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Surgical Management of Diseased Intracavitary Coronary Arteries
Surgical Management of Diseased Intracavitary Coronary Arteries John L. Ochsner and Noel L. Mills Ann Thorac Surg 1984;38:356-362 DOI: 10.1016/S0003-4975(10)62285-0
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The Annals of Thoracic Surgery is the official journal of The Society of Thoracic Surgeons and the Southern Thoracic Surgical Association. Copyright © 1984 by The Society of Thoracic Surgeons. Print ISSN: 0003-4975; eISSN: 1552-6259.
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Surgical Management of Diseased Intracavitary CorlonaryArteries John L. Ochsner, M.D., and Noel L. Mills, M.D. ABSTRACT An intracavitarylocation of a coronary artery is rare in our surgical experience with myocardialvascularization. This variant has occurred in the right coronary artery (0.09%) and in the left anterior descending coronary artery (0.2%). The location of the lesion and the pathological condition, length, and size of the coronary artery may dictate exposure of an intracavitary coronary artery for proper revascularization. More commonly, surgeons are unaware of the intracavitaryposition and during intramyocardial dissection of an artery will open a cardiac chamber where the vessel traverses the cavity. Problems that arise are introduction of air, difficulty in exposure due to blood and depth of position, and obstruction of the coronary artery during closure of the myotomy. We report here on 13 patients who required revascularization of intracavitary vessels (four right coronary arteries and six left anterior descending lcoronary arteries). The location and length of the intracavitary portion of the artery determined the surgical management. The methods used to close the cavity varied. The techniques employed were simple closure; moving the artery into an aerial position with cavitary closure behind it; anastomosis in the intracavitary position with closure of the myotomy around the graft; or selection of an altexnate distal site for anastomosis. All patients treated for iintracavitary arteries were successfully revascularized withLout major complications. Coronary arteries usually lie on the surface of the heart, covered only by the epicardium. However, there are variations of this anatomical configuration. The artery may lie above the heart in an aerial position or within the myocardium in a mural (intramyocardial)position, or it may penetrate a cardiac chamber and thus lie in an intracavitary position. A mural coronary artery occurs rather frequently; however, a coronary artery in the aerial or intracavitary location is rare. To our knowledge, only McAlpine [l] has reported the existence of intracavitary arteries. In 1,OOCl dissected, nondiseased hearts, he noted the right coronary artery to be in an intracavitary position in one instance (0.1%)and the left anterior descending (LAD) cclronary artery to be in an intracavitary position in three instances (0.3%). From the Department of Surgery, Othsner Clinic and Alton Ochsner Medical Foundation, New Orleans, LA. Presented at the Twentieth Annual Meeting of The society of Thoracic Surgeons, San Antonio, TX, Jan 23-25, 1984. Address reprint requests to Dr.Ochsner, 1516 Jefferson Hwy, New Orleans, LA 70121.
The operative exposure of an intracavitary coronary artery necessarily opens a cardiac chamber and may introduce technical difficulties, such as entry of air into venous lines, operative hemorrhage, inadequate exposure, postoperative bleeding, and the arduous task of performing closure without injuring or obstructing the coronary artery. Because of the rarity of this coronary anatomical variation and the potential inherent problems, we reviewed our experience with intracavitary arteries. This report discusses the methods by which the condition was managed.
Material and Method The operative experience with direct myocardial revascularization at the Ochsner Clinic from 1969 through 1982 was reviewed. During this period, there were 4,414 operations; in 13 patients we encountered intracavitary coronary arteries during dissection of the arteries for bypass grafting. Only the main right coronary artery and anterior descending branch of the left coronary artery were found to enter a cardiac chamber. The right coronary artery entered the right atrium in 4 patients (0.09%), and the LAD branch entered the right ventricle in 9 patients (0.2%). The intracavitary right coronary artery entered the right atrium shortly after its origin in 2 patients and entered at the acute margin in the other 2. In all 4 patients, the artery emerged to a surface position on the posterior aspect of the heart. The arteries remained in an intraatrial position for only a short distance in 1 patient; however, in the other 3 patients the artery did not emerge to the surface until after the takeoff at the right posterior descending branch on the diaphragmatic surface of the heart. The location of the intracavitary LAD coronary arteries was not consistent. Six occurred in the lower portion of the upper third and 3 were encountered in the midportion of the middle third of this artery. In only 1patient was the diagnosis of an intracavitary coronary artery entertained preoperatively. In this patient, the configuration and position of the LAD coronary artery in the lateral projection of the coronary cineangiogram suggested that the artery may lie within the right ventricular cavity (Fig 1). Even a retrospective review of the angiograms was disappointing in revealing intracavitary arteries. In only 1 other patient with an intracavitary LAD coronary artery did the angiogram suggest such a location. Usually, the intracavitary LAD enters the right ventricle early in its descending course and emerges to the surface subtly in a long curve. Occasionally, the artery changes depth of course acutely. When this occurs, one may suspect an intracavitarylocation.
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357 Ochsner and Mills: Surgical Management of Intracavitary Coronary Arteries
Fig 1 . Coronary angiogram in left lateral position. Arrow points to acute deep angulation of the left anterior descending coronary artery from the surface of heart.
