Bioprosthetic Mitral Valve Research Articles

Use of the Valvular Resistance in the Separation of Normal and Stenotic Hancock Mitral Valves

Recent data suggests that the pressure-flow relationship for normal bioprosthetic mitral valves is linear. If this is correct, the valve resistance may provide a better indicator of normal mitral function than the Gorlin valve area. We compared the Gorlin valve area to the valve resistance (calculated as flow/pressure) in order to determine which better separated normal and stenotic Hancock mitral valves. Measurements were made using left atrial and left ventricular catheters in 42 patients undergoing Hancock mitral valve replacement. Patients were studied during pacing and isoproterenol infusion for a total of 141 measurements. Stenotic Hancock mitral valve hemodynamics were obtained at cardiac catheterization from eight patients who were studied at rest and during atrial pacing and from an additional eight patients culled from the literature (a total of 23 stenotic measurements). The Gorlin valve area ranged from 1.1 to 4.4 cm2 for the normally functioning Hancock valves and from 0.4 to 1.54 cm2 for the stenotic valves. Six measurements in patients with confirmed stenotic valves yielded Gorlin areas larger than the lowest area found in the normal valves and no value of the Gorlin valve area correctly classified all of the normal and the stenotic valves.(ABSTRACT TRUNCATED AT 250 WORDS)

Detection, localization, and quantitation of bioprosthetic mitral valve regurgitation. An in vitro two-dimensional color-Doppler flow-mapping study.

The usefulness of two-dimensional color-Doppler flow-imaging (2D Doppler) in the detection, localization, and quantitation of bioprosthetic mitral valve regurgitation is uncertain. Mitral bioprostheses, before and after the creation of transvalvular (n = 33), paravalvular (n = 17), or combined (n = 23) defects, were mounted in a pulsed duplication system (flow rates, 2.5-6.5 l/min; pulse rate, 70 beats/min). An Aloka 880 2D Doppler system (Japan) was used to image the regurgitant jets in the simulated left atrial chamber, analogous to images obtained with transesophageal echocardiography. Jet area was corrected to an estimate of stroke volume: 2D Doppler measurements were divided by [(valve effective orifice area) X (continuous-wave Doppler-determined mean diastolic filling velocity)]/pulse rate. Regurgitant fraction and regurgitant volume were measured by an electromagnetic flow probe. 2D Doppler correctly identified the presence and location of paravalvular regurgitation. In transvalvular and combined transvalvular-paravalvular defects, there were six incorrect interpretations, all having transvalvular regurgitant volumes less than 4 ml/beat. In the presence of transvalvular regurgitation, jet area, length, and width correlated linearly with regurgitant volume (r = 0.82, 0.80, and 0.68, respectively; p less than 0.0001) and regurgitant fraction (r = 0.62, 0.61, and 0.45, respectively; p less than 0.001). Correlations with regurgitant fraction were improved when 2D Doppler measurements were corrected for stroke volume (r = 0.78, 0.79, and 0.67, respectively; p less than 0.0001). Mitral bioprostheses with transvalvular defects were also studied at varying flow rates (3.2-7.5 l/min) and pulse rates (70, 90, and 110 beats/min). The correlation between jet area and regurgitant volume was improved with a second-order polynomial regression (r = 0.93, p less than 0.0001). Our conclusions are that 1) in this in vitro model analogous to transesophageal imaging, 2D Doppler accurately detects and localizes bioprosthetic mitral valve regurgitation; 2) in transvalvular bioprosthetic mitral valve regurgitation, 2D Doppler measurement of jet area has a curvilinear relation with regurgitant volume, and correlation with regurgitant fraction is improved with correction for stroke volume; and 3) in paravalvular bioprosthetic mitral valve regurgitation, correlations between 2D Doppler measurements and regurgitant volumes are weaker, possibly because of jet eccentricity.

僧帽弁位生体弁機能の経年変化と生体弁機能不全 超音波ドプラ法による検討

僧帽弁位生体弁機能の経年変化と生体弁機能不全 超音波ドプラ法による検討

Seguimento de 9 anos da bioprótese valvular cardíaca de pericárdio bovino IMC-Biomédica: estudo multicêntrico

