CLARKE ET ALII
ATRIOVENTRICULAR CANAL LESIONS
THE SURGICAL MANAGEMENT OF TOTAL ATRIOVENTRICULAR CANAL LESIONS C. P. CLARKE,A. C. WILSONAND J. P. RICHARDSON Division of Cardiac Surgery, Royal Children's Hospital, Melbourne Between 1969 and 1976 sixteen children have had surgery f o r total atrioventricular canal lesions a t t h e Royal Children's Hospital, Melbourne. Twelve infants had palliative banding o f the m a i n pulmonary artery t o control heart failure and prevent the development of pulmonary hypertension, w i t h t w o hospital deaths (17%) and one late death. One other patient has been lost t o follow-up and may also have died. Nine patients have undergone complete repair, with three hospital deaths (33%), and one later death a t reoperation f o r residual m i t r a l Incompetence. Five of these had previously had banding of the m a i n pulmonary artery, and the m o r t a l i t y has occurred exclusively in t h i s group. T h e techniques of repair are discussed, and reasons advanced In favour of early p r i m a r y repair of t h e defect in preference t o palliative banding and later secondary repair.
SEPTALdefects which are located centrally in the heart and are associated with abnormalities of the mitral and tricuspid valve are grouped together as atrioventricular canal defects, and are divided into partial or total varieties depending on whether a significant ventricular septal defect, in addition to the atrial septal defect, is present or not. The surgical management of the partial form of the defect in which there is usually a large primum atrial septal lesion associated with clefts of the mitral and tricuspid valves, is now performed by a standard technique with a low mortality at most centres. T h e total defects, however, still represent a challenge, as the repair is complex, and the majority of patients present in early infancy and die unless managed actively. ANATOMICAL CONSIDERATIONS There is generally a large ostium primum atrial septal defect with complete clefts of both the septal leaflets of the mitral and tricuspid valves, and a high ventricular septal defect Reprints: C. P. Clarke, 35 Park Drive, Parkville, Vic. 3052.
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located immediately beneath the level of the valves. The plane of the leaflets is shifted downwards and anteriorly, and it is this dislocation of the mitral valve which gives the characteristic goose-neck deformity seen at angiocardiography (Baron et a%, 1964). As Van Mierop and Alley (1966) have pointed out, the mitral valve with such a concave origin (Figure I ) needs to be split in order to open adequately, and the cleft cannot be fully sutured without risk of producing mitral stenosis unless the normal convex attachment of the valve to the septum is restored (Figure 2).
Rastelli ct a& (1966) divided the canal defects into three types. In the most common of these, Type A, the atrioventricular valves are connected to the uppermost part of the ventricular septum by a series of chord=. Type B is exceptionally rare, and in this anomaly the majority of the chord= go to a large papillary muscle in the right ventricle. In Type C the anterior leaflets are free floating. Associated cardiac defects are most commonly found with the Type C variety (Tenckhoff and Stamm, 1973), and there is evidence that this represents interference at an 509
ATRIOVENTRICULAR CANAL LESIONS
earlier stage of embryogenesis. As the development of the coronary sinus is intimately bound up with the formation of this area, unroofing of it is not uncommon, and when there is also a persistent left superior vena cava this will drain directly into the left atrium (Clarke and Rubin, 1973). The atrioventricular node and the bundle of His may lie in their normal location or be shifted somewhat to the left, and surgeons in centres using bundle of His mapping techniques
CLARKE ET ALII
with Downs syndrome have total atrioventricular canal lesions, and these are generally of the Type A variety.
PATIENTS A . Patients having palliative procedures.Pulmonary artery banding, introduced by Muller and Dammann (1952)reduces the left to right shunt, and protects the lungs from the effects of pulmonary hypertension. In total atrioventricular canal lesions its efficacy in any case must depend largely on the degree of mitral incompetence present, and on whether the left to right shunt is mainly at atrial or ventricular levels. Our experience with 12 patients is listed in Table I. Only one patient had an associated Downs syndrome, which reflects our policy not to offer treatment to members of this group unless they are living at home and adequate plans have been made for their future care.
V S D FIGURE I : Diagram of the centrally placed septal defect in total atrioventricular canal lesions showing the large atrial ostium primum defect (OP) and shallow ventricular septal defect (VSD) under the plane of the atrioventricular valves which are displaced downwards. C is the central cleft in the valve.
during repair have found that the location of the atrioventricular node can be quite variable (Mills et alii, 1976). In addition to the cleft in the mitral valve, there may be actual deficiency of tissue or tethering by abnormal chord= (Frater, 1965), and the mitral incompetent jet may either go mainly into the right atrium across the central cleft or be directed backwards into the left atrium. There is usually a large obligatory left to right shunt, and if the ventricular septal defect is significant, there are also balanced ventricular pressures with pulmonary hypertension. A large number of patients 510
E’ILURE 2 : Diagram showing Dacron patch placed in defect. Th e area abutting the bundle of His has been closed with interrupted sutures and the remainder with continuous sutures. Th e new level a t which the valves a r e attached is shown by the dotted line.
The two patients who died at operation had significant associated lesions, as did the patient who died three and a half months after surgery from an intercurrent infection. Three patients had a coarctation of the aorta resected at the same time as the main pulmonary artery was banded, and one had previously had a successful repair of a tracheocesophageal fistula. Five patients have subsequently come forward for AUST.N.Z. J. SURG.,VOL. 47-N0.
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ATRIOVENTRICULAR CANAL LESIONS TABLE I Patients Having Banding oj the Main Pulmonary Artery Patient I
Sex
Ag-e (Mths) and Date of Operation
M
0
Remained tachypnceic and cyanosed. revair 2 vrs I mtht ,
15.6.70 2
F
3
F
4
F
5
1M
Outcome
Assoriated Lesions Unexplained cyanosis
3
16.12.69
22.4.70 24.3.72
5
Persistent left superior vena cava to coronary sinus
5
_
Total
Became cyanosed. monthst
Tctal repair 3 years 5
Became cyanosed. monthst
Total repair 3 years 4
Thrived poorly. monthst
Total repair 4 years
Elective total repair 6 years
10
2
months
27. I.70
6
F
7
F
S 24.6.70
Tracheoaesophageal fistula
Lost to follow Up.
