnique for supplenlenting coronary circulation by nlcans of a splenic graft. Rhode Island .\I. .I., :N: 195, 195B. 4. GARAMELLA, J. J. and HAY, L. J. r\utotra~~splantation of spleen: splenosis. Case report and preliminary report of an esperinwntal btutly in revdscularization of the heart. _17~~..Sirr,y., 141): 107, 1954. 5. MOVITZ, D. Kevascularization by pericartli:d ipIenosis and pericdrdiopesy. l’rrlin~inary report. .1..1 .X.;I _, 183: 264. 1963. 6. SEWAI.L, W. 1-I. and KOTH, D. K. Study of value of free autogenous splenic grafts for stirnulsting communications between mammary vessels and coronary circulation. .-Ingiology, 13: 101, 19W. 7. LITVAK, J., SIDERIDES, L. E.. and \‘ISEBERG, A. The experimental production of coronary artery insufficiency and occlusion. .lw. Wt’cirt .I.. 53: ,505, 1957. 8. PERLA, 1~. The regeneration of auto&tic transplants. :lnl. J. Pat/z.. 1%: 665, 1Wi.
splenic
9. GOLDMAN, A., GREENSTONE, S. M.. PRECSS. F. S., STRAUSS, S. H., and CHANG, E. S. Espt~rinlental rnethods for producing a collateral circulation to the heart directly frown the left ventricle. .1. Thoracic Surg., 31: 361. 1056. IO. MASSIMO, C. and BOFFI, L. Myocardinl revascularization by a new method of carryin!: blood directly from the left ventricular cavity into the coronary circulation. J. Thornric. .Clfrq.. 34: 2.57, 1957. 11. VINEBERG, A., BAICHWAL, Ii.. and ,~IYERS, J. Treattnent of acute myocardial infarction by endocardial resection. Surgery, 57: 832. 1965.
of Free
Spleen
Vascularize
Grafts
to
Myocardium
DONALD J. GLOTZER, M.D., ALAN L. POHL, M.D., AND PHILLIP A. STONE, B.S.,
Boston, Massachusetts
From the Departments of Surgery, Tufts University School of Medicine and the New England Medical Center Hospitals, Boston, Masmchusetts. This work was aided by grant No. 782 from the Massachusetts Heart Association and an institutional U.S.P.H.S. research grant.
S
PLEEN
has
been
revascularize
used
splenocardiopexy
[1-31
using the known
ability
to implant (splenosis). ability plant and
We
have
and
to carry tested
either
or as free grafts of fragments
and reconstitute
of free grafts
have
experimentally
the myocardium
blood
[2,4-61 spleens
evaluated
on the pericardium
the
to as a
of spleen
into small
further
ventricular cavity, theoretically providing a pathway for blood from the ventricle to enter the myocardium. To challenge the hearts with intracavitary spleen with coronary ischemia, ameroid constrictors 2.77 mm. in internal diameter previously placed in sterile Vaseline for twenty minutes were placed on the anterior descending coronary or on both anterior descending and left circumflex arteries [7]. Control animals had either one or two ameroids placed without spleen strips. In these animals the ameroids were placed as closely to the origins of the two vessels as possible by ligating and dividing small branches hindering application at the origin; however, larger branches were left in situ. After death or after the animals had been killed with an overdose of a barbiturate, coronary angiography was performed by the injection of sodium diatrizoate under hand syringe pressure through a cannula which was tied into the root of the aorta after the branches had been ligated.
the to im-
to the myocardium
ability
of
graft placed into the left ventricle
a free
spleen
to carry blood
from the lumen of the heart to the myocardium. METHODS In mongrel dogs the spleen was removed through
RESULTS
a laparotomy incision which was then closed. The heart was exposed through a left anterolateral fourth interspace incision. The pericardium was opened anterior to the phrenic nerve. In the first group of experiments the spleen was minced into bits 1 to 2 mm. in diameter and then 2 to 3 ml. of this minced spleen was injected into the myocardium through a No. 14 gauge needle through several tracts which avoided the coronary vessels. An additional 4 to G ml. of spleen was placed in the pericardial sac which was closed tightly to contain the spleen. In most instances prior to placement of the pericardial spleen, the epicardium and pericardium were treated with a 10 per cent solution of formalin. We visualized that an epicardial frosting of vascular spleen with pericardial connections and with branches extending into the myocardium might result from this preparation. In the second group of experiments the spleen was cut into strips measuring 2 to 3 mm. in diameter and the strips were placed in stab wounds made through two walls of the ventricle traversing the
Implantation of Spleen on and in the Heart. Minced
spleen was placed in the pericardial cavity of ten dogs and the hearts studied nine days to two years thereafter. Although some spleen was implanted in each animal, only a small fraction of the amount placed in the pericardial cavity “took” and remained viable. Much of the pericardial spleen in the first days after operation remained as a mixture of blood and necrotic spleen. If the animal survived for a longer period of time, only scattered foci of viable spleen were seen. There were variable degrees of pericardial adhesion. Frequently this type of preparation, which required tight closure of pericardium to contain the spleen, particularly when combined with formalinization of the pericardium, produeed a picture of constrictive pericarditis with marked anasarca, ascites, and hydrothorax leading to death of the 28
The .4 merican Journal of Surgery
Myocardial
Revascularization
This occurred in six of the nine dogs tvhich had pericardial spleen, five of which had bcleri treated with formalin in addition to spleen. In seven of these dogs spleen was injected into the myocardium via a No. 14 gauge needle in addition to that implanted in the pericardial cavity. The myocardial spleen was found more likely to “take” than that in the pericardium. If the bits of spleen were sufficiently small, they apparently did not undergo necrosis before forming a viable splenulus. Larger pieces of spleen became necrotic particularly in their central portions before being absorbed and reconstituted. The spleen strips placed to traverse the ventricular cavity in fifteen dogs were readily implanted. (Fig. 1.) Bleeding fram the ventricle via the tract was not a problem since the spleen strip plugged the tract. Since the animals generally survived this type of implantation, the earlier stages of implantation were not well studied. In one animal that died at seven days, both viable and necrotic spleen were present. Histologically there usually was myocytolysis and later some fibrous tissue reaction about the spleen strips. In contrast to the viable spleen seen in the myocardium, the portion of spleen strip traversing the ventricular cavity ultimately became a fibrous band looking not un-
mitnal~.