Management and Results In each patient, the intracavitary coronary artery was encountered during dissection of a coronary artery lying within an intramyocardial tunnel. Since we routinely use a single atrial catheter for venous drainage, air entered the venous line of extracorporeal circulation in each of the 4 patients in whom the right atrium was opened during dissection of the right coronary artery. The sound of air in the venous line heralded the opening of the right atrium. The problem was easily managed in each instance. In 2 patients, the right atrium was isolated by converting the venous return to double caval siphon drainage with caval tourniquets. In the other two instances, the opening could be managed without the need to isolate the right atrium. Temporary finger approximation of the atriotomy edges controlled the opening while the edges were sutured superficially to the artery in 1patient and deep to the artery in the other. In all 4 patients, a vein was used as the bypass graft. In 1 patient, the anastomosis was performed within the right atrium with closure of the atrium around the graft (Fig
2). In 2 patients, the opening in the atrium was obliterated with horizontal mattress sutures beneath the artery. The coronary artery was thereby placed in an aerial position, and the vein-to-artery anastomosis was performed at this site (Fig 3). In another patient, the atrial opening was sutured, allowing the coronary artery to remain in its intracavitary position, and a distal alternative site was selected for anastomosis where the right posterior descending branch lay in an epicardial position. In 9 patients, the intracavitary LAD artery was encountered as the surgeon dissected this vessel in an intramyocardial course. In 5 patients, the dissection was begun distally from an exposed LAD coronary artery or one of its diagonal branches in an epicardial location, and the right ventricle was entered as the dissection proceeded superiorly through a myocardial tunnel. In the other 4 patients, the right ventricle was entered as the surgeon dissected directly through the fat and myocardium in the interventricular groove to locate the LAD in its proximal position (Fig 4). In each of these four instances, it was the surgeon’s opinion that the dissection was immediately on top of the vessel and the cavity not entered inadvertently as a result of dissection at a distance from the course of the vessel. In only 1 of these patients did air enter into the venous line of extracor-
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358 The Annals of Thoracic Surgery Vol 38 No 4 October 1984
Fig 2 . Saphenous vein-right coronary artery bypass. Anastomosis is within the right atrium, and the atriotcimy is closed around the graft.
Fig 3 . Saphewus vein-right coronary artery bypass. The intracavitary coronary artery is repositioned in!an aerial position, and the anastomosis is performed in the exteriorized artery.
Fig 4 . Incision in interventricular groove. Exposure of coronary artery reveals intracavitary position.
poreal circulation. In all other instances, the opening of the right ventricular cavity was evidenced by the appearance of blood and the characteristic trabecular endocardial surface of the right ventricle. The management of the LAD intracavitary arteries was diverse. In 1 patient, direct suture closure of the myotomy was performed and an alternate distal site was selected for anastomosis. In 7 patients, the ventriculotomy was closed in such a manner as to reposition the LAD in an aerial location by closing the ventriculotomy with buttressed mattress sutures passed beneath the artery (Fig 5). The sutures were buttressed with Teflon felt or epicardial pledgets. In 6 patients, the sutures were passed from epicardial to epicardial surface, while in 1patient, the mattress suture incorporated only the myocardium of the myotomy. In order not to obstruct the coronary artery at either the inlet or outlet of the intramyocardial and intracavitary artery by closure with the mattress sutures, an adequate length of artery must be exposed. The anastomosis in these 7 patients was made at the midportion of the repositioned coronary artery. In 1 patient with a long intracavitary and intramyocardial segment, attempts to reposition the LAD resulted in obstruction of flow. In this patient, the anastomosis was performed, the artery was allowed to remain in its intracavitary position, and the myotomy was closed with a pericardial patch through which the graft traversed. This resulted in unobstructed flow (Fig 6 )*
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359 Ochsner and Mills: Surgical Management of Intracavitary Coronary Arteries
A
B
Fig 5 . (A)Placement of buttressed mattress sutures used to close ventriculotomy. (B)Closure of ventriculotomy elevates the left anterior descending coronary artery into an aerial position.
become clinically important as there are reports of ischemia caused by the milking effect of the systolic contraction of the vessel in this position [8-lo]. The intramyocardial LAD may also be short in length and depth and covered by only a small bridge of myocardial fibers, or it may run the entire length of the heart. The mural artery may become so deep that it assumes an intracavitary position. A thorough knowledge of the coronary anatomy is essential in coronary artery surgical procedures [ll]. One must be cognizant of the normal anatomy as well as the anomalies that exist. The anatomy of the coronary arteries is variable and differs in every individual, somewhat analogous to the dermatoglyphics of the hands and fingers. No two coronary angiograms will match if superimposed; however, certain anatomical patterns have been established to guide the cardiologist and surgeon. Experience enhances one's ability in interpreting the anatomy of the coronary arteries from coronary cineangiograms; however, it is difficult to determine the depth of the coronary arteries and their relation to epicardial fat, myocardial bridges, reaction or adhesions from previous operations, and the chambers of the heart. It would be of value to the surgeon to know preoperatively the precise anatomical configuration of those vessels intended for bypass grafting. One may ascertain
Operative incision of the myocardium and closure of the myotomy resulted in the expected elevation of myocardial isoenzyme levels (MB fraction). The percentage of MB fraction varied from 5 to 10.1%;however, only in the patient with an MB fraction of 10.1%was there electrocardiographic evidence of a perioperative myocardial infarction. Postoperative angiograms were obtained in 5 patients; in each, the graft to the involved artery was patent. There has been no electrocardiographicor radiographic evidence of aneurysm formation in the postoperative follow-up period. To date, none of the 13 patients has died, although the longest follow-up is only 7% years.
