HYPERTROPHIC SUBAORTIC STENOSIS: EVOLUTION OF A SURGICAL TECHNIQUE

HYPERTROPHIC SUBAORTIC STENOSIS: E V O L U T I O N OF A SURGICAL TECHNIQUE A. R. C. Dobell, M.D. (by invitation), Montreal,

and H. J. Scott, M.D. (by

invitation),

Quebec, Canada

Sponsored by Lloyd D. MacLean, M.D., Montreal, Quebec, Canada

S

its first description by Brock6 a few years ago, a perplexing form of heart disease has been recognized with increasing frequency. To a large extent, through the investigations of Braunwald and Morrow 3 ' 4 and their col­ leagues at the National Heart Institute, the veil of mystery has been partially lifted. Idiopathic hypertrophie subaortic stenosis can now be strongly suspected before hemodynamic studies and confirmed by these studies. 4 · 7 · 13 · 17 The patho­ logical nature of the disease, if not understood, is at least appreciated in prin­ ciple. An obstruction to left ventricular ejection results from the contraction of the hypertrophied interventricular septum and adjacent left ventricular wall. During systole this obstruction may be almost complete. That this obstruction is dynamic is immediately appreciated by the surgeon who passes his finger down through the obstruction in a beating heart. The compression around the finger is nothing short of painful. Furthermore the pressure gradient across the obstruction will vary from time to time,19 being modified by the force of ven­ tricular contraction. By the injection of isoproterenol, Whalen and his associ­ ates 19 have produced a pressure gradient of 100 mm. Hg in a young man with the other criteria of hypertrophie subaortic stenosis but no hemodynamic ob­ struction prior to the injection. It is also of interest that a pressure gradient across the aortic outflow tract has been produced by injecting isoproterenol into dogs and into a young man with a secundum atrial septal defect.12 The disease may be familial1· 2· 4· 5· 9 · 1 5 or not and it may obstruct the right ventricular outflow tract as well as the left.2· 4· 9· " · 2 0 Histological examination of the hyper­ trophied myocardium may or may not show abnormalities, such as patchy fibrosis,1'5·15 collagen deposition,15 and a bizarre arrangement of muscle bun­ dles.9· 1S Surgical benefit should depend on the surgeon's ability to resect a portion of the obstructing muscle. Our own progress in this regard is best illustrated by reviewing the 4 cases that comprise our experience. INCE

From the Department of Surgery, The Montreal General Hospital, and McGill University, Montreal, Quebec, Canada. Read at the Forty-third Annual Meeting of The American Association for Thoracic Surgery at Houston, Texas, April 8-10, 1963. 26

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CASE REPORTS CASE I.—The patient, a 31-year-old woman, was operated upon in 1960 with a preoperative diagnosis of valvular aortic stenosis. The pressure gradient between left ventricle and aorta was 100 mm. H g . At operation, with elective asystole, the aortic valve was found to be normal. No localized obstruction could be felt within the arrested left ventricle. Never­ theless an attempt was made to incise the inside of the anterior wall of the left ventricle with a mitral knife. The pressure gradient was unchanged. She recovered after a precarious postoperative course and died suddenly 2 years later.

Continent: We did not fully appreciate the diagnostic criteria of hypertrophic subaortic stenosis when we operated on this woman. A discrete obstruc­ tion could not be palpated in the atonic arrested heart.

Fig. 1.—Photograph of sectioned heart of Case III. The groove produced by resecting muscle in the outflow tract is well shown in the upper two sections. CASE II.—The patient, a 37-year-old woman, had a brother with the same disease and another brother and sister with unexplained heart murmurs. She was operated upon in 1961 with the use of coronary perfusion. The interior of the anterior ventricular wall was incised to a depth of 1.5 cm. from close to the apex back almost to the aortic valve. The pressure gradient of 70 mm. H g was unchanged by operation and she died on the sixth postoperative day. At autopsy the heart weighed 600 grams. There was a fresh posterior infarct.

Comment: The internal myotomy in this patient was ineffective in relieving obstruction. Although it was as extensive as we thought safe at the time, the incision could well have been longer and deeper. CASE III.—The patient was a 48-year-old woman who had had 16 children without difficulty. She was operated upon in March, 1962, with coronary artery perfusion. I t was im­ possible to operate within the left ventricle while the heart was beating because the systolic obstruction was virtually complete. The heart was cooled and muscle was resected from the anterior portion of the interventricular septum with a wire loop scalpel using t h e cutting current from an electrosurgical unit. In this way several strips of muscle tissue were re-

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Pig·. 2.—Operative approach used in Case IV. The mitral valve is exposed by way of the left atrium. The aortic leaflet of the mitral valve is incised from its free margin almost to the mitral annulus. The entire left side of the ventricular septum is thus exposed and the subvalvar hypertrophie prominence is resected with the wire loop of an electrosurgical unit.

moved. The pressure gradient which varied from 70 to 100 mm. H g before operation was reduced to 15 mm. H g with, the systemic pressure in the normal range. She died on the second postoperative day after several episodes of hypotension.