like a chorda tendinea. (Fig. 2.) On tissue section these bands were covered by endothelium and contained very little splenic tissue. being composed of fibrous tissue frequently containing cartilage and on occasion even bone marrow. Ameroid constriction of the coronaries with resultant &hernia did not favor growth of spleen. Blood-Glrrying C@ucity. On microscopic examination the spleen usually contained small blood vessels in which variable numbers of erythrocytes could be seen. Although occasional large vascular channels were seen, the vessels usually were of appropriate size to supply the spleen present, and no other function of these vessels was suggested on morphologic grounds. In only two animals did angiograms show a “blush” that represented filling of the spleen grafts by the contrast material. (Fig. 3.) In most angiograms only the normal vessel pattern was seen or, as in some instances, there would be an actual dearth of vessels in the region of the grafts suggesting devascularization by the tract and the graft. (Fig. 4.) Spleen grafts were found abutting myocardial infarcts produced by ameroid coronary constriction, suggesting a lack of blood-carrying role. In fact, the spleen in infarcted areas frequently also became necrotic.
FIG. 1. Photomicrograph of transmyocardial spleen strip at four and a half months. Kate well preserved architecture and minimal surrounding fibrosis.
FIG. 2. Typical intraventricular portion of spleen strip; these became fibrotic cords which were well endotheliaiized on tissue section.
Vol. II/j.
July 196X
?!I
Glotzer,
30
Pohl, and Stone
3
4
FIG. 3. Best example of angiographic communication of spleen graft with coronary circulation. Arrow points to rectangular piece of spleen which filled from coronary circulation. FIG. 4. Usually the spleen tracts did not fill Ath contrast. In this example there was an actual lack of vessels in the region of implant at the apex (arrow).
Protection against Ameroid Constriction. Six control dogs had 2.77 ml. of ameroids placed on the left anterior descending coronary artery. One of these animals died at eleven days with pleural etIusions and atelectasis, but not myocardial infarct; the remaining animals in this group were sacrificed five to seven months later at which time well organized myocardial infarcts were found in two animals. Six experimental dogs had anterior descending ameroids placed and at the same time had transcavitary spleen strips placed. Although none of these animals died, two dogs had healed myocardial infarcts at the time of sacrifice at five and a half and seven months. Four dogs had spleen strips placed without constrictors and in none did myocardial infarcts develop. Six dogs had ameroids placed on both left anterior descending and left circumflex coronary arteries. Two of these animals died at fifteen and nineteen days, respectively, both with acute myocardial infarcts. An additional animal had a healed infarct at the time of the sacrifice six months later. Five experimental dogs had double ameroids plus spleen placed. In this group there were three deaths, all early and all due to myocardial infarcts. The hearts of the
remaining two dogs in this group showed no evidence of infarct at sacrifice. Thus, with both single and double ameroid constriction there was no apparent protection against ischemia by the implantation of spleen strips. COMMENTS
Splenosis is a term used to describe the phenomenon of autoimplantation of bits of splenic tissue after traumatic rupture or surgery. These bits of tissue are reconstituted to form splenculi with a microscopic structure almost indistinguishable from normal splenic tissue. This phenomenon can be produced experimentally and the steps that take place in so doing have been well described by Perla [8]. It seemed possible to us, as it had to others previously, that the spleen might be a rich source of vessels to supply the ischemic myocardium. Borow [I], Leighninger et al. [Z], and Seltzer and Maddock [3] all used spleen as a pedicle graft to the epicardium for this purpose. Garamella and Hay (PI, Movitz 151, and Sewall and Koth [6] used the phenomenon of splenosis as we had envisioned. Most of these investigators believed that there was some flow from the grafts to the heart by indirect means of The American
Journal of Swr~ery
Myocardial
Revascularization
