Long-term Doppler echocardiographic results of aortic or mitral valve replacement with Biocor porcine bioprosthesis

OBJECTIVES: Our objectives were to evaluate the long-term bioprosthetic and cardiac functional outcome after insertion (over a 10-year period) of a new-generation porcine zero pressure-fixed Biocor bioprosthesis, as well as to determine the echocardiographic accuracy for selection of patients requiring reoperation. The long-term systematic Doppler echocardiographic assessment after valve replacement with this bioprosthesis is lacking. METHODS: Between January 1983 and January 1993, we inserted 756 Biocor prostheses in the aortic (619) or mitral (137) positions. All 51 patients who had a reoperation during the follow-up time were evaluated echocardiographically before reoperation. Additionally, 263 of 446 patients (59%) with aortic bioprostheses and 42 of 74 patients (57%) with mitral bioprostheses who were alive in January 1993 had long-term echocardiographic follow-up. RESULTS: Group A: Normally functioning bioprostheses were found in the aortic position in 242 of 263 patients and in the mitral position in 33 of 42 patients. Group B: Thirty patients had abnormal bioprosthetic function. Eleven patients had regurgitation, 3 had a combined lesion, and signs of calcification appeared in 16 patients with aortic valves, all with a peak gradient of above 60 mm Hg. Group C: Patients who had a reoperation (41 aortic and 10 mitral) within the follow-up period were followed up echocardiographically from the detection of a possible valve dysfunction until reoperation, and the findings accorded well with those at operation in 49 of 51 patients. CONCLUSIONS: These findings suggest that, during a long-term follow-up, most bioprostheses function normally, facilitating improved heart function. Abnormalities in a bioprosthesis usually develop gradually, enabling their detection by Doppler echocardiographic evaluations performed regularly or in case of any symptomatic deterioration.     

Influence of pulmonic position on durability of bioprosthetic heart valves

BACKGROUND: The insertion of bioprosthetic valves into the pulmonic position is not performed commonly because of uncertainty concerning the necessity and durability of such valves. METHODS: We reviewed the long-term outcome of 10 patients who underwent pulmonary valve replacement with bioprostheses between March 1985 and March 1997. A Carpentier-Edwards supraannular bioprosthesis was used in 7 patients, a Hancock II bioprosthesis was used in 2 patients, and a Carpentier-Edwards pericardial bioprosthesis was used in 1 patient. The mean patient age at the time of pulmonary valve replacement was 38.9 +/- 16.3 years (range, 15 to 63 years). The diagnoses were pulmonary valvular regurgitation after corrective surgery for tetralogy of Fallot in 7 patients, right ventricular outflow tract stenosis and absent right pulmonary artery combined with a double-outlet right ventricle in 1 patient, pulmonary valvular regurgitation with pulmonary artery dilatation in 1 patient, and aortic valve stenosis treated with our modification of the Ross procedure using a pulmonary bioprosthesis in 1 patient. Survivors were followed up for a mean of 5 years and 5 months. RESULTS: One patient underwent reoperation because of infective endocarditis of the bioprosthesis. No bioprosthetic valve dysfunction has been observed on Doppler echocardiography during a maximum follow-up period of 12.2 years, except in the patient who underwent replacement at 15 years of age. CONCLUSIONS: Bioprostheses in the pulmonic position are durable in adult patients because they face a minimal hemodynamic load, but they may undergo early leaflet degeneration in younger patients.     

The Carpentier-Edwards porcine valve in the supra annular aortic position. Results after 12 years in a series of 1108 patients