Comment An anomalous intramyocardial course of the LAD coronary artery was described in 1922 by Crainicianu [2]. Since then, many anatomists and angiographers have confirmed this finding, and the reported incidence has been from 0.75 to 85.7% [3-71. The intracavitary artery is an extension of an intramural artery in a deeper position. The identification of an intramyocardial course has
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360 The Annals of Thoracic Surgery Vol 38 No 4 October 1984
Fig 6. Anastomosis of internal mammary a r t e y to 1tft anterior descending coronay artery in intracavitary position. The ventriculotomy is closed with a pericardial patch through which passes the internal mammay artery graft.
angiographically that a coronary artery lies deep within the myocardium by the milking effect on the artery caused by circumferential myocardial contraction during systole. However, when the ariery is within a cavity, the milking effect does not exist. In coronary artery bypass grafting, the ideal site for anastomosis of the bypass graft is immediately distal to the narrowed or obstructive lesion. Such a location allows antegrade flow to the entire artery designated for revascularization and also allows anastomosis to the largest possible diameter of the specific coronary artery. Hence, it is desirable to perform an anastomosis as proximal as possible. One may wish to select a vessel in an intramyocardial position rather than use a more easily accessible, but smaller and less desirable, distal vessel. Also, many years ago, Geiringer [3] demonstrated that coronary arteries lying within the myocardium have thinner intima than those on the epicardium. Clinicians have noted that the intramyocardial coronary arteries often are not arteriosclerotic and hence are especially suited for anastomosis of a bypass graft. It is rarely suggested by the preoperative angiogram
but more commonly noted at operation that a vessel is embedded in muscle and therefore difficult to isolate. Various technical maneuvers, such as palpating the vessel in its hidden course or tracing the vessel either retrograde from a branch or antegrade from a segment of the vessel on the epicardial surface, may be helpful in isolating the desired area. A sterile Doppler flow probe, which determines the frequency shifts in an ultrasound beam as reflected from the moving cells within the vessel, may also be used. Most surgeons dissect out a mural LAD coronary artery by dissecting retrograde from this vessel in its epicardial position. With experience, surgeons become confident in dissecting an intramyocardial LAD in its proximal location by direct incision through the interventricular groove, with care being taken to ligate or dissect clear the concomitant coronary vein. The transverse myocardial fibers overlying the coronary artery are incised; when the artery lies in an intracavitary position, the condition becomes obvious by the appearance of blood and the trabecular endocardia1 surface. The surgeon then needs to determine the best method of management. One can elect to close the myocardium, allow the artery to remain in its original intracavitary position, and perform bypass to a more distal site, or one may choose to perform bypass at the originally desired area, that is, the intracavitary position. Important in the decision are the size and structure of the coronary arteries distally. Surgeons usually prefer to work on the epicardial surface. The fact that the surgeon chooses to dissect an artery in a muscular course indicates that the artery in its epicardial position is unacceptable. When one chooses to perform anastomosis to the intracavitary artery, it is usually desirable to elevate the artery and close the ventriculotomy beneath it. It is difficult to determine the exact incidence of intracavitary arteries through operative experience of dissecting coronary arteries by bypass grafts. Many of the vessels that lie in an intracavitary position may not have proximal obstruction and therefore would not require exposure; or, the site selected for bypass grafting may be distal to the intracavitary portion, and thus the intracavitary portion would not be known. To locate an intracavitary artery, this site must have been selected for bypass and the position have been discovered at the time of dissection. It might be assumed that our incidence of intracavitary lesions is abnormally high because the right ventricle or right atrium was inadvertently entered by dissecting at a distance from the desired vessel. However, it is our policy to dissect directly on the anterior aspect of a coronary artery. In none of the reported instances was the cavity opened away from the vessel, but only on dissection directly on top of the artery. Therefore, we believe that the incidence reported here is accurate. There is no way that we have been able to determine the intracavitary position of a right coronary artery, either preoperatively or in a retrospectivereview of coronary cineangiograms. All intracavitaryLAD coronary ar-
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361 Ochsner and Mills: Surgical Management of Intracavitary Coronary Arteries
teries must descend and ascend in an intramyocardial course before entering the right ventricle. There are certain angiographic clues, such as decrease in the size of the vessel during systole as it lies in an intramyocardial position or an acute angle of the artery toward the ventricular cavity as viewed angiographically on a lateral view. The intracavitary LAD usually assumes the position in a subtle course; occasionally, however, the entrance or exit may be acute. Cognizance of these clues may alert the surgeon to the possibility of an intracavitary coronary artery. Various technical maneuvers can be used to successfully handle an intracavitary coronary artery required for myocardial revascularization [121.
