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NEW OPERATIVE APPROACH IN THE MANAGEMENT OF HYPERTROPHIC SUBAORTIC STENOSIS
N E W OPERATIVE APPROACH I N THE M A N A G E M E N T OE HYPERTROPHIC SUBAORTIC STENOSIS Harris B Shumacker, Jr., M.D., and Harold King, Indianapolis,
M.D.,
Ind.
T
HE clinical entity of idiopathic hypertrophic subaortic stenosis has recently become well recognized and its diagnostic characteristics established. In 1961 Morrow and Brockenbrough 1 reported 2 cases of successful treatment by a maneuver which they termed "subaortic ventriculomyotomy." The operations were carried out through the opened aorta and a longitudinal incision was made through the bulging muscle mass along the anterior or septal side of the ven tricle. Both patients treated in this manner not only did well clinically, but also showed gratifying hemodynamic responses upon subsequent study by cardiac catheterization. An earlier operation performed in similar fashion by Cleland2 had also yielded a good clinical result. It would seem evident, however, that not all patients can be managed successfully by this method. Dobell and Scott 3 believe that resection of the obstructing mass can be facilitated by use of a left transatrial approach with splitting and, subsequently, repairing the aortic leaflet of the mitral valve. In discussing this method, John son4 related an experience in which this maneuver resulted in such damage to the already diseased mitral valve that it had to be excised and replaced with a prosthesis. Lillihei 5 has used a somewhat similar approach. He has temporarily detached the aortic leaflet from the annulus and resutured it afterwards. Both of the patients he operated upon by this technique did well. Before we were aware of these experiences, we treated a patient by removal of the mitral valve, resection of the obstructing left ventricular muscle mass, and insertion of a ball valve prosthesis. The same general approach has now been utilized in 3 cases. In each there was some degree of mitral valvular insufficiency. Since others may encounter patients in whom this method would appear to be the procedure of choice; we are led to describe these experiences.
Prom the Department of Surgery and the Heart Research Center, Indiana University Medical Center, Indianapolis, Ind. This work was supported by the James Whitcomb Riley Memorial Association and a Public Health Research Grant, HE 02035-09, from the National Institutes of Health, U. S. Public Health Service. Received for publication Aug. 5, 1964. 497
SHTJMACKER AND K I N G
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J. Thoracic and Cardiovas. Surg.
CASE REPORTS
CASE 1.—The patient was a 30-year-old man who had first been told he had a cardiac murmur when he was examined for military service in 1951. For 3 or 4 years prior to his admission he had had quite marked symptoms and had complained of excessive fatigability and dyspnea on exertion, of occasional episodes of nocturnal dyspnea, and of much preeordial pain. The pain radiated into the left arm. I t was experienced with exercise, eating, and, rarely, with emotional excitation. I t was not relieved by nitroglycerin. Considerable de terioration had occurred during the previous year in spite of the fact that he had been on digitalis therapy. He was admitted for study in October, 1962. The blood pressure was 100/70 mm. Hg. A faint aortic systolic thrill was palpable. The first heart sound at the apex was virtually obliterated by a high-pitched blowing Grade 3 systolic murmur. There was rough Grade 4 aortic systolic ejection murmur, the second heart sound was paradoxically split, and there was an audible triple rhythm at the apex. On fluoroscopic and x-ray study the heart was observed to be grossly increased in size, with predominant enlargement of the left ventricle and to a lesser extent of the left atrium. The aortic pulsations seemed prominent. The pul monary vasculature was slightly increased. The electrocardiogram showed left axis deviation, P "mitrale," left ventricular hypertrophy, and digitalis effect. Upon cardiac catheterization the cardiac index at rest was found to be normal, 3.05, but increased with exercise only to 4.31 L. per minute per square meter. The pulmonary wedge pressure was elevated at rest and rose further in response to exercise, the means being 17 and 27, respectively. The systolic, diastolic, and mean pressures in the pulmonary artery at rest and a t exercise were 35, 15, 21, and 55, 30, 38, respectively. No measurable gradient was observed across the pulmonary valve or the right ventricular outflow tract. Pressure in the apical portion of the left ventricle, determined by a catheter introduced through the aorta, was 245/12. As the catheter was withdrawn into a sort of infundibular chamber, the pressure fell to 120/12. The aortic pressure was 100/70. On cineangiographic study there seemed to be a rather conical area of obstructive muscular hypertrophy in the region of the outflow tract. This appeared to be approximately 2 cm. in length. The left ventricular cavity was relatively normal in size but had considerable trabeculation. Aortic valve function was normal, but there was moderate mitral insufficiency. The patient was readmitted to the hospital on November 17 for operative repair, and this was carried out on November 19. The aorta was opened and the coronary arteries were catheterized and perfused with arterialized blood. As we looked through the normal aortic valve we could visualize a distal left infundibular chamber about 1.5 or 2 em. in length. We were unable to identify any obstructing muscular tissue which could be separated from the presenting mitral leaflets so as to permit its safe removal or incision. A finger was introduced into the left atrium so that the mitral valve leaflets could be palpated and manipulated. In spite of this maneuver we found no way to proceed with incision or resection of the ob structing muscular mass without injury to the mitral leaflets. Reluctantly, the operative pro cedure was abandoned with the idea that another would be carried out later through a dif ferent approach. Even though nothing had been done except an exploratory procedure the patient developed a complete heart block. Pacemaker wires were sutured to the myocardium and the cardiac rate set by an external pacemaker. The block disappeared the following day. The patient was so ill postoperatively that it seemed for a while he would not survive. The venous pressure tended to stay rather markedly elevated. Weight increased from about 150 to 166.5 pounds, even though he maintained a rather satisfactory urinary output. Respira tions were rapid and labored. He was orthopnic, and there was a rapid gallop rhythm. He developed marked ascites, peripheral edema, and, between December 3 and 11, four thoracenteses were required; a total of 3,500 c.c. of fluid was removed. Toward the end of November he began to have a substantial diuresis and by December 13 he had lost 36 pounds in weight. He was still in a rather precarious condition, however, when the second operation was under taken on December 18. This was also carried out as an open procedure with cardiopulmonary bypass. The heart was approached through an anterolateral right thoracotomy incision. The moderate mitral