In the decision concerning the choice of valvular prosthesis, certain prostheses are considered to be standards of reference: this is the case of the Carpentier-Edwards Supra Annular 2650 porcine bioprosthesis. This study reports the results in a series of patients followed up for 12 years. Between 1983 and 1995, 1108 patients were implanted with this prosthesis for isolated aortic valve replacement. The majority of patients was elderly (mean 78.3 +/- 8.3 years). The follow-up rate was 94%, representing a total of 3 925 patient-years (average 4 +/- 3 years). The survival at 5, 10 and 12 years, operative mortality included, was 70.7%, 46% and 28%. Thromboembolic events to dehiscence represented the commonest complication (0.7% per patient-year). Structural valve degeneration (21 cases) (0.5% per patient-year) was a low risk complication up to 10 years but increased suddenly at the 11th year: age and gender were risk factors for this complication. The actuarial complication-free rate was 94% at 10 years and 82% at 12 years. Other complications were much less common (infectious endocarditis, haemorrage). The Carpentier-Edwards Supra Annular porcine bioprosthesis is associated with a low risk of complications after 10 years' follow-up, especially of valve degeneration. It remains a competitive choice in the register of valve prostheses. As with the other bioprostheses, the main indications are observed in elderly patients.     

Tyrosine phosphorylation of platelet derived growth factor beta receptors in coronary artery lesions: implications for vascular remodelling after directional coronary atherectomy and unstable angina pectoris

BACKGROUND AND AIMS OF THE STUDY: The aim of this study was to evaluate the long-term follow up of the Pericarbon pericardial bioprosthesis implanted in the mitral position. METHODS: Between January 1985 and January 1991, 78 patients (26 males, 52 females; mean age 56.9 +/- 7.8 years) underwent isolated mitral valve replacement with a Pericarbon valve. All bioprostheses were size 29 mm and implanted by the same surgeon. RESULTS: Total follow up was 663.2 pt-years and it was 97% complete. Early mortality was 1.3% (1/78); two minor cerebral embolisms were observed as early complications. At 12 years the overall survival rate was 85.0 +/- and valve-related survival 93.1 +/- 3.0%; freedom from embolic events was 83.0 +/- 4.5% and from endocarditis 98.7 +/- 1.3%. Freedom from primary tissue failure was 56.8 +/- 6.6%; it was 86.3 +/- 7.5% in patients aged > 60 years and 36.8 +/- 8.2% in younger patients. There were 27 reoperations, 26 for primary tissue failure, one for endocarditis. Comparison between basal and follow up echocardiographic studies showed a significant stenotic deterioration of the bioprosthesis and a negligible incidence of regurgitation. Morphological findings of explanted bioprostheses were characterized by stenotic and diffuse microcalcification, but no tissue tear was observed. CONCLUSIONS: These results confirm that the Pericarbon bioprosthesis is structurally safe and free from the fatigue problems which afflicted the first and second generation of pericardial valves. As with other tissue valves, the rate of calcification is age-dependent, suggesting preferential use of the Pericarbon prosthesis in elderly people.     

Echocardiographic and phonocardiographic confirmation of suspected caged mitral valve malfunction

Seven patients studied by echocardiography with and without simultaneous phonocardiography for suspected malfunction of a caged mitral valve prosthesis are presented. In case 1, with inaudible prosthetic clicks, thrombosis of the cage and immobility of the ball were suggested by echocardiographic studies and confirmed at surgery. In case 2, simultaneous echocardiographic and phonocardiographic studies demonstrated wide and variable intervals between the aortic second sound the the opening click and also "sticking" of the ball. In case 3 a thrombus prevented full motion of the ball to the apex of the cage, which was seen on the echocardiogram, while in case 4, with a thrombus within the ventricle and prosthesis, the prosthetic opening click was present intermittently and was associated with only subtle echocardiographic changes. In case 5, echocardiographic studies demonstrated abnormal rocking of the cage secondary to severe prosthetic dehiscence. In case 6, dul prosthetic clicks were to be secondary to a low cardiac-output state. In case 7, with multiple valve prostheses, simultaneous echocardiographic and phonocardiographic studies allowed identification of individual valve sounds and abnormal timing of valve opening. Based on these studies, we believe that echocardiography and simultaneous phonocardiography can yield very useful information in the evaluation of patients with suspected malfunction of a caged mitral valve prosthesis.     