References 1. M d p i n e WA: Heart and Coronary Arteries. New York, Springer-Verlag, 1975 2. Crainicianu A: Anatomische Studien iiber die Coronarterien und experimentelle Untersuchungen iiber ihre Durchgangigkeit. Virchows Arch [Pathol Anat] 238:1, 1922 3. Geiringer E: The mural coronary. Am Heart J 41:359, 1951 4. Noble J, Bouressa MG, Petitderc R, et al: Myocardial bridging and milking effect of the left anterior descending coronary artery: normal variant or obstruction? Am J Cardiol 37993, 1976 5. Amplatz K, Anderson R Angiographic appearance of myocardial bridging of the coronary artery. Invest Radio1 3:213, 1968 6. Rossi L, Dander B, Nidasio GP, et al: Myocardial bridges and ischemic heart disease. Eur Heart J 1239, 1980 7. Blake HA, Manion WC, Mattingly TW, et a1 Coronary artery anomalies. Circulation 30:927, 1964 8. Polacek P, Kralove H. Relation of myocardial bridges and loops on the coronary artery to coronary artery occlusion. Am Heart J 61:44, 1961 9. Ishimori T, Raizner AE, Chahine RA, et al: Myocardial bridges in man: clinical correlation and angiographic accentuation with nitroglycerins. Cathet Cardiovasc Diagn 3:59, 1977 10. Morales AR, Romanelli R, Boucek RJ, et al: The mural left anterior descending coronary artery, strenuous exercise and sudden death. Circulation 62230, 1980 11. Marshall ME, Headley RN: Intramural coronary artery as a cause of unstable angina pectoris. South Med J 71:1304, 1978 12. Ochsner JL, Mills NL: Coronary Artery Surgery. Philadelphia, Lea and Febiger, 1978
Discussion DR. HENDRIK B. BARNER (St. Louis, MO): My colleagues and I are indebted to Drs. Ochsner and Mills for bringing to our attention an important variant in coronary anatomy. In the past year we have found three right coronary arteries lying within the right atrium, and we are delighted that we now know what to call this anatomical variant. With regard to the LAD coronary artery, we have not recognized the intracavitary position. Earlier in our experience, we entered the right ventricle on a number of occasions while exposing a submuscular LAD and assumed that this was secondary to injudicious dissection, whereas it may have been related to an intracavitary position of the LAD. Dr.Ochsner has indicated several angiographic clues for rec-
ognizing the intracavitary LAD. These clues do not exist for the right coronary artery. At operation, the surgeon who is alert to the possibility of this anatomical variant may avoid chamber entry by an anastomosis distal to the intracavitary portion, but diminutive coronary size may dictate use of the intracavitary segment. Dr. Ochsner has provided us with several techniques for closure of the right ventriculotomy or right atriotomy without compromise of coronary flow or the anastomosis. We suggest an alternative technique in which horizontal mattress sutures are placed from the free wall of the right ventricle into the septum beneath the LAD rather than to the opposite cut edge, so that the free wall is displaced posteriorly to close the ventriculotomy . We have not been so confident of our ability to locate a submuscular LAD by direct incision over the septum, and we prefer to dissect retrogradely from the distal epicardial LAD or from a diagonal artery. Alternatively, we make a small incision in the distal LAD and pass a I-mm probe proximally as a guide to precise localization of the submuscular segment. The distal LAD can be closed with an epicardial suture. The Ochsner Clinic has once again provided us with new information of pragmatic value for the clinical surgeon. DR. HERBERT E. WARDEN: Dr. Ochsner, were there any problems in mobilizing the LAD coronary artery as a result of the potential tethering of this vessel by the septa1 perforators?
DR. OCHSNER: In answer to Dr. garner's questions, all 9 of the LAD anomalies were definitely intracavitary arteries. Our series would have been bigger if we had included patients in whom we inadvertently entered the right ventricle. It is amazing that we do not see intracavitary arteries elsewhere, because all of us who do anastomoses to the ramus or the proximal margin observe that the artery dips into the muscle right away. There is, however, a difference in the thickness of the ventricles. The left ventride is so thick that the artery can follow an intramyocardial or intramural course and still not penetrate the ventricle. However, when the LAD courses to the right of its intervent r i d a r course, it does not have to go very deep before it is in the right ventricle. We have entered the right ventricle inadvertently and found that the vessel there was not an intracavitary artery. We do not open the distal arteries and insert probes. In at least half of these patients, the LAD was followed from the distal LAD or from a diagonal branch, but we usually dissect directly onto the vessel. In answer to Dr. Warden's question, you do have to watch out for perforators, particularly when you place the big mattress sutures under the intracavitary artery to elevate it. The first thing we do is lengthen the myotomy sufficiently so that it can be elevated. We were able to do this in all of our patients except the 1 in whom the intracavitary artery was so long that every attempt to close the myotomy resulted in obstruction. I am not sure that we do not get a few perforators; it is inconceivable that some are not encountered in closure of the myocardium beneath the elevated intracavitary artery. In closing the right ventricle, it is important not to tie down the mattress sutures very tightly. All that is necessary is to approximate, because the pressure in the right ventricle is much less than the systemic pressure in the coronary arteries and probably even the diastolic pressure; therefore, filling could occur through the perforators unless they are cut by the sutures. I think we probably do destroy a few perforators, but this can occur without too much damage.
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362 The Annals of Thoracic Surgery Vol 38 No 4 October 1984
VICE PRESIDENT MAGOVERN: When I have encountered intracavitary or intramyocardial arteiies, I have always been struck by the fact that in that position, the vessel always appears to be free from disease. Has that been your experience also and do you have any explanation for it?
DR. OCHSNER: In
1922 Crainicianu noted that all of the vessels in the myocardium were either free from disease or had a very
thin intimal lining. As cliniaans we have observed this to be true. The theory is that the vessels are disease free because they have been milked; the milking effect is similar to that in the leg, where there is less disease in the profunda femoris than in the superficial femoral artery. But at the same time, the intracavitary artery is never completely circumferential in muscle. The fact that the artery is in this area, coupled with the milking effect, probably prevents the formation of arteriosclerotic lesions in the vessel.
Notice from the American Board of Thoracic Surgery The Part I (written) examination will be held at the Amfac Hotel, DallasFort Worth Airport, Dallas, TX, in February, 1986. The closing date for registration is August 1, 1985. To be admissible for the Part I1 (oral) examination, a candidate must have successfullly completed the Part I (written) examination.
A candidate applying for admission to the certifying examination must fulfill all the requirements of the Board in force at the time the application is received. Please address all communications to the American Board of Thoracic Surgery, 14640 E Seven Mile Rd, Detroit, MI 48205.