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insufficiency was confirmed by digital palpation through an incision in the left atrium. Ven tricular fibrillation was induced electrically. The mitral leaflets were excised as were the unusually large papillary muscles and a large mass of muscular tissue from the ventricular wall. The ventricular cavity now seemed to be adequate in size and no obstructing muscular mass was palpable. A ball valve prosthesis was sutured in place. Ventricular contractions were restored by electric shock and the procedure was terminated. The patient had a rather uncomplicated and smooth convalescence in contrast to the stormy time he had had after the first operation. The venous pressure remained within the normal range and the patient showed no other evidence of cardiac failure. He was discharged from the hospital on the eleventh postoperative day. H e was advised to remain on a low sodium diet, to continue on a maintenance dose of digitalis, and to take Coumadin. He continued to do well. H e was readmitted to the hospital on Nov. 20, 1963, for re assessment. He had been operating a combine on a farm 8 hours a day without difficulty. Ordinary physical activity and eating large meals caused no distress. H e stated that he would become slightly short of breath if he ran upstairs rapidly or for any great distance. There was no history of orthopnea, paroxysmal dyspnea, precordial pain, syncope with exer tion, cough or hemoptysis, palpations, embolism, or edema. He was on an unrestricted diet and was taking 0.2 mg. of digitoxin and 5 mg. of Coumadin daily. Prothrombin time was not being maintained within the therapeutic range. The precordium was quiet, the rhythm and rate of the heart were normal. There was no thrill. A Grade 3 aortic systolic ejection type murmur was heard but there was no apical systolic or basal diastolic murmur. There was no evidence of failure. The electrocardiogram showed left axis deviation, left atrial hypertrophy, complete left bundle branch block, and nonspecific ST-T changes. The transverse diameter of the heart appeared to be within, normal limits on x-ray study. Cardiac catheterization was performed on November 21. The cardiac index was normal at rest and increased, but probably not quite normally, in response to exercise, the values being 3.07 and 4.88 L. per minute per square meter, respectively. The wedge pulmonary capillary venous pressure was very slightly elevated a t rest and rose somewhat in response to exercise, the mean values being 12 and 22 mm. Hg, respectively. The right ventricular and right atrial pressures were normal, the former being 26/2 after exercise and the latter 4 / 0 . There was no left ventricular pressure gradient and the left ventricular diastolic pressure was normal. The left ventricular pressure was 100/10, and the aortic pressure 100/70. Cineangiographic study revealed the mitral and aortic valves to be competent, the left ventricular contractions vigorous, and what appeared to be, perhaps, slight residual narrowing of the subvalvular area. On December 6 he had several momentary cerebral episodes which must be interpreted as a probable result of minute emboli. Uneventful recovery ensued and he has remained well. CASE 2.—The patient was a 20-year-old man who for 4 years had complained of substernal pain with exercise which was always associated with dyspnea. He also had substernal pain after eating and dyspnea on exertion. Symptoms had been progressive during the previous year. Examination revealed a normal cardiac rhythm and rate and a blood pressure of 88/55 mm. H g . There was a systolic thrill, and a pansystolic Grade 4 to 6 murmur was heard over the entire precordium. No diastolic murmur was audible. There was paradoxical splitting of the second heart sound. On cardiac catheterization, performed on Feb. 21, 1963, the wedge pressure was found to be elevated (19 mm. Hg, mean) and it increased with exercise. The right ventricular pres sure was 36/8 at rest and the main pulmonary artery pressure was 34/15. The left ven tricular end diastolic pressure was 25 a t rest. The systolic pressure in the left ventricle dif fered somewhat in different parts of the cavity. Pull-out pressures across the aortic valve did not seem to reveal a valvular obstruction. No large gradient was established across the left ventricular outflow tract, even following the administration of Isuprel when it was only 17 mm. Hg. The cineangiograms, however, showed a definite conical tapering in the subvalvular region of the left ventricular cavity. There was evidence of mild mitral insufficiency. Operation was performed on May 3. I n view of the experience in the first case, it was
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planned to use the same approach. The right atrium was not particularly enlarged, but the left atrium was big and seemed to pulsate with ventricular contractions. The pulmonary arteries felt tense. When the mitral valve was palpated through an incision in the left atrium, the insufficiency jet seemed considerably greater than one would have judged would be the case from the cineangiograms. The mitral leaflets were palpably scarred and there seemed to be a cleft in the caudal portion of the aortic leaflet. Ventricular fibrillation wag induced. The mitral valve and the papillary muscles were excised. There was a large protruding muscle mass just beneath the aortic ring which seemed to arise principally from the left anterolateral part of the ventricular wall and the ventricular septum and to pass posteriorly around to the right underneath the mural leaflet. I n the subaortic area this bulging muscle mass had a glistening white covering which appeared to be fibrous in nature. A great deal of the presenting obstructing muscle mass was excised. A ball valve prosthesis was sutured in place, conversion to a sinus rhythm was accomplished with electric shock, and the operation was terminated. The patient had a relatively smooth postoperative course and was discharged on the tenth postoperative day. He returned to the outpatient clinic on June 24, and examination revealed rales in the lungs and rapid atrial fibrillation. I t was impossible to learn when the atrial fibrillation had begun. Marked improvement occurred with rapid digitalization and he was discharged without evidence of failure and with a satisfactory cardiac rate on June 27. During this admission no murmur was heard. He was advised to return to the outpatient clinic 6 weeks later but failed to do so. On July 14 he was admitted in a moribund condition to another hospital with the story that he had developed fever, cough, hemoptysis, orthopnea, and