Surgical treatment of subaortic stenosis: a seventeen-year experience

OBJECTIVE: The aim of the study was to analyze the long-term results of subaortic stenosis relief and the risk factors associated with recurrence and reoperation. METHODS: One hundred sixty patients with subaortic stenosis underwent biventricular repair. Before the operation the mean left ventricle-aorta gradient was 80 +/- 35 mm Hg, 57 patients had aortic regurgitation, and 34 were in New York Heart Association functional class III or IV. Median age at repair was 10 years. For discrete subaortic stenosis (n = 120), 39 patients underwent isolated membranectomy, 67 underwent membranectomy with associated septal myotomy, and 14 underwent septal myectomy. Tunnel subaortic stenosis (n = 34) was treated by myotomy in 10 cases, myectomy in 12, septoplasty in 7, Konno procedure in 3, and apical conduit in 2. Aortic valve replacement was performed in 6 cases, mitral valve replacement in 2 cases, and mitral valvuloplasty in 4 cases. RESULTS: There were 5 early (3.1%) and 4 late (4.4%) deaths. Within 3.6 +/- 3.3 years a recurrent gradient greater than 30 mm Hg was found in 42 patients (27%), 20 of whom had 26 reoperations. According to multivariable Cox regression analysis survival was influenced by hypoplastic aortic anulus (P =.01) and mitral stenosis (P =.048); recurrence and reoperation were influenced by coarctation and immediate postoperative left ventricular outflow tract gradients. At a median follow-up of 13.3 years, mean left ventricle-aorta gradient was 20 +/- 13 mm Hg. Relief of the subaortic stenosis improved the degree of aortic regurgitation in 86% of patients with preoperative aortic regurgitation. Actuarial survival and freedom from reoperation rates at 15 years were 94% +/- 1.3% and 85% +/- 6%, respectively. CONCLUSION: Although surgical treatment provides good results, recurrence and reoperation are significantly influenced by previous coarctation repair and by the quality of initial relief of subaortic stenosis.     

The perioperative fate of residual gradients after repair of discrete subaortic stenosis and time-related blood levels of catecholamines

The fate of the residual peak systolic left ventricular-aortic gradient was studied perioperatively in 14 patients with membranous discrete subaortic stenosis. In nine (group A) the initial postrepair left ventricular-aortic gradient was greater than 35 mm Hg (mean 56.8 +/- 13.4), and in five (group B) there was no significant postoperative gradient (mean 15.3 +/- 3.2 mm Hg). The operation included membranectomy and myectomy. Peak left ventricular-aortic pressure gradient, endogenous levels of norepinephrine, peak rate of rise of left ventricular pressure, cardiac index, systemic vascular resistance, heart rate, and central venous pressure were recorded at the end of cardiopulmonary bypass and in 3-hour intervals for the next 9 hours. In group A during that period there was a 67% reduction in peak systolic left ventricular-aortic gradient (from 56.8 +/- 13.4 to 18 +/- 14 mm Hg, p less than 0.001). Concomitant reduction in the initial endogenous norepinephrine level was observed (from 982.1 +/- 181 to 422.6 +/- 109 pg/ml, p less than 0.001). A consistent linear relationship between norepinephrine levels and peak systolic left ventricular-aortic gradient was found (r = 0.78). Systolic left ventricular pressure decreased from 174.2 +/- 24.8 to 113.8 +/- 14.7 mm Hg (p less than 0.001). Marked reduction in peak rate of rise of left ventricular pressure (from 3455 +/- 636 to 2161 +/- 680 mm Hg/sec, p less than 0.001) was observed. Cardiac index increased and systemic vascular resistance decreased during the study period (from 2.11 +/- 0.2 to 3.07 +/- 0.26 L/min, p less than 0.001, and from 2172 +/- 331 to 1233 +/- 202 dynes/sec/cm-5, p less than 0.001, respectively). There were no significant changes in heart rate (p = not significant) and central venous pressure p = not significant). Conclusion: Some of the residual perioperative left ventricular-aortic gradients in patients with discrete subaortic stenosis undergoing repairs are dynamic and transient, and are probably related to increased postoperative sympathetic activity.     