Idiopathic perforation of a porcine aortic bioprosthesis in the aortic position

The report of a failure of glutaraldehyde-preserved porcine aortic xenograft bioprosthesis in the aortic position after 13 months is presented. Severe aortic regurgitation resulted from three "idiopathic" perforations in one of the cusps, and a linear tear in another cusp. Light and electron microscopy showed generalized degeneration of collagen thoughout the faulty valve. The absence of a platelet-fibrin coat on edges of the tear suggested a recent origin, compatible with cardiac catheter manipulation during unsuccessful attempts to cross the valve. The histopathologic data from this valve correlate with previously reported failures with formaldehyde preserved xenograft valves.     

Repair of mitral valve prolapse by resection and sliding plasty

There have been many techniques applied to the repair of mitral valve prolapse, and the method used in a particular case is usually selected according to the position and extent of the lesion. To simplify and standardize the technique of mitral valve repair, we have adopted the resection, sliding plasty and ring annuloplasty methods since December 1992. Of 10 consecutive surgical cases, 2 involved prolapse of the anterior leaflet, 1 the posteromedial commissural, and 7 the posterior leaflet. One patient with posterior leaflet prolapse required valve replacement due to dehiscence of the plastied site on the 3rd postoperative day, and one died because of sepsis. However, the remaining patients were doing well without mitral regurgitation at a mean of 20 months (range: 8-32) after the operation. The advantages of these techniques include easy adjustment of the height of the leaflet and a good chance of long-term durability, since the affected lesion is resected.     

The effect of prosthesis-patient mismatch on aortic bioprosthetic valve hemodynamic performance and patient clinical status

BACKGROUND: High pressure gradients occurring through normally functioning prosthetic valves appear to be related to a mismatch between the effective orifice area of the prosthesis and the patient's body surface area. OBJECTIVE: To determine whether prosthesis-patient mismatch affects clinical and hemodynamic status, a group of patients with a bioprosthetic heart valve in the aortic position was prospectively evaluated at 6.2+/-4.4 years after implantation by transthoracic Doppler echocardiography. METHODS: Manufacturer-derived in vitro valve areas were available in 61 patients allowing classification into two subgroups, with or without mismatch, based on a valve area at implantation indexed for body surface area 0.85 cm2/m2 or less, or greater than 0.85 cm2/m2. Clinical and hemodynamic parameters evaluated at follow-up included New York Heart Association (NYHA) class distribution, mean transprosthetic gradient, prosthetic valve area and cardiac index. RESULTS: Prosthesis-patient mismatch was present in 32 of 61 patients (52%). Although NYHA class of the patients was similar in both groups, hemo-dynamic performance of the aortic bioprostheses was worse in patients with mismatch than in patients with no mismatch, as indicated by a higher mean gradient (22+/-9 versus 15+/-8 mm Hg, P=0.002) and a lower cardiac index (3.0+/-0.7 versus 3.4+/-0.7 L/min/m2, P=0.04). The prevalence and severity of intrinsic prosthetic dysfunction were similar in both groups. Despite similar NYHA functional class distribution in both groups, the occurrence of syncope, acute pulmonary edema and angina pectoris was significantly higher in patients with mismatch (50% versus 21%, P=0.017). CONCLUSIONS: Prosthesis-patient mismatch is associated with worse hemodynamic performance and higher prevalence of adverse clinical events. However, mismatch did not promote accelerated hemodynamic or structural deterioration of the bioprosthesis.     

Flutter of left ventricular structures in patients with aortic regurgitation, with special reference to patients with associated mitral stenosis

Echocardiography was performed in 45 patients with aortic regurgitation. Forty showed a high frequency diastolic flutter of the mitral valve, which was holodiastolic in all but the patients with associated mitral stenosis. Of four patients with coexisting mitral stenosis, mitral flutter was absent in two; in the other two, in atrial fibrillation, mitral flutter occurred, but only during a fixed interval after mitral valve opening, irrespective of cycle length. A fine flutter of similar frequency was observed on the left ventricular aspect of the ventricular septum in 12 patients. In six of these it was of slight degree and restricted to early diastole and the high septum; in four others (three of whom had associated mitral stenosis), the septal flutter was more marked, holodiastolic, and present over all parts of the septum scanned; in two, it was holodiastolic over the high septum but early diastolic at lower septal levels. Aortography performed in 19 patients showed that septal flutter was present in seven of 12 patients in whom the regurgitant aortic jet was directed forward to the ventricular septum, whereas in the other seven patients with no septal flutter, the jet was directed away from the septum. Septal flutter is useful as an echocardiographic sign of aortic regurgitation, especially in the presence of mitral stenosis when mitral flutter may be absent or exceeded by septal flutter in both amplitude and duration, and when the mitral valve has been replaced by a prosthetic valve. Vibration of the septum appears to be attributable to the regurgitant aortic jet impinging on it and may contribute to the production and radiation of the characteristic diastolic murmur of aortic regurgitation.     