marked dyspnea 3 days beforehand. He was found to be slightly icteric and dyspneic with a blood pressure of 110/60 mm. H g and a rapid irregular peripheral pulse. He had a dusky cyanosis. The liver was enlarged. The electrocardiogram showed atrial fibrillation with a rate at times as rapid as 150, left bundle branch block, and left axis deviation. The serum bilirubin was 3.48. He died the evening of admission. Postmortem examination revealed marked congestion of the lungs and liver and some hydrothorax. He was thought to have cardiac cirrhosis. The formalinfixed heart was returned to us for examination. I t weighed 1,050 grams. There was marked hypertrophy of both ventricles. The thickness of the left ventricular wall was judged to be 30 mm., that of the right wall 20 mm., and that of the septum 40 mm. As one passed his finger through the aortic valve and annulus into the left ventricular cavity he could feel the protruding ball valve prosthesis but no evidence of any muscular obstruction. The entire left ventricular cavity of the fixed specimen accommodated with ease the palpating finger but there was little room to spare. I t seemed to have just about the same diameter in all portions. The width of the ventricular cavity was approximately 3 cm. and it was about 8.5 cm. long. The mitral valve seemed well seated and appeared to have been working competently. As far as one could tell, the left ventricular obstruction had been relieved by the opera tive procedure. The patient withstood the operation well, recovered quickly, and appeared to be in good health when he left the hospital. He developed evidence of failure with the onset of rapid fibrillation and responded dramatically to control of the cardiac rate with digitalis. We do not know whether conversion to a sinus rhythm might have been accomplished at this time or whether conversion might have prevented his terminal illness which was also asso ciated with uncontrolled rapid atrial fibrillation. CASE 3.—The patient was a 29-year-old man in whom the presence of a cardiac murmur had been discovered at the age of 11 years. For 6 months prior to admission he had been having some nocturnal difficulty with breathing. While swimming 2 months previously he had experienced the sudden onset of pain in the left hemithorax and back associated with shortness of breath and "congestion of his lungs." The shortness of breath lasted for several hours. Following this episode he had dyspnea on exertion. For 1 month he had complained of discomfort in the upper abdomen and a tendency toward nausea. He had been digitalized 3 weeks before admission. While climbing a hill 10 days before admission he became dyspneic
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experienced a recurrence of severe chest pain and "congestion of the lungs." With rest, symptoms gradually subsided but the difficulty in breathing and the chest pain lasted an additional several hours. Eight days later he developed paroxysmal nocturnal dyspnea orthopnea. I t seemed clear from his story that he had undergone rapid deterioration. Moist rales could be heard bilaterally. The pulse rate was 84 and regular, the blood pressure 110/80 mm. Hg. There was an apical systolic thrill and an ejection type systolic murmur, best heard at the apex. The electrocardiogram revealed inverted T waves in Leads I , aV L and V„, marked left axis deviation, and slight prolongation of the QES complex. I t was the opinion that the electrocardiographic tracing was consistent with left ventricular hyper trophy or an intraventricular conduction defect. X-ray films revealed evidence of left atrial, left ventricular, and right ventricular enlargement with prominence of the pulmonary outflow tract. Cardiac catheterization was performed on May 14, 1963. The mean left atrial pressure was found to be elevated to 28. The pulmonary artery pressure was 49/27 mm. Hg. The left ventricular end-diastolie pressure was markedly elevated (30 mm. H g ) . The systolic pressure in the left ventricle was 196 and in the aorta 108, the gradient being 88 mm. The cardiac output was 7.6 L. per minute. The oxygen consumption, however, was 400 c.c. at the time, indicating that the patient was not in a basal state. The eineangiograms revealed moderate mitral insufficiency and a conical muscular obstruction in the subvalvular area. Operation was performed on May 23. The same approach was utilized. The mitral in sufficiency was confirmed by palpation. The mitral valve was excised, a large mass of ob structing muscular tissue was removed from the subvalvular area, and a ball valve prosthesis was sutured in place. This procedure also was carried out under induced ventricular fibrilla tion. Conversion was accomplished with electric shock. As the chest was being closed, the patient developed a complete heart block with a rate of 40 per minute. Pacemaker wires were inserted and external pacing was carried out for a few days. By this time the cardiac rhythm and rate were normal. After discharge the patient did exceedingly well, led a normal life, and had no cardiac symptoms. On April 17, 1964, however, he developed malaise, chills and fever, intermittent severe headaches, and periods of expressive aphasia. He was hospitalized 4 days later. Ex amination revealed no positive neurologic findings save for some dyscalculia. The spinal fluid and blood cultures were negative. The spinal fluid showed an increased protein (74 mg. per cent) and leukocyte count (57, 84 per cent lymphocytes). The electroencephalogram was abnormal and indicated some diffuse cerebral process. The electrocardiogram showed a first degree A-V block and left bundle branch block. The patient did well, remained afebrile, and was discharged on May 12. He was readmitted on J u n e 16 because of recurring headaches and episodes of aphasia. Examination was not remarkable. He remained afebrile. The spinal fluid contained 7 leukocytes per cubic millimeter and 119 per cent protein. Carotid arteriograms were normal. An electroencephalogram made on J u n e 25 showed marked improvement. The patient was discharged on June 27, bright, alert, and without any positive neurologic findings. I t was believed that his symptoms were probably best explained on the basis of minute cerebral emboli. DISCUSSION
Although the clinical picture of hypertrophic subaortic stenosis can be suspected clinically and substantiated by cardiac catheterization and angiographic study, much remains to be learned about the precise anatomic abnor mality. From experience to date there would appear to be considerable varia tion in'the nature of the obstructing muscular mass and also some differences with respect to the relationship of the mitral annulus to the ventricular cavity. Many of the patients are found to have some degree of mitral insufficiency. In some, this may possibly be entirely functional and related to the ventricular obstruction. In others, however, there is organic derangement of the mitral valve.