Operation for hypertrophic subaortic stenosis in the aged

To determine if operative palliation of idiopathic hypertrophic subaortic stenosis (IHSS) is worthwhile in the elderly, hemodynamic, cardiac conduction, symptomatological, functional, and survival data were examined in 52 patients (39 women) 65 years old and older (mean age, 69 years; range, 65 to 81 years) who had a left ventricular myotomy and myectomy (LVMM) (Morrow procedure) alone or with concomitant operations. Seventy-four percent of all operative survivors underwent catheterization an average of 6 months postoperatively. The mean follow-up was 54 months (range, 5 to 120 months). The population was divided for analyses into those with coronary artery disease (CAD) (N = 11,21%) and those without (N = 41). The peak resting left ventricular outflow tract gradient was reduced from 65 +/- 16 mm Hg to 3 +/- 1 mm Hg (p less than 0.01) in the group with CAD and from 95 +/- 13 mm Hg to 17 +/- 9 mm Hg (p less than 0.001) in the group without CAD. Significant reductions in peak gradients in response to provocation also occurred in both groups. New conduction abnormalities occurred in 72% of survivors, 85% of whom showed improvement in regard to symptoms. The overall average New York Heart Association Functional Class was 3.2 +/- 0.1 preoperatively and at latest follow-up, 1.9 +/- 0.1 (p less than 0.001). The hospital mortality for LVMM alone in the absence of CAD was 8% with a 5-year actuarial survival of 75 +/- 8%. LVMM in the presence of CAD resulted in an operative mortality of 27% (N = 3); all deaths were related to an acquired ventricular septal defect.(ABSTRACT TRUNCATED AT 250 WORDS)     

Surgical options in subaortic stenosis associated with endocardial cushion defects

Over a 15-year period, 12 patients with endocardial cushion defects undergoing correction had subaortic stenosis requiring operative intervention. Ages ranged from 4 months to 17 years (mean, 7 +/- 6 years) and subaortic gradients from 15 to 100 mm Hg (mean, 60 +/- 25 mm Hg). Subaortic stenosis was due to discrete fibromuscular tissues in 7 patients, mitral valve malattachment in 3, and tunnel outflow in 2. In 2, the subaortic stenosis was clinically significant at the time of endocardial cushion defects repair, whereas in 10 it was noted 2 to 14 years postoperatively (mean, 6.3 +/- 5 years). Surgical relief of subaortic stenosis was accomplished by resection of muscle tissues in 7, apicoaortic conduit insertion in 2, modified Konno procedure (aortic valve preserved) in 2, and lifting of malattached mitral valve from the outflow in 1. There was no early death and one late death (infected conduit). Severe mitral insufficiency developed in the patient who had the mitral valve lifted and necessitated valve replacement. Postoperative echocardiographic gradient in 9 patients ranged from 0 to 36 mm Hg (mean, 10.5 +/- 14 mm Hg). Clinically significant subaortic stenosis has not developed in any patient in 15 years of follow-up (mean, 5 +/- 4 years). We conclude that in subaortic stenosis associated with endocardial cushion defects, resection is effective for discrete obstruction, whereas a modified Konno procedure is preferable for obstruction due to tunnel outflow or mitral valve malattachment.     

Relationship of right and left ventricular negative diastolic pressures, hypercontractility, and relief of outflow tract obstructions

Continuous postoperative right and left ventricular diastolic pressures were measured in 12 consecutive patients undergoing pulmonic valvotomy and in 13 consecutive patients undergoing membranectomy and myectomy for discrete subaortic stenosis. All 25 patients had positive preoperative diastolic ventricular pressures. Negative ventricular diastolic pressure was detected immediately postoperatively in all 25. The lowest left ventricular negative diastolic pressure was -38 mm Hg, and the lowest right ventricular negative diastolic pressure was -28 mm Hg. Intravenous administration of volume (blood) reduced the right ventricular negative diastolic pressure significantly (from -14.8 +/- 9.2 to -6.4 +/- 6.8 mm Hg, p less than 0.001) and decreased right ventricular rate of pressure rise from 1100 +/- 320 to 380 +/- 180. Left ventricular negative diastolic pressure was not significantly affected (from -17 +/- 11 to -14.7 +/- 11 mm Hg). Left ventricular negative diastolic pressure disappeared spontaneously 6 to 9 hours postoperatively in association with a spontaneous decrease of left ventricular rate of pressure rise (from 3450 +/- 610 to 2100 +/- 660 mm Hg/sec). We conclude that negative right and left ventricular pressures are common findings immediately after surgical relief of outflow obstructions. Hypercontractility is the main reason for these phenomena. Volume load reduces the right ventricular negative diastolic pressure, but has insignificant effect on left ventricular negative diastolic pressure. The pathogenesis of the hypercontractility is discussed.     