Complete heart Mock ; anomalous systemic veins ; polysplenia
Dicd at opcration.
Coarctation of aorta*
Died aged 4 months
Coarctation of aorta*
Satisfactory progress
Downs
Satisfactory progrcss
Coarctation of aorta*
Satisfactory progress
Supravalvar aortic stenosis ; polysplenia
Died at operation
2
20.5.70
S
M
2
weeks
10.12.71
9
M
4
15.3.74 I0
F
2
30.9.75 I1
F
6
17.12.7j 12
* Repaired
t Died.
M
week 13.5.76
I
a t same operation.
total repair. The only patient who did so electively has done well, and the others have died either at the time of repair, or in one case later, when mitral valve replacement had to be undertaken for residual mitral incompetence, I n each case they had not really thrived after banding, and three were cyanosed, as they developed a right to left shunt. One of these had not been effectively banded, as he had been mildly cyanosed for reasons which were not clear before banding. and this had led to the band being placed somewhat more loosely than usual, and he remained with a large left to right shunt and moderate pulmonary hypertension. B. Patients having total repair.-Nine patients have undergone total repair, and are listed in Table 2. Seven of these had Type A lesions, and two Type C. Five had previously had pulmonary artery banding, and one had an associated mild coarctation which was of no hzmodynaniic consequence. One had a persistent left superior vena cava draining directly into the left atrium, and a n anomalous return of the pulmonary veins to the upper part of the right atrium. AUST. N.Z. J. SURG., VOL.47-No.
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OPERATIVE PROCEDURES All patients but one had repair under heartlung bypass with moderate hypothermia, the cannuke being placed into the superior vena cava through the tip of the right atrium, and into the inferior vena cava at its junction with the right atrium, the atrium being then opened with an oblique incision. The principles described by Rastelli et alii (1968) were followed in that the valves were separated along their midline and a Dacron patch placed on to the right side of the ventricular septum. While interrupted stitches were placed between the midpoint of the septum and the coronary sinus, the heart was allowed to beat, and the electrocardiogram was carefully monitored to avoid damage to the bundle of His. Once this danger area had been passed, the aorta was c r o s clamped intermittently, and the insertion of the patch was completed with a running suture. If the mitral valve could be restructured the cleft was closed with interrupted sutures approximating the “kissing” edges, and then reattached to the Dacron patch at the level at which it would normally lie (Figure 2 ) . The
ATRIOVENTRICULAR CANAL LESIONS
CLARKE ET ALII TABLE z
Pafients Having Total Repair of Atrioventricular Canal Lesions
Patient
Sex
Age and Date of Operation
Type of Defect
Associated Lesions
Preoperative Catheter Study
Operation
+
Outcome ~~
I
M
2
years I month 7.10.71
A
Pulmonary artery band; unexplained cyanosis
Balanced ventricular pressures; persisting L to R shunt; pulmonary hypertension :moderate M.I.
Rastelli Died patch pulmonary artery
2
F
3 years 5 months
A
Pulmonary artery band
Balanced ventricular pressures ; normal pulmonary artery pressure; R to L shunt ; moderate M.I.
Rastelli + Congestive cardiac patch pulfailure ; restudy MI/ monary artery MS; pulmonary hypertension, mitral valve replacement (B-S) 6monthslater; died.
20.2.73
3
F
3 years 4 months 19.6.73
C
Pulmonary artery band
Balanced ventricular pressures ; normal pulmonary artery pressure; R to L shunt ; moderate M.I.
Rastelli + Died patch pulmonary artery; severe M.I. required MVR (B-S)
4
F
4 years
C
Pulmonary artery band. left superior vena cava f to coronary sinus
Balanced ventricular pressures ; normal pulmonary artery pressure; R to L shunt ; moderate M.I.
Dacron patch Died MVR (H); patch pulmonaryartery
5
M
6 years 10 months 8.6.76
A
Pulmonary artery band ; mild coarctation of aorta; left superior vena cava to coronary sinus
Balanced ventricular pressures ; normal pulmonary artery pressure ; moderate M.I.
Dacron patch Clinically well MVR (H); patch pulmonary artery
13
F
I
yearz months 11.10.70
A
Balanced pressures; L to R shunt Z/I; severe M.I.
See text
2 months 8.12.75
+
+
Restudy (a) a t six weeks residual lesions with pulmonary hypertension ; (brat z years normal right sided pressures trivial M.I. and ;mall residual shunt.
.
14
M
8 years 16.3.71
A
Patent ductus arteriosus
15
M
5 years 7 months
A
-
19.9.72
Balanced pressures ; large L to R shunt ; moderate M.I.
Rastelli
Restudy-normal right-sided pressures; no shunts ; trivial M.I.
Pulmonary artery 78/20 ; aorta 126/72; L to R shunt A/I : mild M.I.
Rastelli
Clinically well ; persisting signs of mild M.I.
.I
I
~~
~
(H)= Hancock heterograft valve. (B-S) = Bjorck-Shiley prosthetic valve. M.I. =Myocardial insu5ciency.
tricuspid valve was similarly reattached, but could rarely be sutured along the cleft because of an apparent absence of tissue. The heart appears to tolerate well the absence of septa1 tissue of the tricuspid valve (Wait and Mustard, 1965; Mustard ef alii, 1965), and when there was doubt when dividing the valves, the mitral valve was always favoured. The remainder of the Dacron patch was then used to close the ostium primum defect. When a pulmonary artery band was present it was incised across the stricture, and the pulmonary
artery reconstituted with a small pericardial patch. The mitral valve was judged to be functioning satisfactorily after this type of repair in only four patients. In the others it was excised and replaced with a prosthetic valve because of significant incompetence. The valve was placed in the mitral annulus along its mural part, but was attached centrally to the Dacron patch, thus avoiding the bundle area. The patient who was treated in infancy was managed with profound hypothermia, with AUST. N.Z. J. SURG.,VOL. 47-"o.
