Search

Neste trabalho, pretende-se abordar a defesa da utilidade do conhecimento em Descartes, considerando aquilo que o fi lósofo entende como ‘conhecimentos que sejam úteis à vida’, porém não a partir de um enfoque moral, mas com ênfase no planejamento de construção de máquinas e artefatos que, além de auxiliarem a ciência, facilitem o trabalho dos homens. Tal propósito pode ser encontrado em alguns textos do fi lósofo, dos quais se destaca o pequeno tratado sobre as mecânicas que compõem a carta a Huygens de 5 de outubro de 1637, as duas partes fi nais do Discurso do Método e o discurso X da Dióptrica. Com base em textos selecionados, e sem perder o caráter unificador da proposta cartesiana, enfatizar-se-á, tomando de empréstimo uma expressão de Nicolas Grimaldi, a “obsessão tecnológica” presente na obra do filósofo.

Surgical repair of anterior leaflet prolapse has evolved and widely expanded over the past decade. A number of surgical techniques have been developed. In this study a review of all reparative techniques has been provided. A classification has been proposed according to the involvement of valve components and, eventually, to graft employment. For each technique the following points have been detailed: a) advantages and drawbacks; b) likelihood of effective valve repair based on morpho-pathologic variability of degenerative mitral disease; c) long-term outcome as freedom from reoperation. The authors provide indications for early surgical anterior leaflet prolapse repair and recommend that surgeons should be familiar with many reparative procedures to select the right option and improve their operative results.

Severe ventricular dysfunction and concomitant infection are considered absolute contraindications for major thoracic operations and immunosuppressive therapy, respectively. However, cardiac transplantation represents the first-choice treatment in advanced heart failure. We report the case of a patient with dilated cardiomyopathy and severe left ventricular dysfunction (ejection fraction = 25%), initially not considered as a potential heart transplant candidate due to the presence of a lung abscess. The patient subsequently underwent atypical pulmonary resection with intraoperative and perioperative intraaortic balloon counter-pulsation for circulatory support and was then listed for cardiac transplant. Pitfalls and intra/postoperative strategy, all of which are potentially important aspects in minimizing operative risk, are discussed.

In this study, we reviewed our experience in heart valve replacement with the St. Jude BioImplant heart valve, which is a low-profile, low-pressure glutaraldehyde-fixed porcine prosthesis mounted on a flexible Delrin stent.During the period May 1989-January 1996, 117 patients were implanted with 132 BioImplant prostheses; three patients were lost to follow up and excluded from the series. Mean age was 67.5 +/- 9.8 years (range: 19 to 82 years); myocardial revascularization was performed in 22 (19.3%) patients. In-hospital mortality rate was 6% (7/117 patients). By January 1996, 114 patients (53 males, 61 females), in whom 59 aortic, 35 mitral, 15 mitro-aortic and five tricuspid prostheses had been implanted, were eligible for the analysis. Mean follow up was 40.4 +/- 21.7 months (range: 1 to 76 months).The survival probability of survivors was 72.1 +/- 6.5 at 77 months. Seventeen patients died during follow-up. The mean NYHA class improved from 3.1 +/- 0.6 preoperatively to 1.4 +/- 0.6 postoperatively. The freedom probabilities were respectively 89.5 +/- 5.3% from thromboembolism, 93.2 +/- 3.7% from infective endocarditis, 84.5 +/- 10.3% from structural dysfunction, 99.1 +/- 0.9% from non-structural dysfunction, and 80.1 +/- 10.2% from reoperation. The freedom probability for valve-related events was respectively 75.3 +/- 12.3%, 98.0 +/- 1.9% and 67.2 +/- 17.2% for patients who underwent mitral, aortic and mitro-aortic heart valve replacement (p = 0.05 comparing only patients who underwent mitral or aortic replacement); moreover the freedom probability from valve-related events was 71.6 +/- 11.2% in patients agedor = 65 years and 90.2 +/- 6.6% in patients aged65 years (p = 0.006).The BioImplant heart valve, in our experience, seems to be a valuable device which shows a mid-term performance similar to that of other porcine prostheses.

