Method of Managing the Small Aortic Annulus during Valve Replacement Richard H. Blank, M.D., Dennis F. Pupello, M.D., Luis N. Bessone, M.D., Eric E. Harrison, M.D., and Sheldon Sbar, M.D. ABSTRACT In a series of 130 patients undergoing Clinical Material and Technique aortic valve replacement, 20 had the ascending aorta One hundred thirty patients underwent aortic enlargedwith a Dacron patch. Eight of these required valve replacement during the period from July, division of the annulus with extension of the incision 1972, through September, 1975. Twenty patients inferiorly to the anterior leaflet of the mitral valve. had enlargement of the ascending aorta using an The resulting separation of the annulus allowed a appropriately tailored Dacron patch. In 8 of larger size valve to be inserted. Glutaraldehyde-fixed them the aortic root was small, necessitating porcine heterografts were used in all patients having enlargement of the aortic annulus by the techthe annulus enlarged. No deaths occurred in those nique to be described. There were 7 women and patients having annular enlargement, and the post- 1man. Six patients had aortic stenosis and 2 had operative studies show no evidence of mitral valve aortic insufficiency. Preoperative and postdysfunction. operative catheterization data are summarized
in the Table. The estimated aortic annulus Replacement of the aortic valve in the presence diameter in this group ranged from 18 to 21 mm. of a normal or large aortic root can be accomThe heart was exposed through a midline plished with ease and safety in most instances sternotomy, and standard cannulation tech[l, 2,121. The presence of a diminutive annulus, niques were used. Moderate systemic hypohowever, remains a problem in that both thermia combined with perfusion at a relamechanical prostheses and stent-mounted tis- tively low flow rate was employed. Myocardial sue valves have significant resting gradients in protection was provided by profound local the smaller sizes [3, 91. In addition, a recent hypothermia using a continuous cold saline irreport [4] suggests that use of the small tilting- rigation of the pericardial well. Once stable perdisc valve (Bjork-Shiley) predisposes to throm- fusion was achieved, the aorta was crossbotic complications. clamped and opened transversely and the Based on encouraging follow-up studies of incision was extended inferiorly into the nonthe Hancock glutaraldehyde-stabilized porcine coronary sinus. The aortic leaflets were resected, heterograft [13], we have used this prosthesis in and all calcific deposits were carefully removed. patients having an annular diameter less than 25 The interior of the heart was irrigated with cold mm. In those instances when the annulus was saline as the annulus was measured. too small to accept a prosthesis of adequate size, For those patients whose aortic root was a technique has been used to allow expansion of deemed too small to accept a valve of suitable the annulus, thereby permitting insertion of the size, the incision was extended into the base of next larger size valve. This report presents our the anterior mitral leaflet (Figs l A , 2). This experience in managing the small aortic root. created a V-shaped defect through the annulus and subvalvular segment of what McAlpine [81 From the Division of Thoracic and Cardiovascular Surgery, has termed the aortoventricular membrane. The University of South Florida School of Medicine, and The length of the incision, measured from the anTampa General Hospital, Tampa, FL. nulus inferiorly, varied from 5 to 10 mm. Sizing We wish to express our gratitude to Miss Christine Binda and Mr. Bill Kickliter for their technical assistance in the of the orifice was repeated and the appropriate preparation of the manuscript. valve was selected. Horizontal mattress sutures Presented at the Twelfth Annual Meeting of The Society of of 2-0 Tevdek were passed through the margins Thoracic Surgeons, Washington, DC, Jan 26-28, 1976. of the V (Fig lB), and the annulus was rimmed Address reprint requests to Dr. Blank, 1 Davis Blvd, Tampa, FL 33606. with similar sutures. Since the left atrial reflec356
357
Blank et al: Managing the Small Aortic Annulus during Valve Replacement
Preoperative and Postoperative Cardiac Catheterization Data in 8 Patients with Small Aortic Root Patient's Age (yr) & Sex
53, F 56, F 70, M 64, F 60, F 50, F 73, F 71, F
Gradient (mm Hg) Preop
140 80 78 90 90 0" 0'
110
Postop
. . .a
24b 10 7
. . .a
3 4 15
Heterograft
Valve Size (mm)
21 23 23 21 23 23 23 23
aRefused restudy. bPullbackgradient only.
A
'Aortic insufficiency.
tion forms an acute angle at its junction with the anterior mitral leaflet, it was possible to avoid opening this chamber. In the event that the left atrium was entered, it would be closed by simply including the cut edges of the atrium in the same mattress sutures that were used to approximate the opened annulus to the underside of the valve sewing ring. After the valve was seated and the sutures were tied, a Dacron patch was sutured to the superior margin of the exposed sewing ring, filling the gap created by the annular enlargement (Fig 1C). The ascending aorta was thereby widened as the patch was sutured in place. All air was evacuated from the aorta and the crossclamp was removed. The heart was defibrillated after 10 to 12 minutes of rewarming.