Comment: Nothing approaching adequate exposure was obtained in this operation, even after hypothermie cardiac arrest. The cutting current through the wire loop scalpel effectively permitted strips of myocardium to be resected from inside the ventricle, although the danger of damaging the mitral valve or its supporting structures was constantly recognized. Fig. 1 is a photograph of this heart at autopsy which shows the trench produced by the muscle re­ section. CASE IV.—This patient was a 17-year-old girl who first developed dyspnea on exertion at 13 years of age. Her father suffers from a milder degree of the same condition and her sister had developed a murmur in the previous 2 years. By the age of 15, shortness of breath had become so prominent that she was forced to drop out of school. Typical angina on effort developed so that she led the life of a complete invalid. The heart was enlarged to the sixth

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intercostal space at the nipple line. There was an ejection murmur audible over the precordium, maximal at the fourth left intercostal space. Cineangiocardiographie studies showed hypertrophie obstruction about an inch below the aortic valve. The pressure in the lower left ventricle was 260 mm. H g systolic, while that in the aorta was 100. There was a slight leak of contrast material back into the left atrium. She was operated upon in May, 1962, through a left thoracotomy. The left ventricular contractions were grossly abnormal in that there was barely any change in the outer contour of the ventricular mass with each systole. Cardiopulmonary bypass was established with an outflow cannula in the right ventricular outflow tract and an occluding tape about the pul­ monary artery. The left atrium was widely incised from the apex of the auricular appendage back to the entrance of the pulmonary veins. The aortic leaflet of the mitral valve was ex­ posed and the central point of the free margin of the leaflet was identified. From this point an incision was made at right angles to the free margin to extend almost to the annulus (Fig. 2 ) . With the aortic leaflet of the mitral valve thus bisected and the halves retracted by traction sutures, excellent exposure of the ventricular septum was obtained. There was a marked prominence about an inch below the aortic valve. This bulge measured 3 cm. in the axis of the aortic outflow tract and extended around to the wall of the left ventricle. I t was covered with thick white endocardium.

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Fig. 3—Photograph of muscle resected from Case IV.

This prominence was carefully and easily removed with the use of a wire loop with a cutting current. Four grams of myocardium were resected (Fig. 3 ) . There was no difficulty in protecting the papillary muscles. The ventricular septum from which the muscle had been removed was perfectly smooth after the resection. The incision in the aortic leaflet of the mitral valve was repaired with interrupted sutures. The operation was terminated without event. There was a noticeable difference in the heart action after bypass. The heart now seemed able to contract and expel its blood. The sytolic pressure at the apex of the left ventricle was 105 mm. H g and t h a t in the aorta 100. Her postoperative course was satisfactory. In the months following she gradually in­ creased her activities to the point where she led a full active life and took on full-time em­ ployment. She was readmitted for postoperative investigation 4 months after operation. She confirmed that she was completely free of symptoms, although a harsh systolic murmur and thrill were detected over the precardium. The electrocardiogram showed left bundle branch block.

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Retrograde left ventricular catheterization showed a residual gradient of 100 mm. H g across the aortic outflow tract. Narrowing of the outflow could be seen angiocardiographically.

Comment: From the purely technical standpoint, the transatrial approach with bisection of the aortic leaflet of the mitral valve proved ideal. The residual pressure gradient across the aortic outflow tract is discussed below. DISCUSSION

These 4 cases have been described to illustrate the evolution of our current surgical treatment of hypertrophie subaortic stenosis. There are significant advantages in visualizing the interior of the left ventricle through bisection of the aortic leaflet of the mitral valve. These are: (1) no interference with coronary blood flow, (2) incision in low pressure atrium rather than aorta, and (3) wide exposure of the entire left side of the ventricular septum. The single disadvantage to this approach is the addition of an incision in the aortic leaflet of the mitral valve. The closure of this incision should be secure if it is made and closed with care. The suture line is similar to that following repair of the cleft mitral valve in an endocardial cushion defect save that, in the latter, the apposing leaflet edges are thicker. The normal valve be­ comes thicker as the free margin is approached and holds sutures well. Ex­ perience with repair of the septal leaflet of the tricuspid valve following the right transatrial approach for ventricular defect closure has been satisfactory. 10 Once the hypertrophied septum has been exposed how should it be dealt with? We used a cutting current applied to a wire loop to obtain as smooth a bare area following the resection as possible. It was hoped this would reduce the danger of emboli from myocardial debris or of mural thrombi. This has proved to be the case in experimental animals in which resection of myocardium within the right ventricle has been carried out under inflow occlusion. Two months later the resected area has been covered with a thin fibrotic lining. There has been no suggestion of contraction and it would seem most unlikely that the residual pressure gradient in our last patient was due to postoperative contraction of scar tissue overlying the resected area. How then may the postoperative gradient be explained? Our concept of this disease is that of an anatomical hypertrophy which is grossly discernible with a superimposed systolic narrowing brought about by over-contraction or, perhaps, premature contraction of the musculature surrounding the aortic outflow tract. This is also the view of Goodwin and his associates.9 On examining autopsy specimens of patients with this disease one can see a band of circum­ ferential muscle fibers surrounding the outflow tract. This we assume to be the deep bulbospiral muscle which has been described16 as a strong circular cuff surrounding both the mitral orifice and the aorta (Pig. 4). Others 8 have ad­ vanced the concept that this muscle and the deep sinospiral muscle take the blood which has been " w r u n g " out of the lower third of the heart and force it into the aorta. The deep bulbospiral muscle is thus pictured as contracting later than the other muscle fibers. Robb and Robb16 stated in their article of 1942 that, "If the deep bulbospiral contracted early, it would produce nar­ rowing of the aortic outlet, and this would be equivalent to aortic stenosis."