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Certain aspects of hypertrophic subaortic stenosis remain obscure. For example, there is the occasional patient with severe disease and massive ven tricular hypertrophy, such as our second, in whom it is not possible to demon strate on cardiac catheterization the expected large gradient. Another relates to the findings at operation. Morrow and Braunwald's early experience 6 included 2 patients with preoperative evidence of subaortic obstruction in whom no obstruction could be demonstrated in the arrested heart. It is possible that the anatomic obstruction would have been evident in the beating heart. In 1 of our patients, however, with a resting preoperative systolic gradient across the area of stenosis of 114 mm. Hg, and with the area clearly visible on cineangiographic study, no obstruction was demonstrable either by palpation or inspection, even though a strong heartbeat was maintained as the result of perfusion of the coronary arteries with oxygenated blood. Unfortunately, we did not assess the situation following the administration of Isuprel. Patients with hypertrophic subaortic stenosis have been treated with reason able success by utilizing a number of approaches. In some, a good result has been obtained by simple ventriculomyotomy performed through the opened aorta. 1 ' 2 Lillihei's initial experiences 5 were with a combined aortic and left ventricular approach. He abandoned this method because of the difficulty en countered in visualizing clearly the obstructing muscle mass. Kirklin and Ellis 7 have used a combined aortic and left ventricular approach with satisfaction. Julian 8 has been pleased with the use of a large left ventriculotomy incision. Swan, 9 while palpating and inspecting the left ventricular outflow tract through the opened aorta, has introduced through the left ventricular apical area an instrument for coning out the obstructing muscular tissue. Harkin 10 has re moved part of the thick septal wall through a right ventriculotomy incision by means of a finger placed into the left ventricle through the open aorta for aid in estimating the depth of resection. As we mentioned previously, some have thought that the best approach was through the surgically split aortic mitral leaflet,3 or through the mitral ring following detachment of the aortic leaflet from the annulus. 5 In patients with mitral insufficiency we would be fearful that either incision of the aortic leaflet or detaching it from the annulus with subsequent suture repair might worsen the state of insufficiency. Starr 1 1 believes that 1 patient was lost be cause there was too much residual mitral insufficiency following detachment and resuture of the leaflet.* The method we have employed has the advantages of providing optimal exposure for resection of the obstructing muscle mass and of insuring mitral valvular competence. I t has the potential disadvantages inherent in the use of ball valve prosthesis which are sometimes associated with embolic difficulties. Hopefully, there may be developed new prosthetic valves which will be free of embolic troubles. The method altogether appears to be a •He had another disastrous experience with 1 patient who had pure mitral regurgitation without any gradient across the left ventricular outflow tract. In this case the smallest ball valve prosthesis resulted in left ventricular outflow obstruction and the patient died on the operating table. The ventricular wall was markedly thickened and had, he thought, the anatomic configuration of hypertrophic subaortic stenosis. We have encountered no difficulty of this sort. Certainly it would make one hesitant to use a prosthesis for mitral regurgitation when it is associated with an unusually small ventricular cavity and hypertrophic ventricular wall.
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reasonable approach in those patients who have some degree of mitral in sufficiency. Subsequent to the treatment of these 3 patients we have become accustomed to carrying out mitral valve replacement through a median sternotomy incision. We no longer use induced ventricular fibrillation. Instead, the heart is kept beating vigorously throughout and, during the period when the atrium is open, left ventricular decompression is maintained by suction upon a catheter passed into the ventricular cavity. "We are led to believe that this would prove the preferable approach in cases of subaortic hypertrophic stenosis. Except in instances of marked mitral insufficiency, resulting from organic changes in the mitral valve, it would seem wise first to cross-clamp the aorta, make an aortotomy incision, and institute coronary artery perfusion. This would permit one to palpate and inspect the left ventricular outflow tract as the initial maneuver. Very likely the outflow obstruction could be relieved in some by manipulations through the aortic annulus. If there were no residual significant mitral insuf ficiency, nothing else would be required. I n case, however, the obstruction could not be relieved adequately through the aortic annulus or in case of definite mitral insufficiency one could make a left atriotomy incision, resect the mitral valve, and remove the obstructing muscle mass. Very likely this could be ac complished more completely and effectively by virtue of one being able to feel and see the outflow area through the aortic ring, as well as through the mitral annulus. If necessary, one could also utilize palpation of the ventricular septum through a small right ventriculotomy as an additional safeguard for resecting the desired amount of septal muscle. SUMMARY
A method for dealing with hypertrophic subaortic stenosis is described. It involves excision of the mitral valve, resection of the obstructing muscular tissue, and prosthetic mitral valve replacement. REFERENCES
1. Morrow, A. G., and Brockenbrough, E . C.: Surgical Treatment of Idiopathic Hypertrophic Subaortic Stenosis: Techuic and Hemodynamic Eesults of Subaortic Ventriculomyotomy, Ann. Surg. 154: 181, 1961. 2. Goodwin, J . F . , Hollman, A., Cleland, W. P . , and Teare, D . : Obstructive Cardiomyopathy Simulating Aortic Stenosis, Brit. Heart J . 22: 403, 1960. 3. Dobell, A. R. C , and Scott, H . F . : Hypertrophic Subaortic Stenosis: Evolution of a Surgical Technique, J . THORACIC & CARDIOVAS. SURG. 4 7 : 26, 1964.
4. Johnson, J . : Discussion of Dobell and Scott. 3 5. Lillihei, C. W . ; Discussion of Dobell and Scott. 3 6. Morrow, A. G., and Braunwald, E . : Functional Aortic Stenosis: A Malformation Char acterized by Resistance to Left Ventricular Outflow Without an Anatomic Ob struction, Circulation 20: 181, 1959. 7. Kirklin, J . W., and Ellis, F . H., J r . : Surgical Relief of Diffuse Subvalvular Aortic .Stenosis, Circulation 24: 739, 1961. 8: Julian, O.: Personal communication. 9. Swan, H . : Subaortic Muscular Stenosis: A New Surgical Technique for Repair, J . THORACIC & CARDIOVAS. SURG. 4 7 : 681, 1964.