Aortoventriculoplasty for different types of left ventricular outflow tract obstructions

Since the first clinical application of aortoventriculoplasty for tunnel subaortic stenosis in 1974 the indication for this method was extended to other types of left ventricular outflow tract stenoses (LVOTO). The operative technique consists of enlarging both the left and right ventricular outflow tracts and inserting an aortic prosthetic valve. 47 operations have been performed in patients with various types of LVOTO: 8 narrow annulus, 23 diffuse subaortic stenosis (multiple level stenosis), 9 complex forms of tunnel subaortic stenosis (Shone complex) 3 outgrown prosthesis, 4 obstructive idiopathic hypertrophic subaortic stenosis. Patients ages ranged from 4 to 35 years. Overall mortality was 13%, there were no late deaths, in the last 34 patients there was no death. In 25 patients there had been 1, and in 13 patients 2 previous procedures. As a result of the operation 9 patients developed complete right bundle branch block or left anterior hemi-block; 2 patients developed total a-v block with the need of a permanent pacemaker 25 patients had catheterization postoperatively. The mean gradient across the left ventricular outflow tract was significantly reduced from 91.5 +/- 21 mm Hg to 13.1 +/- 15 mm Hg. According to our experience aortoventriculoplasty can be used routinely in all forms of diffuse subaortic stenosis, narrow aortic annulus, reoperation in HOCM, multiple level stenosis and outgrown aortic prosthesis.     

Conal enlargement for diffuse subaortic stenosis

Twelve patients underwent conal enlargement for diffuse subaortic stenosis over a 3 1/2-year period. The subaortic stenosis was due to tunnel outflow in 11 and malattached mitral valve in one. Mean age was 4.4 +/- 4 years and mean subaortic gradient was 50 +/- 21 mm Hg. Three infants had a malalignment ventricular septal defect. In eight patients significant obstruction occurred 2 to 7 years (mean 4 +/- 2) after simple resection of subaortic stenosis (n = 2), ventricular septal defect closure (n = 2), ventricular septal defect closure and subaortic stenosis resection (n = 2), and canal repair (n = 2). In three infants the tunnel outflow distal to a malalignment ventricular septal defect was enlarged and closed with the defect. In three patients with subaortic stenosis proximal to a previously repaired ventricular septal defect, transatrial conal enlargement through the ventricular septal defect was performed. Another patient without a ventricular septal defect had transatrial conal enlargement. The remaining five patients had the modified Konno procedure. Two patients had postoperative complete heart block and one infant had insertion of an apicoaortic conduit for aortic anulus hypoplasia 9 months later. One patient died of pneumonia during the follow-up period. Postoperative echographic outflow gradients up to 3 1/2 years (mean 1.2 +/- 1) ranged up to 25 mm Hg (mean 7 +/- 11) and were mainly at the aortic level. The 11 surviving patients are doing well up to 3 1/2 years of follow-up (mean 1.5 +/- 1). We conclude that conal enlargement procedures with aortic valve preservation are preferable, effective, and can be safely performed for diffuse subaortic stenosis in infants and children.     