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This may be the case. The problem then may not be that of a too vigorous contraction of the deep bulbospiral muscle but rather a too early contraction. One could go further and suggest that the basic problem might be an anomaly of the Purkinje network whereby this muscle was excited sooner than it ought to be. The success 14 ' 20 reported following the internal myotomy which was first performed by Cleland9 might then be due to interruption of nervous pathways rather than to the division of the muscle fibers themselves. This point was commented on by Morrow and Brockenbrough 14 who pointed out that in one of their two good results a left bundle branch block was produced. In the patient whose symptoms were relieved by Cleland,9 a left bundle branch block resulted.

Fig. 4.—This illustration shows on the left the deep sinospiral muscle which encircles the outflow tracts of both ventricles and on the right the deep bulbospiral muscle which surrounds the mitral orifice and the left ventricular outflow tract. One can easily see how premature or excessive contraction ofM the deep bulbospiral muscle could obstruct the aortic outflow tract. (From Robb and Robb. )

Our last patient, with a high pressure gradient 4 months after operation, also has a left bundle branch block. Certainly one cannot picture permanent separa­ tion of the divided muscle fibers such as results with a pyloromyotomy. In the heart the incision must heal by fibrosis to again complete the muscular ring. Should the simple incision prove an adequate operation it could well be done under direct vision through the approach herein described. Our own plan at the present time would be to excise the anatomic prominence and then make one or two longitudinal incisions within the left ventricle. In our hands the myotomy has been difficult when performed through an aortotomy incision. Kirklin and Ellis 11 described a technique for resection of hypertrophied muscle that gave satisfactory results in 2 patients. The ascending aorta was incised and then a short incision was made in the wall of the left ventricle, the optimal area for the incision being selected by retrograde palpation through the aortic valve. Hypertrophied muscle was then excised through the ventriculotomy. The transatrial approach would seem to offer significant advantages, despite the excellent results achieved in the 2 cases reported.

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CONCLUSIONS

Four patients with severe left ventricular outflow tract obstruction pro­ duced by hypertrophie subaortie stenosis have been operated upon. With each procedure the operation was modified until a satisfactory technique was de­ veloped. The preferred approach was by way of the left atrium with bisection of the aortic leaflet of the mitral valve. The left side of the ventricular septum was thus exposed and hypertrophied muscle resected. A striking symptomatic result has been maintained for 11 months in the one patient operated upon in this manner. Hypertrophie subaortie stenosis remains a surgical challenge. REFERENCES 1. Bereu, B. A., Diettert, G. A., Danforth, W. H., Pund, E. E. Jr., Ahlvin, R. C , and Belliveau, R. R. : Pseudoaortic Stenosis Produced by Ventricular Hypertrophy, Am. J . Med. 25: 814, 1958. 2. Bevegard, S., Jonsson, B., and Karlof, I. : Low Subvalvular Aortic and Pulmonic Stenosis Caused by Asymmetrical Hypertrophy and Derangement of Muscle Bundles of the Ventricular Wall, Acta med. scandinav. 172: 269, 1962. 3. Braunwald, E., Brockenbrough, E. C , and Morrow, A. G. : Hypertrophie Subaortie Steno­ sis—A Broadened Concept, Circulation 26: 161, 1962. 4. Braunwald, E., Morrow, A. G., Cornell, W. P., Aygen, M. M., and Hilbish, T. F . : Idio­ pathic Hypertrophie Subaortie Stenosis. Clinical Hemodynamic and Angiographie Manifestations, Am. J . Med. 29: 924, 1960. 5. Brent, L. B., Aburano, A., Fisher, D. L., Moran, T. J., Myers, J . D., and Taylor, W. J. : Familial Muscular Subaortie Stenosis. An Unrecognized Form of ' ' Idiopathic Heart Disease," With Clinical and Autopsy Observations, Circulation 21: 167, 1960. 6. Brock, R. C. : Functional Obstruction of the Left Ventricle, Guy's Hosp. Rep. 106: 221, 1957. 7. Brock, R.: Functional Obstruction of the Left Ventricle, Guy's Hosp. Rep. 108: 126, 1959. 8. Flett, R. L. : The Musculature of the Heart With I t s Application to Physiology, and a Note on H e a r t Rupture, J . Anat. 62: 439, 1927. 9. Goodwin, J . F., Hollman, A., Cleland, W. P., and Teare, D. : Obstructive Cardiomyopathy Simulating Aortic Stenosis, Brit. Heart J . 22: 403, 1960. 10. Hudspeth, A. S., Cordell, A. R., Meredith, J . H., and Johnston, F . R. : An Improved Transatrial Approach to the Closure of Ventricular Septal Defects, J . THORACIC & CARDIO­ VAS. SURG. 4 3 : 157,

1962.