10. Harkin, D. E . : Discussion of Dobell and Scott. 3 11. Starr, A . : Personal communication.
M.D.,
Ind.
T
HE clinical entity of idiopathic hypertrophic subaortic stenosis has recently become well recognized and its diagnostic characteristics established. In 1961 Morrow and Brockenbrough 1 reported 2 cases of successful treatment by a maneuver which they termed "subaortic ventriculomyotomy." The operations were carried out through the opened aorta and a longitudinal incision was made through the bulging muscle mass along the anterior or septal side of the ven tricle. Both patients treated in this manner not only did well clinically, but also showed gratifying hemodynamic responses upon subsequent study by cardiac catheterization. An earlier operation performed in similar fashion by Cleland2 had also yielded a good clinical result. It would seem evident, however, that not all patients can be managed successfully by this method. Dobell and Scott 3 believe that resection of the obstructing mass can be facilitated by use of a left transatrial approach with splitting and, subsequently, repairing the aortic leaflet of the mitral valve. In discussing this method, John son4 related an experience in which this maneuver resulted in such damage to the already diseased mitral valve that it had to be excised and replaced with a prosthesis. Lillihei 5 has used a somewhat similar approach. He has temporarily detached the aortic leaflet from the annulus and resutured it afterwards. Both of the patients he operated upon by this technique did well. Before we were aware of these experiences, we treated a patient by removal of the mitral valve, resection of the obstructing left ventricular muscle mass, and insertion of a ball valve prosthesis. The same general approach has now been utilized in 3 cases. In each there was some degree of mitral valvular insufficiency. Since others may encounter patients in whom this method would appear to be the procedure of choice; we are led to describe these experiences.
Prom the Department of Surgery and the Heart Research Center, Indiana University Medical Center, Indianapolis, Ind. This work was supported by the James Whitcomb Riley Memorial Association and a Public Health Research Grant, HE 02035-09, from the National Institutes of Health, U. S. Public Health Service. Received for publication Aug. 5, 1964. 497
SHTJMACKER AND K I N G
498
J. Thoracic and Cardiovas. Surg.
CASE REPORTS
CASE 1.—The patient was a 30-year-old man who had first been told he had a cardiac murmur when he was examined for military service in 1951. For 3 or 4 years prior to his admission he had had quite marked symptoms and had complained of excessive fatigability and dyspnea on exertion, of occasional episodes of nocturnal dyspnea, and of much preeordial pain. The pain radiated into the left arm. I t was experienced with exercise, eating, and, rarely, with emotional excitation. I t was not relieved by nitroglycerin. Considerable de terioration had occurred during the previous year in spite of the fact that he had been on digitalis therapy. He was admitted for study in October, 1962. The blood pressure was 100/70 mm. Hg. A faint aortic systolic thrill was palpable. The first heart sound at the apex was virtually obliterated by a high-pitched blowing Grade 3 systolic murmur. There was rough Grade 4 aortic systolic ejection murmur, the second heart sound was paradoxically split, and there was an audible triple rhythm at the apex. On fluoroscopic and x-ray study the heart was observed to be grossly increased in size, with predominant enlargement of the left ventricle and to a lesser extent of the left atrium. The aortic pulsations seemed prominent. The pul monary vasculature was slightly increased. The electrocardiogram showed left axis deviation, P "mitrale," left ventricular hypertrophy, and digitalis effect. Upon cardiac catheterization the cardiac index at rest was found to be normal, 3.05, but increased with exercise only to 4.31 L. per minute per square meter. The pulmonary wedge pressure was elevated at rest and rose further in response to exercise, the means being 17 and 27, respectively. The systolic, diastolic, and mean pressures in the pulmonary artery at rest and a t exercise were 35, 15, 21, and 55, 30, 38, respectively. No measurable gradient was observed across the pulmonary valve or the right ventricular outflow tract. Pressure in the apical portion of the left ventricle, determined by a catheter introduced through the aorta, was 245/12. As the catheter was withdrawn into a sort of infundibular chamber, the pressure fell to 120/12. The aortic pressure was 100/70. On cineangiographic study there seemed to be a rather conical area of obstructive muscular hypertrophy in the region of the outflow tract. This appeared to be approximately 2 cm. in length. The left ventricular cavity was relatively normal in size but had considerable trabeculation. Aortic valve function was normal, but there was moderate mitral insufficiency. The patient was readmitted to the hospital on November 17 for operative repair, and this was carried out on November 19. The aorta was opened and the coronary arteries were catheterized and perfused with arterialized blood. As we looked through the normal aortic valve we could visualize a distal left infundibular chamber about 1.5 or 2 em. in length. We were unable to identify any obstructing muscular tissue which could be separated from the presenting mitral leaflets so as to permit its safe removal or incision. A finger was introduced into the left atrium so that the mitral valve leaflets could be palpated and manipulated. In spite of this maneuver we found no way to proceed with incision or resection of the ob structing muscular mass without injury to the mitral leaflets. Reluctantly, the operative pro cedure was abandoned with the idea that another would be carried out later through a dif ferent approach. Even though nothing had been done except an exploratory procedure the patient developed a complete heart block. Pacemaker wires were sutured to the myocardium and the cardiac rate set by an external pacemaker. The block disappeared the following day. The patient was so ill postoperatively that it seemed for a while he would not survive. The venous pressure tended to stay rather markedly elevated. Weight increased from about 150 to 166.5 pounds, even though he maintained a rather satisfactory urinary output. Respira tions were rapid and labored. He was orthopnic, and there was a rapid gallop rhythm. He developed marked ascites, peripheral edema, and, between December 3 and 11, four thoracenteses were required; a total of 3,500 c.c. of fluid was removed. Toward the end of November he began to have a substantial diuresis and by December 13 he had lost 36 pounds in weight. He was still in a rather precarious condition, however, when the second operation was under taken on December 18. This was also carried out as an open procedure with cardiopulmonary bypass. The heart was approached through an anterolateral right thoracotomy incision. The moderate mitral