De dezembro de 1977 a novembro de 1986, foi usado o bioenxerto valvular cardiaco de pericardio bovino IMC-Biomedica na posicao mitral, em 798 pacientes, com idade media de 42 anos. Os 722 pacientes sobreviventes foram observados por um periodo de ate 9 anos, representando 27036 meses, ou 2253 anos. O estudo indicou um indice de sobrevida de 66% para os adultos e 69% para os jovens, sendo de 94% e 80% o indice de sobrevida para os adultos e jovens, respectivamente, com pos-operatorio de 5 anos. A frequencia das complicacoes diante da amostra analisada foi: 0,4% de rotura do tecido; 0,4% de vazamento paravalvular; 2,7% de acidente vascular cerebral; 3,2% de endocardite infecciosa; 4,4% de calcificacao. A curva atuarial de calcificacao entre os anos de 1978 e 1982 (Grupo I) mostrou 94% dos adultos e 12% dos jovens livres dessa complicacao. Por outro lado, de 1982 a 1986 (Grupo II), esse indice subiu para 99,0% entre os adultos e 92,0% para os jovens. Deste modo, concluimos que a nossa opcao pela bioprotese de pericardio bovino foi apropriada, visto que 96% dos pacientes estiveram livres de complicacoes fatais relacionadas a bioprotese, o que significa que, em 9 anos, o potencial da bioprotese foi apenas de 4%.

Doppler and echocardiographic features of normal and dysfunctioning bioprosthetic valves

Echocardiographic and Doppler studies were performed on 183 clinically normal and 58 severely dysfunctioning bioprosthetic mitral, aortic and tricuspid valves. The valve dysfunction resulted from spontaneous cusp degeneration in 49 instances and from paravalvular regurgitation in 9. The pulsed Doppler study demonstrated regurgitant flow in 36 (92%) of 39 regurgitant valves and 8 (90%) of 9 paravalvular regurgitant valves. Diagnostic echocardiographic features were present in only 51 and 10% of the patients, respectively. Although the Doppler regurgitant jet was peripheral in seven of the nine patients with paravalvular regurgitation, it was not possible to differentiate these patients from those who had valve degeneration and cusp tear at the periphery of the valve ring. Eight patients presented with a musical holosystolic murmur of mitral insufficiency. In all eight there was a characteristic honking intonation on the audio signal and a striated shuddering appearance on the video Doppler signal. Ten stenotic mitral bioprosthetic valves (less than or equal to 1.1 cm2 valve orifice) were identified by Doppler study. Diagnostic echocardiographic features were present in only two of these patients. The Doppler-derived valve orifice dimension correlated well (r = 0.83) with cardiac catheterization values. Fourteen asymptomatic or minimally symptomatic patients had echocardiographically thickened mitral cusps (greater than or equal to 3 mm). These patients had a significantly (p less than 0.0001) smaller valve area as compared with normal control valves, and during 4 to 24 months of follow-up, five of these patients developed severe valve regurgitation or stenosis. Doppler ultrasound is more sensitive than echocardiography in diagnosing bioprosthetic valve stenosis and regurgitation.(ABSTRACT TRUNCATED AT 250 WORDS)

An eight-year experience with porcine bioprosthetic cardiac valves

A total of 589 porcine bioprostheses were implanted in 509 patients from January, 1976, through December, 1983. Of the valves implanted, 390 were Hancock and 199 were Carpentier-Edwards. A total of 1,633 patient-years was accrued, with a mean follow-up of 38 months per patient. Two hundred eight patients had aortic valve replacement, 209 had mitral valve replacement, and 79 had multiple valve replacements, of which 46 were aortic and mitral replacements. The mortality for isolated aortic valve replacement was 5.8%; for isolated mitral replacement, 8.6%, and for all patients, 10.9%. Late mortality was 3.9% per patient-year. The actuarial survival rate at 5 years was 79% for aortic, 68% for mitral, and 76% for aortic-mitral valve replacement. There were 12 thromboembolic events (0.73% per patient-year). Two episodes occurred in patients with an aortic bioprosthesis, nine in patients with a porcine mitral valve, and one in a patient with mitral and tricuspid bioprosthetic valves. The probability of remaining free of thromboembolism at 5 years was 99% for the group having aortic valve replacement, 93% for those having mitral replacement, and 100% for the group having aortic-mitral valve replacements. Thirteen episodes of endocarditis occurred (0.8% per patient-year). Seven of the 13 patients died as a direct result of endocarditis. The probability of remaining free of prosthetic endocarditis at 5 years was 97% for the aortic valve replacement group, 95% for the mitral group, and 97% for the aortic-mitral group. There were 20 instances of xenograft failure (1.2% per patient-year). The probability of remaining free of valve failure at 5 years was 96% for the aortic valve replacement group, 93% for the mitral group, and 93% for the aortic-mitral replacement group. Primary tissue failure of a prosthesis occurred in seven patients, all with Hancock valves (0.43% per patient-year). As yet there has been no primary tissue failure of the Carpentier-Edwards prosthesis. There also appears to be a lower incidence of thromboembolism (Edwards, 0.3% per patient-year; Hancock, 0.8% per patient-year) and endocarditis (Edwards, 0.6% per patient-year; Hancock, 1.0% per patient-year). The low incidence of complications with the porcine bioprosthetic valve, especially the Carpentier-Edwards, encourages us to recommend its continued use, especially in situations in which anticoagulation is contraindicated.