B
Results Aortic cross-clamp time ranged from 46 to 86 minutes in the patients having annular enlargement. This is 12 minutes longer than average clamping time in the overall isolated aortic Fig 1. ( A ) The aortic incision is continuedinferiorly in the noncoronary sinus, dividing the annulus and extending into the margin of the anterior mitral leaflet. (B)Placement of horizontal mattress sutures in the defect. (0The defect is bridged by the sewing ring as the sutures are tied.
C
358 The Annals of Thoracic Surgery Vol 22 No 4 October 1976
Fig2. Dissected postmortem specimen with atria removed. Silk sutures placed in the divided aortic annulus show extension of the incision into the margin of the anterior mitral leaflet. (The incision usually ends near the left atrial reflection but has been extended to allow adequate demonstration of the divided aortic annulus.)
valve replacement group. All 8 patients survived the operation, and 6 of them have had repeat cardiac catheterizations. Ventriculograms in all studied patients showed no alteration in the relationship of the mitral annulus to the aortic outflow tract. One patient had had intermittent bouts of atrioventricular dissociation preoperatively and required insertion of a permanent pacemaker. All patients were alive and remained improved from ten to eighteen months postoperatively.
Comment All currently available stent-mounted tissue valves have the disadvantage of the orifice being compromised by the mounting device. Bjork and his colleagues [2, 31 developed a semicentral-flow, tilting-disc valve because of their dissatisfaction with the high gradients associated with the smaller caged ball valves. The 21 mm Bjork-Shiley prosthesis has been used successfully in patients with a narrow aortic root, but it has a resting mean gradient of approximately 20 mm Hg that increases linearly with exercise [3]. Najafi and his co-workers [lo1 called attention to the difficulty attending valve replacement in patients having a small aorta and described the technique of enlarging the ascending aorta using a Teflon patch. Konno and as-
sociates [71 reported a technique for enlarging the aortic annulus by continuing the incision inferiorly to the left of the right coronary ostium into the ventricular septum. This requires opening and enlarging the right ventricular outflow tract as well as repair of the resulting septa1 defect. Nicks and his associates 1111 first described extension of the aortotomy, inferiorly dividing the noncoronary cusp attachment line (annulus) and continuing the incision to the origin of the anterior mitral leaflet. A Dacron patch was sewn to the edges of the defect, thus allowing a larger size (9-10A) Starr-Edwards prosthesis to be used. Certain anatomical features of the aortic root suggest that the noncoronary sinus is the logical site for expansion of the annulus. Portions of the left and noncoronary sinuses bear a constant relationship to the anterior leaflet of the mitral valve (Fig-3). This portion of the mitral apparatus does not participate in active contraction of the mitral annulus; the remaining threefourths of the valve, which is contiguous with the ventricular myocardium, does [5]. In addition, the right fibrous trigone is close to the incision line and adds to valve support at this level [6]. The incision passes immediately to the left of the right fibrous trigone, sufficiently posFig3. Relationship ofthe noncoronary andleft coronary sinuses to the anterior mitral leaflet. (The incision is represented by the dotted line.)
359
Blank et al: Managing the Small Aortic Annulus during Valve Replacement
terior to avoid the conducting system. In our experience, intrusion of a portion of the prosthetic sewing ring in the subvalvular segment of the aortoventricular membrane [81 does not produce mitral valve dysfunction. Our preference for using the porcine heterograft is supported by the work of Zuhdi's group [131, indicating a low instance of valve failure in patients followed for up to sixty months. Thromboembolic phenomena are negligible, and the valve demonstrates excellent hemodynamics. We prefer to use a porcine heterograft 23 mm or larger, although in those instances when it was necessary to use a smaller valve, the resulting gradient appears to be well tolerated. References 1. Barnhorst DA, Oxman HA, Connolly DC, et al: Isolated replacement of the aortic valve with the Starr-Edwards prosthesis: a nine year review. J Thorac Cardiovasc Surg 70:113, 1975 2. Bjork VO, Henze A, Holmgren A: Five years' experience with the Bjork-Shiley tilting-disc valve in isolated aortic valve disease. J Thorac Cardiovasc Surg 68:393, 1974 3. Bjork VO, Henze A, Holmgren A, et al: Evaluation of the 21 mm Bjork-Shiley tilting disc valve in patients with narrow aortic roots. Scand J Thorac Cardiovasc Surg 7:203, 1973 4. Byrd CL, Yahr WZ, Greenberg JJ: Long-term results of "simple" thrombectomy for thrombosed Bjork-Shiley aortic valve prostheses. Ann Thorac Surg 20:265, 1975 5. Frater RWM: Mitral valve anatomy and prosthetic valve design. Proc Staff Meet Mayo Clin 36:582, 1961 6. Goss CM (Ed): Anatomy of the Human Body by Henry Gray (29th ed). Philadelphia, Lea & Febiger, 1973 7. Konno S, Imai Y, Iida Y, et al: A new method for prosthetic valve replacement in congenital aortic stenosis associated with hypoplasia of the aortic valve ring. J Thorac Cardiovasc Surg 70:909,1975 8. McAlpine WA: Heart and Coronary Arteries. New York, Springer Verlag, 1975, p 10 9. Morris DC, Wickliffe CW, King SB III, et al: Hemodynamic evaluation of the porcine heterograft in the aortic position. Presented at the 48th Scientific Session of the American Heart Association, Anaheim, CA, November 1975 10. Najafi H, Ostermiller WE, Hushang J: Narrow aortic root complicating aortic valve replacement. Arch Surg 99:690, 1969 11. Nicks R, Cartmill T, Bernstein L: Hypoplasia of the aortic root. Thorax 25:339, 1970