Porcine aortic leaflet arrangement may contribute to clinical xenograft failure

Clinical experience with the first generation porcine xenograft shows significant deterioration and mechanical failure after 7-8 years post-implantation. Although many mechanisms of valve failure have been identified, the inherent differences between porcine and human aortic valves have not been emphasized. To determine if these differences are significant, the authors studied the anatomy of the aortic valve in 10 post-mortem porcine hearts. The authors found that the non-coronary leaflet was the smallest and the right leaflet was the largest based on the dimensions of area, perimeter, weight, and attached edge length (p < 0.05). These results differ from reported analyses of human aortic valves, in which the smallest cusp is generally the right the largest is the non-coronary. The authors believe that these differences between the human and porcine aortic valves may result in atypical mechanical stresses and the disruption of blood flow patterns in the sinuses of Valsalva, and may decrease the long-term stability of the porcine bioprostheses. In other words, the failure found with porcine bioprostheses after 8 years of implantation might be expected from the inherent structure (and associated fluid dynamics) of the porcine aortic valve positioned in the human aortic root.     

Relation between mitral orifice surface area and extent of hemodynamic disorder of the pulmonary circulation in patients with mitral stenosis

Mitral annulus and valves form the mitral orifice area with the size between 4.0-6.0 cm2. Every area which is smaller than this, represents mitral stenosis. As a consequence of mitral stenosis hemodynamic gradients occur over the mitral orifice with circulation disturbances below and above the stenotic mitral valve. The size of transmitral gradient is important in the evaluation of functional or/and structural changes in the blood vessels of pulmonary circulation. This investigation included 40 patients with mitral stenosis (or accompanying minimal mitral regurgitation). All patients underwent echocardiographic examination: area of the mitral orifice was determined and hemodynamic procedure with the left and right heart catheterization was performed. The following hemodynamic parameters were measured: mean capillary wedge pressure, left ventricular filling pressure, left ventricular mean diastolic pressure, mean pulmonary artery pressure. According to these parameters resistance in the pulmonary circulation was measured. The size of the mitral orifice was determined according to oximetry blood analyses and hemodynamic parameters. All patients were divided into 4 groups: minimal (2.5-4.0 cm2), mild (1.5-2.5 cm2), moderate (1.0-1.5 cm2) and severe mitral stenosis (1.0 cm2). The comparison of echocardiographic and hemodynamic parameters revealed a high and positive correlation between the area of mitral orifice. There was also a negative and moderate correlation between the values of stenotic mitral orifice area and total pulmonary resistance, i.e. in all patients with severe mitral stenosis there was an increased pulmonary arteriolar resistance. CONCLUSION: Noninvasive echocardiographic method is valid in the evaluation of stenotic mitral valve area. In the evaluation of hemodynamic parameters in the pulmonary circulation the index of arteriolar pulmonary systemic vascular resistance is very important. In all patients with the area of stenotic mitral orifice 1.0 cm2, there are functional or pathomorphologic changes in the pulmonary circulation of the blood vessel wall.     