Surgical intervention for coronary artery disease (CAD) is determined by the viability of coronary artery branches. When peripheral coronary artery disease is present, conventional bypass grafting is not suitable. Research has recently been done on alternative methods such as transmyocardial laser revascularization (TMLR). TMLR works through the vascular connections that are present between the cardiac chambers and the myocardial muscle in the human heart. The creation of 1-mm transmural cardiotomies through a CO2 laser should improve myocardial perfusion.From February to June of 1996, twelve patients (9 males and 3 females with a mean age of 67.8 +/- 4.6) with CAD (mean n0 of diseased vessels 2.7), angina (mean CCS class 3.5 +/- 0.5), mean ejection fraction 47.8% and viable ischemic myocardium on scintiscan in segments without graftable coronary branches, underwent TMLR at our institute. Nine of the 12 patients also underwent associated CABG (mean number of anastomoses per patient: 2.5). Cardiopulmonary bypass was never used, since coronary anastomoses and laser cardiotomies were performed on the beating heart.Perioperative mortality was 2/12 (16.6%). Postoperative inotropic support and diuretic therapy was required in most cases. At a mean follow-up period of 4.2 months, all remaining patients are still alive: 5/10 are angina-free (CCS 0), 4/10 are in CCS class 1 and 1/10 is in CCS class 2 (mean 0.6 +/- 0.7).We believe that TMLR could be considered an effective mean to treat symptomatic myocardial ischemic disease in which coronary bypass grafting is not suitable. During the immediate postoperative period, contractile myocardial dysfunction occurs in a high percentage of patients treated using TMLR and consequently it would be worthwhile to invest in further research.

Primary heart neoplasms occur in 0.002-0.3% of autopsies: 30% are myxomas and 20-30% are malignancies, almost always sarcomas. Cardiac metastases are 10 to 40 times more frequent than primary heart cancer. We describe a case of a left atrial sarcoma erroneously diagnosed as myxomas preoperatively. Standard surgical indication for resection of cardiac myxomas is based on echocardiography. Because of the severity of cardiac malignant lesions than can mimic atrial myxomas at echocardiography, through preoperative investigation should be accomplished, best by magnetic resonance imaging. In case of suspected malignancy, total body computed tomography should be performed to avoid unnecessary cardiac operations in case of disseminated cancer. To date the only good medium and long-term results in the therapeutic management of heart sarcomas have been achieved by transplantation: the probable explanation is that criteria of surgical radicality should be those followed for soft tissue tumors located elsewhere in the organism.

The distinction between fibrotic and viable myocardium is a key issue in patients with coronary artery disease and left ventricular dysfunction. Metabolic imaging with positron emission tomography (PET) and labeled tracers, along with the study of myocardial perfusion, is now available to identify hibernating myocardium. However, PET imaging of myocardial metabolism is a high-cost and time-consuming technique, and requires an on-site cyclotron. The aim of this study is to test the reliability of dobutamine echocardiography (DE) compared with PET imaging, for the identification of hibernating myocardium. In 16 patients, scheduled for myocardial revascularization, left ventricular shapes were divided in eight segments both for echocardiographic and nuclear study evaluation. All patients underwent a technetium 99m MIBI single-photon emission tomography stress-rest study of perfusion, a fluorine-18-labeled deoxyglucose (FDG(/PET study of metabolism, and a DE test (baseline, at a 5 micrograms/kg/min infusion of dobutamine for 8 minutes and at a 10 micrograms/kg/min dose for additional 8 minutes). Neither myocardial ischemia nor arrhythmia occurred during the DE test. Baseline echocardiograms showed 90 segments with wall motion abnormalities: wall motion impairment was decreased or reversed in 33 of 90 segments; it remained unchanged in 57 of 90 segments. In 32 of 33 segments considered viable on the basis of DE and in 21 of 57 segments with unchanged kinesis, some degree of FDG was detected. Thus, sensitivity and specificity of DE compared with nuclear studies was 60% and 97% respectively. Moreover, a good correlation and agreement (kappa = 0.51) between DE and the presence of FDG were found. We conclude that DE is a safe and reliable test for the screening of hibernating myocardium in patients with chronic coronary artery disease and left ventricular dysfunction.