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Surgical Management of Diseased Intracavitary Coronary Arteries John L. Ochsner and Noel L. Mills Ann Thorac Surg 1984;38:356-362 DOI: 10.1016/S0003-4975(10)62285-0 Updated Information & Services
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The online version of this article, along with updated information and services, is located on the World Wide Web at: http://ats.ctsnetjournals.org
The Annals of Thoracic Surgery is the official journal of The Society of Thoracic Surgeons and the Southern Thoracic Surgical Association. Copyright © 1984 by The Society of Thoracic Surgeons. Print ISSN: 0003-4975; eISSN: 1552-6259.
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Surgical Management of Diseased Intracavitary CorlonaryArteries John L. Ochsner, M.D., and Noel L. Mills, M.D. ABSTRACT An intracavitarylocation of a coronary artery is rare in our surgical experience with myocardialvascularization. This variant has occurred in the right coronary artery (0.09%) and in the left anterior descending coronary artery (0.2%). The location of the lesion and the pathological condition, length, and size of the coronary artery may dictate exposure of an intracavitary coronary artery for proper revascularization. More commonly, surgeons are unaware of the intracavitaryposition and during intramyocardial dissection of an artery will open a cardiac chamber where the vessel traverses the cavity. Problems that arise are introduction of air, difficulty in exposure due to blood and depth of position, and obstruction of the coronary artery during closure of the myotomy. We report here on 13 patients who required revascularization of intracavitary vessels (four right coronary arteries and six left anterior descending lcoronary arteries). The location and length of the intracavitary portion of the artery determined the surgical management. The methods used to close the cavity varied. The techniques employed were simple closure; moving the artery into an aerial position with cavitary closure behind it; anastomosis in the intracavitary position with closure of the myotomy around the graft; or selection of an altexnate distal site for anastomosis. All patients treated for iintracavitary arteries were successfully revascularized withLout major complications. Coronary arteries usually lie on the surface of the heart, covered only by the epicardium. However, there are variations of this anatomical configuration. The artery may lie above the heart in an aerial position or within the myocardium in a mural (intramyocardial)position, or it may penetrate a cardiac chamber and thus lie in an intracavitary position. A mural coronary artery occurs rather frequently; however, a coronary artery in the aerial or intracavitary location is rare. To our knowledge, only McAlpine [l] has reported the existence of intracavitary arteries. In 1,OOCl dissected, nondiseased hearts, he noted the right coronary artery to be in an intracavitary position in one instance (0.1%)and the left anterior descending (LAD) cclronary artery to be in an intracavitary position in three instances (0.3%). From the Department of Surgery, Othsner Clinic and Alton Ochsner Medical Foundation, New Orleans, LA. Presented at the Twentieth Annual Meeting of The society of Thoracic Surgeons, San Antonio, TX, Jan 23-25, 1984. Address reprint requests to Dr.Ochsner, 1516 Jefferson Hwy, New Orleans, LA 70121.
The operative exposure of an intracavitary coronary artery necessarily opens a cardiac chamber and may introduce technical difficulties, such as entry of air into venous lines, operative hemorrhage, inadequate exposure, postoperative bleeding, and the arduous task of performing closure without injuring or obstructing the coronary artery. Because of the rarity of this coronary anatomical variation and the potential inherent problems, we reviewed our experience with intracavitary arteries. This report discusses the methods by which the condition was managed.
Material and Method The operative experience with direct myocardial revascularization at the Ochsner Clinic from 1969 through 1982 was reviewed. During this period, there were 4,414 operations; in 13 patients we encountered intracavitary coronary arteries during dissection of the arteries for bypass grafting. Only the main right coronary artery and anterior descending branch of the left coronary artery were found to enter a cardiac chamber. The right coronary artery entered the right atrium in 4 patients (0.09%), and the LAD branch entered the right ventricle in 9 patients (0.2%). The intracavitary right coronary artery entered the right atrium shortly after its origin in 2 patients and entered at the acute margin in the other 2. In all 4 patients, the artery emerged to a surface position on the posterior aspect of the heart. The arteries remained in an intraatrial position for only a short distance in 1 patient; however, in the other 3 patients the artery did not emerge to the surface until after the takeoff at the right posterior descending branch on the diaphragmatic surface of the heart. The location of the intracavitary LAD coronary arteries was not consistent. Six occurred in the lower portion of the upper third and 3 were encountered in the midportion of the middle third of this artery. In only 1patient was the diagnosis of an intracavitary coronary artery entertained preoperatively. In this patient, the configuration and position of the LAD coronary artery in the lateral projection of the coronary cineangiogram suggested that the artery may lie within the right ventricular cavity (Fig 1). Even a retrospective review of the angiograms was disappointing in revealing intracavitary arteries. In only 1 other patient with an intracavitary LAD coronary artery did the angiogram suggest such a location. Usually, the intracavitary LAD enters the right ventricle early in its descending course and emerges to the surface subtly in a long curve. Occasionally, the artery changes depth of course acutely. When this occurs, one may suspect an intracavitarylocation.
356
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357 Ochsner and Mills: Surgical Management of Intracavitary Coronary Arteries
Fig 1 . Coronary angiogram in left lateral position. Arrow points to acute deep angulation of the left anterior descending coronary artery from the surface of heart.