Doppler haemodynamic assessment of clinically and echocardiographically normal mitral and aortic Allcarbon valve prostheses. Valve Prostheses Ligurian Cooperative Doppler Study

Doppler echocardiographic characteristics of normally functioning Allcarbon prostheses were studied in 149 consecutive patients with 157 valves in the mitral (n = 73) and aortic (n = 84) positions whose function was considered normal by clinical and echocardiographic evaluation. In the mitral position, the mean gradient and the effective mitral orifice area were not significantly different in either the 25-mm or the 31-mm size valves (from 5 +/- 1 to 4 +/- 1 mmHg and from 2.2 +/- 0.6 to 2.8 +/- 0.9 cm2, respectively; P = ns for both). Conversely, peak gradient was significantly and inversely correlated to actual orifice area (r = -0.70; P < 0.0006), decreasing from 15 +/- 3 mmHg in the 25-mm size valve to 9 +/- 1 mmHg in the 31-mm size. In the aortic position, the mean gradient was 29 +/- 8 mmHg in the 19-mm size valve; it decreased to 8 +/- 2 mmHg in the 29-mm size. Effective prosthetic aortic valve area, calculated using the continuity equation, ranged between 0.9 +/- 0.1 cm2 for the 19-mm size valve to 4.1 +/- 0.7 cm2 for the 29-mm size. By analysis of variance, effective prosthetic aortic valve area differentiated various valve sizes (F = 25.3; P < 0.0001) better than peak (F = 5.34; P = 0.012) or mean (F = 4.34; P = 0.0052) gradients alone, and it correlated better with actual orifice area (r = 0.89, r = -0.70 and r = -0.65, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)     

Early clinical and hemodynamic evaluation of the aortic intact porcine bioprosthesis

Between October 1990 and June 1992, 89 patients underwent aortic valve replacement using the Intact porcine bioprosthesis. Their mean age (+/- SD) was 74.6 +/- 7.8 years (range 48 to 92). Seventy-five percent were in NYHA Class III-IV, 79 (89%) had AS or AS/AI, 10 (11%) had had previous cardiac surgery and 25 (32%) had an EF < 0.50. Associated procedures included CABG 45 (51%), septal myectomy 13 (15%), annular enlargement eight (9%), LV aneurysmectomy one, ascending aortic replacement one, and arch replacement one. Hospital mortality was four (4.5%). Hemodynamics were assessed with 2D echo with Doppler at seven days, six weeks and 12 months, and compared with 130 standard Carpentier-Edwards (C-E) porcine bioprostheses. At follow up, two patients have 2/4 perivalvular AI. The transvalvular gradients for the Intact valve were as follows: 21 mm-16.9 +/- 7.4 mmHg; 23 mm-18.9 +/- 6.2 mmHg; 25 mm-17.1 +/- 5.4 mmHg; 27 mm-15.0 +/- 3.7 mmHg; and 29 mm-15.0 +/- 2.1 mmHg. When compared to the standard Carpentier-Edwards porcine bioprostheses, the 21 mm Intact valve had the same gradient as the C-E prosthesis. However, the transvalvular gradients were slightly higher for the Intact valve for sizes 23-29 mm when compared to the corresponding C-E valve. The effective orifice area and effective orifice area index was no different between the two valves. Satisfactory hemodynamics are seen in the smaller prostheses when valves are matched for BSA and when aortic annular enlargement is performed when necessary.     

The normal spectrum of mitral and aortic valve discontinuity

The relationship of the base of the left and noncoronary sinuses of the aortic valve and the adjacent aortic leaflet of the mitral valve was studied in 106 normal heart specimens and 184 specimens with isolated VSD. The results show a spectrum of persistence of the tissue along the inner curvature of the heart. This may help settle the recent controversy in the interpretation of echocardiograms of this area because the recorded mitral-aortic discontinuity may be due to this spectrum rather than to variations in technique.     

Normal echocardiographic characteristics of the Sorin Bicarbon bileaflet prosthetic heart valve in the mitral and aortic positions