This study evaluated the use of monitoring blood levels of the isoenzyme of creatine phosphokinase, troponin T (tnT) and myosin in the detection of perioperative myocardial damage after coronary artery surgery. Serial blood samples were collected in 24 patients undergoing myocardial revascularization. The patients were retrospectively divided into three groups: group A with no changes in their electrocardiogram; group B showing non-specific signs of perioperative myocardial infarction such as deep and permanent T wave inversion; and group C with definite electrocardiographic signs of perioperative myocardial infarction (new persistent Q-waves and loss of R-waves). Group A (n = 17) demonstrated a mean(s.d.) troponin T peak blood level of 0.64(0.35) ng/ml at 12-24 h after surgery, a myosin peak of 1030(670) mu units/l at 3-6 days afterwards, and a creatine phosphokinase isoenzyme peak of 25.8(10.6) units/l. In group B (n = 5), mean(s.d.) troponin T levels were elevated to a peak of 4.8(3.9) ng/ml 24 h after intervention, while myosin rose to 2074(340) mu units/l 3-6 days after surgery and creatine phosphokinase isoenzyme reached 57.8(38) units/l. Group C (n = 2) had a mean(s.d.) troponin T peak of 4.8(2.6) ng/ml, a myosin peak of 2404(392) mu unit/l and a creatine phosphokinase isoenzyme peak of 88.5(20) units/l. Peak values of troponin T and myosin in groups B and C were statistically different from those in group A (P0.001). These results suggest that troponin T and myosin are reliable indicators of perioperative myocardial damage. In particular, troponin T may allow the differentiation of reversible from irreversible myocardial injury.

From March 1988 to May 1993, 1,125 patients with coronary artery disease (CAD) underwent coronary surgery at our Institute. In the same period 74 patients (mean age 59 +/- 7 years; range 36-73) with left ventricular dysfunction (LVD) were referred for surgical decision making. All patients underwent [99mTc]MIBI/SPET to assess perfusion at rest and [99mTc]MIBI first pass radionuclide angiography to assess the ejection fraction (EF). In 44/74 patients we performed [18F]FDG/PET in fasting conditions and pharmacologic wash-out, in order to identify viable myocardium. We divided patients with LVD into 3 groups: Group A (30 patients) operated on without preoperative [18F]FDG/PET, Group B (37 patients) operated on with FDG uptake in segments with wall motion abnormalities, and Group C (7 patients) with no FDG uptake, who were excluded from coronary surgery; there was no significant difference among the 3 groups with respect to age, sex, CAD, risk factors and EF (Group A: 29.1% +/- 6.6%, range 16-39%; Group B: 30.8 +/- 5.6%, range 20-40%; Group C: 26.5 +/- 6.8%, range 18-37%). The study of perfusion and EF was repeated 6 months postoperatively in Group A and B. Left ventricular end-dyastolic pressure at cardiac catheterization was 19.9 +/- 5.1 mmHg, 20.4 +/- 4.7 mmHg and 26.8 +/- 9.2 mmHg in Group A, B and C, respectively. Myocardial protection was achieved according to the Buckberg protocol.(ABSTRACT TRUNCATED AT 250 WORDS)

Mechanical and conventional stented bioprostheses, because of need for anticoagulants, hemodynamic characteristics and long-term durability, do not represent the optimal heart valve replacement device. In this study we compared the hemodynamic function of a stented aortic bioprosthesis (St Jude Bioimplant), implanted in 10 patients, with a stentless porcine aortic bioprosthesis (Biocor) implanted in 7 patients, by means of Doppler echocardiography early postoperative at rest (T1) and 6 months later at rest (T2a) and during exercise (T2b). Mean and peak systolic gradients across stentless porcine prostheses were significantly lower than across stented bioprostheses (T1 p = 0.008 and p = 0.004; T2a p0.0001 and p0.0001; T2b p0.0001 and p0.0001, respectively). Our results show that systolic and diastolic mechanical stress on biological components of a glutaraldehyde-fixed stentless porcine aortic bioprosthesis is much lesser than on stented bioprostheses. This feature has appeared evident at rest and much more after exercise testing. The reduction of systolic and diastolic stress is expected to determine lower calcification degree and longer durability of stentless porcine aortic bioprostheses. Moreover, aortic valve replacement by means of stentless bioprostheses allows the implantation of a 1 size (2 mm) larger device, appearing favourable especially in small aortic annulus. On the basis of these promising results we suggest that stentless bioprostheses are a valid alternative to stented bioprostheses for aortic valve replacement. However, patient population is too small and the follow-up is too short to draw a definite statement about long-term hemodynamic performance of this device.