12. Starr A, Bonchek LI, Anderson RP, et al: Late complications of aortic valve replacement with cloth-covered, composite-seat prostheses. Ann Thorac Surg 19:289, 1975 13. Zuhdi N, Hawley W, Voehl V, et al: Porcine aortic valves as replacements for human heart valves. Ann Thorac Surg 17:479, 1974
Discussion DR. HASSAN NAJAFI (Chicago,
IL): Dr. Blank has presented an imaginative, bold, and seemingly highly successful contribution to this very difficult area in aortic valve surgery. At the 1975 meeting of the American Heart Association in Anaheim, I was equally impressed with a report from Middlesex, England, that surgeons at that institution had inserted adult-size, fresh aortic homografts in 8 patients 18 months to 15 years of age without any early deaths. Although Dr. Blank kindly referred to our work in enlarging the aortic root, I have to admit that we have not been courageous enough to extend the incision down or through the aortic valve annulus. But when I received a copy of their fine manuscript, it stimulated me to go to the morgue and test this technique in the autopsy room. I can assure you that it is feasible, although at the end one would wonder whether the junction between the patch, the sewing ring, and the biological tissues, which is really the edge of the left atrium, would withstand the 150 to 200 mm Hg pressure and not bleed. Apparently this has been so in their experience. Our experience at Presbyterian-St. Luke's Hospital over two and one-half years includes 205 isolated aortic valve replacements. In 48 of these, or one-fourth of the patients, we used Bjork-Shiley valves. When I reviewed these cases I noted that the choice of the valve had been governed by the anatomy, mostly narrowing of the aortic root and small size of the valve annulus. It was interesting that of the 157 patients who received the Starr-Edwards prostheses, a No. 8 valve was used in 11. I think this is a marginal ball-valve prosthesis and should probably not be considered. Certainly a No. 7 should almost never be utilized clinically. The single patient who received a No. 7 valve actually had had a No. 9 Starr-Edwards prosthesis implanted in 1966, and she did well until a year ago when she started having thromboembolic manifestations. At that time the No. 9 valve was removed and a size 7 was inserted. In one year she has gone on to develop cardiomegaly, pulmonary hypertension, and pulmonary congestion, all pointing most probably to a guarded prognosis. (Houston, TX): For relief of some of the more complicated problems involving stenosis of the aortic valve, subvalvular region, and ascending aorta, we have employed a method origiDR. DENTON A . COOLEY
360 The Annals of Thoracic Surgery Vol 22 No 4 October 1976
nally reported by Sarnoff, who used this technique in animals, and by Templeton, who used it in a limited clinical series. The technique creates a double-outlet left ventricle. A woven Dacron graft containing a Hancock porcine valve is sutured to the apex of the left ventricle, and the valve is placed intraabdominally just below the diaphragm. The distal end of the graft is sutured to the proximal abdominal aorta proximal to the origin of the celiac axis. An angiogram in our first patient, who was operated upon in August, 1975, revealed the unusual appearance of the double-outlet left ventricle and the tortuous course of the conduit into the abdominal aorta. The preoperative left ventricular pressure had been 250 mm Hg systolic, and the gradient across the valve was 100 mm Hg. Postoperatively a residual gradient of 15 mm Hg was present between the ventricle and the ascending aorta. Since that initial case we have operated on 3 other patients using this technique, a total of 2 girls and 2 male patients with ages ranging from 7 to 36 years. The 36-year-old man had an atypical kind of obstructive cardiomyopathy and had been unsuccessfully operated on twice previously using standard techniques. The gradients in all these patients had exceeded 100 mm Hg preoperatively. Postoperatively the maximum was 20 mm Hg. It was interesting to quantitate the volume of flow through the ascending aorta against that through the graft conduit using a special flow-tipped catheter. The flows through the conduit were calculated at 29, 41, 33, and 32% of left ventricular output, respectively. In the last 2 patients we temporarily occluded the ascending aorta while the thoracotomy was still open. No changes occurred in systemic arterial pressure, indicating that the entire cardiac output could be delivered through the conduit. One advantage of this technique may be evident if in the future replacement of the Hancock valve becomes necessary: it could be accomplished rather simply by a laparotomy. (Atlanta, GA): Dr. Charles Hatcher and I at Emory University Hospital have used the Hancock aortic prosthesis in approximately 110 patients over the last year and a half with l death. We consider the hemodynamics of the valve good. We have had the opportunity to restudy 22 of these patients with complete right and left heart catheterization at rest and during exercise. The average resting peak systolic left ventricular-aortic pressure gradient for the 19 and 21 mm prostheses was 28 and 25 mm Hg, respectively. By comparison, the average for the 25 mm prosthesis was 20 mm Hg. A similar gradient relationship existed between the smaller and larger prostheses during exercise. It must be noted, however, that most of the individuals in whom the 19 and 21 mm prostheses were used were female patients with a small body surface area and a correspondingly DR. ELLIS L. JONES