11. Kirklin, J . W., and Ellis, F . H., J r . : Surgical Relief of Diffuse Subvalvular Aortic Stenosis, Circulation 24: 739, 1961. 12. Krasnow, N., Rolett, E., Hood, W. B., J r . , Yurchak, P . M., and Gorlin, R. : Reversible Obstruction of the Ventricular Outflow Tract, Am. J . Cardiol. 11: 1, 1963. 13. Menges, H. Jr., Brandenburg, R. O., and Brown, A. L., J r . : The Clinical Hemodynamic and Pathologic Diagnosis of Muscular Subvalvular Aortic Stenosis, Circulation 24: 1126, 1961. 14. Morrow, A. G., and Brockenbrough, E. C. : Surgical Treatment of Idiopathic Hypertrophie Subaortie Stenosis: Technic and Hemodynamic Results of Subaortie Ventriculomyotomy, Ann. Surg. 154: 181, 1961. 15. Pare, J . A. P., Fraser, R. G., Pirozynski, W. J., Shanks, J . A., and Stubington, D.: Hereditary Cardiovascular Dyplasia. A Form of Familial Cardiomyopathy, Am. J . Med. 3 1 : 37, 1961. 16. Robb, J . S., and Robb, R. C. : The Normal Heart. Anatomy and Physiology of the Struc­ tural Units Am. Heart J . 2 3 : 455, 1942. 17. Soulie, P., Joly, F., and Carlotti, J . : Idiopathic Stenosis of the Outflow Chamber of the Left Ventricle. (Apropos of 10 Cases), Acta cardiol. (Bruxelles) 17: 335, 1962. 18. Teare, D. : Asymmetrical Hypertrophy of the Heart in Young Adults, Brit. Heart J . 20: 1, 1958. 19. Whalen, R. E., Cohen, A. I., Sumner, R. G., and Mclntosh, H. D. : Demonstration of the Dynamic Nature of Idiopathic Hypertrophie Subaortie Stenosis, Am. J . Cardiol. 11: 8, 1963. 20. Wigle, E. D., Heimbecker, R. O., and Gunton, R. W. : Idiopathic Ventricular Septal Hypertrophy Causing Muscular Subaortie Stenosis, Circulation 26: 325, 1962.

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DISCUSSION

DR. J U L I A N J O H N S O N , Philadelphia, Pa.—I called Dr. Dobell before I operated upon such a patient some time ago, and we reviewed this technique. Unhappily we didn't do as well as he did. I thought that when I was trying to expose the heart through a left thoracotomy I was making a mistake and I should have used a right thoracotomy. Our exposure was very poor, at least as we used it. I believe the exposure from the right side would have been better. I t may be that I did not use the left-sided approach properly since I am accustomed to use the right approach for the insertion of a Starr valve in the mitral area. I n removing the muscle with a wire loop, we unfortunately created heart block which has required a perma­ nent pacemaker. In addition, the patient's mitral valve was sufficiently diseased preoperatively so that the damage we did to it could not be repaired and we had to replace it. The woman is alive and feels improved but I have the feeling that we d i d n ' t do very well by her. DR. MAX G. CARTER, New Haven, Conn.—Certainly, Drs. Dobell and Scott should be commended for this excellent presentation of what is becoming now an increasingly wellrecognized and, I am sure, increasingly important condition. I am sure we would all agree that in the past a large number of these patients have been missed, and many more of them will require operation. I have a short film strip which is a portion of a larger motion picture on aortic valve disease. If we may have the film we can have a view of the pathologic condition seen through the opened aortic root which may be of interest to those of you who perhaps have not as yet seen such a patient. [Motion picture] This was a 44-year-old woman with extreme symptoms, left ventricular enlargement, and a normal aortic arch; there was no post-stenotic dilatation. Huge dilatation of the left atrium was present and, indeed, the murmurs suggested mitral valve insufficiency, which was present. Retrograde aortic angiography, in systole, shows narrowing a t the level of the infundibular hypertrophy. The ascending aorta is not dilated. In diastole there is a wide ventricular chamber, as you see. The coronary arteries are visualized. In the lateral view, which is said to be diagnostic, one can see the level of the valve, the subvalvular area, and the area of contraction. The coronary arteries are rilled. In systole one sees the extreme narrowing, also the tongue, which is said to be characteristic of the ventricular chamber, and, on the right side, the anterior leaflet of the mitral valve. This operation was done by the technique suggested by Drs. Kirklin and Ellis. You are looking directly down from the head of the table toward the aortic root. The heart was not arrested except by aortic cross-clamping and very modest systemic hypothermia, since we anticipated a rather short procedure; and this turned out to be true. You will see a normal aortic valve which is uncommon, of course, in patients with aortic stenosis. There are nice, pliable leaflets. With the speculum inserted one gets a view within the heart. The mitral leaflet is on the floor. The hypertrophied ridge is on the ceil­ ing transversely, covered with the thickened white endocardium as described by Dr. Dobell. The heart is arrested, but, by introducing the left hand forefinger, one can palpate this rigid muscle as described by Kirklin and Ellis. In this patient the operation was continued with a left ventriculotomy at a site localized by the palpating forefinger on the interior, the thumb on the exterior, and, with pituitary rongeurs, generous amounts of muscle were excised. The patient has exhibited an excellent result to date, although she has not been recatheterized as yet. DR. D W I G H T E. H A R K E N , Boston, Mass.—This is an ingenious approach. I ask the authors if they are not concerned about sutures holding after surgical incision of relatively normal mitral leaflets. Dr Johnson has voiced some pertinent reservations. Also, the left thoracotomy approach, while excellent for mitral valve exposure, sometimes might present quite a " D u t c h d y k e " syndrome if one did cut through the septum and interrupt the venous bypass. I would like to mention three points. First, with respect to the pathology of these lesions, I think we oversimplify it by saying that we have a diaphragm or subvalvular