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insufficiency was confirmed by digital palpation through an incision in the left atrium. Ven tricular fibrillation was induced electrically. The mitral leaflets were excised as were the unusually large papillary muscles and a large mass of muscular tissue from the ventricular wall. The ventricular cavity now seemed to be adequate in size and no obstructing muscular mass was palpable. A ball valve prosthesis was sutured in place. Ventricular contractions were restored by electric shock and the procedure was terminated. The patient had a rather uncomplicated and smooth convalescence in contrast to the stormy time he had had after the first operation. The venous pressure remained within the normal range and the patient showed no other evidence of cardiac failure. He was discharged from the hospital on the eleventh postoperative day. H e was advised to remain on a low sodium diet, to continue on a maintenance dose of digitalis, and to take Coumadin. He continued to do well. H e was readmitted to the hospital on Nov. 20, 1963, for re assessment. He had been operating a combine on a farm 8 hours a day without difficulty. Ordinary physical activity and eating large meals caused no distress. H e stated that he would become slightly short of breath if he ran upstairs rapidly or for any great distance. There was no history of orthopnea, paroxysmal dyspnea, precordial pain, syncope with exer tion, cough or hemoptysis, palpations, embolism, or edema. He was on an unrestricted diet and was taking 0.2 mg. of digitoxin and 5 mg. of Coumadin daily. Prothrombin time was not being maintained within the therapeutic range. The precordium was quiet, the rhythm and rate of the heart were normal. There was no thrill. A Grade 3 aortic systolic ejection type murmur was heard but there was no apical systolic or basal diastolic murmur. There was no evidence of failure. The electrocardiogram showed left axis deviation, left atrial hypertrophy, complete left bundle branch block, and nonspecific ST-T changes. The transverse diameter of the heart appeared to be within, normal limits on x-ray study. Cardiac catheterization was performed on November 21. The cardiac index was normal at rest and increased, but probably not quite normally, in response to exercise, the values being 3.07 and 4.88 L. per minute per square meter, respectively. The wedge pulmonary capillary venous pressure was very slightly elevated a t rest and rose somewhat in response to exercise, the mean values being 12 and 22 mm. Hg, respectively. The right ventricular and right atrial pressures were normal, the former being 26/2 after exercise and the latter 4 / 0 . There was no left ventricular pressure gradient and the left ventricular diastolic pressure was normal. The left ventricular pressure was 100/10, and the aortic pressure 100/70. Cineangiographic study revealed the mitral and aortic valves to be competent, the left ventricular contractions vigorous, and what appeared to be, perhaps, slight residual narrowing of the subvalvular area. On December 6 he had several momentary cerebral episodes which must be interpreted as a probable result of minute emboli. Uneventful recovery ensued and he has remained well. CASE 2.—The patient was a 20-year-old man who for 4 years had complained of substernal pain with exercise which was always associated with dyspnea. He also had substernal pain after eating and dyspnea on exertion. Symptoms had been progressive during the previous year. Examination revealed a normal cardiac rhythm and rate and a blood pressure of 88/55 mm. H g . There was a systolic thrill, and a pansystolic Grade 4 to 6 murmur was heard over the entire precordium. No diastolic murmur was audible. There was paradoxical splitting of the second heart sound. On cardiac catheterization, performed on Feb. 21, 1963, the wedge pressure was found to be elevated (19 mm. Hg, mean) and it increased with exercise. The right ventricular pres sure was 36/8 at rest and the main pulmonary artery pressure was 34/15. The left ven tricular end diastolic pressure was 25 a t rest. The systolic pressure in the left ventricle dif fered somewhat in different parts of the cavity. Pull-out pressures across the aortic valve did not seem to reveal a valvular obstruction. No large gradient was established across the left ventricular outflow tract, even following the administration of Isuprel when it was only 17 mm. Hg. The cineangiograms, however, showed a definite conical tapering in the subvalvular region of the left ventricular cavity. There was evidence of mild mitral insufficiency. Operation was performed on May 3. I n view of the experience in the first case, it was
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planned to use the same approach. The right atrium was not particularly enlarged, but the left atrium was big and seemed to pulsate with ventricular contractions. The pulmonary arteries felt tense. When the mitral valve was palpated through an incision in the left atrium, the insufficiency jet seemed considerably greater than one would have judged would be the case from the cineangiograms. The mitral leaflets were palpably scarred and there seemed to be a cleft in the caudal portion of the aortic leaflet. Ventricular fibrillation wag induced. The mitral valve and the papillary muscles were excised. There was a large protruding muscle mass just beneath the aortic ring which seemed to arise principally from the left anterolateral part of the ventricular wall and the ventricular septum and to pass posteriorly around to the right underneath the mural leaflet. I n the subaortic area this bulging muscle mass had a glistening white covering which appeared to be fibrous in nature. A great deal of the presenting obstructing muscle mass was excised. A ball valve prosthesis was sutured in place, conversion to a sinus rhythm was accomplished with electric shock, and the operation was terminated. The patient had a relatively smooth postoperative course and was discharged on the tenth postoperative day. He returned to the outpatient clinic on June 24, and examination revealed rales in the lungs and rapid atrial fibrillation. I t was impossible to learn when the atrial fibrillation had begun. Marked improvement occurred with rapid digitalization and he was discharged without evidence of failure and with a satisfactory cardiac rate on June 27. During this admission no murmur was heard. He was advised to return to the outpatient clinic 6 weeks later but failed to do so. On July 14 he was admitted in a moribund condition to another hospital with the story that he had developed fever, cough, hemoptysis, orthopnea, and marked dyspnea 3 days beforehand. He was found to be slightly icteric