small aortic root. The calculated orifice size showed increasing values, from 0.99 cm2for the 19 mm prosthesis to 1.42 cm2 for the 25 mm prosthesis. From our experience, we recommend that the largest valves, that is, 23 mm or greater, be considered mandatory for male patients with an average or large body surface area; smaller sizes, such as the 21 mm, still may be used satisfactorily for small women in whom cardiac output is not as great even during exercise. When a slightly larger prosthesis is required, an annulus-enlarging procedure such as described by Dr. Blank may be used. In patients with extreme hypoplasia of the aortic annulus or in young children, a procedure in which the aortic annulus is completely divided midway between the right and left coronary ostia down into the ventricular septum may be used. DR. CLARENCE s. WELDON (St Louis, MO): Several techniques have been devised for enlarging a small aortic annulus so that the aortic valve may be replaced with a sizable prosthesis. I think these techniques are very helpful. There are, however, some problems they do not solve. One of these is obstruction to left ventricular outflow that cannot be resected. Another is the terrible problem of putting a prosthetic valve in a child; I say terrible problem because I am convinced that we don't have a valve with durability equal to normal life expectancy. I would like to describe our experience in creating a second left ventricular outflow tract with a valvebearing conduit interposed between the left ventricular apex and the aorta. A child was operated on at the age of 3 years for biventricular obstruction. He had gradients above 100 mm Hg in both the right and left ventricle. Muscle was resected from the right ventricle, and a myotomy was performed in the left ventricle. The right ventricular pressure gradient was relieved but the left ventricular gradient was not. We have approached this problem a bit differently from the way Dr. Cooley has. We use a Hancock prosthesis but adapt it by inserting onto the end a rigid cylinder covered with cloth. This cylinder is designed to project into the left ventricular cavity and thus to maintain the opening at the left ventricular apex. Of course, putting a new outflow tract on the other side of the obstruction completely relieves the gradient, A second patient, a 16-year-old girl, had a very severe midventricular obstruction which at the time of operation appeared to be fibrous tunnel obstruction of the left ventricular outflow tract. She had a gradient of 100 mm Hg in her left ventricle and 50 mm Hg in her right ventricle. We first operated through the aortic valve and removed the subvalvular fibrous tissue. Lower obstruction could not be resected, and therefore we constructed an apical-aortic shunt. We put the distal end of this graft into the infrarenal aorta. I think it works quite well there; it is simple to expose this area, and as Dr. Cooley said, it is also easy to
361
Blank et al: Managing the Small Aortic Annulus during Valve Replacement
change the valve at some future time when it wears out. This second patient was fairly remarkable. At recatheterization, not only was the gradient absent from her left ventricle, but the gradient of 50 mm Hg due to septa1 movement had disappeared from her right ventricle. So she now has absolutely no gradients in her heart, and pressures are normal in both sides. In the first patient, retrograde flow through the apical-aortic outflow tract went all the way to the left subclavian artery. In the second, when the middle of the ventricle was injected, the inferior outflow tract filled only to the level of the diaphragm. The amount of flow through the new outflow tract depends upon the degree of obstruction in the natural outflow tract. DR. BLANK: I thank the discussants for their comments, particularly Dr. Cooley and Dr. Weldon for describing their interesting management of various small aortic roots. To answer Dr. Najafi’s question, we were fearful that doing an annular enlargement procedure would actually not allow a double-valve replacement. Until late in this study, if we incised the subannular tissues, I always thought we were cutting into the mitral valve. But in a patient who has the V-shaped defect
and in whom the annulus has been stretched, if one looks closely at the anatomy, it is apparent that the subannular tissues can be incised from 5 to 10 mm in some instances-achieving, admittedly, a very small increase in transverse diameter. Another point I would like to make is that the sutures are placed through the subannular tissue and then pulled to the undersurface of the sewing flange on the Hancock prosthesis. The Dacron patch is then sewn to the sewing flange. We consider this a very strong point in the repair. After this study was completed we had a patient in whom the aorta was friable, and we did reinforce it with Teflon-felt pledgets. Dr. Jones, we were aware of the work you mentioned and have actually communicated with the Emory group. One of the factors that stimulated our interest in this area was the marked increase in crosssectional area-20 to 25%, depending on the individual valve-when one goes from a 21 to 23 mm porcine heterograft since there is no standardization of orifice diameter in the pig valve at the present time. I was also aware of the experience from England reported at Anaheim and have written to the surgeon inviting him to come and discuss it with us or to let us know what technique he used. As far as I know, his paper has not been published.