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muscular hypertrophy when indeed what we really have is a spectrum from a very simple subvalvular diaphragm with fibroelastosis to extensive hypertrophy, defining a spectrum of surgical difficulty from the very simple to the nigh impossible. [Slide] My second point is a series on which you don't need review—the usual pulse pressure patterns of aortic stenosis versus supravalvular stenosis—but I would like to call your attention to a diagnostic point to which I think we should give eponymic credit to Richard Gorlin of the Peter Bent Brigham Hospital. I n subaortic muscular stenosis, as opposed to diaphragmatic subvalvular stenosis, there is in this upflow sweep of the left ventricle pressure curve a little ' ' blip ' ' that I think represents the point at which the muscle comes together, and everything above that point is the ' ' grunt from the left ventricle. ' ' If the obstruction is complete, the pressure peak in the subvalvular chamber will be at that level. If a little blood is squeezed through by that extra effort of the left ventricule, the peak will be higher. [Slide] This is an actual tracing with the same " b l i p " [or irregularity of the up­ stroke] in it where the muscle comes together, and in this particular case there was complete obstruction. At this point none of this extra effort of the left ventricle was registered in the subvalvular chamber or in the aortic arch pressure tracing. [Slide] As the third, and final, point I should like to mention another type of surgical approach to subvalvular muscular stenosis that I have had an opportunity to use only once since this idea came to me. However, it seems so eminently simple and practical that 1 present it for your consideration. Dr. Dobell and Dr. Scott presented the pathologic pattern quite like the one I treated. We make a direct sternal splitting anterior approach which brings us down to conventional exposure of the aortic base. We then open the aorta by transverse incision, inspecting the zone. If the lesion can be dealt with either by excision or loop diathermy scalpel, of course this is satisfactory, but if the muscular subvalvular stenosis is extensive, a transverse incision can be made through the right ventricle and a tremendous amount of material can be excised. This, if carried anterior to the mid-axis of the right side of the interventricular septum, will not [Dr. Maurice Lev tells me] disturb the right bundle and we can get a tremendous amount of muscle out. This is directed by a finger through the aorta into the left ventricle. As a matter of fact, it does no harm if we do get into the left ventricle, because the septal defect produced thereby can readily be repaired. In this particular case I did produce temporary complete heart block and put in a pacemaker. The heart reverted to normal sinus rhythm in a week, and we may elect to remove the battery from the pacemaker in another month or so. The patient is doing very well and is completely asymptomatic; indeed she only has a murmur with the pacemaker systole. This useful right-sided, trans-right ventricular approach to left ventricular subaortic obstruction with muscle excision will be separately reported in detail.

DR. H A R R I S B SHUMACKER, JR., Indianapolis, Ind.—I would certainly agree with Drs. Dobell and Scott that not all patients with this disorder can be treated successfully by the transaortic approach. The problem is emphasized by my recent experience with a 30-year-old man who for 3 years had had marked symptoms of fatigue on exertion, dyspnea, nocturnal dyspnea, and frequent and very distressing episodes of precordial pain. Catheterization revealed a gradient of 125 mm. H g across the area of obstruction. The cineangiograms showed a rather conical area of muscular hypertrophy, approximately 2 cm. long, which demonstrated moderate mitral incompetence. At operation in November, 1962, the left ventricular cavity was visualized through the aortic annulus. I t was immediately apparent t h a t we could not possibly relieve the obstruction without damaging the mitral leaflets. This was still evident when the mitral leaflets were manipulated by means of a finger introduced through the left atrial appendage. Although nothing was done except the exploration, a temporary heart block developed. Postoperatively the patient was dreadfully ill, with a gallop rhythm, rapid, labored respira­ tions, orthopnea, pleural effusion, ascites, and peripheral edema. When he finally began to