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ATRIOVENTRICULAR CANAL LESIONS
heart-lung bypass during the rewarming phase (Clarke et a%, 1g71), and because of the limited time available when using this technique, repair was effected by suturing the atrioventricular valve down to the topmost part of the ventricular septum after closing the medial part of the cleft in the anterior leaflet of the mitral valve, and then using a Dacron patch to close the ostium primum defect. W e now cannulate the venz cavx separately in infants, which allows operative manceuvres to be continued during the rewarming phase and would not compromise the techniques of repair. In the patient with a persistent left superior vena cava draining into the left atrium and anomalous return of the pulmonary veins, a Dacron patch was placed as a tunnel so that the pulmonary veins drained to the left atrium, and the anomalous left superior vena cava was redirected to the right atrium. This necessitated a dry operative field, and accordingly the patient was cooled to 25°C and several short periods of total circulatory arrest were used. The mitral valve was replaced, as it was feared that the unusual shape of the patch could distort the mitral ring and the resultant small left atrium would not tolerate any degree of mitral incompetence.
RESULTS The patient having repair at 14 months of age had a rather stormy postoperative course, and initially there was little improvement in her clinical condition. A repeat catheter study six weeks after repair showed both significant mitral incompetence and a residual shunt, and she required continued medical therapy. During the next two years, however, her clinical condition gradually improved, and a restudy two years after the repair showed almost normal h;emodynamics, with only trivial mitral incompetence and a trivial residual left to right shunt. Both of the two patients who had not previously been banded and had Rastelli type repairs have done well clinically, but have some residual mitral incompetence. One has been restudied and shown to have a normal pulmonary artery pressure, with no shunts and only trivial mitral incompetence, and the other has clinical mild mitral incompetence. The other patient who presented for surgery without prior banding, but required repair of AUST. N Z. J. SURG., VOL.47-"o. Q
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anomalously draining pulmonary veins and a persistent left superior vena cava at the same time, had some evidence of neurological damage immediately after surgery, but this has almost entirely resolved and he is now clinically well. The results were markedly less favourable in the group of five patients who had previously had a pulmonary artery band. Three died in a low output state following surgery. One survived a Rastelli type of repair, but continued to have congestive failure, and a further catheter study showed that she had both mitral steiiosis and incompetence with pulmonary hypertension. Some six months after repair she came forward for mitral valve replacement, but did not survive operation, and a post-mortem examination showed that the prosthesis had distorted the left ventricular outflow tract with probable obstruction, and there was histological evidence of moderately severe pulmonary vascular disease. One patient who had previously had a pulmonary artery band required mitral valve replacement at the time of surgery and has clinically done well. Thus no patient who had prior pulmonary artery banding has survived repair with conservative mitral valve reconstruction alone, and the only long-term survivor required mitral valve replacement notwithstanding a favourable course after banding, and preoperative catheter evidence of no more than moderate mitral incompetence.
DISCUSSION Patients with total atrioventricular canal lesions tend to get into difficulty early in life, with tachypnoea and failure to thrive. Unless they are treated at this stage, the majority will either die or develop pulmonary vascular changes which preclude subsequent correction. A significant proportion of these patients will have Downs syndrome, and opinion differs as to the advisability of offering surgery to this group, especially as it has been found that when institutionalized they are particularly liable to be carriers of serum hepatitis. Our own policy has been only to accept those patients with a stable home environment, and who are Australian antigen negative. In the early reported series of patients having repair of total atrioventricular canal
513
ATRIOVENTRICULAR CANAL LESIONS
CLARKE ET ALII
lesions there was a high operative mortality (Ellis et alii, 1960; Mustard et a&, 1965), and amongst the survivors residual mitral incompetence was a significant problem. The modern fundamentals of repair were described by Rastelli et alii (1968), who laid down the principles of dividing the tricuspid and mitral leaflets in the midline, and placing a common patch between the ventricles and atria and reattaching the repaired mitral valve at its optimum position. Using these principles, McMullen et a& (1972) were able to report a 7% mortality in 27 patients, with a favourable early postoperative follow-up from the point of view of residual mitral incompetence. However, only two of these patients had been previously banded, and both had come to repair electively. An alternative method in that the mitral valve is electively replaced in order to obviate residual mitral incompetence has been advocated by Castaneda st alii ( 1971). The limiting factor of this approach is the long-term durability of the prosthetic valve. Banding of the main pulmonary artery as a palliative measure has not been widely used for atrioventricular canal defects despite the good results reported by Somerville et a& (167). Although our initial results were promising in that the only hospital mortality was amongst the patients with complex associated lesions, the subsequent course after banding has in most cases been indifferent, with failure to thrive and the onset of cyanosis requiring correction of the defect before the optimum age of five to seven years. At the time of correction debanding has not proved a problem, but the repair has, and the mortality has been exclusively amongst this group. Of the two survivors, one had had a particularly good response to banding, but even so required mitral valve replacement at the time of surgery, and the other survived the Rastelli procedure, but remained in heart failure and died at the subsequent attempt to replace the mitral valve. This implies that the patients who get into trouble at an early age are those with insufficiency of mitral valve tissue or particularly distorted valves. I n marked contrast, none of the patients in our series who had not previously had pulmonary artery banding died, and the only patient in this group who required mitral valve replacement also had complex associated
anomalies. Both of the Rastelli type repairs in older children have done well, and one child has been shown to have virtually normal hamodynamics. A patient treated by a somewhat inferior technique in early infancy initially had significant residual problems, but these have cured themselves with the passage of time, and the child is now symptomatically well. There have been several reports of success with total repair in infancy (BarrattBoyes, 1972; McGoon et a&, 1973; Mills et alii, 1976) and this, along with our experience, suggests that total repair is preferable to preliminary banding and later repair, even in this age group. The argument against early repair in infancy is that the mitral valve may be unreconstructable, but it is doubtful whether patients with such severe lesions would survive banding, as this does nothing to alleviate the mitral incompetence. Our single experience of repair in infancy also suggests that contrary to the fear that the mitral deformity would tend to worsen after repair because of fibrosis along the sutured cleft, the heart in fact retains the capability of adjusting the hamodynamic situation as it matures.
