Minimally invasive mitral valve repair using transthoracic aortic occlusion

This report describes a minimally invasive mitral valve repair done through a limited (6-cm) thoracic incision. The patient was supported by peripheral extracorporeal perfusion with cardiac arrest established using a new transthoracic aortic cross-clamp and antegrade blood cardioplegia. The patient was discharged on postoperative day 3 with minimal pain. This less invasive approach to mitral valve surgery may offer combined advantages to patients by increasing comfort, expediting recovery, and decreasing surgical costs by using modified traditional methods compared with specialized intraaortic occlusive balloons.     

Operative results after the Cox/maze procedure combined with a mitral valve operation

BACKGROUND: There have been few reports on postoperative morbidity and mortality analyses after concomitant mitral valve operation and the Cox/maze procedure. METHODS: Between April 1993 and August 1995, 87 consecutive patients with chronic atrial fibrillation underwent a mitral valve operation and concomitant Cox/maze procedure at Iwate Medical University. The patients were divided into the replacement group (n = 31) and repair group (n = 56) according to the method of mitral valve replacement. Our initial experience with the combined operative procedures is presented along with the operative mortality and morbidity rates. Univariate analysis on preoperative and intraoperative variables affecting early mortality and morbidity is carried out retrospectively. RESULTS: Total cardiopulmonary bypass time in all patients was 177.2 +/- 70.1 minutes. Total aortic cross-clamp time was 121.7 +/- 30.8 minutes. Total intensive care unit stay was 5.3 +/- 7.9 days. The average intubation period was 55.5 +/- 187.6 hours. The intensive care unit stay and the intubation period of the replacement group were longer than those of the repair group. There were four operative deaths among the 87 patients (4.6%). All repair group patients survived operation, whereas 4 replacement group patients died after operation. In all patients, the New York Heart Association functional class was higher (p = 0.028) in those who died than in those who survived. The overall restoration rate from atrial fibrillation was 79.5% (66 of 83 survivors). Seventeen patients (20.5%) had persistent atrial fibrillation postoperatively. Sick sinus syndrome occurred in 7 patients (8.4%). In the repair group, the restoration rate was 76.8%, whereas in the replacement group it was 85.2% for the survivors. CONCLUSIONS: The Cox/maze procedure can be combined with a mitral valve operation with acceptably low operative risk. Analysis of risk factors of early mortality revealed that the type of mitral valve operation (replacement versus repair) and higher preoperative New York Heart Association functional class were associated with mortality. Long-term results from this combined procedure should be clearly demonstrated before its universal acceptance.     

Video-assisted minimally invasive mitral valve surgery

OBJECTIVE: This study was done to determine the potential benefits of minimally invasive mitral surgery performed with intraoperative video assistance. METHODS: From May 1996 until March 1997, a minithoracotomy and video assistance were used in 31 consecutive patients undergoing mitral repair (n = 20) and replacement (n = 11). Their ages ranged from 18 to 77 years (59 +/- 2.6 years; mean +/- standard error of the mean). Ejection fractions were 35% to 62% (55% +/- 1.5%). Operations were done with either antegrade/retrograde (n = 10) or antegrade (n = 19) cold blood cardioplegia and a new transthoracic crossclamp or with ventricular fibrillation (n = 2). Peripheral arterial cannulation (n = 28) and pump-assisted right atrial drainage (n = 26) were used most often. RESULTS: No hospital deaths occurred, but the 30-day mortality was 3.2%. Complications included deep venous thrombosis and a phrenic nerve palsy in one patient each. No patient had a stroke or required reoperation for bleeding. Postoperative echocardiography showed excellent valve function in all but one patient. Cardiopulmonary bypass and arrest times averaged 183 +/- 7.2 and 136 +/- 5.5 minutes, respectively. Compared with 100 patients having conventional mitral valve operations, these patients had significantly shorter hospitalization times (8.6 +/- 0.5 vs 5.1 +/- 0.9 days, p = 0.05). Moreover, 81% of the later cohort were discharged between day 3 and 5 (3.6 +/- 0.2 days). Hospital charges (decreases 27%, p = 0.05) and costs (decreases 34%, p < 0.05) were less than in conventional operations. Patient follow-up suggested minimal perioperative pain and rapid recovery. CONCLUSIONS: Early results suggest that video-assisted minimally invasive mitral operations can be done safely. These methods may benefit patients through less morbidity, earlier discharge, and lower cost.     