A case of coronary artery spasm developed 6 hours after myocardial revascularization inducing both hemodynamic and electrocardiographic changes, is reported. The spasm was documented by coronary angiography, and it was not reversed by intracoronary infusion of isosorbide dinitrate. Intravenous infusion of nifedipine (initial dose of 0.0104 mg/min to final dose of 0.0208 mg/min), along with infusion of glyceronitrate (1.0 micrograms/kg/min) was able to significantly improve hemodynamic impairment and to reverse electrocardiographic changes in 12 hours. Coronary angiography, repeated in postoperative day 3, after 48 hours of continuous nifedipine infusion, showed a resolution of coronary spasm. There was no evidence of myocardial infarction as resulted from total CPK and MB isoenzyme release. Nifedipine infusion was gradually reduced as oral administration of slow release nifedipine (40 mg twice daily) was started. The combined intravenous infusion of glyceronitrate and nifedipine seems to be able to control and overcome coronary artery spasm following coronary surgery.

From March 1988 to March 1992, 69 patients with coronary artery disease (CAD) and left ventricular dysfunction (LVD) were referred to our Institute for surgical decision making. Sixty-nine (8.2%) had LVD. In 39/69 patients we performed the identification of viable myocardium with the use of [18F] FDG/PET in fasting conditions. We divided patients with LVD into 3 groups: Group A (30 patients) operated on without preoperative [18F] FDG/PET, Group B (32 patients) with FDG uptake in akinetic segments, and Group C (7 patients) with no FDG uptake; there was no significant difference among the 3 groups in age, sex, CAD, risk factors and ejection fraction EF (Group A: 29.1 +/- 6.6%, range 16-40; Group B: 32.9 +/- 6.5%, range 20-40; Group C: 26.5 +/- 6.8%, range 18-37). All patients underwent [99mTc] MIBI/SPET to assess perfusion at rest and [99mTc] MIBI first pass radionuclide angiography to assess the EF. The study of perfusion and EF was repeated 6 months postoperatively in Group A and B. Myocardial protection was achieved according to the Buckberg protocol. Operative results in Group A and B were respectively: in-hospital deaths 2 (6.6%) versus 0 (NS), perioperative myocardial infarction 1 (3.3%) versus 1 (3.1%) (NS), IABP 10 (33.3%) versus 4 (12.5%) (p = 0.048). Postoperative EF improved both in Group A (35.1 +/- 7.1%, range 20-50; p = 0.01) and in Group B (44.2 +/- 7.7%, range 26-62; p0.001). In Group C 6/7 patients were scheduled for heart transplantation according to standard criteria.(ABSTRACT TRUNCATED AT 250 WORDS)

Eighty-two consecutive patients undergoing reoperation for coronary revascularization from January 1980 to November 1990 were reviewed to determine early and late results and predictors of survival. Seventy patients were male and 12 female; age ranged from 36 to 75 years (mean 56.4 +/- 8.1). All were symptomatic for angina. The mean interval between first and second operation was 62.8 +/- 47.8 months (range 1 to 220 months). Angiographic indications for reoperation were: graft failure (34.1%), progression of atherosclerosis in the native coronary circulation (6.1%) and combination of the two (59.8%). Mean ejection fraction was 45.9 +/- 10.2 (range 11 to 67). Surgical indication was elective in 79.3%, urgent in 14.6% and emergent in 6.1%; 199 grafts were performed (2.4 +/- 1 grafts/patient). Hospital mortality was 6.1% (5 cases). Late mortality was 5.2% (4 cases). Actuarial survival rate (including hospital mortality) was 87.9% at 3, 5 and 10 years. Multivariate analysis identified left main stenosis (p = 0.00001), family history of coronary disease (p = 0.003), urgent/emergency operation (p = 0.015) as predictors of increased in-hospital mortality; postoperative myocardial infarction (p = 0.002) and preoperative heart failure (p = 0.01) as predictors of increased late mortality. Follow-up of in-hospital survivors (mean interval 42.7 +/- 25.8 months, range 3 to 120 months) documented 27 cardiac major events (other than death) in 24 patients (32.9%). Actuarial rates of freedom from major cardiac events were 70%, 52.9% and 48.1% at 3, 5 and 10 years respectively. Multivariate analysis identified preoperative ejection fraction (p = 0.01) as predictor of recurrence of angina and preoperative heart failure (p = 0.02) as predictor of occurrence of cardiac major events.