514
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REFERENCES BARON,M. G., WOLF,B. S., STEINFELD, L. and VAN MIEROP,L. H. S. (1964), Amer. J. Cardiol., 13: I 62. BARRATT-BOYES, B. G. (1972), Open Heart Surgery in Infancy, Proceedings of International Symposium held in Bergamo, ed. Parenzan, L. and Carcassonne, M., Sapil, Milan : 223. BURCHELL, H. B., DUSHANE,J. W. and BRANDENBERG,R. 0. ( r g b ) , Amer. J. Cardiol., 6 : 575. D. M., MOLLER, J. H. CASTANEDA, A. R., NICOLOFF, and LUCAS,R. V. ( I ~ I ) J. , thorac. cardiovosc. Surg., 62: 926. CLARKE,C. P., BROWN,T. C. K., MCKIE, B. D., JONES,P. G. and VENABLES, A. W. (1971), Med. J. Aust., 2 : 710. CLARKE,C. P. and RUBIN,S. Z. (1973), AUST. N.Z. J. SURG.,42: 242. LLLIS, F. H., MCGOON,D. C. and KIRKLIN,J. W. (I@o), Amer. J. Cardiol., 6 : 598. FRATER, R. W. M. (1965), Circulation, 32: 120. MCGOON,D. C., MCMULLAN, M. H. and MAIR,D. D. and DANIELSON,G. K. (I973), Proc. Mayo Clin., 48: 769. MCMULLAN,M. H., WALLACE, R. B., WEIDMAN,W. H. and MCGOON,D. C. (1972), Surgery, 72: 905.
MILLS,N., OCHSNER,J. L. and KING,T. D. (1976). J. thorac. cardiovasc. Surg., 71: 20. 4, AUGUST, 1977
RIGHT CORONARY ENDARTERECTOMY
GALE ET ALII
J. F. (1952), Surg. SOMERVILLE, J., AGNEW,T., STARK,J., WATERSTON, MULLER,W. H. and DAMMANN, Gynec. Obstet., 95: 213. D. J., AEERDEEN,E., BONHAM-CARTER, R. E. MUSTARD,W. T., NIGUIDULA,F. N. and TRUSLER, and WAICH, S. (1967), Brif. Heart J., 29: 816. TENCKHOFF,L. and STAMM, S. J. (1973), CirculaG. A. (1&5), Brit. Heart J., 28: 768. RASTELLI,G. C., KIRKLIN,J. W. and TITUS, J. L. tion, 48: 416. (1966), Proc. M a y o Clin., 41 : 296. VAN MIEROP,L. H. S. and ALLEY,R. D. (1g66), Ann. thorac. Surg., 2 : 416. RASTELLI,G. C., ONGLEY,P. A., KIRKLIN,J. W. and M c G o o ~ , D. C. (1968), -7. thoruc. cardiovusc. WAIT,J. H. and MUSTARD, W. T. (rg65), 1. thomc. Surg., 5 5 : 299. cardiovasc. Swg., 49: 968.
RIGHT CORONARY ENDARTERECTOMY: A PROCEDURE WITH INCREASED RISK OF PERIOPERATIVE INFARCTlON ALANW. GALE,VICTORP. CHANG, MARKX. SHANAHAN AND HARRY M. WINDSOR Cardiac Surgical Unit of St Viment's Hospitd, Sydney Although right coronary endarterectomy extends operability en this vessel, the procedure is associated with increased risk of perioperative infarctlon. Forty-nine patients a t S t Vincent's Hospital underwent endarterectomy and saphenous vein graftlng to the distal right coronary artery, with a hospltal mortality of 6.1% and a perloperative infarction rate of 20-4y0, compared with rates of 4.2% and 10.9% respectively I n a group of patients who did not require endarterectomy. These figures show a trend toward rtatiotical rignificance which suggests that careful. patient selection for endarterectomy is required to obviate an Increased risk of complications with this procedure.
THEright main coronary artery is involved by atheromatous obstruction in 80% to 90% of patients presenting for myocardial revascularization and is frequently the vessel most extensively affected (Groves et alii, 1972). Endarterectomy has extended operability on this vessel, and when combined with reversed autogenous saphenous vein bypass grafts, has allowed more complete attempts at total myocardial revascularization. This report reviews the early experience with 49 patients who received vein grafts and endarterectomy of their right coronary arteries.
Reprints : H. M. Windsor, Medical Centre, St Vincent's Hospital, Darlinghurst, N.S.W. 2010.