Management and Results In each patient, the intracavitary coronary artery was encountered during dissection of a coronary artery lying within an intramyocardial tunnel. Since we routinely use a single atrial catheter for venous drainage, air entered the venous line of extracorporeal circulation in each of the 4 patients in whom the right atrium was opened during dissection of the right coronary artery. The sound of air in the venous line heralded the opening of the right atrium. The problem was easily managed in each instance. In 2 patients, the right atrium was isolated by converting the venous return to double caval siphon drainage with caval tourniquets. In the other two instances, the opening could be managed without the need to isolate the right atrium. Temporary finger approximation of the atriotomy edges controlled the opening while the edges were sutured superficially to the artery in 1patient and deep to the artery in the other. In all 4 patients, a vein was used as the bypass graft. In 1 patient, the anastomosis was performed within the right atrium with closure of the atrium around the graft (Fig
2). In 2 patients, the opening in the atrium was obliterated with horizontal mattress sutures beneath the artery. The coronary artery was thereby placed in an aerial position, and the vein-to-artery anastomosis was performed at this site (Fig 3). In another patient, the atrial opening was sutured, allowing the coronary artery to remain in its intracavitary position, and a distal alternative site was selected for anastomosis where the right posterior descending branch lay in an epicardial position. In 9 patients, the intracavitary LAD artery was encountered as the surgeon dissected this vessel in an intramyocardial course. In 5 patients, the dissection was begun distally from an exposed LAD coronary artery or one of its diagonal branches in an epicardial location, and the right ventricle was entered as the dissection proceeded superiorly through a myocardial tunnel. In the other 4 patients, the right ventricle was entered as the surgeon dissected directly through the fat and myocardium in the interventricular groove to locate the LAD in its proximal position (Fig 4). In each of these four instances, it was the surgeon’s opinion that the dissection was immediately on top of the vessel and the cavity not entered inadvertently as a result of dissection at a distance from the course of the vessel. In only 1 of these patients did air enter into the venous line of extracor-
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358 The Annals of Thoracic Surgery Vol 38 No 4 October 1984
Fig 2 . Saphenous vein-right coronary artery bypass. Anastomosis is within the right atrium, and the atriotcimy is closed around the graft.
Fig 3 . Saphewus vein-right coronary artery bypass. The intracavitary coronary artery is repositioned in!an aerial position, and the anastomosis is performed in the exteriorized artery.
Fig 4 . Incision in interventricular groove. Exposure of coronary artery reveals intracavitary position.
poreal circulation. In all other instances, the opening of the right ventricular cavity was evidenced by the appearance of blood and the characteristic trabecular endocardial surface of the right ventricle. The management of the LAD intracavitary arteries was diverse. In 1 patient, direct suture closure of the myotomy was performed and an alternate distal site was selected for anastomosis. In 7 patients, the ventriculotomy was closed in such a manner as to reposition the LAD in an aerial location by closing the ventriculotomy with buttressed mattress sutures passed beneath the artery (Fig 5). The sutures were buttressed with Teflon felt or epicardial pledgets. In 6 patients, the sutures were passed from epicardial to epicardial surface, while in 1patient, the mattress suture incorporated only the myocardium of the myotomy. In order not to obstruct the coronary artery at either the inlet or outlet of the intramyocardial and intracavitary artery by closure with the mattress sutures, an adequate length of artery must be exposed. The anastomosis in these 7 patients was made at the midportion of the repositioned coronary artery. In 1 patient with a long intracavitary and intramyocardial segment, attempts to reposition the LAD resulted in obstruction of flow. In this patient, the anastomosis was performed, the artery was allowed to remain in its intracavitary position, and the myotomy was closed with a pericardial patch through which the graft traversed. This resulted in unobstructed flow (Fig 6 )*
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359 Ochsner and Mills: Surgical Management of Intracavitary Coronary Arteries
A
B
Fig 5 . (A)Placement of buttressed mattress sutures used to close ventriculotomy. (B)Closure of ventriculotomy elevates the left anterior descending coronary artery into an aerial position.
become clinically important as there are reports of ischemia caused by the milking effect of the systolic contraction of the vessel in this position [8-lo]. The intramyocardial LAD may also be short in length and depth and covered by only a small bridge of myocardial fibers, or it may run the entire length of the heart. The mural artery may become so deep that it assumes an intracavitary position. A thorough knowledge of the coronary anatomy is essential in coronary artery surgical procedures [ll]. One must be cognizant of the normal anatomy as well as the anomalies that exist. The anatomy of the coronary arteries is variable and differs in every individual, somewhat analogous to the dermatoglyphics of the hands and fingers. No two coronary angiograms will match if superimposed; however, certain anatomical patterns have been established to guide the cardiologist and surgeon. Experience enhances one's ability in interpreting the anatomy of the coronary arteries from coronary cineangiograms; however, it is difficult to determine the depth of the coronary arteries and their relation to epicardial fat, myocardial bridges, reaction or adhesions from previous operations, and the chambers of the heart. It would be of value to the surgeon to know preoperatively the precise anatomical configuration of those vessels intended for bypass grafting. One may ascertain
Operative incision of the myocardium and closure of the myotomy resulted in the expected elevation of myocardial isoenzyme levels (MB fraction). The percentage of MB fraction varied from 5 to 10.1%;however, only in the patient with an MB fraction of 10.1%was there electrocardiographic evidence of a perioperative myocardial infarction. Postoperative angiograms were obtained in 5 patients; in each, the graft to the involved artery was patent. There has been no electrocardiographicor radiographic evidence of aneurysm formation in the postoperative follow-up period. To date, none of the 13 patients has died, although the longest follow-up is only 7% years.