in the Table. The estimated aortic annulus Replacement of the aortic valve in the presence diameter in this group ranged from 18 to 21 mm. of a normal or large aortic root can be accomThe heart was exposed through a midline plished with ease and safety in most instances sternotomy, and standard cannulation tech[l, 2,121. The presence of a diminutive annulus, niques were used. Moderate systemic hypohowever, remains a problem in that both thermia combined with perfusion at a relamechanical prostheses and stent-mounted tis- tively low flow rate was employed. Myocardial sue valves have significant resting gradients in protection was provided by profound local the smaller sizes [3, 91. In addition, a recent hypothermia using a continuous cold saline irreport [4] suggests that use of the small tilting- rigation of the pericardial well. Once stable perdisc valve (Bjork-Shiley) predisposes to throm- fusion was achieved, the aorta was crossbotic complications. clamped and opened transversely and the Based on encouraging follow-up studies of incision was extended inferiorly into the nonthe Hancock glutaraldehyde-stabilized porcine coronary sinus. The aortic leaflets were resected, heterograft [13], we have used this prosthesis in and all calcific deposits were carefully removed. patients having an annular diameter less than 25 The interior of the heart was irrigated with cold mm. In those instances when the annulus was saline as the annulus was measured. too small to accept a prosthesis of adequate size, For those patients whose aortic root was a technique has been used to allow expansion of deemed too small to accept a valve of suitable the annulus, thereby permitting insertion of the size, the incision was extended into the base of next larger size valve. This report presents our the anterior mitral leaflet (Figs l A , 2). This experience in managing the small aortic root. created a V-shaped defect through the annulus and subvalvular segment of what McAlpine [81 From the Division of Thoracic and Cardiovascular Surgery, has termed the aortoventricular membrane. The University of South Florida School of Medicine, and The length of the incision, measured from the anTampa General Hospital, Tampa, FL. nulus inferiorly, varied from 5 to 10 mm. Sizing We wish to express our gratitude to Miss Christine Binda and Mr. Bill Kickliter for their technical assistance in the of the orifice was repeated and the appropriate preparation of the manuscript. valve was selected. Horizontal mattress sutures Presented at the Twelfth Annual Meeting of The Society of of 2-0 Tevdek were passed through the margins Thoracic Surgeons, Washington, DC, Jan 26-28, 1976. of the V (Fig lB), and the annulus was rimmed Address reprint requests to Dr. Blank, 1 Davis Blvd, Tampa, FL 33606. with similar sutures. Since the left atrial reflec356
357
Blank et al: Managing the Small Aortic Annulus during Valve Replacement
Preoperative and Postoperative Cardiac Catheterization Data in 8 Patients with Small Aortic Root Patient's Age (yr) & Sex
53, F 56, F 70, M 64, F 60, F 50, F 73, F 71, F
Gradient (mm Hg) Preop
140 80 78 90 90 0" 0'
110
Postop
. . .a
24b 10 7
. . .a
3 4 15
Heterograft
Valve Size (mm)
21 23 23 21 23 23 23 23
aRefused restudy. bPullbackgradient only.
A
'Aortic insufficiency.
tion forms an acute angle at its junction with the anterior mitral leaflet, it was possible to avoid opening this chamber. In the event that the left atrium was entered, it would be closed by simply including the cut edges of the atrium in the same mattress sutures that were used to approximate the opened annulus to the underside of the valve sewing ring. After the valve was seated and the sutures were tied, a Dacron patch was sutured to the superior margin of the exposed sewing ring, filling the gap created by the annular enlargement (Fig 1C). The ascending aorta was thereby widened as the patch was sutured in place. All air was evacuated from the aorta and the crossclamp was removed. The heart was defibrillated after 10 to 12 minutes of rewarming.
B
Results Aortic cross-clamp time ranged from 46 to 86 minutes in the patients having annular enlargement. This is 12 minutes longer than average clamping time in the overall isolated aortic Fig 1. ( A ) The aortic incision is continuedinferiorly in the noncoronary sinus, dividing the annulus and extending into the margin of the anterior mitral leaflet. (B)Placement of horizontal mattress sutures in the defect. (0The defect is bridged by the sewing ring as the sutures are tied.