284 patients received reversed autogenous saphenous vein grafts to the right main coronary artery (Group I ) , and an additional 49 patients had saphenous vein grafts to the right coronary artery following endarterectomy (Group 2) (Table I ) . The indication for surgery was chronic stable angina in 76% (216) of Group I patients and 90% (4) of Group 2, whereas unstable angina was the indication in 16% (61) of Group I patients and 2% ( I ) of Group 2. Recurrent arrhythmia, acute myocardial infarction, angiographic abnormality, and reoperation, accounted for the other indications, there being no difference in the incidence in either group. A history of previous myocardial infarction was obtained in approximately 45% of patients in each group. Evidence of i s c h m i c changes was present in the anterior leads in the electrocardiographs
AUGUST, 1977
515
PATIENTS During the period November 1969 to March 1976, 543 patients underwent surgery at St Vincent's Hospital for coronary artery disease ;
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THE SURGICAL MANAGEMENT OF TOTAL ATRIOVENTRICULAR CANAL LESIONS C. P. CLARKE,A. C. WILSONAND J. P. RICHARDSON Division of Cardiac Surgery, Royal Children's Hospital, Melbourne Between 1969 and 1976 sixteen children have had surgery f o r total atrioventricular canal lesions a t t h e Royal Children's Hospital, Melbourne. Twelve infants had palliative banding o f the m a i n pulmonary artery t o control heart failure and prevent the development of pulmonary hypertension, w i t h t w o hospital deaths (17%) and one late death. One other patient has been lost t o follow-up and may also have died. Nine patients have undergone complete repair, with three hospital deaths (33%), and one later death a t reoperation f o r residual m i t r a l Incompetence. Five of these had previously had banding of the m a i n pulmonary artery, and the m o r t a l i t y has occurred exclusively in t h i s group. T h e techniques of repair are discussed, and reasons advanced In favour of early p r i m a r y repair of t h e defect in preference t o palliative banding and later secondary repair.
SEPTALdefects which are located centrally in the heart and are associated with abnormalities of the mitral and tricuspid valve are grouped together as atrioventricular canal defects, and are divided into partial or total varieties depending on whether a significant ventricular septal defect, in addition to the atrial septal defect, is present or not. The surgical management of the partial form of the defect in which there is usually a large primum atrial septal lesion associated with clefts of the mitral and tricuspid valves, is now performed by a standard technique with a low mortality at most centres. T h e total defects, however, still represent a challenge, as the repair is complex, and the majority of patients present in early infancy and die unless managed actively. ANATOMICAL CONSIDERATIONS There is generally a large ostium primum atrial septal defect with complete clefts of both the septal leaflets of the mitral and tricuspid valves, and a high ventricular septal defect Reprints: C. P. Clarke, 35 Park Drive, Parkville, Vic. 3052.
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located immediately beneath the level of the valves. The plane of the leaflets is shifted downwards and anteriorly, and it is this dislocation of the mitral valve which gives the characteristic goose-neck deformity seen at angiocardiography (Baron et a%, 1964). As Van Mierop and Alley (1966) have pointed out, the mitral valve with such a concave origin (Figure I ) needs to be split in order to open adequately, and the cleft cannot be fully sutured without risk of producing mitral stenosis unless the normal convex attachment of the valve to the septum is restored (Figure 2).
Rastelli ct a& (1966) divided the canal defects into three types. In the most common of these, Type A, the atrioventricular valves are connected to the uppermost part of the ventricular septum by a series of chord=. Type B is exceptionally rare, and in this anomaly the majority of the chord= go to a large papillary muscle in the right ventricle. In Type C the anterior leaflets are free floating. Associated cardiac defects are most commonly found with the Type C variety (Tenckhoff and Stamm, 1973), and there is evidence that this represents interference at an 509
ATRIOVENTRICULAR CANAL LESIONS
earlier stage of embryogenesis. As the development of the coronary sinus is intimately bound up with the formation of this area, unroofing of it is not uncommon, and when there is also a persistent left superior vena cava this will drain directly into the left atrium (Clarke and Rubin, 1973). The atrioventricular node and the bundle of His may lie in their normal location or be shifted somewhat to the left, and surgeons in centres using bundle of His mapping techniques
CLARKE ET ALII
with Downs syndrome have total atrioventricular canal lesions, and these are generally of the Type A variety.
PATIENTS A . Patients having palliative procedures.Pulmonary artery banding, introduced by Muller and Dammann (1952)reduces the left to right shunt, and protects the lungs from the effects of pulmonary hypertension. In total atrioventricular canal lesions its efficacy in any case must depend largely on the degree of mitral incompetence present, and on whether the left to right shunt is mainly at atrial or ventricular levels. Our experience with 12 patients is listed in Table I. Only one patient had an associated Downs syndrome, which reflects our policy not to offer treatment to members of this group unless they are living at home and adequate plans have been made for their future care.
V S D FIGURE I : Diagram of the centrally placed septal defect in total atrioventricular canal lesions showing the large atrial ostium primum defect (OP) and shallow ventricular septal defect (VSD) under the plane of the atrioventricular valves which are displaced downwards. C is the central cleft in the valve.
during repair have found that the location of the atrioventricular node can be quite variable (Mills et alii, 1976). In addition to the cleft in the mitral valve, there may be actual deficiency of tissue or tethering by abnormal chord= (Frater, 1965), and the mitral incompetent jet may either go mainly into the right atrium across the central cleft or be directed backwards into the left atrium. There is usually a large obligatory left to right shunt, and if the ventricular septal defect is significant, there are also balanced ventricular pressures with pulmonary hypertension. A large number of patients 510
E’ILURE 2 : Diagram showing Dacron patch placed in defect. Th e area abutting the bundle of His has been closed with interrupted sutures and the remainder with continuous sutures. Th e new level a t which the valves a r e attached is shown by the dotted line.
The two patients who died at operation had significant associated lesions, as did the patient who died three and a half months after surgery from an intercurrent infection. Three patients had a coarctation of the aorta resected at the same time as the main pulmonary artery was banded, and one had previously had a successful repair of a tracheocesophageal fistula. Five patients have subsequently come forward for AUST.N.Z. J. SURG.,VOL. 47-N0.
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ATRIOVENTRICULAR CANAL LESIONS TABLE I Patients Having Banding oj the Main Pulmonary Artery Patient I
Sex
Ag-e (Mths) and Date of Operation
M
0
Remained tachypnceic and cyanosed. revair 2 vrs I mtht ,
15.6.70 2
F
3
F
4
F
5
1M
Outcome
Assoriated Lesions Unexplained cyanosis
3
16.12.69
22.4.70 24.3.72
5
Persistent left superior vena cava to coronary sinus
5
_
Total
Became cyanosed. monthst
Tctal repair 3 years 5
Became cyanosed. monthst
Total repair 3 years 4
Thrived poorly. monthst
Total repair 4 years
Elective total repair 6 years
10
2
months
27. I.70
6
F
7
F
S 24.6.70
Tracheoaesophageal fistula
Lost to follow Up.