Doppler echocardiographic characteristics of normally functioning Sorin Bicarbon prostheses were prospectively assessed in 226 consecutive patients (135 male and 91 female patients, mean age 61 +/- 10 years) with 233 valves in the mitral (n = 67) and aortic (n = 166) positions whose function was considered normal by clinical and echocardiographic evaluation. Patterns of "normal" transprosthetic leakage were assessed with transthoracic echocardiography in all valves and with transesophageal echocardiography in six selected mitral valve prostheses. For the mitral valve prostheses, we found that peak and mean gradient, as well as pressure half-time, were not significantly different in either the 25 or the 31 mm valves (median values from 15 to 10 mm Hg, from 4 to 4 mm Hg, and from 70 to 83 ms; p = Not significant for all). On transthoracic study, 12 patients (17%) with a Sorin Bicarbon valve in the mitral position showed minimal transprosthetic leakage. On transesophageal study, all patients showed a transprosthetic leakage whose spatial distribution had a complex pattern: in planes orthogonal to the leaflet axis, two to four jets arising from the hinge points and converging toward the center of the valve plane could be visualized; in planes parallel to the leaflet axis, there were three jets, the two lateral ones diverging and the central one perpendicular to the valve plane. For the aortic valve prostheses, there was a significant decrease in transprosthetic gradients and an increase in effective orifice areas as prosthesis size increased. Peak and mean gradients decreased from a median value of 25 and 13 mm Hg in the 19 mm valves to 9 and 5 mm Hg in the 29 mm valves, respectively. Effective prosthetic valve area calculated with the continuity equation increased from a median value of 0.97 cm2 for the 19 mm size valves to 3.45 cm2 for the 29 mm size. With analysis of variance, effective prosthetic aortic valve area differentiated various valve sizes (F = 40.9, p < 0.0001) better than peak (F = 10.3, p < 0.0001) or mean (F = 8.04, p < 0.0001) gradients alone did. Furthermore, effective prosthetic aortic valve area correlated better than peak and mean gradients with prosthetic size (r = 0.76, r = -0.45, and r = -0.39, respectively). On transthoracic study, 109 patients (66%) showed minimal transprosthetic leakage. These normal values, obtained in a large number of patients with normofunctioning mitral and aortic Sorin Bicarbon valves, may help to identify Sorin Bicarbon prosthesis dysfunction.     

Objectives of high blood pressure treatment: left ventricular hypertrophy, diastolic function, and coronary reserve

The authors report the cases of two patients admitted to hospital for investigation of haemolytic anaemia. Both had undergone, 10 and 12 years previously, mitral valve replacement with a Ionescu-Shiley bioprosthesis. In both cases, in the absence of signs of cardiac failure, Doppler echocardiography showed mitral regurgitation. The association of haemolytic anaemia and dysfunction of the bioprosthesis led to redux valve replacement and correction of the anaemia. Haemolytic anaemia was the presenting sign of bioprosthetic valve dysfunction requiring replacement of the prosthesis. This complication is common with mechanical valve prostheses but much more rare in bioprosthetic valves.     

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.     

A comparison of outcomes in men 11 years after heart-valve replacement with a mechanical valve or bioprosthesis. Veterans Affairs Cooperative Study on Valvular Heart Disease

BACKGROUND: Mechanical heart valves are durable but thrombogenic, and their use requires that the patient receive anticoagulants. In contrast, bioprosthetic valves are less thrombogenic, but they have limited durability because of tissue deterioration. METHODS: To compare the outcomes of patients who receive these two types of valves, we randomly assigned 575 men scheduled to undergo aortic-valve or mitral-valve replacement to receive either a mechanical or a bioprosthetic valve. The primary end points were death from any cause and any valve-related complication. RESULTS: During an average follow-up of 11 years, there was no difference between the two groups in the probability of death from any cause (11-year probability for mechanical valves, 0.57; for bioprostheses, 0.62; P = 0.57) or in the probability of any valve-related complication (0.65 and 0.69, respectively; P = 0.39). There was a much higher rate of structural valve failure among patients who received bioprosthetic valves (11-year probability, 0.15 for the aortic valves and 0.36 for the mitral valves) than among those who received mechanical valves (no valve failures; P < 0.001). However, this difference was offset by a higher rate of bleeding complications among patients with mechanical valves than among those with bioprosthetic valves (11-year probability, 0.42 and 0.26, respectively; P < 0.001) and by a greater frequency of peri-prosthetic valvular regurgitation among patients with mechanical mitral valves than among those with mitral bioprostheses (11-year probability, 0.17 and 0.09, respectively; P = 0.05). CONCLUSIONS: After 11 years, the rates of survival and freedom from all valve-related complications were similar for patients who received mechanical heart valves and those who received bioprosthetic heart valves. However, structural failure was observed only with the bioprosthetic valves, whereas bleeding complications were more frequent among patients who received mechanical valves.     