C
358 The Annals of Thoracic Surgery Vol 22 No 4 October 1976
Fig2. Dissected postmortem specimen with atria removed. Silk sutures placed in the divided aortic annulus show extension of the incision into the margin of the anterior mitral leaflet. (The incision usually ends near the left atrial reflection but has been extended to allow adequate demonstration of the divided aortic annulus.)
valve replacement group. All 8 patients survived the operation, and 6 of them have had repeat cardiac catheterizations. Ventriculograms in all studied patients showed no alteration in the relationship of the mitral annulus to the aortic outflow tract. One patient had had intermittent bouts of atrioventricular dissociation preoperatively and required insertion of a permanent pacemaker. All patients were alive and remained improved from ten to eighteen months postoperatively.
Comment All currently available stent-mounted tissue valves have the disadvantage of the orifice being compromised by the mounting device. Bjork and his colleagues [2, 31 developed a semicentral-flow, tilting-disc valve because of their dissatisfaction with the high gradients associated with the smaller caged ball valves. The 21 mm Bjork-Shiley prosthesis has been used successfully in patients with a narrow aortic root, but it has a resting mean gradient of approximately 20 mm Hg that increases linearly with exercise [3]. Najafi and his co-workers [lo1 called attention to the difficulty attending valve replacement in patients having a small aorta and described the technique of enlarging the ascending aorta using a Teflon patch. Konno and as-
sociates [71 reported a technique for enlarging the aortic annulus by continuing the incision inferiorly to the left of the right coronary ostium into the ventricular septum. This requires opening and enlarging the right ventricular outflow tract as well as repair of the resulting septa1 defect. Nicks and his associates 1111 first described extension of the aortotomy, inferiorly dividing the noncoronary cusp attachment line (annulus) and continuing the incision to the origin of the anterior mitral leaflet. A Dacron patch was sewn to the edges of the defect, thus allowing a larger size (9-10A) Starr-Edwards prosthesis to be used. Certain anatomical features of the aortic root suggest that the noncoronary sinus is the logical site for expansion of the annulus. Portions of the left and noncoronary sinuses bear a constant relationship to the anterior leaflet of the mitral valve (Fig-3). This portion of the mitral apparatus does not participate in active contraction of the mitral annulus; the remaining threefourths of the valve, which is contiguous with the ventricular myocardium, does [5]. In addition, the right fibrous trigone is close to the incision line and adds to valve support at this level [6]. The incision passes immediately to the left of the right fibrous trigone, sufficiently posFig3. Relationship ofthe noncoronary andleft coronary sinuses to the anterior mitral leaflet. (The incision is represented by the dotted line.)
359
Blank et al: Managing the Small Aortic Annulus during Valve Replacement
terior to avoid the conducting system. In our experience, intrusion of a portion of the prosthetic sewing ring in the subvalvular segment of the aortoventricular membrane [81 does not produce mitral valve dysfunction. Our preference for using the porcine heterograft is supported by the work of Zuhdi's group [131, indicating a low instance of valve failure in patients followed for up to sixty months. Thromboembolic phenomena are negligible, and the valve demonstrates excellent hemodynamics. We prefer to use a porcine heterograft 23 mm or larger, although in those instances when it was necessary to use a smaller valve, the resulting gradient appears to be well tolerated. References 1. Barnhorst DA, Oxman HA, Connolly DC, et al: Isolated replacement of the aortic valve with the Starr-Edwards prosthesis: a nine year review. J Thorac Cardiovasc Surg 70:113, 1975 2. Bjork VO, Henze A, Holmgren A: Five years' experience with the Bjork-Shiley tilting-disc valve in isolated aortic valve disease. J Thorac Cardiovasc Surg 68:393, 1974 3. Bjork VO, Henze A, Holmgren A, et al: Evaluation of the 21 mm Bjork-Shiley tilting disc valve in patients with narrow aortic roots. Scand J Thorac Cardiovasc Surg 7:203, 1973 4. Byrd CL, Yahr WZ, Greenberg JJ: Long-term results of "simple" thrombectomy for thrombosed Bjork-Shiley aortic valve prostheses. Ann Thorac Surg 20:265, 1975 5. Frater RWM: Mitral valve anatomy and prosthetic valve design. Proc Staff Meet Mayo Clin 36:582, 1961 6. Goss CM (Ed): Anatomy of the Human Body by Henry Gray (29th ed). Philadelphia, Lea & Febiger, 1973 7. Konno S, Imai Y, Iida Y, et al: A new method for prosthetic valve replacement in congenital aortic stenosis associated with hypoplasia of the aortic valve ring. J Thorac Cardiovasc Surg 70:909,1975 8. McAlpine WA: Heart and Coronary Arteries. New York, Springer Verlag, 1975, p 10 9. Morris DC, Wickliffe CW, King SB III, et al: Hemodynamic evaluation of the porcine heterograft in the aortic position. Presented at the 48th Scientific Session of the American Heart Association, Anaheim, CA, November 1975 10. Najafi H, Ostermiller WE, Hushang J: Narrow aortic root complicating aortic valve replacement. Arch Surg 99:690, 1969 11. Nicks R, Cartmill T, Bernstein L: Hypoplasia of the aortic root. Thorax 25:339, 1970