A 53-year-old man was admitted for treatment of an aberrant right subclavian artery aneurysm that had been diagnosed 5 years earlier and had recently begun to enlarge. The aneurysm, which involved the right subclavian artery from its origin, measured 47 mm in diameter and about 10 cm in length. Because of the lesion's size and friability, a 2-stage operation was performed. In the 1st stage, the right subclavian and right vertebral arteries were revascularized with double bypass grafts via a right cervical approach. In the 2nd stage, the patient was repositioned and a left thoracotomy incision was made. With the aid of left-heart bypass, the aorta was cross-clamped proximal and distal to the lesion, and the aneurysmal orifice was closed with a Dacron patch. The patient was discharged from the hospital on the 17th postoperative day and remains asymptomatic 24 months later. We recommend the 2-stage technique for similar cases because it prevents limb ischemia and reduces the risk of hemorrhagic and embolic complications.

From 1 March 1977 through 31 December 1987, 1,252 patients underwent mitral valve replacement with a SORIN-Biomedica 60° tilting-disc prosthesis at our institution. Hospital mortality was 7.3% (91 patients); prosthesis-related deaths, expressed as a percentage of hospital mortality, accounted for 12.1% of these early deaths. The 1,161 patients who survived hospitalization have been followed up for a total of 4,835 patient-years (range, 1 to 128 months; mean, 50.4 ± 27.3 months). Forty-three (3.7%) of these patients were lost to follow-up. The late mortality was 6.3% (1.5% ± 0.2% per patient-year), and the 10-year actuarial survival rate, excluding hospital mortality, was 89.1% ± 1.6%. The 10-year actuarial (and linearized) rates of freedom from valve-related complications were as follows: embolism, 94.4% ± 1.0% (0.93% ± 0.1% per patient-year); thrombosis of the prosthesis, 99.8% ± 0.1% (0.06% ± 0.03% per patient-year; hemorrhage, 93.7% ± 1.5% (0.95% ± 0.1% per patient-year); prosthetic valve endocarditis, 99.3% ± 0.3% (0.14% ± 0.05% per patient-year); reoperation, 90.6% ± 2.1% (1.1% ± 0.2% per patient-year); and overall complications, 76.6% ± 2.5% (2.9% ± 0.2% per patient-year). No structural deterioration was noted. These data not only confirm our previous reports concerning the reliability and durability of the SORIN prosthesis but also reveal a significant reduction, over the long term, in the overall incidence of valve-related complications. (Texas Heart Institute Journal 1991;18:16-23)

Ninety patients who underwent emergency cardiac valve surgery from January 1976 to December 1981 are reported. Patients were divided in two groups: those operated on native valves are included in group I; patients with prosthetic valves operated because of leakage or malfunction, in group II. In group I (57 patients) the aetiology was: rheumatic heart disease (34 cases); acute endocarditis (16 cases); sequelae of recent endocarditis (2 cases); luetic infection (1 case); sequelae of myocardial infarction (1 case); rupture of mitral chordae in mixomatous valve (3 cases). The emergency operation was prompted in 22 patients by cardiogenic shock, in 13 patients by intractable pulmonary edema, in 21 patients by low output syndrome, in one case by ventricular arrhythmias. In group II (33 cases) the causes of reoperation were: in 27 cases leakage (in 13 due to active endocarditis); in 6 cases variance of the occluder or thrombosis. The emergency originated in 12 cases from cardiogenic shock, in 11 cases from intractable pulmonary edema, in 9 cases from low output syndrome, in 1 case from ventricular arrhythmias. Twenty-six patients died perioperatively in group I and 17 in group II. Mean follow-up in group I was 26 months. Among 27 patients there were two deaths; 25 patients are alive and well (one has been reoperated again). Mean follow-up in group II was 21 months. Among the 15 patients observed there were 6 deaths (3 after re-reoperation); 9 patients are alive and well (one has been re-reoperated).' The Authors feel that surgery is mandatory in all such patients to ensure satisfying long term results, in spite of high perioperative mortality rate.

Ninety-eight pregnancies in 57 patients with mechanical (ball or tilting disc) prosthetic heart valves are described. Sixty-one pregnancies developed in 36 patients with a mitral prosthesis, 12 pregnancies in 9 patients with an aortic prosthesis, 17 pregnancies in 10 patients with both mitral and aortic prostheses and 8 pregnancies in 2 patients with mitral and tricuspid prostheses. All patients were in I or in II NYHA class at conception and no significative change was noted during pregnancy. All the patients were treated with oral anticoagulant therapy at conception. Different kinds of antithrombotic and antiembolic prophylaxis were employed. There were 13 voluntary interruptions of pregnancy and 37 spontaneous abortions. In the 47 newborn 2 malformation complications (1 warfarin syndrome, 1 cleft palate) and 4 haemorrhagic complications (without sequelae) were noted. Two fatal thromboses of a mitral prosthesis occurred; systemic embolic complications were noted in 7 cases. These observations suggested different incidences of complications regarding the antithrombotic and anti-embolic prophylaxis. The authors point out the high risk of thrombotic and embolic complications and the low rate of successful outcome of pregnancy in these patients.