Complete heart Mock ; anomalous systemic veins ; polysplenia
Dicd at opcration.
Coarctation of aorta*
Died aged 4 months
Coarctation of aorta*
Satisfactory progress
Downs
Satisfactory progrcss
Coarctation of aorta*
Satisfactory progress
Supravalvar aortic stenosis ; polysplenia
Died at operation
2
20.5.70
S
M
2
weeks
10.12.71
9
M
4
15.3.74 I0
F
2
30.9.75 I1
F
6
17.12.7j 12
* Repaired
t Died.
M
week 13.5.76
I
a t same operation.
total repair. The only patient who did so electively has done well, and the others have died either at the time of repair, or in one case later, when mitral valve replacement had to be undertaken for residual mitral incompetence, I n each case they had not really thrived after banding, and three were cyanosed, as they developed a right to left shunt. One of these had not been effectively banded, as he had been mildly cyanosed for reasons which were not clear before banding. and this had led to the band being placed somewhat more loosely than usual, and he remained with a large left to right shunt and moderate pulmonary hypertension. B. Patients having total repair.-Nine patients have undergone total repair, and are listed in Table 2. Seven of these had Type A lesions, and two Type C. Five had previously had pulmonary artery banding, and one had an associated mild coarctation which was of no hzmodynaniic consequence. One had a persistent left superior vena cava draining directly into the left atrium, and a n anomalous return of the pulmonary veins to the upper part of the right atrium. AUST. N.Z. J. SURG., VOL.47-No.
4, AUGUST, 1977
OPERATIVE PROCEDURES All patients but one had repair under heartlung bypass with moderate hypothermia, the cannuke being placed into the superior vena cava through the tip of the right atrium, and into the inferior vena cava at its junction with the right atrium, the atrium being then opened with an oblique incision. The principles described by Rastelli et alii (1968) were followed in that the valves were separated along their midline and a Dacron patch placed on to the right side of the ventricular septum. While interrupted stitches were placed between the midpoint of the septum and the coronary sinus, the heart was allowed to beat, and the electrocardiogram was carefully monitored to avoid damage to the bundle of His. Once this danger area had been passed, the aorta was c r o s clamped intermittently, and the insertion of the patch was completed with a running suture. If the mitral valve could be restructured the cleft was closed with interrupted sutures approximating the “kissing” edges, and then reattached to the Dacron patch at the level at which it would normally lie (Figure 2 ) . The
ATRIOVENTRICULAR CANAL LESIONS
CLARKE ET ALII TABLE z
Pafients Having Total Repair of Atrioventricular Canal Lesions
Patient
Sex
Age and Date of Operation
Type of Defect
Associated Lesions
Preoperative Catheter Study
Operation
+
Outcome ~~
I
M
2
years I month 7.10.71
A
Pulmonary artery band; unexplained cyanosis
Balanced ventricular pressures; persisting L to R shunt; pulmonary hypertension :moderate M.I.
Rastelli Died patch pulmonary artery
2
F
3 years 5 months
A
Pulmonary artery band
Balanced ventricular pressures ; normal pulmonary artery pressure; R to L shunt ; moderate M.I.
Rastelli + Congestive cardiac patch pulfailure ; restudy MI/ monary artery MS; pulmonary hypertension, mitral valve replacement (B-S) 6monthslater; died.
20.2.73
3
F
3 years 4 months 19.6.73
C
Pulmonary artery band
Balanced ventricular pressures ; normal pulmonary artery pressure; R to L shunt ; moderate M.I.
Rastelli + Died patch pulmonary artery; severe M.I. required MVR (B-S)
4
F
4 years
C
Pulmonary artery band. left superior vena cava f to coronary sinus
Balanced ventricular pressures ; normal pulmonary artery pressure; R to L shunt ; moderate M.I.
Dacron patch Died MVR (H); patch pulmonaryartery
5
M
6 years 10 months 8.6.76
A
Pulmonary artery band ; mild coarctation of aorta; left superior vena cava to coronary sinus
Balanced ventricular pressures ; normal pulmonary artery pressure ; moderate M.I.
Dacron patch Clinically well MVR (H); patch pulmonary artery
13
F
I
yearz months 11.10.70
A
Balanced pressures; L to R shunt Z/I; severe M.I.
See text
2 months 8.12.75
+
+
Restudy (a) a t six weeks residual lesions with pulmonary hypertension ; (brat z years normal right sided pressures trivial M.I. and ;mall residual shunt.
.
14
M
8 years 16.3.71
A
Patent ductus arteriosus
15
M
5 years 7 months
A
-
19.9.72
Balanced pressures ; large L to R shunt ; moderate M.I.
Rastelli
Restudy-normal right-sided pressures; no shunts ; trivial M.I.
Pulmonary artery 78/20 ; aorta 126/72; L to R shunt A/I : mild M.I.
Rastelli
Clinically well ; persisting signs of mild M.I.
.I
I
~~
~
(H)= Hancock heterograft valve. (B-S) = Bjorck-Shiley prosthetic valve. M.I. =Myocardial insu5ciency.
tricuspid valve was similarly reattached, but could rarely be sutured along the cleft because of an apparent absence of tissue. The heart appears to tolerate well the absence of septa1 tissue of the tricuspid valve (Wait and Mustard, 1965; Mustard ef alii, 1965), and when there was doubt when dividing the valves, the mitral valve was always favoured. The remainder of the Dacron patch was then used to close the ostium primum defect. When a pulmonary artery band was present it was incised across the stricture, and the pulmonary
artery reconstituted with a small pericardial patch. The mitral valve was judged to be functioning satisfactorily after this type of repair in only four patients. In the others it was excised and replaced with a prosthetic valve because of significant incompetence. The valve was placed in the mitral annulus along its mural part, but was attached centrally to the Dacron patch, thus avoiding the bundle area. The patient who was treated in infancy was managed with profound hypothermia, with AUST. N.Z. J. SURG.,VOL. 47-"o.