Surgical treatment of subaortic obstruction in adolescent and adults: long-term follow-up

Subaortic stenosis (SAS) is a wide spectrum of anatomical derangements ranging from a discrete fibrous membrane to tortuous fibrous tunnel with or without aortic annulus hypoplasia. We have reviewed 88 patients undergoing surgery for SAS over a 15-year period. There were 47 male and 41 female patients with a mean age of 19.8 +/- 10.6 years (range 11 to 39). Fifty-eight patients had discrete subaortic membrane, and 30 patients had diffuse tunnel subvalvular stenosis. The mean systolic pressure gradients were found to be 86.5 +/- 31.4 mmHg (range 48 to 145 mmHg). Ten patients had mild and 13 patients had moderate-to-severe aortic insufficiency (AI) preoperatively. Nine patients had bicuspid aortic valve. Forty patients (45.4%) had associated cardiac lesions. Isolated membranectomy was performed in six patients. Membranectomy associated with septal myectomy was done in 52 patients. Fifteen patients of them associated hypoplasia of the aortic orifice necessitated aortic valve replacement (AVR) using the Konno-Rastan procedure. Fifteen patients with tunnel SAS and normal aortic valves underwent a combined approach for valve sparing, a modified Konno procedure with patch septoplasty. Also eight patients required AVR because of the severity of AI and five patients aortic reconstruction procedures. Aortic commissurotomy was performed to relief of stenosis in four patients. There were three early deaths (3.4%) and one late death (1.1%) all after the Konno-Rastan procedure. Eight patients (9.1%) had permanent conduction abnormalities. Postoperative left ventricle-aorta gradient was significantly decreased at early postoperative period (p < 0.001) and ranged from 10 to 25 mmHg (mean 14.1 +/- 4.3). Fourteen patients (16.5%) were reoperated for recurrent obstruction or progression of AI. The mean reoperation interval was 4.4 +/- 1.7 years (range 2 to 8 years). Five-year reoperation-free survival was 88.0 +/- 3.6% and 12.5-year reoperation-free survival was 75.5 +/- 7.0%. Our results of aggressive surgical approach of subvalvular aortic stenosis produces relief of obstruction and frees the valve leaflets, significantly reducing associated AI with long-term survival and long-term adequate relief of left ventricular outflow tract obstruction.     

Late results after resection of discrete and tunnel subaortic stenosis

From May 1969 to June 1988, 84 consecutive patients ranging in age from 6 months to 61 years (mean 18 years) underwent surgery for fixed subaortic stenosis (SAS). A discrete fibrous or fibromuscular structure was present in 81 patients, while 3 presented with a tunnel type of obstruction. SAS was treated by sharp resection of the tissue and routine myotomy or myectomy of the hypertrophied left ventricular (LV) muscle (57 patients, group 1), while more recently, the lesion was treated by simple fibrous tissue enucleation (27 cases, group 2). There were 3 hospital deaths (3.6%) and 3 late deaths (overall mortality 7.1%). Eight patients required late reoperation because of recurrent SAS [3], aortic valve stenosis [2], aortic incompetence (AI) [2] and persistent mitral incompetence [1]. Seventy of 78 late survivors were reevaluated 3 months to 110 months after surgery (mean 75 +/- 48 months) by means of a complete cardiac catheterization or by 2-D echo and Doppler. The transaortic peak pressure gradient decreased from 97 +/- 43 (range 20-205 mmHg) to 11 +/- 16 mmHg (range 0-60 mmHg) in group 1 and from 72 +/- 38 mmHg (range 18-160 mmHg) to 3 +/- 7 mmHg (range 0-25 mmHg) in group 2 (P = NS). In 55 patients who have not undergone surgery on the aortic valve, AI remained unchanged in 31, decreased from mild to nil in 21 and from moderate to mild in 3. We conclude that simple blunt enucleation of SAS is an effective procedure in relieving LV outflow obstruction even if a myotomy or myectomy of the underlying hypertrophied muscle is not routinely used.(ABSTRACT TRUNCATED AT 250 WORDS)     

Advantages of early relief of subaortic stenosis in single ventricle equivalents.