Upper T mini-sternotomy for aortic valve operations

OBJECTIVES: New minimally invasive approaches for cardiac surgical procedures are constantly being developed in the hope of decreasing patient morbidity and enhancing the postoperative recovery. This report reviews the use of an upper T mini-sternotomy approach to aortic valve surgery. PATIENTS: Nine consecutive nonselected patients (5 men, 4 women, mean age, 66 years) underwent isolated aortic valve replacement with the use of this approach. Two patients had isolated aortic valve stenosis, three had isolated aortic valve incompetence, and four patients had mixed aortic valve disease. RESULTS: In all cases, an excellent view of the aortic valve was obtained, aortic valve replacement with a bileaflet mechanical prostheses was performed, and no intraoperative difficulties were encountered. Mean aortic cross-clamp time was 83 min and mean cardiopulmonary bypass perfusion time was 97 min. All patients were extubated in the operating room at the end of the surgical procedure, and there were no postoperative complications. All patients were discharged home on postoperative day 3, and there were no late complications. CONCLUSION: Through an upper T mini-sternotomy, aortic valve surgery can be performed in the conventional manner using standard surgical instruments with no alteration in cardiopulmonary bypass and myocardial protection routines. With this method, postoperative pain is reduced and patient recovery is expeditious.     

Minimally invasive valve operations

BACKGROUND: To reduce the morbidity from valvular heart operations, a right parasternal approach was introduced. We report our initial experience with the procedure. METHODS: From January 1996 through July 1996, 115 patients underwent primary isolated valve procedures. One hundred (85%) patients underwent the operation through a right parasternal incision. RESULTS: There was one hospital death secondary to a stroke on the fifth postoperative day. Three patients (two with aortic valve operations and one having a mitral valve procedure) required conversion to sternotomy. Mean aortic occlusion time was 71 minutes; mean cardiopulmonary bypass time was 93 minutes. Mean stay in the intensive care unit was 27 hours and mean hospital postoperative stay was 5.7 days. Seventy-seven percent of the patients did not receive blood transfusions. Comparison with median sternotomy demonstrated a reduction in both postoperative length of stay and direct hospital costs. CONCLUSIONS: We conclude that this minimally invasive approach is safe for a variety of valve procedures and is effective in reducing surgical trauma and cost.     

Facile minimally invasive cardiac surgery via ministernotomy

BACKGROUND: The public's and surgeons' perception of minimally invasive operations are frequently at odds. Nevertheless, real or perceived benefits may result from limiting skin and skeletal trauma. METHODS: Beginning in January 1996, we began approaching most infant and pediatric open heart procedures through an upper sternal split incision using a 1- to 3-inch skin opening and then extended this technique using a 2.5- to 3.5-inch incision for adult aortic and mitral valve replacement. RESULTS: A total of 82 patients, 57 infants and children and 25 adults, have been operated on using this approach (age range, newborn to 81 years). Operations accomplished through ministernotomy have included aortic valvotomy, arterial switch, tetralogy of Fallot, atrial or ventricular septal defect closure, aortic valve replacement, mitral valve replacement and repair, redo aortic or mitral valve replacement, double valve replacement, aortic root replacement, and complex arch reconstruction. In adults, the sternum was divided and then a T incision was made at the second, third, or fourth intercostal space. The mitral valve was reached through the roof of the left atrium. In children, a lower sternal split was used for atrial septal defect repairs. All cannulas were introduced through the ministernotomy incision, eliminating femoral cannulation. No new instruments, retractors, or ports were used. Mediastinal drainage was accomplished through a Blake drain connected to Heimlich-valved grenade suction. All but 2 patients were extubated immediately. Hospital stay was from 1 to 20 days (median 2 days). Patient and family acceptance is very high. CONCLUSIONS: On the basis of this initial experience, we attempt all congenital cardiac and isolated adult valve operations through ministernotomy.     