4, AUGUST,1977
ATRIOVENTRICULAR CANAL LESIONS
heart-lung bypass during the rewarming phase (Clarke et a%, 1g71), and because of the limited time available when using this technique, repair was effected by suturing the atrioventricular valve down to the topmost part of the ventricular septum after closing the medial part of the cleft in the anterior leaflet of the mitral valve, and then using a Dacron patch to close the ostium primum defect. W e now cannulate the venz cavx separately in infants, which allows operative manceuvres to be continued during the rewarming phase and would not compromise the techniques of repair. In the patient with a persistent left superior vena cava draining into the left atrium and anomalous return of the pulmonary veins, a Dacron patch was placed as a tunnel so that the pulmonary veins drained to the left atrium, and the anomalous left superior vena cava was redirected to the right atrium. This necessitated a dry operative field, and accordingly the patient was cooled to 25°C and several short periods of total circulatory arrest were used. The mitral valve was replaced, as it was feared that the unusual shape of the patch could distort the mitral ring and the resultant small left atrium would not tolerate any degree of mitral incompetence.
RESULTS The patient having repair at 14 months of age had a rather stormy postoperative course, and initially there was little improvement in her clinical condition. A repeat catheter study six weeks after repair showed both significant mitral incompetence and a residual shunt, and she required continued medical therapy. During the next two years, however, her clinical condition gradually improved, and a restudy two years after the repair showed almost normal h;emodynamics, with only trivial mitral incompetence and a trivial residual left to right shunt. Both of the two patients who had not previously been banded and had Rastelli type repairs have done well clinically, but have some residual mitral incompetence. One has been restudied and shown to have a normal pulmonary artery pressure, with no shunts and only trivial mitral incompetence, and the other has clinical mild mitral incompetence. The other patient who presented for surgery without prior banding, but required repair of AUST. N Z. J. SURG., VOL.47-"o. Q
4, AUGUST, 1977
CLARKE ET ALII
anomalously draining pulmonary veins and a persistent left superior vena cava at the same time, had some evidence of neurological damage immediately after surgery, but this has almost entirely resolved and he is now clinically well. The results were markedly less favourable in the group of five patients who had previously had a pulmonary artery band. Three died in a low output state following surgery. One survived a Rastelli type of repair, but continued to have congestive failure, and a further catheter study showed that she had both mitral steiiosis and incompetence with pulmonary hypertension. Some six months after repair she came forward for mitral valve replacement, but did not survive operation, and a post-mortem examination showed that the prosthesis had distorted the left ventricular outflow tract with probable obstruction, and there was histological evidence of moderately severe pulmonary vascular disease. One patient who had previously had a pulmonary artery band required mitral valve replacement at the time of surgery and has clinically done well. Thus no patient who had prior pulmonary artery banding has survived repair with conservative mitral valve reconstruction alone, and the only long-term survivor required mitral valve replacement notwithstanding a favourable course after banding, and preoperative catheter evidence of no more than moderate mitral incompetence.
DISCUSSION Patients with total atrioventricular canal lesions tend to get into difficulty early in life, with tachypnoea and failure to thrive. Unless they are treated at this stage, the majority will either die or develop pulmonary vascular changes which preclude subsequent correction. A significant proportion of these patients will have Downs syndrome, and opinion differs as to the advisability of offering surgery to this group, especially as it has been found that when institutionalized they are particularly liable to be carriers of serum hepatitis. Our own policy has been only to accept those patients with a stable home environment, and who are Australian antigen negative. In the early reported series of patients having repair of total atrioventricular canal
513
ATRIOVENTRICULAR CANAL LESIONS
CLARKE ET ALII
lesions there was a high operative mortality (Ellis et alii, 1960; Mustard et a&, 1965), and amongst the survivors residual mitral incompetence was a significant problem. The modern fundamentals of repair were described by Rastelli et alii (1968), who laid down the principles of dividing the tricuspid and mitral leaflets in the midline, and placing a common patch between the ventricles and atria and reattaching the repaired mitral valve at its optimum position. Using these principles, McMullen et a& (1972) were able to report a 7% mortality in 27 patients, with a favourable early postoperative follow-up from the point of view of residual mitral incompetence. However, only two of these patients had been previously banded, and both had come to repair electively. An alternative method in that the mitral valve is electively replaced in order to obviate residual mitral incompetence has been advocated by Castaneda st alii ( 1971). The limiting factor of this approach is the long-term durability of the prosthetic valve. Banding of the main pulmonary artery as a palliative measure has not been widely used for atrioventricular canal defects despite the good results reported by Somerville et a& (167). Although our initial results were promising in that the only hospital mortality was amongst the patients with complex associated lesions, the subsequent course after banding has in most cases been indifferent, with failure to thrive and the onset of cyanosis requiring correction of the defect before the optimum age of five to seven years. At the time of correction debanding has not proved a problem, but the repair has, and the mortality has been exclusively amongst this group. Of the two survivors, one had had a particularly good response to banding, but even so required mitral valve replacement at the time of surgery, and the other survived the Rastelli procedure, but remained in heart failure and died at the subsequent attempt to replace the mitral valve. This implies that the patients who get into trouble at an early age are those with insufficiency of mitral valve tissue or particularly distorted valves. I n marked contrast, none of the patients in our series who had not previously had pulmonary artery banding died, and the only patient in this group who required mitral valve replacement also had complex associated
anomalies. Both of the Rastelli type repairs in older children have done well, and one child has been shown to have virtually normal hamodynamics. A patient treated by a somewhat inferior technique in early infancy initially had significant residual problems, but these have cured themselves with the passage of time, and the child is now symptomatically well. There have been several reports of success with total repair in infancy (BarrattBoyes, 1972; McGoon et a&, 1973; Mills et alii, 1976) and this, along with our experience, suggests that total repair is preferable to preliminary banding and later repair, even in this age group. The argument against early repair in infancy is that the mitral valve may be unreconstructable, but it is doubtful whether patients with such severe lesions would survive banding, as this does nothing to alleviate the mitral incompetence. Our single experience of repair in infancy also suggests that contrary to the fear that the mitral deformity would tend to worsen after repair because of fibrosis along the sutured cleft, the heart in fact retains the capability of adjusting the hamodynamic situation as it matures.