Comment An anomalous intramyocardial course of the LAD coronary artery was described in 1922 by Crainicianu [2]. Since then, many anatomists and angiographers have confirmed this finding, and the reported incidence has been from 0.75 to 85.7% [3-71. The intracavitary artery is an extension of an intramural artery in a deeper position. The identification of an intramyocardial course has
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360 The Annals of Thoracic Surgery Vol 38 No 4 October 1984
Fig 6. Anastomosis of internal mammary a r t e y to 1tft anterior descending coronay artery in intracavitary position. The ventriculotomy is closed with a pericardial patch through which passes the internal mammay artery graft.
angiographically that a coronary artery lies deep within the myocardium by the milking effect on the artery caused by circumferential myocardial contraction during systole. However, when the ariery is within a cavity, the milking effect does not exist. In coronary artery bypass grafting, the ideal site for anastomosis of the bypass graft is immediately distal to the narrowed or obstructive lesion. Such a location allows antegrade flow to the entire artery designated for revascularization and also allows anastomosis to the largest possible diameter of the specific coronary artery. Hence, it is desirable to perform an anastomosis as proximal as possible. One may wish to select a vessel in an intramyocardial position rather than use a more easily accessible, but smaller and less desirable, distal vessel. Also, many years ago, Geiringer [3] demonstrated that coronary arteries lying within the myocardium have thinner intima than those on the epicardium. Clinicians have noted that the intramyocardial coronary arteries often are not arteriosclerotic and hence are especially suited for anastomosis of a bypass graft. It is rarely suggested by the preoperative angiogram
but more commonly noted at operation that a vessel is embedded in muscle and therefore difficult to isolate. Various technical maneuvers, such as palpating the vessel in its hidden course or tracing the vessel either retrograde from a branch or antegrade from a segment of the vessel on the epicardial surface, may be helpful in isolating the desired area. A sterile Doppler flow probe, which determines the frequency shifts in an ultrasound beam as reflected from the moving cells within the vessel, may also be used. Most surgeons dissect out a mural LAD coronary artery by dissecting retrograde from this vessel in its epicardial position. With experience, surgeons become confident in dissecting an intramyocardial LAD in its proximal location by direct incision through the interventricular groove, with care being taken to ligate or dissect clear the concomitant coronary vein. The transverse myocardial fibers overlying the coronary artery are incised; when the artery lies in an intracavitary position, the condition becomes obvious by the appearance of blood and the trabecular endocardia1 surface. The surgeon then needs to determine the best method of management. One can elect to close the myocardium, allow the artery to remain in its original intracavitary position, and perform bypass to a more distal site, or one may choose to perform bypass at the originally desired area, that is, the intracavitary position. Important in the decision are the size and structure of the coronary arteries distally. Surgeons usually prefer to work on the epicardial surface. The fact that the surgeon chooses to dissect an artery in a muscular course indicates that the artery in its epicardial position is unacceptable. When one chooses to perform anastomosis to the intracavitary artery, it is usually desirable to elevate the artery and close the ventriculotomy beneath it. It is difficult to determine the exact incidence of intracavitary arteries through operative experience of dissecting coronary arteries by bypass grafts. Many of the vessels that lie in an intracavitary position may not have proximal obstruction and therefore would not require exposure; or, the site selected for bypass grafting may be distal to the intracavitary portion, and thus the intracavitary portion would not be known. To locate an intracavitary artery, this site must have been selected for bypass and the position have been discovered at the time of dissection. It might be assumed that our incidence of intracavitary lesions is abnormally high because the right ventricle or right atrium was inadvertently entered by dissecting at a distance from the desired vessel. However, it is our policy to dissect directly on the anterior aspect of a coronary artery. In none of the reported instances was the cavity opened away from the vessel, but only on dissection directly on top of the artery. Therefore, we believe that the incidence reported here is accurate. There is no way that we have been able to determine the intracavitary position of a right coronary artery, either preoperatively or in a retrospectivereview of coronary cineangiograms. All intracavitaryLAD coronary ar-
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361 Ochsner and Mills: Surgical Management of Intracavitary Coronary Arteries
teries must descend and ascend in an intramyocardial course before entering the right ventricle. There are certain angiographic clues, such as decrease in the size of the vessel during systole as it lies in an intramyocardial position or an acute angle of the artery toward the ventricular cavity as viewed angiographically on a lateral view. The intracavitary LAD usually assumes the position in a subtle course; occasionally, however, the entrance or exit may be acute. Cognizance of these clues may alert the surgeon to the possibility of an intracavitary coronary artery. Various technical maneuvers can be used to successfully handle an intracavitary coronary artery required for myocardial revascularization [121.