From March 1977 to December 1981, 872 patients at our institution underwent valve replacement with a pyrolytic carbon tilting disc prosthesis manufactured in Italy by SORIN-Biomedica. To verify the performance characteristics of this prosthesis, we analyzed the intermediate-term results obtained over a cumulative total of 3,041 patient-years (pt-yr) of follow-up. Three hundred sixty-nine patients underwent mitral valve replacement (MVR), 309 had aortic valve replacement (AVR), and 194 had both mitral and aortic (double) valve replacement (DVR). Expressed in actuarial terms (% [+/- standard error of the mean] free of adverse events at 5 years) and in linearized terms (% pt-yr), respectively, valve-related complications occurred at the following rates: Thromboembolism, 89.9 +/- 1.9% and 2.1 +/- 0.4% pt-yr (MVR); 92.1 +/- 1.9% and 1.7 +/- 0.4% (AVR); 90.5 +/- 5.0% and 2.2 +/- 0.6% (DVR). Anticoagulant-related hemorrhage, 95.2 +/- 1.5% and 1.4 +/- 0.3% (MVR); 95.9 +/- 1.5% and 1.3 +/- 0.3% (AVR); 96.0 +/- 2.0% and 0.9 +/- 0.4% (DVR). Prosthetic valve endocarditis, 99.0 +/- 0.6% and 0.2 +/- 0.1% (MVR); 97.4 +/- 1.0% and 0.6 +/- 0.2% (AVR); 94.5 +/- 1.7% and 1.4 +/- 0.4% (DVR). Reoperation, 92.6 +/- 1.5% and 1.7 +/- 0.3% (MVR); 89.4 +/- 1.9% and 2.4 +/- 0.4% (AVR); 82.3 +/- 2.9% and 4.8 +/- 0.8% (DVR). The total valve-related morbidity and mortality was 79.6 +/- 2.6% and 4.9 +/- 0.6% (MVR); 79.7 +/- 2.6% and 5.1 +/- 0.6% (AVR); 70.5 +/- 4.0% and 7.7 +/- 1.1% (DVR). The 5-year actuarial survival rate without hospital mortality was 86.8 +/- 2.0% (MVR), 91.0 +/- 1.7% (AVR), and 78.8 +/- 3.7% (DVR). The intermediate-term survival and complication rates showed the performance of the SORIN prosthesis to be quite satisfactory.

From January 1978 to December 1984, 214 patients underwent a total of 243 reoperations for repair or replacement of a prosthetic heart valve. On the basis of the number of valve reoperations in the same anatomic position within the heart, the patients were divided into three groups. Overall hospital mortality was 23.4% (CL 20.3-26.7) in Group I (214 patients), 48% (CL 36.1-60.1) in Group II (25 patients), 25% (CL 3.3-62.6) in Group III (4 patients). Hospital mortality appeared to be related to urgency of reoperation (p less than 0.001 in Group I; p = 0.037 in Group II), primary indication for reoperation (p = 0.034 in Group I; p = 0.022 in Group II), association with other cardiac surgical procedures (p = 0.00253 in Group I). Hospital mortality in Group I was significantly higher (p = 0.0056) when reoperation was performed within one year after valve replacement. No significant differences in urgency and emergency rate were noted between reoperations on mechanical heart valves and bioprostheses. No significant differences in bleeding complications were noted between reoperations and initial valve replacement. Mean follow-up is 37.4 +/- 21.8 months (range 2 to 85 months). Actuarial survival rate is 82.8 +/- 3.1% at 1 year, 78.7 +/- 3.5% at 2 years and 71.5 +/- 5.1% at 5 years; 90.9% (CL 87.4-93.6) of the followed patients are in I or II NYHA class. The results appear to suggest that when significant (on clinical or instrumental criteria) prosthetic disfunction is diagnosed, reoperation should be undertaken early to minimize operative risk. The Authors point out that surgery in such patients also ensures satisfying long-term results.