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improve a bit, some weeks later, he lost 36 pounds of water. In spite of this improvement he was still very ill when the second operation was carried out on December 18. Through a right thoracotomy approach the mitral valve was visualized and was ex­ cised. I t was now quite easy to expose the very large papillary muscles and the intimately associated hypertrophie muscle mass. A ball valve prosthesis was inserted. I n contrast to the stormy course after the first operation, he now had a very smooth one, and left the hospital 11 days later. He has done well, has no complaints, and has returned to work. He will be studied by catheterization next month. In this case, I know of no other way in which the muscular obstruction could have been safely and adequately removed. DE. F E A N K C. SPENCER, Lexington, Ky.—I enjoyed Dr. Dobell's presentation and would certainly like to compliment him upon an ingenious approach. Thus far we have been satisfied with the transaortic approach in operating upon 2 children with this condition, since realizing what the functional pathology is. I think our satisfaction may be related to the fact that we have only operated upon children, because, certainly, in a patient like Case 3, which Dr. Dobell showed, in whom virtually all of the ventricular cavity was obliterated by the ventricular hypertrophy, not much can be done. We have used continuous coronary perfusion to keep the heart beating so one can tell by palpation whether the obstruction has been relieved. One other critical point is to limit deep resection of muscle to beneath the commissure between the right and the left coronary cusp. In this area only can one safely cut deeply into the muscle as far as necessary. This point can be observed in the autopsy room when the pathologist will open the left ventricle by inserting a knife from the left ventricular cavity into the aorta and then cut through the overlying ventricular wall. This incision will go through the aortic ring near the commissure between the right and left coronary cusps. An incision made in this area may injure the mitral valve on one side or the ventricular septum and the bundle of His on the other. [Slide] This slide shows our pre- and postoperative pressure gradients on a 12-year-old boy operated upon several months ago. This is the preoperative gradient, showing a ven­ tricular pressure of 190 mm., and a gradient of 90 mm. The obstruction could be readily palpated as a diffuse hypertrophy over a distance of about 3 cm. The segment of muscle removed was about 4 cm. in length and about 1 cm. in depth. Following operation the gradient was reduced to 10 mm. Hg. He has not yet had his scheduled postoperative catheterization study; so I think one must be cautious regarding ultimate prognosis because this is a disease of unknown etiology and uncertain behavior. At present, he is fully active and asymptomatic. DE. H E N B Y SWAN, I I , Denver, Colo.—It is now just slightly over 7 years since the first successful open operation on the aortic valve was performed at the University of Colorado on a 28-year-old man who had acquired valvular stenosis. We applied that operation immediately to patients with congenital disease, and we have had experience with approxi­ mately 30 patients with congenital aortic obstruction. Of these, 7 had subvalvular obstruc­ tion and, of these, 5 were of the membranous type,, whereas 3 were of the hypertrophie muscular variety, which is the subject for discussion here this morning. I think Dr. Dobell is to be congratulated on the excellence of his presentation and also on the excellence of the illustrations that he gave of the diffuse nature of this disease. Dr. Morrow has emphasized in his approach to the problem that one must make a very long incision—that is, the incision or excision must extend the full length of the ventricle. The picture you saw this morning, and the experience of others, clearly emphasizes what has been said here—that you must remove a large volume of tissue. In our recent approach to this problem we thought it might be possible to devise a coring instrument which would remove a tunnel of the ventricular septum or, rather, of this hypertrophied muscle on the septal side.

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DOBELL AND SCOTT

J. Thoracic and Cardiovas. Surg.

[Slide] This slide shows the development of this instrument, which is simply a corkboring instrument that has been sharpened at one end, and a little plastic probe has been made to act as an obturator. The operation consists of a transverse sternal splitting, bilateral thoracotomy, Dr. Johnson, because this gives quite adequate exposure for this type of pro­ cedure. The patient is put on bypass. We use mild hypothermia, and it is not necessary to perfuse the coronary arteries. [Slide] This shows the type of tissue which can be obtained by the use of this in­ strument. The incision is made in the aorta just above the valve and, by direct inspection and by palpation with the finger of the left hand, one can make an incision in the ventricular apex and insert this coring instrument', and simply core out a cylinder of the tissue, pro­ tecting the mitral valve with the back of the index finger and by inspection from above. Because the top of the obstruction is shelf-like and comes very close to the aortic annulus, one must be very careful at the upper end not to injure the aortic valve. This has been very successful, Dr. Shumacker, in removing an adequate amount of tissue from the septal side. We have not had time to re-catheterize the 32-year-old man whom we did about 2 months ago, but clinically he is very much improved. DE. W I L F R E D G. BIGELOW, Toronto, Ontario.—I am sorry to prolong the discus­ sion on this interesting lesion. I am sure we all admire Dr. Dobell 's dedicated attempt to develop a definitive procedure for this subaortic stenosis. About 2 years ago our cardiologists had 12 of these patients on record, and we were presented with the problem of attempting to correct them. I n reviewing the cases that had been done at that time, it appeared that the more radical approach, the fewer the survivors. Since anything we could do to a pathologic lesion of this kind would probably be palliative, it seemed reasonable just to do a simple myotomy. Accordingly, we took 4 pa­ tients who were clinically most seriously involved, and we subjected them to operation with bypass and with an aortic approach. I n one case we made a cut into the big interventricular muscle mass, and in the other 3 cases this bar of muscle, which extends from the inter­ ventricular septum up over the anterior wall of the outflow tract of the left ventricle, was cut. This cutting was continued with periodic palpation until we seemed to reach a depth where the thick, firm muscle appeared to separate from normal heart muscle. That was ob­ served in all 4 cases. This line of cleavage has not been described pathologically but that is what we found. Interestingly enough, 3 of the 4 patients have done well clinically. [Slide] The fourth patient is not any better, and I think it is because he has con­ tinuing right ventricular outflow obstruction and some degree of preoperative mitral in­ sufficiency. I n these 4 cases, some interesting features are shown. I t is interesting that the systolic gradient has been dropped to zero in each case; and if you think that Dr. Douglas Wigle the cardiologist was amazed when he found that, it was nothing to the amazement of the surgeon. The left ventricular end diastolic pressure also has been reduced. One wonders why, with a systolic gradient of zero, it would still be 14 as shown here. This is an inflow as well as an outflow obstructive lesion. [Slide] This slide shows the changes in the aortic pressure curves. Preoperatively there is a high percussion wave. This percussion wave is changed to normal with a tidal wave that is higher, after operation. [Slide] Dr. Glen Morrow's group have shown in subaortic obstruction that the pulse pressure is reduced in the beat following an extrasygtole. Surgery has also eliminated this abnormality in all 4 cases. This series is not helping much to develop a definitive surgical technique, but the results of this simple procedure have been remarkable, although they may be of a temporary nature. SIR RUSSELL BROCK, London, England.—I congratulate Dr. Dobell on his presenta­ tion of a very interesting and indeed excellent technical approach to the aortic subvalvar region. I note, however, that he stated the condition remains a surgical challenge but I am