References 1. M d p i n e WA: Heart and Coronary Arteries. New York, Springer-Verlag, 1975 2. Crainicianu A: Anatomische Studien iiber die Coronarterien und experimentelle Untersuchungen iiber ihre Durchgangigkeit. Virchows Arch [Pathol Anat] 238:1, 1922 3. Geiringer E: The mural coronary. Am Heart J 41:359, 1951 4. Noble J, Bouressa MG, Petitderc R, et al: Myocardial bridging and milking effect of the left anterior descending coronary artery: normal variant or obstruction? Am J Cardiol 37993, 1976 5. Amplatz K, Anderson R Angiographic appearance of myocardial bridging of the coronary artery. Invest Radio1 3:213, 1968 6. Rossi L, Dander B, Nidasio GP, et al: Myocardial bridges and ischemic heart disease. Eur Heart J 1239, 1980 7. Blake HA, Manion WC, Mattingly TW, et a1 Coronary artery anomalies. Circulation 30:927, 1964 8. Polacek P, Kralove H. Relation of myocardial bridges and loops on the coronary artery to coronary artery occlusion. Am Heart J 61:44, 1961 9. Ishimori T, Raizner AE, Chahine RA, et al: Myocardial bridges in man: clinical correlation and angiographic accentuation with nitroglycerins. Cathet Cardiovasc Diagn 3:59, 1977 10. Morales AR, Romanelli R, Boucek RJ, et al: The mural left anterior descending coronary artery, strenuous exercise and sudden death. Circulation 62230, 1980 11. Marshall ME, Headley RN: Intramural coronary artery as a cause of unstable angina pectoris. South Med J 71:1304, 1978 12. Ochsner JL, Mills NL: Coronary Artery Surgery. Philadelphia, Lea and Febiger, 1978
Discussion DR. HENDRIK B. BARNER (St. Louis, MO): My colleagues and I are indebted to Drs. Ochsner and Mills for bringing to our attention an important variant in coronary anatomy. In the past year we have found three right coronary arteries lying within the right atrium, and we are delighted that we now know what to call this anatomical variant. With regard to the LAD coronary artery, we have not recognized the intracavitary position. Earlier in our experience, we entered the right ventricle on a number of occasions while exposing a submuscular LAD and assumed that this was secondary to injudicious dissection, whereas it may have been related to an intracavitary position of the LAD. Dr.Ochsner has indicated several angiographic clues for rec-
ognizing the intracavitary LAD. These clues do not exist for the right coronary artery. At operation, the surgeon who is alert to the possibility of this anatomical variant may avoid chamber entry by an anastomosis distal to the intracavitary portion, but diminutive coronary size may dictate use of the intracavitary segment. Dr. Ochsner has provided us with several techniques for closure of the right ventriculotomy or right atriotomy without compromise of coronary flow or the anastomosis. We suggest an alternative technique in which horizontal mattress sutures are placed from the free wall of the right ventricle into the septum beneath the LAD rather than to the opposite cut edge, so that the free wall is displaced posteriorly to close the ventriculotomy . We have not been so confident of our ability to locate a submuscular LAD by direct incision over the septum, and we prefer to dissect retrogradely from the distal epicardial LAD or from a diagonal artery. Alternatively, we make a small incision in the distal LAD and pass a I-mm probe proximally as a guide to precise localization of the submuscular segment. The distal LAD can be closed with an epicardial suture. The Ochsner Clinic has once again provided us with new information of pragmatic value for the clinical surgeon. DR. HERBERT E. WARDEN: Dr. Ochsner, were there any problems in mobilizing the LAD coronary artery as a result of the potential tethering of this vessel by the septa1 perforators?
DR. OCHSNER: In answer to Dr. garner's questions, all 9 of the LAD anomalies were definitely intracavitary arteries. Our series would have been bigger if we had included patients in whom we inadvertently entered the right ventricle. It is amazing that we do not see intracavitary arteries elsewhere, because all of us who do anastomoses to the ramus or the proximal margin observe that the artery dips into the muscle right away. There is, however, a difference in the thickness of the ventricles. The left ventride is so thick that the artery can follow an intramyocardial or intramural course and still not penetrate the ventricle. However, when the LAD courses to the right of its intervent r i d a r course, it does not have to go very deep before it is in the right ventricle. We have entered the right ventricle inadvertently and found that the vessel there was not an intracavitary artery. We do not open the distal arteries and insert probes. In at least half of these patients, the LAD was followed from the distal LAD or from a diagonal branch, but we usually dissect directly onto the vessel. In answer to Dr. Warden's question, you do have to watch out for perforators, particularly when you place the big mattress sutures under the intracavitary artery to elevate it. The first thing we do is lengthen the myotomy sufficiently so that it can be elevated. We were able to do this in all of our patients except the 1 in whom the intracavitary artery was so long that every attempt to close the myotomy resulted in obstruction. I am not sure that we do not get a few perforators; it is inconceivable that some are not encountered in closure of the myocardium beneath the elevated intracavitary artery. In closing the right ventricle, it is important not to tie down the mattress sutures very tightly. All that is necessary is to approximate, because the pressure in the right ventricle is much less than the systemic pressure in the coronary arteries and probably even the diastolic pressure; therefore, filling could occur through the perforators unless they are cut by the sutures. I think we probably do destroy a few perforators, but this can occur without too much damage.
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362 The Annals of Thoracic Surgery Vol 38 No 4 October 1984
VICE PRESIDENT MAGOVERN: When I have encountered intracavitary or intramyocardial arteiies, I have always been struck by the fact that in that position, the vessel always appears to be free from disease. Has that been your experience also and do you have any explanation for it?
DR. OCHSNER: In
1922 Crainicianu noted that all of the vessels in the myocardium were either free from disease or had a very
thin intimal lining. As cliniaans we have observed this to be true. The theory is that the vessels are disease free because they have been milked; the milking effect is similar to that in the leg, where there is less disease in the profunda femoris than in the superficial femoral artery. But at the same time, the intracavitary artery is never completely circumferential in muscle. The fact that the artery is in this area, coupled with the milking effect, probably prevents the formation of arteriosclerotic lesions in the vessel.
Notice from the American Board of Thoracic Surgery The Part I (written) examination will be held at the Amfac Hotel, DallasFort Worth Airport, Dallas, TX, in February, 1986. The closing date for registration is August 1, 1985. To be admissible for the Part I1 (oral) examination, a candidate must have successfullly completed the Part I (written) examination.
A candidate applying for admission to the certifying examination must fulfill all the requirements of the Board in force at the time the application is received. Please address all communications to the American Board of Thoracic Surgery, 14640 E Seven Mile Rd, Detroit, MI 48205.
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Surgical Management of Diseased Intracavitary Coronary Arteries John L. Ochsner and Noel L. Mills Ann Thorac Surg 1984;38:356-362 DOI: 10.1016/S0003-4975(10)62285-0 Updated Information & Services
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