Mini-sternotomy for aortic valve surgery

In the recent years more and more efforts have been made widely to introduce new techniques in the minimally invasive cardiac surgery. At our Department and the Link?ping University Hospital, Cardiothoracic Surgery Department, from August 1996 to January 1997, aortic valve surgery was performed in 23 adult patients (9 female, 14 male), age 28-86 years (mean age 62.5 years). Twenty-two patients had aortic valve replacement, among these, in 3 cases concomitant aortic annulus dilatation was made and in one case reduction-plasty of the dilated ascending aorta. In another one case resection of a sub-aortic membrane was performed. The operations and postoperative period were free of complications in all patients. Following an average 36 hours intensive care all patients were discharged after an average of 11.2 day hospital stay. The authors introduce the new surgical technique and present its advantages and disadvantages. Mini-sternotomy has less detrimental structural and functional effects on the thorax. Moreover, due to its minimal surgical trauma, this less invasive technique reduces patient morbidity, hospital stay and cost of care. Since mini-sternotomy is a safe and advantageous technique, the authors recommend applying this new technique in most of aortic valve operations.     

Minimally invasive valve surgery versus the conventional approach

As a result of reports touting the effectiveness of minimally invasive valve operations, many cardiovascular surgeons and their patients are beginning to believe that smaller incisions are always better. According to its proponents, the minimally invasive approach results in less pain, a faster recovery, and a more satisfactory cosmetic result. Proponents also believe that the operation can be done safely and effectively at a lower cost than traditional surgical approaches. This may not be the case, however, and additional prospective studies must be done before firm conclusions can be drawn. For example, cardiopulmonary bypass, myocardial ischemia, and overall operative times are significantly longer (40% or more) for minimally invasive surgical procedures. Morbidity and mortality rates do not appear to be decreased, the length of hospital stay varies by only 1 or 2 days, and patients do not necessarily report less postoperative pain. When the conventional technique is used, the operation can be performed precisely and expeditiously. Should complications occur, the surgeon will have direct access to the heart. The cost of a conventional procedure should not be much more than that of a minimally invasive procedure, and in some instances it may even be less-particularly when the less invasive procedure significantly extends the operating room time or requires additional monitors or costly disposables.     

Clinical study on re-surgery of the combined valvular disease: simultaneous double valve replacement]

Between June, 1984 and December, 1993, 36 patients who underwent simultaneous double valve replacement for re-surgery of combined valvular disease were analyzed in this study. The indications for re-surgery were malfunction of mechanical valve in the aortic position, primary tissue failure of biological valve in the mitral position, deterioration of valvular disease and prosthetic valve endocarditis. Re-surgery was performed ranging from 4 to 15 years, with a mean period of 9.5 years, following initial operation. Early operative mortality was 5.5% (2 cases) and late mortality 8.3% (3 cases). There were no cardiac deaths during the late postoperative period. Despite of technical difficulty due to dissection of the adhesion around the heart and re-replacement of prosthetic valve, the operative mortality and morbidity were relatively low because of the improved operative technique and myocardial protection.     

Valve repair in infective endocarditis

From 1985 to 1995, 12 patients with native valve endocarditis underwent valve repair instead of replacement. Mean age was 41.9 years (range from 5 to 79 years). Eight patients had active and 4 patients inactive infection. The mitral valve was involved in 6 patients, the aortic valve in 1, both valves in 2, the tricuspid valve in 2, and the mitral and pulmonary valves in 1. The pathological findings were as follows: leaflet perforation in 2 patients, chordal rupture in 3, and vegetations in 10. Valve sparing procedures were carried out on the mitral valve in 8 patients, on the aortic valve in 1, on the tricuspid valve in 2, and on the pulmonary valve in 1. The following repair techniques were used: vegetectomy in 10 patients, leaflet patching in 2, posterior mitral leaflet resection in 3, mitral annuloplasty in 4, and pulmonary valve repair in 1. Uncontrolled sepsis, progressive heart failure, peripheral embolism, and echocardiographically demonstrated vegetations were the indications for surgery. There was no operative or late mortality and all infections were cured with no recurrences. One patient required valve replacement following aortic valve repair because of progressive aortic regurgitation. Postoperative Doppler echocardiography showed trivial to no regurgitation in 11 patients after valve repair. The overall outcome was favorable during the mean follow-up period of 39.3 months (range from 1 to 120 months). Reparative or reconstructive approaches for native valve endocarditis should be considered and can be successfully performed. Their advantages include (1) improved hemodynamics, (2) no recurrence, (3) no mortality, and (4) favorable long-term results.     