12. Starr A, Bonchek LI, Anderson RP, et al: Late complications of aortic valve replacement with cloth-covered, composite-seat prostheses. Ann Thorac Surg 19:289, 1975 13. Zuhdi N, Hawley W, Voehl V, et al: Porcine aortic valves as replacements for human heart valves. Ann Thorac Surg 17:479, 1974
Discussion DR. HASSAN NAJAFI (Chicago,
IL): Dr. Blank has presented an imaginative, bold, and seemingly highly successful contribution to this very difficult area in aortic valve surgery. At the 1975 meeting of the American Heart Association in Anaheim, I was equally impressed with a report from Middlesex, England, that surgeons at that institution had inserted adult-size, fresh aortic homografts in 8 patients 18 months to 15 years of age without any early deaths. Although Dr. Blank kindly referred to our work in enlarging the aortic root, I have to admit that we have not been courageous enough to extend the incision down or through the aortic valve annulus. But when I received a copy of their fine manuscript, it stimulated me to go to the morgue and test this technique in the autopsy room. I can assure you that it is feasible, although at the end one would wonder whether the junction between the patch, the sewing ring, and the biological tissues, which is really the edge of the left atrium, would withstand the 150 to 200 mm Hg pressure and not bleed. Apparently this has been so in their experience. Our experience at Presbyterian-St. Luke's Hospital over two and one-half years includes 205 isolated aortic valve replacements. In 48 of these, or one-fourth of the patients, we used Bjork-Shiley valves. When I reviewed these cases I noted that the choice of the valve had been governed by the anatomy, mostly narrowing of the aortic root and small size of the valve annulus. It was interesting that of the 157 patients who received the Starr-Edwards prostheses, a No. 8 valve was used in 11. I think this is a marginal ball-valve prosthesis and should probably not be considered. Certainly a No. 7 should almost never be utilized clinically. The single patient who received a No. 7 valve actually had had a No. 9 Starr-Edwards prosthesis implanted in 1966, and she did well until a year ago when she started having thromboembolic manifestations. At that time the No. 9 valve was removed and a size 7 was inserted. In one year she has gone on to develop cardiomegaly, pulmonary hypertension, and pulmonary congestion, all pointing most probably to a guarded prognosis. (Houston, TX): For relief of some of the more complicated problems involving stenosis of the aortic valve, subvalvular region, and ascending aorta, we have employed a method origiDR. DENTON A . COOLEY
360 The Annals of Thoracic Surgery Vol 22 No 4 October 1976
nally reported by Sarnoff, who used this technique in animals, and by Templeton, who used it in a limited clinical series. The technique creates a double-outlet left ventricle. A woven Dacron graft containing a Hancock porcine valve is sutured to the apex of the left ventricle, and the valve is placed intraabdominally just below the diaphragm. The distal end of the graft is sutured to the proximal abdominal aorta proximal to the origin of the celiac axis. An angiogram in our first patient, who was operated upon in August, 1975, revealed the unusual appearance of the double-outlet left ventricle and the tortuous course of the conduit into the abdominal aorta. The preoperative left ventricular pressure had been 250 mm Hg systolic, and the gradient across the valve was 100 mm Hg. Postoperatively a residual gradient of 15 mm Hg was present between the ventricle and the ascending aorta. Since that initial case we have operated on 3 other patients using this technique, a total of 2 girls and 2 male patients with ages ranging from 7 to 36 years. The 36-year-old man had an atypical kind of obstructive cardiomyopathy and had been unsuccessfully operated on twice previously using standard techniques. The gradients in all these patients had exceeded 100 mm Hg preoperatively. Postoperatively the maximum was 20 mm Hg. It was interesting to quantitate the volume of flow through the ascending aorta against that through the graft conduit using a special flow-tipped catheter. The flows through the conduit were calculated at 29, 41, 33, and 32% of left ventricular output, respectively. In the last 2 patients we temporarily occluded the ascending aorta while the thoracotomy was still open. No changes occurred in systemic arterial pressure, indicating that the entire cardiac output could be delivered through the conduit. One advantage of this technique may be evident if in the future replacement of the Hancock valve becomes necessary: it could be accomplished rather simply by a laparotomy. (Atlanta, GA): Dr. Charles Hatcher and I at Emory University Hospital have used the Hancock aortic prosthesis in approximately 110 patients over the last year and a half with l death. We consider the hemodynamics of the valve good. We have had the opportunity to restudy 22 of these patients with complete right and left heart catheterization at rest and during exercise. The average resting peak systolic left ventricular-aortic pressure gradient for the 19 and 21 mm prostheses was 28 and 25 mm Hg, respectively. By comparison, the average for the 25 mm prosthesis was 20 mm Hg. A similar gradient relationship existed between the smaller and larger prostheses during exercise. It must be noted, however, that most of the individuals in whom the 19 and 21 mm prostheses were used were female patients with a small body surface area and a correspondingly DR. ELLIS L. JONES