nleasuremt’nt, but direct evidence of blood flow through the grafts was meager. Actually Sewall and Koth [S] demonstrated that the vascular connections \zere primarily venous. Our experiments confirmed the previous work insofar as \W axail demonstrated that free splenic grafts \~uld implant on the epicardium and pericardium. However, as in previous work, there \IYLSa disappointing lack of a tendency of the grafts to penetrate deeper into the heart even when the spleen was injected into myocardial tracts. IVe therefore attempted to assure that a continuous strip of spleen would penetrate from the epicardium into the myocardium and 50 began to place spleen strips into the myocardium This did not improve vascular connections between pericardial vessels and the myocardium. When one of these spleen strips was inadvertently introduced into the ventricle, it recalled experiments of Goldman et al. [9], 1Iassimo and Boffi [IO], and Vineberg, Baichwal. and Myers [II] who attempted to bring oxygenated blood from the ventricle into the myocardium by using vessel grafts, polyethylene tubes, or endocardial resections. Although these previous efforts failed because of obliteration of the ventricular openings, it seemed possible that spleen might provide a better type of tract since it already contained blood vessels and was not a foreign body. Initially it seemed that our dogs were being protected against double ameroid constriction, but final analysis of the results indicates that the control animals had equal survival to the experimental ones. The apparent protection in the early experiments proved to be due to the fact that coronary branches close to the origins of the left circumflex and left anterior descending coronary arteries were spared when the ameroid constrictors were applied. Furthermore at autopsy the ventricular portion of these spleen tracts invariably was well endothelialized and therefore protected from the blood stream. This was true whether or not the heart was challenged lvith ischemia. The most telling evidence against any major blood-carrying role of the spleen in these animals was the infrequent and meager angiographic filling of the experimentally implanted spleen. Therefore, although one might hypothesize that spleen as a vascular and perhaps somewhat primitive tissue capable of growing blood
I,‘ol. 110. July
1968
:
vessels might be a useful IINWI~ of InI-ocartlial vascularization, these cxprriment~ XII(I the rcsults of others reported UUIM ~nakr it appear that spleen, although readilv implat~tablc in or about the heart, is not a &ful meant of mvocardial revascularization. 1. An attempt has been made to use free grafts of spleen as a means of myocardial revascularization both as pericardial and n~vocardial grafts and as a means of carrvinx blood from the ventricle to the myocardiun;. 2. Although free spleen grafts become readily implanted in the myocardium. they arc not a useful means of carrying blood from either pericardial vessels or the ventricular cavity. RFFERENCFS i ,. 1. BOROW, hf. The use of cardiosplenopexy
to rev:~scularize the myocardiun~. .-1))I. .I ~‘/PoIv,-~,-.S’Z~J*:‘.1: 683, 1965. 2. LEIGHNIS(;ER, D. S., BECK, C. S., KVE(;EK. K. and I+XCHI, S. Spleen gK$ftS upon the heart. Fffect upon intercoronary blood flow. .i. T’horcr,-i~ $ cu/diowsc-. .shrg., 45: 412, 1Rtx~. 3. SELTZER. E. I. and MADDOCK, S. J. ‘l‘wllnique for supplenlenting coronary circulation by nlcans of a splenic graft. Rhode Island .\I. .I., :N: 195, 195B. 4. GARAMELLA, J. J. and HAY, L. J. r\utotra~~splantation of spleen: splenosis. Case report and preliminary report of an esperinwntal btutly in revdscularization of the heart. _17~~..Sirr,y., 141): 107, 1954. 5. MOVITZ, D. Kevascularization by pericartli:d ipIenosis and pericdrdiopesy. l’rrlin~inary report. .1..1 .X.;I _, 183: 264. 1963. 6. SEWAI.L, W. 1-I. and KOTH, D. K. Study of value of free autogenous splenic grafts for stirnulsting communications between mammary vessels and coronary circulation. .-Ingiology, 13: 101, 19W. 7. LITVAK, J., SIDERIDES, L. E.. and \‘ISEBERG, A. The experimental production of coronary artery insufficiency and occlusion. .lw. Wt’cirt .I.. 53: ,505, 1957. 8. PERLA, 1~. The regeneration of auto&tic transplants. :lnl. J. Pat/z.. 1%: 665, 1Wi.
splenic
9. GOLDMAN, A., GREENSTONE, S. M.. PRECSS. F. S., STRAUSS, S. H., and CHANG, E. S. Espt~rinlental rnethods for producing a collateral circulation to the heart directly frown the left ventricle. .1. Thoracic Surg., 31: 361. 1056. IO. MASSIMO, C. and BOFFI, L. Myocardinl revascularization by a new method of carryin!: blood directly from the left ventricular cavity into the coronary circulation. J. Thornric. .Clfrq.. 34: 2.57, 1957. 11. VINEBERG, A., BAICHWAL, Ii.. and ,~IYERS, J. Treattnent of acute myocardial infarction by endocardial resection. Surgery, 57: 832. 1965.