Risk of reoperative valve replacement for failed mitral and aortic bioprostheses

BACKGROUND: One factor influencing the choice of mechanical versus bioprosthetic valves is reoperation for bioprosthetic valve failure. To define its operative risk, we reviewed our results with valve reoperation for bioprosthetic valve failure. METHODS: Records of 400 consecutive patients having reoperative mitral, aortic, or mitral and aortic bioprosthetic valve replacement from January 1985 to March 1997 were reviewed. RESULTS: Reoperations were for failed bioprosthetic mitral valves in 219 patients, failed aortic valves in 153 patients, and failed aortic and mitral valves in 28 patients. Including 26 operations (6%) for acute endocarditis, 153 operations (38%) were nonelective. One hundred nine patients (27%) had other valves repaired or replaced, and 72 (18%) had coronary bypass grafting. The incidence of death in the mitral, aortic, and double-valve groups was respectively, 15 (6.8%), 12 (7.8%), and 4 (14.3%); and the incidence of prolonged postoperative hospital stay (>14 days) was, respectively, 57 (26.0%), 41 (26.8%), and 8 (28.6%). Only 7 of 147 patients (4.8%) having elective, isolated, first-time valve reoperation died. Multivariable predictors (p < 0.05) of hospital death were age greater than 65 years, male sex, renal insufficiency, and nonelective operation; and predictors of prolonged stay were acute endocarditis, renal insufficiency, any concurrent cardiac operation, and elevated pulmonary artery systolic pressure. CONCLUSIONS: Reoperative bioprosthetic valve replacement can be performed with acceptable mortality and hospital stay. The best results are achieved with elective valve replacement, without concurrent cardiac procedures.     

Mortality and morbidity among patients who undergo combined valve and coronary artery bypass surgery: early and late results

AIM: To describe mortality and morbidity early and late after combined valve surgery and coronary artery bypass grafting (CABG) as compared with CABG alone. PATIENTS and METHODS: All patients from western Sweden in whom CABG in combination with valve surgery or CABG alone was carried out in 1988-1991. RESULTS: Among 2116 patients who underwent CABG, 35 (2%) had this combined with mitral valve surgery and 134 (6%) had this combined with aortic valve surgery, whereas the remaining 92% underwent CABG alone. Patients who underwent combined valve surgery and CABG were older, included more women and had a higher prevalence of previous congestive heart failure and renal dysfunction but on the other hand a less severe coronary artery disease. Among patients who underwent mitral valve surgery in combination with CABG the mortality over the subsequent 5 years was 45%). The corresponding figure for patients who underwent aortic valve surgery in combination with CABG was 24%. Both were higher than for CABG alone (14%; P < 0.0001 and P = 0.003, respectively). In a stepwise multiple regression model mitral valve surgery in combination with CABG was found to be an independent significant predictor for death but aortic valve surgery in combination with CABG was not. Among patients who underwent mitral valve surgery in combination with CABG and were discharged alive from hospital 77% were rehospitalized during the 2 years following the operation as compared with 48% among patients who underwent aortic valve surgery in combination with CABG and 43% among patients with CABG alone. Multiple regression identified mitral valve surgery in combination with CABG as a significant independent predictor for rehospitalization but not aortic valve plus CABG. CONCLUSION: Among patients who either underwent CABG in combination with mitral valve surgery or aortic valve surgery or CABG alone, mitral valve surgery in combination with CABG was independently associated with death and rehospitalization, but the combination of aortic valve surgery and CABG was not.     

Congenital malformations of the mitral valve in children. Pathology and surgical treatment

A systematic study of congenital mitral valve malformations was undertaken on a surgical basis in an attempt to develop techniques of valvular reconstruction adapted to the various lesions. Forty-seven children between the ages of 4 months and 12 years (average 6 years, 4 months) have been operated upon between January, 1970, and March, 1976. Valvular lesions were classified into four group: Group I, mitral insufficiency owing to valvular lesions: Group II mitral insufficiency with subvalvular lesions; Group III, mitral insufficiency and stenosis; Group IV, stenosis. Associated lesions (ventricular or atrial septal defects, coarctation, or aortic valve stenosis) were present in 31 patients (65 per cent) and were corrected during the same operation. Valve reconsruction was possible in 38 patients whereas valve replacement was necessary in 9 patients. In the valve repair group there were three operative deaths (8 per cent), no late deaths, one reoperation for residual ventricular septal defect, and one myocardial infarction. In the valve replacement group of 9 patients, there were three operative deaths, three late deaths, and one case of repeated embolization. Thirty-one of 38 patients in the valve repair group were classified into Functional Class I after the operation (86 per cent), 2 were in Class II, and one in Class III. Minimal or moderate regurgitation and cardiomegaly persisted in the majority of the patients. Pulmonary artery pressure significantly decreased, however, as demonstrated by postoperative catheterization in 17 patients.     