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AUST.N.Z. J. SURG, VOL. 47-N0.
REFERENCES BARON,M. G., WOLF,B. S., STEINFELD, L. and VAN MIEROP,L. H. S. (1964), Amer. J. Cardiol., 13: I 62. BARRATT-BOYES, B. G. (1972), Open Heart Surgery in Infancy, Proceedings of International Symposium held in Bergamo, ed. Parenzan, L. and Carcassonne, M., Sapil, Milan : 223. BURCHELL, H. B., DUSHANE,J. W. and BRANDENBERG,R. 0. ( r g b ) , Amer. J. Cardiol., 6 : 575. D. M., MOLLER, J. H. CASTANEDA, A. R., NICOLOFF, and LUCAS,R. V. ( I ~ I ) J. , thorac. cardiovosc. Surg., 62: 926. CLARKE,C. P., BROWN,T. C. K., MCKIE, B. D., JONES,P. G. and VENABLES, A. W. (1971), Med. J. Aust., 2 : 710. CLARKE,C. P. and RUBIN,S. Z. (1973), AUST. N.Z. J. SURG.,42: 242. LLLIS, F. H., MCGOON,D. C. and KIRKLIN,J. W. (I@o), Amer. J. Cardiol., 6 : 598. FRATER, R. W. M. (1965), Circulation, 32: 120. MCGOON,D. C., MCMULLAN, M. H. and MAIR,D. D. and DANIELSON,G. K. (I973), Proc. Mayo Clin., 48: 769. MCMULLAN,M. H., WALLACE, R. B., WEIDMAN,W. H. and MCGOON,D. C. (1972), Surgery, 72: 905.
MILLS,N., OCHSNER,J. L. and KING,T. D. (1976). J. thorac. cardiovasc. Surg., 71: 20. 4, AUGUST, 1977
RIGHT CORONARY ENDARTERECTOMY
GALE ET ALII
J. F. (1952), Surg. SOMERVILLE, J., AGNEW,T., STARK,J., WATERSTON, MULLER,W. H. and DAMMANN, Gynec. Obstet., 95: 213. D. J., AEERDEEN,E., BONHAM-CARTER, R. E. MUSTARD,W. T., NIGUIDULA,F. N. and TRUSLER, and WAICH, S. (1967), Brif. Heart J., 29: 816. TENCKHOFF,L. and STAMM, S. J. (1973), CirculaG. A. (1&5), Brit. Heart J., 28: 768. RASTELLI,G. C., KIRKLIN,J. W. and TITUS, J. L. tion, 48: 416. (1966), Proc. M a y o Clin., 41 : 296. VAN MIEROP,L. H. S. and ALLEY,R. D. (1g66), Ann. thorac. Surg., 2 : 416. RASTELLI,G. C., ONGLEY,P. A., KIRKLIN,J. W. and M c G o o ~ , D. C. (1968), -7. thoruc. cardiovusc. WAIT,J. H. and MUSTARD, W. T. (rg65), 1. thomc. Surg., 5 5 : 299. cardiovasc. Swg., 49: 968.
RIGHT CORONARY ENDARTERECTOMY: A PROCEDURE WITH INCREASED RISK OF PERIOPERATIVE INFARCTlON ALANW. GALE,VICTORP. CHANG, MARKX. SHANAHAN AND HARRY M. WINDSOR Cardiac Surgical Unit of St Viment's Hospitd, Sydney Although right coronary endarterectomy extends operability en this vessel, the procedure is associated with increased risk of perioperative infarctlon. Forty-nine patients a t S t Vincent's Hospital underwent endarterectomy and saphenous vein graftlng to the distal right coronary artery, with a hospltal mortality of 6.1% and a perloperative infarction rate of 20-4y0, compared with rates of 4.2% and 10.9% respectively I n a group of patients who did not require endarterectomy. These figures show a trend toward rtatiotical rignificance which suggests that careful. patient selection for endarterectomy is required to obviate an Increased risk of complications with this procedure.
THEright main coronary artery is involved by atheromatous obstruction in 80% to 90% of patients presenting for myocardial revascularization and is frequently the vessel most extensively affected (Groves et alii, 1972). Endarterectomy has extended operability on this vessel, and when combined with reversed autogenous saphenous vein bypass grafts, has allowed more complete attempts at total myocardial revascularization. This report reviews the early experience with 49 patients who received vein grafts and endarterectomy of their right coronary arteries.
Reprints : H. M. Windsor, Medical Centre, St Vincent's Hospital, Darlinghurst, N.S.W. 2010.
284 patients received reversed autogenous saphenous vein grafts to the right main coronary artery (Group I ) , and an additional 49 patients had saphenous vein grafts to the right coronary artery following endarterectomy (Group 2) (Table I ) . The indication for surgery was chronic stable angina in 76% (216) of Group I patients and 90% (4) of Group 2, whereas unstable angina was the indication in 16% (61) of Group I patients and 2% ( I ) of Group 2. Recurrent arrhythmia, acute myocardial infarction, angiographic abnormality, and reoperation, accounted for the other indications, there being no difference in the incidence in either group. A history of previous myocardial infarction was obtained in approximately 45% of patients in each group. Evidence of i s c h m i c changes was present in the anterior leads in the electrocardiographs
AUGUST, 1977
515
PATIENTS During the period November 1969 to March 1976, 543 patients underwent surgery at St Vincent's Hospital for coronary artery disease ;
AUST. N.Z. J. SURG., VOL. 47-"o.
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