Vol. 47, No. 1 January, 1964

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by no means convinced that this is so. With an obstructive condition of the left ventricular outflow, the mind of course first turns towards doing an operation and this is unquestion­ ably the correct procedure in those examples because of fibrous narrowing. I think, however, we must remember not to confuse the strictly organic obstruction with the condition we are discussing this morning which is essentially muscular and not organic. I am not convinced that it is really sound surgery to attempt to relieve this con­ dition by an operation. Indeed, it may well be harmful to attempt to do so. As you know, observations have been made at the National Heart Institute, Bethesda, and at other heart centers in the United States, indicating that a muscular obstruction can be relieved or worsened as a result of the use of certain drugs. I suggest, therefore, that instead of this condition remaining a surgical challenge it may in fact be a pharmacological or medical challenge. We have listened to interesting and, indeed, brilliant presentations of various approaches to the subvalvar region; but, until we know for certain that these provide a permanent and lasting cure, I am not willing to accept them. I look forward to the day when we may be able to treat this condition by the exhibition of suitable drugs. DR. C. WALTON L I L L E H E I , Minneapolis, Minn.—Diffuse hypertrophie subaortic stenosis is being recognized with increasing frequency. Our first experiences with this lesion were through a combined approach from the aorta and left ventricle, and although both patients survived the operative procedure and were discharged from the hospital, this ap­ proach was frustrating from the standpoint of adequate and clear visualization of the ob­ structing pathology and quite unsatisfactory as far as late hemodynamic results were con­ cerned. This experience stimulated a fundamental change in our thinking, and the next 2 patients were approached by a' similar but somewhat different technique than Dr. Dobell has described this morning. We have approached this lesion through the right chest via a standard posterolateral incision (bed of fourth or fifth rib) and left atriotomy anterior to the pulmonary veins. We have then detached the anterior leaflet of the mitral valve along its annulus which has given us beautiful exposure. And, as a matter of fact, it was the first time we really saw the true pathology in this condition. Two patients have been operated upon by this technique and both have done very well clinically and both have been recatheterized postoperatively. [Slide] The first patient, a young woman of 26 years of age whose angiocardiogram is shown here, had a systolic gradient of 65 to 70 mm. H g and, in many of those with diffuse hypertrophie subaortic stenosis, had rather severe mitral insufficiency also. This preoperative angiocardiogram shows the diffuse subaortic stenosis with a normal aortic valve. The severe mitral insufficiency is responsible for the intense atrial opacification from the left ventricle. By this new approach it was easy to correct both the subaortic stenosis and the mitral insufficiency. [Slide] This photograph shows the multiple large chunks of muscle removed at the time of operation. One of the interesting things that I have already alluded to was that previously we had not clearly seen the pathology—namely, this whitish material, fibroelastic deposits, which cover the obstructing muscle and are very helpful to the surgeon in indi­ cating the extent of these diffuse obstructions. [Slide] This patient was recatheterized 2 weeks postoperatively, just before discharge from the hospital, and this study showed that the gradient had been reduced to 30 mm. H g , and angiography indicated that the mitral insufficiency had been completely corrected. This result was considered satisfactory, but indicated to us that in the next case we needed to be even more radical in our resection of the obstructing muscle. [Slide] This is a phonocardiogram which shows the murmur before operation and after operation in this first patient and demonstrates the marked reduction of the systolic mur­ mur following corrective surgery. [Slide] The second patient had a systolic gradient of about 200 mm. Hg. The obstruc­ tion is seen at this point in the left ventriculogram, far below the aortic valve, and un­ changing during systole and diastole.