A new operative technique for pulmonary artery banding: adjustment of pulmonary artery bands by mitral valve flow velocity

We developed a new technique to adjust the pulmonary artery band at surgery by monitoring the mitral valve flow velocity, which is indirectly indicative of the pulmonary flow. We employed this technique for 10 consecutive patients aged from 5 days to 5 months (mean, 1 months) weighing from 2.7 to 4.4 kg (mean, 3.3 kg). Underlying disease was aortic coarctation or interrupted+ventricular septal defect in 7 patients, single ventricule in 1 patients and miscellaneous defects in 2 patients. The pulmonary artery was exposed through a left lateral thoracotomy and a 3 mm wide Teflon tape was placed around the main pulmonary artery. The transducer of the Doppler echocardiography was placed along the left sternal border. The band was tightened gradually until the maximum velocity of the mitral valve flow decreased to around 70% of the previous level. During banding procedure, arterial oxygen saturation, heart rate and left ventricular contractility were monitored continuously. If bradycardia, unacceptable hypoxemia or ventricular dysfunction occurred, the band was released. The mitral valve flow velocity decreased rapidly by just a little additional tightness of the band between the range of 50% to 80% of the previous level. This technique enabled a very fine adjustment (less than 0.5 mm plication) and postoperative management has become very easy. Although there is a limitation of this technique that monitoring of the mitral valve flow velocity cannot be applied to the patients with significant interatrial shunt or mitral regurgitation, we conclude that this technique is simple and useful to obtain the optimum constriction of the pulmonary artery with excessive pulmonary blood flow.     

Effect of IciA protein on the expression of the nrd gene encoding ribonucleoside diphosphate reductase in E. coli

BACKGROUND AND AIMS OF THE STUDY: This study investigated the efficacy of postoperative ticlopidine as antiplatelet therapy in patients shortly after heart valve repair or replacement. METHODS: Between 1990 and 1995, 235 consecutive patients underwent either valve repair (n = 67) or replacement with a bioprosthesis (n = 168). The bioprostheses used were Carpentier-Edwards porcine or pericardial (n = 158) valves, Prima stentless valves (n = 3) and cryopreserved homografts (n = 7). Types of repair were aortic (one), mitral annuloplasty with Carpentier ring (65) and tricuspid repair (one). Mean patient age was 67 (range: 16 to 83) years for valve replacement and 57 (range: 32 to 74) years for repair (p < 0.01). Atrial fibrillation occurred in 34% of patients. The hospital mortality rate was 11% (26 patients). Of the 209 survivors, 137 were assigned to antiplatelet treatment with ticlopidine for the first three months of follow up. The other 72 received either oral anticoagulation (coumadin; n = 40), aspirin (n = 14) or no medication (n = 18). In 15 patients, ticlopidine treatment was interrupted due to diarrhea (13 cases), mild allergic reaction (one) or anemia (one). The mean follow up was 3.2 years (range: 1 month to 6 years); cumulative follow up was 684 patient-years (pt-yr) and was complete in 96% of cases. RESULTS: There were two episodes of thromboembolism in the ticlopidine group at 1 month and 6 months respectively, with a linearized incidence of 0.5% pt-yr. In the coumadin group there were four episodes of thromboembolism, three within the first three months of follow up. The linearized incidence was 3% pt-yr (p < 0.01). There were three episodes of hemorrhage in the ticlopidine group in the first three months of follow up and one in the coumadin group. The linearized incidence was 0.75% pt-yr. CONCLUSIONS: Following heart valve repair or replacement with a bioprosthesis, the first three months is a high-risk period for thromboembolism. Ticlopidine seems to prevent this complication better than conventional therapy with oral anticoagulants. Nevertheless, hemorrhage continues to be a problem with ticlopidine therapy.