Thirteen patients with single ventricle equivalents and subaortic stenosis underwent relief of the stenosis and subsequent Fontan operation. Nine patients, group 1, had the obstruction relieved at 3.6 +/- 1.6 years of age whenever the pressure gradient became apparent. Four patients, group 2, had the subaortic stenosis operated on at the neonatal period, 10.5 +/- 10 days old, before hemodynamic evidence of obstruction. Preoperative pressure gradient across the outflow tract was 44.2 +/- 4.7 mm Hg in group 1 versus 4.7 +/- 5 mm Hg in group 2 (p = 0.002). Ventricular muscle mass was 186% +/- 18% in group 1 versus 114% +/- 5% of normal in group 2 (p = 0.0001), and mass/volume ratio was 1.12 +/- 0.62 in group 1 versus 0.62 +/- 0.16 in group 2 (p = 0.003). Relief of subaortic stenosis was achieved by proximal pulmonary artery to ascending aorta or aortic arch anastomosis and by systemic to distal pulmonary artery shunt. There was no hospital mortality or complication related to the procedure. At evaluation before Fontan operation, 4.3 +/- 1.6 years after relief of subaortic stenosis in group 1 and 3.2 +/- 0.9 years in group 2, the pressure gradient across the ventricular outflow tract was 4 +/- 3 mm Hg in group 1 versus 3 +/- 2 mm Hg in group 2 (p = not significant), ventricular muscle mass was 184% +/- 31% in group 1 versus 114% +/- 5% of normal in group 2 (p = 0.003), and the mass/volume ratio was 1.17 +/- 0.2 in group 1 versus 0.62 +/- 0.2 in group 2 (p = 0.003).(ABSTRACT TRUNCATED AT 250 WORDS)     

Long-term results after excision of fixed subaortic stenosis

Forty-nine patients underwent surgical excision of fixed subaortic stenosis (discrete fibrous ring and tunnel) between 1968 and 1984 and were followed up for 1 to 16 years (5.8 +/- 4). Twenty-six patients (Group I) had isolated subaortic stenosis and 23 (Group II) had subaortic stenosis and associated cardiac defects. Discrete fibrous ring was present in 46 and tunnel type of obstruction in three patients. For the discrete ring, excision alone was done in 32 patients (four recurrences) and excision with myotomy in 17 (three recurrences). In Group I, there were no operative deaths and one late death from a noncardiac cause. In Group II, one early and two late deaths occurred. The actuarial survival rate for 10 years is 88%. Reoperations were performed in 10 patients, seven for recurrence and three for aortic valve replacement for preexisting aortic regurgitation that had progressed since the primary operation. Cardioplegia was used in 28 patients (one recurrence) and was not used in 21 patients (six recurrences). An operative residual gradient of less than 15 mm Hg was achieved in 25 of 28 patients in whom cardioplegia was used compared to 12 of 21 patients in whom cardioplegia was not used (p = 0.017). These results indicate that complete excision of the ring with the aid of cardioplegia has significantly reduced the recurrence rate of subaortic stenosis (p = 0.033), elimination of the residual gradient at the initial operation has been a significant factor in reducing the recurrence rate (p = 0.017), and addition of myotomy in this series has not altered the outcome.     

Surgical experience with an infant with discrete subaortic stenosis successfully treated by aortoventriculoplasty

A 3-year-old female with discrete subaortic stenosis is presented. Angiocardiographic studies showed a long segmental narrowing below the aortic valve. Although membranectomy and myectomy were selected as a surgical treatment, a longitudinal aortotomy was performed in order to extend the operation to ventriculoseptoplasty. During the operation, the right coronary cusp was seriously damaged and therefore aortoventriculoplasty was applied. The aortic valve was replaced with a 21 mm St. Jude Medical mechanical prosthesis. The left ventricular outflow tract was adequately enlarged, and postoperative course was uneventful.     

Subvalvar aortic stenosis: timing of operation

Subvalvar aortic stenosis can be associated with progressive left ventricular outflow tract obstruction, aortic insufficiency, and infective endocarditis. We reviewed the records of 36 surgical patients who underwent 39 operations for subaortic stenosis. Seventeen patients had associated congenital cardiac anomalies. One perioperative death occurred in a patient with tetralogy of Fallot. The mean preoperative left ventricular outflow tract systolic pressure gradient was 64 +/- 5 mm Hg (+/- standard error of the mean) and decreased to 9 +/- 2 mm Hg postoperatively (p less than 0.001). Reliable preoperative and postoperative information regarding aortic valve function was available for 27 patients. Aortic insufficiency was found in 17 (63%) of those patients preoperatively. Postoperatively, insufficiency increased in 3 patients and decreased in 4; none of these changes was major. Severity of preoperative aortic insufficiency increased significantly with age (p less than 0.05), but did not correlate with left ventricular outflow tract gradient. The information from this study and previous studies suggests that resection of subaortic stenosis is safe and effective, and operation at the time of diagnosis, regardless of left ventricular outflow tract gradient or symptomatic status, is a reasonable therapeutic alternative.     