Assessment of oxidative stress in a pancreatic warm ischemia-reperfusion model

A simple technique for minimally invasive valve operations is described. With a 10-cm midline skin incision, excellent exposure of both the mitral and aortic valves is achieved through a right-sided partial sternotomy, which enables us to perform easy repair or replacement of these valves.     

Aortic valve replacement with cryopreserved aortic allograft: ten-year experience

OBJECTIVE: Cryopreserved aortic allograft can be used for aortic valve replacement in congenital, rheumatic, degenerative, and infected native valve conditions, as well as failed prosthetic valves. This study was conducted to determine the long-term results of aortic valve replacement with cryopreserved aortic allografts. METHODS: Aortic valve replacement with cryopreserved aortic allografts was performed in 117 patients from July 1985 until August 1996. All patients requiring aortic valve replacement regardless of valve disease were considered for allograft replacement; the valve was preferentially used in patients under age 55 years and in the setting of bacterial endocarditis. Four operative techniques involving cryopreserved aortic allografts were used: freehand aortic valve replacement with 120-degree rotation, freehand aortic valve replacement with intact noncoronary sinus, aortic root enlargement with intact noncoronary sinus, and total aortic root replacement. Valve function was assessed by echocardiography during the operation in 78 patients (66%) and after the operation in 77 patients (65%). RESULTS: One-hundred eighteen aortic valve replacements with cryopreserved aortic allografts were performed on 117 patients; mean age was 45.6 years (range 15 to 83 years) and mean follow-up was 4.6 years (range up to 11 years). Intraoperative echocardiography disclosed no significant aortic valve incompetence. There were four operative deaths (3%) and seven late deaths; freedom from valve-related mortality at 10 years was 9:3% +/- 4.55%. New York Heart Association functional status at latest follow-up was normal in 98 (94%) patients. On postoperative echocardiography, 90% had no or trivial aortic valve incompetence. Freedom from thromboembolism at 10 years was 100% and from endocarditis, 98% +/- 2.47%. Seven (6%) patients required valve explantation, four for structural deterioration. At 10 years, freedom from reoperation for allograft-related causes was 92% +/- 3.47%. CONCLUSIONS: Aortic valve replacement with cryopreserved aortic allografts can be performed with low perioperative and long-term mortality. Most patients have excellent functional status, and reoperation for valve-related causes is unusual. Aortic valve replacement with cryopreserved aortic allografts demonstrates excellent freedom from thromboembolism, endocarditis, and progressive valve incompetence.     

Relationship between hamstring strains and leg muscle strength. A follow-up study of collegiate track and field athletes

Between August 1988 and October 1992, 1,052 patients underwent 1,522 valve procedures in our institution. Their mean age was 32.69 years (range 1-90). The etiology was rheumatic in 724 (68.8%), congenital in 120 (11.4%), degenerative in 99 (9.4%), infective in 58 (5.5%) and ischemic in 17 (1.6%). The mean preoperative functional class (NYHA) was 2.95 and 780 (74.1%) were in sinus rhythm. Repair was possible in 885 (58.1%) valves. The rate of repair versus replacement was 94.5% for the tricuspid, 56.2% for the mitral and 43.6% for the aortic valve. The total hospital mortality was 4.18%. For isolated mitral surgery it was 2.94%, for isolated aortic 4.12% and for isolated tricuspid 15%. Double valve surgery carried a mortality of 3% and triple valve surgery 13%. Hospital mortality for isolated mitral and isolated aortic surgery was lower for repair than for replacement (1.5% vs. 5% and 0 vs. 6.8%). The follow-up was 94.65% complete. The total incidence of embolic events was 2.93% with an actuarial freedom at 48 months of 92.71 +/- 5.35% for repair, 88.22 +/- 6.26% for replacement and 90.31 +/- 5.65% for patients with repair and replacement. Late mortality was 4.5%. The actuarial survival excluding hospital deaths was 94.89 +/- 2.10% for repair, 86.84 +/- 2.84% for replacement and 91.33 +/- 2.73% for the mixed group. The reoperation rate was higher for repair (13%) than for replacement (0.1%). This rate was highest for the rheumatic mitral patients with an age below 20 years (25.2%).(ABSTRACT TRUNCATED AT 250 WORDS)     