small aortic root. The calculated orifice size showed increasing values, from 0.99 cm2for the 19 mm prosthesis to 1.42 cm2 for the 25 mm prosthesis. From our experience, we recommend that the largest valves, that is, 23 mm or greater, be considered mandatory for male patients with an average or large body surface area; smaller sizes, such as the 21 mm, still may be used satisfactorily for small women in whom cardiac output is not as great even during exercise. When a slightly larger prosthesis is required, an annulus-enlarging procedure such as described by Dr. Blank may be used. In patients with extreme hypoplasia of the aortic annulus or in young children, a procedure in which the aortic annulus is completely divided midway between the right and left coronary ostia down into the ventricular septum may be used. DR. CLARENCE s. WELDON (St Louis, MO): Several techniques have been devised for enlarging a small aortic annulus so that the aortic valve may be replaced with a sizable prosthesis. I think these techniques are very helpful. There are, however, some problems they do not solve. One of these is obstruction to left ventricular outflow that cannot be resected. Another is the terrible problem of putting a prosthetic valve in a child; I say terrible problem because I am convinced that we don't have a valve with durability equal to normal life expectancy. I would like to describe our experience in creating a second left ventricular outflow tract with a valvebearing conduit interposed between the left ventricular apex and the aorta. A child was operated on at the age of 3 years for biventricular obstruction. He had gradients above 100 mm Hg in both the right and left ventricle. Muscle was resected from the right ventricle, and a myotomy was performed in the left ventricle. The right ventricular pressure gradient was relieved but the left ventricular gradient was not. We have approached this problem a bit differently from the way Dr. Cooley has. We use a Hancock prosthesis but adapt it by inserting onto the end a rigid cylinder covered with cloth. This cylinder is designed to project into the left ventricular cavity and thus to maintain the opening at the left ventricular apex. Of course, putting a new outflow tract on the other side of the obstruction completely relieves the gradient, A second patient, a 16-year-old girl, had a very severe midventricular obstruction which at the time of operation appeared to be fibrous tunnel obstruction of the left ventricular outflow tract. She had a gradient of 100 mm Hg in her left ventricle and 50 mm Hg in her right ventricle. We first operated through the aortic valve and removed the subvalvular fibrous tissue. Lower obstruction could not be resected, and therefore we constructed an apical-aortic shunt. We put the distal end of this graft into the infrarenal aorta. I think it works quite well there; it is simple to expose this area, and as Dr. Cooley said, it is also easy to
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change the valve at some future time when it wears out. This second patient was fairly remarkable. At recatheterization, not only was the gradient absent from her left ventricle, but the gradient of 50 mm Hg due to septa1 movement had disappeared from her right ventricle. So she now has absolutely no gradients in her heart, and pressures are normal in both sides. In the first patient, retrograde flow through the apical-aortic outflow tract went all the way to the left subclavian artery. In the second, when the middle of the ventricle was injected, the inferior outflow tract filled only to the level of the diaphragm. The amount of flow through the new outflow tract depends upon the degree of obstruction in the natural outflow tract. DR. BLANK: I thank the discussants for their comments, particularly Dr. Cooley and Dr. Weldon for describing their interesting management of various small aortic roots. To answer Dr. Najafi’s question, we were fearful that doing an annular enlargement procedure would actually not allow a double-valve replacement. Until late in this study, if we incised the subannular tissues, I always thought we were cutting into the mitral valve. But in a patient who has the V-shaped defect
and in whom the annulus has been stretched, if one looks closely at the anatomy, it is apparent that the subannular tissues can be incised from 5 to 10 mm in some instances-achieving, admittedly, a very small increase in transverse diameter. Another point I would like to make is that the sutures are placed through the subannular tissue and then pulled to the undersurface of the sewing flange on the Hancock prosthesis. The Dacron patch is then sewn to the sewing flange. We consider this a very strong point in the repair. After this study was completed we had a patient in whom the aorta was friable, and we did reinforce it with Teflon-felt pledgets. Dr. Jones, we were aware of the work you mentioned and have actually communicated with the Emory group. One of the factors that stimulated our interest in this area was the marked increase in crosssectional area-20 to 25%, depending on the individual valve-when one goes from a 21 to 23 mm porcine heterograft since there is no standardization of orifice diameter in the pig valve at the present time. I was also aware of the experience from England reported at Anaheim and have written to the surgeon inviting him to come and discuss it with us or to let us know what technique he used. As far as I know, his paper has not been published.