The results of operation in patients with hypertrophic cardiomyopathy and pulmonary hypertension

The clinical course and hemodynamic results in patients undergoing operation for obstructive hypertrophic cardiomyopathy with preoperative pulmonary arterial hypertension were unknown. The hypothesis tested in this retrospective study was that operative relief of left ventricular outflow tract obstruction resulted in a substantial reduction in pulmonary artery pressures and mitral regurgitation without necessitating mitral valve replacement. Patients were included if their preoperative pulmonary systolic pressure was greater than 35 mm Hg and if they were without concomitant cardiac disease, with the exception of mitral regurgitation. Since 1962, 49 patients who fit our criteria underwent left ventricular myotomy and myectomy with 98% follow-up. Mean follow-up was 7.9 +/- 0.7 (mean +/- standard error of the mean) years with a range of 0.8 to 18.4 years. Early hospital mortality rate was 12% (n = 6); two deaths from low cardiac output and four from arrhythmia. There were 43 (88%) hospital survivors and 18 late deaths. Actuarial survival rate after operation was 87% +/- 5% (n = 31) at 5 years and 55% +/- 8% (n = 9) at 10 years. Thirty-nine of 43 survivors (91%) returned 9 +/- 1 months postoperatively for follow-up evaluation including cardiac catheterization. The majority (83%) were in New York Heart Association functional class I or II postoperatively. Cardiac catheterizations indicated a fall in pulmonary arterial systolic pressure from 62 +/- 3 (range = 36 to 105) to 38 +/- 2 (range = 21 to 65) mm Hg (p = 0.0001) with no difference in right atrial pressure or cardiac output. Pulmonary arterial wedge mean pressure decreased from 24 +/- 1 to 16 +/- 5 mm Hg (p = 0.0002) and preoperative mitral regurgitation improved or was abolished in 85% of patients studied (n = 13). Rest and maximal provocable left ventricular outflow tract gradients decreased from 81 +/- 7 and 103 +/- 5 to 14 +/- 3 and 45 +/- 8 mm Hg, respectively (p = 0.0001). Comparison of the above-mentioned patients, operated on since 1982, with a preoperatively matched group who underwent mitral valve replacement in the same interval showed no statistically significant difference in mortality, morbidity, hemodynamic outcome, or functional outcome with a mean follow-up of 2 years. We conclude that a consistent, significant reduction (mean = 40%) in preoperative pulmonary arterial systolic pressure, clinical symptoms, and mitral regurgitation occurs with relief of outflow tract obstruction by left ventricular myotomy and myectomy and that pulmonary hypertension and mitral regurgitation are not indications for mitral valve replacement in these patients.     

The outcome of surgical treatment of hypertrophic obstructive cardiomyopathy. Experience over 15 years

From 1972 through 1987, 115 patients between the ages of 1 and 83 years (mean, 44.5 years) underwent operation for hypertrophic obstructive cardiomyopathy. Methods of relief of left ventricular outflow obstruction were septal myectomy/myotomy (n = 109), mitral valve replacement (n = 4), and myectomy/myotomy plus mitral valve replacement (n = 2); concomitant procedures included coronary artery bypass (n = 19) and aortic valve replacement (n = 9). Systolic gradient (peak-to-peak) from the left ventricle to the aorta decreased from 70 +/- 38 mm Hg (mean +/- standard deviation) to 9 +/- 11 mm Hg. There were six hospital deaths, for an overall operative risk of 5.2%; one death occurred among 83 patients less than age 65 years (operative risk, 1.2%), and five deaths occurred in 32 older patients (operative risk, 15.6%; p = 0.008 for difference between age groups). Four (22.2%) of 18 patients with a residual gradient greater than 15 mm Hg died, compared with two (2.1%) of 97 patients with a lower gradient (p = 0.003). Follow-up ranged from 0.5 to 16 years (mean, 5.1 years), and 5-year actuarial survival rate, including hospital deaths, was 84% +/- 4%. The 5-year survival rate was decreased in patients who had operative procedures other than myectomy/myotomy (69% versus 91%, p less than 0.005) and in patients aged 65 years or older (54% versus 93%, p less than 0.005). No correlation was found between preoperative symptoms, functional class, left ventricle-aorta pressure gradient, or mitral valve insufficiency and operative or late mortality. Preoperative symptoms were relieved in 57 (76%) of 75 patients with dyspnea, 49 (83%) of 59 patients with angina, and 22 (96%) of 23 patients with syncope. This experience confirms the effectiveness of operation for relief of symptoms in patients with the obstructive form of hypertrophic cardiomyopathy. The current operative mortality rate is low, especially in patients less than 65 years of age (1.2%). Our experience suggests that incomplete relief of left ventricular outflow obstruction may increase the risk of early postoperative death.     