Bioprosthetic mitral valve dysfunction following blunt chest trauma

Bioprosthetic mitral valve dysfunction following blunt chest trauma

Early and late risk of mitral valve replacement: A 12 year concomitant comparison of the porcine bioprosthetic and prosthetic disc mitral valves

A consecutive series of 706 mitral valve replacements was performed from January, 1972, to January, 1984. The follow-up ranged from 6 to 150 months with a mean of 50 and a median of 43 months. Seven percent (50) of the patient were lost to follow-up. There were 243 men and 463 women, whose ages ranged from 17 to 86 years (mean 58). A porcine bioprosthetic valve was implanted in 528 patients (514 Hancock and 14 Carpentier-Edwards valves) and a prosthetic disc valve in 178 patients (102 standard disc Björk-Shiley, 34 Beall, and 42 Harken disc valves). Seven patients were in Functional Class II, 325 in Class III, and 374 in Class IV. A concomitant operative procedure was performed in 253 of the 706 patients (36%). Mitral regurgitation was the primary hemodynamic lesion in 363 and mitral stenosis in 343. Operative mortality figures were as follows: 77 of 706 (11%) for the overall group, 34 of 453 (7.5%) for isolated mitral valve replacement, 30 of 169 (17.5%, p = 0.001) for mitral replacement plus coronary bypass, 49 of 528 (9%) for the bioprosthetic valve group, and 28 of 178 (16%) for the prosthetic disc valve group (p = 0.01). After the operation, 262 patients were in Functional Class I, 99 in Class II, and 18 in Class III. The long-term survival rate was significantly lower in patients who had an associated procedure (45% +/- 6%), who had mitral regurgitation rather than mitral stenosis (53% +/- 5% versus 67% +/- 4%) (p = 0.002), who were in Functional Class IV rather than Classes I to III (51% +/- 4% versus 70% +/- 4%) (p = 0.001), and who received a prosthetic disc valve rather than a bioprosthesis (40% +/- 6% versus 67% +/- 4%) (p = 0.001). Thromboembolic rates were significantly higher with prosthetic valves than with bioprosthetic valves (4.6% +/- 0.22% versus 2.4% +/- 0.5% per patient-year of follow-up), and the incidence of anticoagulant-related hemorrhage was significantly higher in the prosthetic valve group (1.65% versus 0.43% per patient-year). Primary valve dysfunction was significantly more common in the bioprostheses (1.23% versus 0.40% per patient-year).(ABSTRACT TRUNCATED AT 400 WORDS)

Huge Left Atrial Thrombus and Valve Degeneration in a Patient with a Bioprosthetic, Porcine, Mitral Valve

A 43 year old man with a Hancock porcine bioprosthetic valve in the mitral position developed a huge thrombus filling the entire left atrium and chronic degeneration of the bioprosthetic mitral valve. The effective valve orifice was less than 2 mm. These severe findings leading to the patient's death remained undetected while he was alive. This case illustrates the great need for a serial phonoechocardiographic studies in all patients with prosthetic valves.

Calcification of aortic versus mitral porcine bioprosthetic heart valves: A radiographic study comparing amounts of calcific deposits in valves explanted from the same patient

Calcium detected by radiography was compared in 10 pairs of aortic and mitral glutaraldehyde-treated porcine bioprosthetic heart valves explanted from 10 patients (7 men and 3 women), aged 19 to 68 years (mean 43). Both valves of 6 pairs of valves had undergone primary tissue failure (revealed by cardiac catheterization and angiography) and 1 valve of the other 4 pairs of valves had undergone primary tissue failure. These porcine valves had been implanted from 2 1/4 to 9 years (mean 5 3/4). All 20 explanted valves contained calcium. The grade of calcium was the same in 4 pairs of valves (grade 2+ or 3+), and 1 grade different in 4 pairs of valves (grade 1+ to 4+), with the greater calcium evenly divided between the 2 valve positions. There was more than 1 grade greater mitral valve calcium in 2 pairs of valves (grade 3+ and 4+ mitral vs 1+ and 2+ aortic, respectively). Thus, calcium is usually present in both aortic and mitral valve positions when bioprosthetic valves of this type in either valve position fail as a result of primary tissue failure, and radiographic calcium in porcine bioprosthetic valves is usually similar in grade in both the aortic and mitral valve positions.