Valve operations through a minimally invasive approach

BACKGROUND: We analyzed in-hospital results of 87 patients undergoing minimally invasive valvular operations (right parasternal incision through third and fourth cartilages). METHODS: Age was 21 to 84 years (mean, 56.2 +/- 16); 45 patients (51.7%) were female. Five (5.7%) had a previous valvular operation and 8 (9.2%) had severe left ventricular dysfunction. Valve diseases were as follows: aortic in 35 patients (40.2%), mitral in 44 (50.5%), double in 5 (5.7%), tricuspid regurgitation in 2 (2.2%), and mitral periprosthetic leak in 1 (1.1%). RESULTS: Nineteen mitral repairs (21.9%), 22 replacements (25.3%), 1 leak closure (1.1%), 1 tricuspid repair (1.1%), and 1 replacement (1.1%) were performed. Thirty-one patients (35.7%) underwent aortic replacement, 2 (2.3%) aortic decalcification, 1 (1.1%) subaortic membrane resection, 4 (4.6%) a double-valve procedure, and 5 (5.7%) a single-valve operation combined with myocardial revascularization. In-hospital mortality was 5.7% (5 patients). Univariate analysis was significant for previous operation, New York Heart Association class IV and severe ventricular dysfunction. Multivariate analysis was significant for previous operation and severe ventricular dysfunction. Atrial fibrillation (12.6%) was the most frequent complication. Postoperative stay was 6.5 +/- 6 days. CONCLUSIONS: The minimally invasive approach is a useful technique in valvular surgery. Patients with a previous valvular operation, severe ventricular dysfunction, and New York Heart Association class IV dyspnea have higher in-hospital mortality.     

Minimally invasive heart surgery--a fad or a clinically recognized therapy method?

Within the last 5 years new less invasive surgical techniques have been developed in the field of cardiac surgery. This new field named "minimally invasive cardiac surgery" can be subdivided into techniques which do not require cardiopulmonary bypass and are used mainly for coronary artery surgery (called minimally invasive direct coronary artery surgery, MIDCAB technique). This MIDCAB procedure can be done through a small left anterior thoracotomy or a sternotomy. In addition there are other methods which allow the performance of complex cardiac surgery through small accesses in combination with the use of an endovascular CPB system and internal aortic clamping to achieve cardioplegic arrest (so-called Port-Access method). Also for valvular surgery, new surgical techniques were developed allowing access to mitral and aortic valves through limited incisions. In addition, new less invasive techniques were developed for congenital heart surgery. This article will describe the various surgical techniques and define the indications for minimally invasive cardiac surgery.     

Mitral valve repair for patients with pure mitral insufficiency. 1- to 15-year follow-up

Mitral valve repair rather than replacement was performed in 133 of 183 patients (73%) with considerable mitral valve insufficiency requiring surgery. There were seven operative deaths (50%) and 16 late deaths in the 133 patients followed up from 1 to 15 years. Only four of the late deaths were possibly related to the underlying valvular heart disease. Repair is preferable to replacement with present-day mitral valve prostheses.     

Four years' experience of valve replacement with the Bj?rk-Shiley tilting-disc prosthesis

105 valve replacements with the Bj?rk-Shiley tilting-disc prosthesis have been performed in 99 patients with an overall mortality of 12%. The hospital mortality for 73 single aortic valve replacements was 10%, for 24 single mitral valve replacements 13%, and for 5 double valve operations 20%. One late death (1%) occurred in a case with single aortic valve replacement. The follow-up period of the first patients with aortic valve replacement is 4 1/2 years, and that of those with mitral valve replacement over 2 1/2 years. The most common late complication in patients with mitral valve replacement was a paravalvular leak (19%), whereas in patients with aortic valve replacement slight haemolytic anaemia (4%) and late thromboembolism (3%) occurred most frequently. 84 of the 87 survivors showed manifest clinical improvement in their preoperative status and increased exercise tolerance.