Clinical experience with the use of a valve-bearing conduit to construct a second left ventricular outflow tract in cases of unresectable intra-ventricular obstruction.

Two patients, ages 7 and 17, with unresectable obstructions within the left ventricular cavity, have been managed by interposing a conduit bearing a porcine aortic valve between the apex of the left ventricle and the infra-renal abdominal aorta. The younger child had idiopathic hypertrophic subaortic stenosis (IHSS) recognized in infancy. At the age of three, a right ventricular myomectomy and a trans-aortic left ventricular myotomy were performed. Symptoms were progressive with congestive failure, diaphoresis, syncope , and angina pectoris. Following construction of a second left ventricular outflow tract with relief of intraventricular obstruction, the patient has become asymptomatic. The second patient has fibrous tunnel obstruction of the left ventricular outflow tracting providing a 100 mm Hg gradient. Fibrous tissue was resected in part through the transaortic route, and a second outflow tract was constructed. A postoperative cardiac catheterization revealed an obliteration of the previous intraventricular gradients and an equal distribution of left ventricular output through the two available outflow tracts. She remains asymptomatic.     

The late prognosis after localized resection for fixed (discrete and tunnel) left ventricular outflow tract obstruction

We studied the follow-up status of 56 patients after operation for fixed left ventricular outflow tract obstruction (LVOTO), 42 with discrete LVOTO consisting of an obstructing membranous ring in the left ventricular outflow tract (LVOT) and 14 with tunnel (diffuse) LVOTO. Forty-one of the 56 patients were available for long-term follow-up. Patients with discrete LVOTO fared better than patients with tunnel LVOTO postoperatively in their functional class status (discrete: 21 in Class I, five in Class II; tunnel: one in Class I, four in Class II; p less than 0.05), their LVOT peak systolic gradients (discrete: 22 +/- 4 mm Hg; tunnel: 98 +/- 23 mm Hg; p less than 0.02), their actuarially determined survival probabilities (discrete: 82% +/- 9% at 20 years; tunnel: 40% +/- 19% at 20 years; p less than 0.1), and their survival probabilities without an adverse event, i.e., (1) death, (2) reoperation, (3) residual gradient greater than 50 mm Hg, (4) significant aortic regurgitation, (5) bacterial endocarditis, or (6) complete heart block (discrete: 43% +/- 9% at 4 years, 36% +/- 9% at 10 years, and 15% +/- 9% at 20 years; tunnel: 0% at 4 years; p less than 0.02). Thus most patients who undergo operation for fixed LVOTO will survive late postoperatively; resection of the membrane is adequate for relief of LVOTO and for relief of symptoms in most patients with discrete LVOTO; the majority of patients with tunnel LVOTO who undergo only local resection will have an unsatisfactory operative result; most patients with discrete as well as tunnel LVOTO surviving operation will have clinically significant adverse events early or late postoperatively. This last observation dictates continuing long-term follow-up evaluations of patients operated upon for fixed LVOTO.     