and dyspneic with a blood pressure of 110/60 mm. H g and a rapid irregular peripheral pulse. He had a dusky cyanosis. The liver was enlarged. The electrocardiogram showed atrial fibrillation with a rate at times as rapid as 150, left bundle branch block, and left axis deviation. The serum bilirubin was 3.48. He died the evening of admission. Postmortem examination revealed marked congestion of the lungs and liver and some hydrothorax. He was thought to have cardiac cirrhosis. The formalinfixed heart was returned to us for examination. I t weighed 1,050 grams. There was marked hypertrophy of both ventricles. The thickness of the left ventricular wall was judged to be 30 mm., that of the right wall 20 mm., and that of the septum 40 mm. As one passed his finger through the aortic valve and annulus into the left ventricular cavity he could feel the protruding ball valve prosthesis but no evidence of any muscular obstruction. The entire left ventricular cavity of the fixed specimen accommodated with ease the palpating finger but there was little room to spare. I t seemed to have just about the same diameter in all portions. The width of the ventricular cavity was approximately 3 cm. and it was about 8.5 cm. long. The mitral valve seemed well seated and appeared to have been working competently. As far as one could tell, the left ventricular obstruction had been relieved by the opera tive procedure. The patient withstood the operation well, recovered quickly, and appeared to be in good health when he left the hospital. He developed evidence of failure with the onset of rapid fibrillation and responded dramatically to control of the cardiac rate with digitalis. We do not know whether conversion to a sinus rhythm might have been accomplished at this time or whether conversion might have prevented his terminal illness which was also asso ciated with uncontrolled rapid atrial fibrillation. CASE 3.—The patient was a 29-year-old man in whom the presence of a cardiac murmur had been discovered at the age of 11 years. For 6 months prior to admission he had been having some nocturnal difficulty with breathing. While swimming 2 months previously he had experienced the sudden onset of pain in the left hemithorax and back associated with shortness of breath and "congestion of his lungs." The shortness of breath lasted for several hours. Following this episode he had dyspnea on exertion. For 1 month he had complained of discomfort in the upper abdomen and a tendency toward nausea. He had been digitalized 3 weeks before admission. While climbing a hill 10 days before admission he became dyspneic
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experienced a recurrence of severe chest pain and "congestion of the lungs." With rest, symptoms gradually subsided but the difficulty in breathing and the chest pain lasted an additional several hours. Eight days later he developed paroxysmal nocturnal dyspnea orthopnea. I t seemed clear from his story that he had undergone rapid deterioration. Moist rales could be heard bilaterally. The pulse rate was 84 and regular, the blood pressure 110/80 mm. Hg. There was an apical systolic thrill and an ejection type systolic murmur, best heard at the apex. The electrocardiogram revealed inverted T waves in Leads I , aV L and V„, marked left axis deviation, and slight prolongation of the QES complex. I t was the opinion that the electrocardiographic tracing was consistent with left ventricular hyper trophy or an intraventricular conduction defect. X-ray films revealed evidence of left atrial, left ventricular, and right ventricular enlargement with prominence of the pulmonary outflow tract. Cardiac catheterization was performed on May 14, 1963. The mean left atrial pressure was found to be elevated to 28. The pulmonary artery pressure was 49/27 mm. Hg. The left ventricular end-diastolie pressure was markedly elevated (30 mm. H g ) . The systolic pressure in the left ventricle was 196 and in the aorta 108, the gradient being 88 mm. The cardiac output was 7.6 L. per minute. The oxygen consumption, however, was 400 c.c. at the time, indicating that the patient was not in a basal state. The eineangiograms revealed moderate mitral insufficiency and a conical muscular obstruction in the subvalvular area. Operation was performed on May 23. The same approach was utilized. The mitral in sufficiency was confirmed by palpation. The mitral valve was excised, a large mass of ob structing muscular tissue was removed from the subvalvular area, and a ball valve prosthesis was sutured in place. This procedure also was carried out under induced ventricular fibrilla tion. Conversion was accomplished with electric shock. As the chest was being closed, the patient developed a complete heart block with a rate of 40 per minute. Pacemaker wires were inserted and external pacing was carried out for a few days. By this time the cardiac rhythm and rate were normal. After discharge the patient did exceedingly well, led a normal life, and had no cardiac symptoms. On April 17, 1964, however, he developed malaise, chills and fever, intermittent severe headaches, and periods of expressive aphasia. He was hospitalized 4 days later. Ex amination revealed no positive neurologic findings save for some dyscalculia. The spinal fluid and blood cultures were negative. The spinal fluid showed an increased protein (74 mg. per cent) and leukocyte count (57, 84 per cent lymphocytes). The electroencephalogram was abnormal and indicated some diffuse cerebral process. The electrocardiogram showed a first degree A-V block and left bundle branch block. The patient did well, remained afebrile, and was discharged on May 12. He was readmitted on J u n e 16 because of recurring headaches and episodes of aphasia. Examination was not remarkable. He remained afebrile. The spinal fluid contained 7 leukocytes per cubic millimeter and 119 per cent protein. Carotid arteriograms were normal. An electroencephalogram made on J u n e 25 showed marked improvement. The patient was discharged on June 27, bright, alert, and without any positive neurologic findings. I t was believed that his symptoms were probably best explained on the basis of minute cerebral emboli. DISCUSSION
Although the clinical picture of hypertrophic subaortic stenosis can be suspected clinically and substantiated by cardiac catheterization and angiographic study, much remains to be learned about the precise anatomic abnor mality. From experience to date there would appear to be considerable varia tion in'the nature of the obstructing muscular mass and also some differences with respect to the relationship of the mitral annulus to the ventricular cavity. Many of the patients are found to have some degree of mitral insufficiency. In some, this may possibly be entirely functional and related to the ventricular obstruction. In others, however, there is organic derangement of the mitral valve.