38

DOBELL AND SCOTT

J. Thoracic and Cardiovas. Surg.

[Slide] The preoperative left ventricular systolic pressure was 300 mm. Hg. The aorta was 100 mm. H g systolic. [Slide] This is the specimen, seen from above, excised in the second case, indicating the orifice of about 4 mm. You see also the large amount of muscle excised. [Slide] Here again you may see the whitish deposits that characteristically cover these obstructions. [Slide] This patient postoperatively had no murmur remaining as indicated in this phonocardiogram. [Slide] Postoperative recatheterization, 2 weeks after operation, shows that the large preoperative systolic gradient of 200. had been reduced to zero. Our surgical technique is to enter the right chest through a standard posterolateral incision in the bed of the fifth rib and, after cardiopulmonary bypass, the left atrium is entered anterior to the pulmonary veins. The anterior leaflet of the mitral valve is detached parallel to and 3 to 4 mm. from its annular attachment. The anterior leaflet of the mitral valve is then retracted towards the mitral lumen, which gets the chordae tendineae and papillary muscles completely out of the way and puts the surgeon right on top of this obstructing mass of muscle. Sharp excision of this fibromuscular tissue is then easily carried out. I n the second case, we found it helpful to insert a finger into the right ventricle via a small slit in the right atrium. By this maneuver the tremendous thickness of the ven­ tricular septum could be better appreciated and a radical excision can be carried out with­ out fear of perforation. [Slide] In the first patient there was an associated mitral insufficiency. Therefore, after removing the muscular tissue, a regular leaflet advancement ( J . Thoracic & Cardiovas. Surg. 4 5 : 434, 1963) was done by insertion of an oval patch of woven teflon into the mitral valve incision as the valve was reconstructed. In the second case we did not need such a prosthesis and the mitral valve was re-attached directly to its annulus by continuous and interrupted stitches of fine silk. DE. BODMAN E. TABER, Detroit, Mich.— I would like to offer for your considera­ tion another approach which, although it is not the ingenious one Dr. Dobell has presented, does have the quality of directness. [Slide] This approach is used in treating ventricular aneurysm, namely, left ventriculotomy. I n this slide we see the anterior surface of the heart, and in this case the subaortic stenosis is due to a little different cause, namely, a rhabdomyoma. [Slide] This is a slide in a 9-year-old boy. A left ventrieulotomy has been done and this is the anterior descending coronary artery. [Slide] This slide shows the exposure. I t gives an idea of the obstruction in this ventricle, which extended from the apex to beneath the aortic valve. This child has been catheterized postoperatively and has no residual gradient. This approach has been used in one other individual, a 10-year-old child who had a previous transvalvular attempt at re­ section of subaortic stenosis. This had not proved satisfactory, and so at re-operation this left ventrieulotomy exposure was used successfully. DR. J O S E P H W. GILBERT, JR., Bethesda, Md.—I should also like to compliment the essayists on this excellent presentation of a subject in which we have been very interested at the National Heart Institute. Several references already have been made to Dr. Morrow's experience in this area, and in his absence I should like to be presumptuous enough to recall one particular ex­ perience of his with the entity of idiopathic hypertrophie subaortic stenosis. We agree with Dobell in his preference for actual excision of hypertrophie muscle from the outflow tract. The first such patient operated upon by Dr. Morrow 2 % years ago was a man with massive left ventricular hypertrophy and a gradient of approximately 90 mm. H g across the out­ flow tract. Although he was treated by simple incision of the obstructive mass, i.e., " v e n triculomyotomy, ' ' recent left heart catheterization demonstrated complete abolition of the

Vol. 47, No. 1

January, 1964

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systolic gradient across the outflow tract, normal response to exercise, and normal left ventricular end diastolic pressure. Thus we are inclined to agree with the statement in Dr. Dobell's abstract: " O u r understanding of hypertrophie subaortie stenosis is by no means complete. ' ' DR. HAROLD F . K N I G H T , Hartford, Conn.—I would like to discuss very briefly a complication that Dr. Dobell mentioned, t h a t is, embolization of myocardial fragments from the site of resection. [Slide] This slide shows the heart of a 35-year-old man in whom we approached the hypertrophied aortic stenosis via the transventricular route. Beneath the aortic valve is the area of the excision. Notice near the apex of the heart a very large myocardial infarction. [Slide]He died one week postoperatively. This is a cross-section of the anterior descend­ ing coronary artery filled with an embolus of cardiac muscle. We were aware of this pos­ sibility and made such attempts as we could to prevent embolization, but obviously were unsuccessful. DR. B E N S O N B. ROE, San Francisco, Calif.—The nature of this idiopathic disease may be similar to that seen on the right side of the heart. This was suggested by an ex­ perience we had 2 years ago in a 22-year-old man who had large muscular columns which were excised transaortically with a pituitary rongeur. At the completion of the procedure the gradient had been satisfactorily reduced from about 130 down to 70 mm. Hg. He was recatheterized 18 months later and the gradient had completely disappeared. His exercise tolerance and cardiac output had returned from a state of severe impairment to t h a t of an entirely normal individual. This experience suggests that the conservative approach may have greater safety and a satisfactory outcome. DR. DOBELL (Closing).—I would like to thank all the discussers very sincerely for their comments. Time does not permit a detailed discussion of all the points that have come up. I would simply like to say that in this particular patient exposure obtained in the manner described was superb and adequate. I think the disease varies from patient to patient and, as we know, it varies from day to day in the same patient. As Sir Russell suggested, it can be modified by drugs, and I do think one should operate upon only those patients who are obviously doomed unless operation is carried out. I think Dr. Bigelow has probably the best results reported, and is in a highly enviable position of not having the wealth of pathologic material that we have. I think Dr. Templeton should be congratulated for his imaginative approach to this disease.