Reoperation for persistent outflow obstruction in hypertrophic cardiomyopathy

This study compares results of a second left ventricular myotomy and myectomy (M + M) with those of mitral valve replacement (MVR) as reoperative procedures for persistent left ventricular outflow obstruction after M + M in hypertrophic cardiomyopathy. Comparison of the second M + M group (n = 12) with the MVR group (n = 11) disclosed significant difference (p less than 0.05) in mean age at the initial operation (29 +/- 11 years versus 40 +/- 8 years), interval between operations (46 +/- 57 months versus 18 +/- 13 months), and age at reoperation (33 +/- 10 years versus 42 +/- 8 years); and insignificant differences in mean preoperative functional class, cardiac index, left ventricular outflow gradients at rest or with provocation, and hospital mortality at reoperation (2/12 versus 1/11). At 6 months after reoperation, comparison of results of a second M + M with MVR showed that mean functional class, cardiac index, and left ventricular outflow gradient at rest were similarly improved, but the outflow gradient with provocation was significantly higher in the second M + M group (57 +/- 44 mm Hg versus 14 +/- 9 mm Hg, p less than 0.05). Total follow-up was 108 patient-years (100% complete) with an average of 5.9 years per patient in the second M + M group and 3.4 years per patient in the MVR group. Actuarial survival, including hospital mortality, at 3 and 5 years was 83% and 76%, respectively, after the second M + M, which was similar to 92% and 77% after MVR.(ABSTRACT TRUNCATED AT 250 WORDS)     

Discrete subaortic stenosis: assessing adequacy of myectomy by transesophageal echocardiography

BACKGROUND: Membranectomy and myectomy are standard therapy for discrete subaortic stenosis (DS) and are associated with low rates of endocarditis, recurrence, and aortic insufficiency. Extensive myectomy increases risk of complications such as conduction tissue damage and iatrogenic ventricular septal defect (VSD). MATERIALS AND METHODS: Forty-five adult patients with DS underwent operations in Gulhane Military Medical Academy. Exertional dyspnea was the principal symptom in 29 (64.4%) patients. Transesophageal echocardiography (TEE) was performed routinely in all patients to assess the length and depth of needed myectomy during the perioperative period. Aortic insufficiency (AI) was also noted preoperatively in 31 (68.9%) and a history of aortic valve endocarditis was present in 4 (8.9%) patients. RESULTS: Myectomy was performed according to TEE measurements. An average of 10 mm in width, 10 mm in depth, and 2.3 mm in length of septal tissue was resected. The mean left ventricle-aorta peak systolic gradient decreased from 70.2+/-9.7 to 17.2+/-2.7 mmHg (p < 0.001). Aortic valve repair was performed in 8 (7.8%) patients and aortic valve replacement in 11 (24.4%) patients at the initial operation. Iatrogenic VSD did not occur in any of the patients. Average postoperative left ventricular outflow tract diameter was 21+/-1.5 mm. Temporary complete heart block occurred in three patients. There was an early residual gradient (36+/-8 mmHg) resulting from temporary hypercontraction that decreased (18+/-5 mmHg) in the first postoperative day. CONCLUSIONS: Myectomy under perioperative TEE measurement is safe and effective in the treatment of DS. TEE-guided myectomy reduces complications such as complete heart block and iatrogenic VSD.     

70例主动脉瓣下狭窄的外科治疗

目的：总结70例主动脉瓣下狭窄的手术治疗经验。方法：全组70例中男46例，女24例；年龄3～46岁。平均11．8岁。均经超声心动图、左心导管和造影检查及术中证实为主动脉瓣下狭窄，局限型64例(纤维隔膜型42例、纤维肌隔型22例)，隧道型6例。局限型行狭窄隔膜切除术58例，加左室肌肉切除术6例；隧道型行左室流出道疏通术6例。合并畸形59例，同期行矫正手术。结果：手术死亡2例。仅l例发生二尖瓣损伤。术后38例左室主动脉收缩压力差0～30mmHg(1mmHg=0．133kPa)，平均7．5mmHg。术后经1、3、5、10、20年各随访58、54、48、32、6例，随访率分别为83％、77％、68％、45％、9％。症状均消失。无再狭窄需手术者。结论：本病一旦确诊，应尽快手术；术前超声心动图检查及术中常规主动脉根部探查，对防止有合并畸形时本病的漏诊尤为重要；手术关键是彻底疏通左室流出道，术中防止二尖瓣、主动脉瓣及传导束损伤。