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Certain aspects of hypertrophic subaortic stenosis remain obscure. For example, there is the occasional patient with severe disease and massive ven tricular hypertrophy, such as our second, in whom it is not possible to demon strate on cardiac catheterization the expected large gradient. Another relates to the findings at operation. Morrow and Braunwald's early experience 6 included 2 patients with preoperative evidence of subaortic obstruction in whom no obstruction could be demonstrated in the arrested heart. It is possible that the anatomic obstruction would have been evident in the beating heart. In 1 of our patients, however, with a resting preoperative systolic gradient across the area of stenosis of 114 mm. Hg, and with the area clearly visible on cineangiographic study, no obstruction was demonstrable either by palpation or inspection, even though a strong heartbeat was maintained as the result of perfusion of the coronary arteries with oxygenated blood. Unfortunately, we did not assess the situation following the administration of Isuprel. Patients with hypertrophic subaortic stenosis have been treated with reason able success by utilizing a number of approaches. In some, a good result has been obtained by simple ventriculomyotomy performed through the opened aorta. 1 ' 2 Lillihei's initial experiences 5 were with a combined aortic and left ventricular approach. He abandoned this method because of the difficulty en countered in visualizing clearly the obstructing muscle mass. Kirklin and Ellis 7 have used a combined aortic and left ventricular approach with satisfaction. Julian 8 has been pleased with the use of a large left ventriculotomy incision. Swan, 9 while palpating and inspecting the left ventricular outflow tract through the opened aorta, has introduced through the left ventricular apical area an instrument for coning out the obstructing muscular tissue. Harkin 10 has re moved part of the thick septal wall through a right ventriculotomy incision by means of a finger placed into the left ventricle through the open aorta for aid in estimating the depth of resection. As we mentioned previously, some have thought that the best approach was through the surgically split aortic mitral leaflet,3 or through the mitral ring following detachment of the aortic leaflet from the annulus. 5 In patients with mitral insufficiency we would be fearful that either incision of the aortic leaflet or detaching it from the annulus with subsequent suture repair might worsen the state of insufficiency. Starr 1 1 believes that 1 patient was lost be cause there was too much residual mitral insufficiency following detachment and resuture of the leaflet.* The method we have employed has the advantages of providing optimal exposure for resection of the obstructing muscle mass and of insuring mitral valvular competence. I t has the potential disadvantages inherent in the use of ball valve prosthesis which are sometimes associated with embolic difficulties. Hopefully, there may be developed new prosthetic valves which will be free of embolic troubles. The method altogether appears to be a •He had another disastrous experience with 1 patient who had pure mitral regurgitation without any gradient across the left ventricular outflow tract. In this case the smallest ball valve prosthesis resulted in left ventricular outflow obstruction and the patient died on the operating table. The ventricular wall was markedly thickened and had, he thought, the anatomic configuration of hypertrophic subaortic stenosis. We have encountered no difficulty of this sort. Certainly it would make one hesitant to use a prosthesis for mitral regurgitation when it is associated with an unusually small ventricular cavity and hypertrophic ventricular wall.
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reasonable approach in those patients who have some degree of mitral in sufficiency. Subsequent to the treatment of these 3 patients we have become accustomed to carrying out mitral valve replacement through a median sternotomy incision. We no longer use induced ventricular fibrillation. Instead, the heart is kept beating vigorously throughout and, during the period when the atrium is open, left ventricular decompression is maintained by suction upon a catheter passed into the ventricular cavity. "We are led to believe that this would prove the preferable approach in cases of subaortic hypertrophic stenosis. Except in instances of marked mitral insufficiency, resulting from organic changes in the mitral valve, it would seem wise first to cross-clamp the aorta, make an aortotomy incision, and institute coronary artery perfusion. This would permit one to palpate and inspect the left ventricular outflow tract as the initial maneuver. Very likely the outflow obstruction could be relieved in some by manipulations through the aortic annulus. If there were no residual significant mitral insuf ficiency, nothing else would be required. I n case, however, the obstruction could not be relieved adequately through the aortic annulus or in case of definite mitral insufficiency one could make a left atriotomy incision, resect the mitral valve, and remove the obstructing muscle mass. Very likely this could be ac complished more completely and effectively by virtue of one being able to feel and see the outflow area through the aortic ring, as well as through the mitral annulus. If necessary, one could also utilize palpation of the ventricular septum through a small right ventriculotomy as an additional safeguard for resecting the desired amount of septal muscle. SUMMARY
A method for dealing with hypertrophic subaortic stenosis is described. It involves excision of the mitral valve, resection of the obstructing muscular tissue, and prosthetic mitral valve replacement. REFERENCES
1. Morrow, A. G., and Brockenbrough, E . C.: Surgical Treatment of Idiopathic Hypertrophic Subaortic Stenosis: Techuic and Hemodynamic Eesults of Subaortic Ventriculomyotomy, Ann. Surg. 154: 181, 1961. 2. Goodwin, J . F . , Hollman, A., Cleland, W. P . , and Teare, D . : Obstructive Cardiomyopathy Simulating Aortic Stenosis, Brit. Heart J . 22: 403, 1960. 3. Dobell, A. R. C , and Scott, H . F . : Hypertrophic Subaortic Stenosis: Evolution of a Surgical Technique, J . THORACIC & CARDIOVAS. SURG. 4 7 : 26, 1964.
4. Johnson, J . : Discussion of Dobell and Scott. 3 5. Lillihei, C. W . ; Discussion of Dobell and Scott. 3 6. Morrow, A. G., and Braunwald, E . : Functional Aortic Stenosis: A Malformation Char acterized by Resistance to Left Ventricular Outflow Without an Anatomic Ob struction, Circulation 20: 181, 1959. 7. Kirklin, J . W., and Ellis, F . H., J r . : Surgical Relief of Diffuse Subvalvular Aortic .Stenosis, Circulation 24: 739, 1961. 8: Julian, O.: Personal communication. 9. Swan, H . : Subaortic Muscular Stenosis: A New Surgical Technique for Repair, J . THORACIC & CARDIOVAS. SURG. 4 7 : 681, 1964.
10. Harkin, D. E . : Discussion of Dobell and Scott. 3 11. Starr, A . : Personal communication.