Frequency spectra of the first heart sound and of the aortic component of the second heart sound in patients with degenerated porcine bioprosthetic valves

To determine the usefulness of the frequency of heart sounds in the assessment of porcine bioprosthetic valve degeneration, frequency spectra of phonocardiograms of the first heart sound and the aortic component of the second sound were analyzed in 31 patients with degenerated porcine bioprosthetic valves. Comparisons were made with 35 control patients whose valves were inserted 1 month or less. Among 23 patients with degenerated porcine bioprosthetic valves in the mitral position, the dominant frequency of the first heart sound was 95 ± 11 Hz, which exceeded the first sound in 18 controls (51 ± 3 Hz) (p < 0.01). The degenerated mitral porcine bioprosthetic valves of 14 patients showed calcification or fibrosis and the first heart sound in these patients was 115 ± 16 Hz, which exceeded that of control subjects (p < 0.001). The degenerated mitral porcine bioprosthetic valves of 9 patients showed torn leaflets only, and the first heart sound in these patients was 64 ± 9 Hz, which did not differ from that of control subjects. In the aortic position, 8 valves were degenerated and the aortic component of the second sound was 109 ± 12 Hz, which was higher than that in 17 control subjects (63 ± 4 Hz) (p < 0.001). Only 2 of these degenerated valves showed tears unaccompanied by calcific deposits or fibrosis, and the frequencies were comparable to that of control subjects. These observations indicate that the frequency of heart sounds in patients with degenerated porcine bioprosthetic valves becomes abnormally elevated when degeneration is accompanied by calcification or fibrosis, which causes the cusps to stiffen.

Hemodynamic determinants of the frequency and amplitude of a musical murmur produced by a regurgitant mitral bioprosthetic valve

The purpose of this study was to assess the hemodynamic determinant of the amplitude and frequency of a musical murmur produced by a regurgitant degenerated bioprosthetic valve in the mitral position. The prosthetic valve, obtained at surgery, was studied in the mitral position of an in vitro pulse duplicating system. In vitro, the valve produced a musical murmur that was caused by flutter of a flail leaflet. When the peak pressure difference between the left ventricle and left atrium was increased from 95 to 150 mm Hg, the fundamental frequency of the musical murmur increased from 91 to 187 hertz and the amplitude increased from 2,080 to 11,420 dynes/cm 2. The fundamental frequency of the musical murmur was linearly related to the peak systolic pressure difference between the left ventricle and the left atrium (correlation coefficient [r] = 0.99). Similarly, the fundamental frequency of the musical murmur was linearly related to the magnitude of regurgitant flow across the valve (r = 0.99); and the regurgitant flow as expected was linearly related to the systolic pressure difference between the left ventricle and left atrium. The amplitude of the musical murmur was also related to both the peak systolic pressure difference between the left ventricle and left atrium (r = 0.99) and the magnitude of regurgitant flow (r = 0.99). These results indicate that the magnitude of regurgitant flow, determined by the systolic pressure difference between the left ventricle and left atrium, was a determinant of both the amplitude and the frequency of the musical murmur.

Two-dimensional echocardiographic evaluation of mitral bioprosthetic function in infants and children

Two-dimensional echocardiography (2DE) was performed on 13 bioprosthetic mitral valves in 11 pediatric patients, 1 week to 46 months following implantation. Cardiac catheterization confirmed the echocardiographic findings of seven valves. The 11 normally functional bioprosthetic mitral valves by 2DE had leaflet thickness not exceeding 2.0 mm, freely moving leaflets, and normal sewing ring motion. The left atrium (LA) was enlarged only in the presence of mitral valve obstruction, atrial fibrillation, or left ventricular (LV) dysfunction. One bovine valve was stenotic due to fibrous tissue beneath normal valve leaflets; 2DE demonstrated limited leaflet motion, tissue beneath a thin valve leaflet, increase rocking motion of the sewing ring, and LA enlargement. In another patient, a bovine valve produced subaortic LV obstruction due to growth of fibrous tissue outside the stent; 2DE showed that the valve leaflets were thin and moved normally without excessive rocking of the valve ring, and identified the abnormal fibrous tissue in the LV outflow tract.

Platelet reactivity in patients with degenerated porcine bioprosthetic valves

The reactivity of circulating platelets from 6 patients with degenerated porcine bioprosthetic valves inserted for from 4 to 7 years was assessed just prior to removal of the bioprosthesis. The degree of surface response (cytoplasmic spreading exhibited by single, adherent platelets) and amount of aggregation shown by these platelet populations were evaluated using an in vitro test system in which platelets were exposed to a Formvar film under standardized conditions. Circulating platelets from 5 of the 6 patients were hyperactive. Each of the patients with an abnormal platelet response had platelets deposited onto the surface of the excised degenerated bioprosthetic valve when it was examined by scanning electron microscopy. Platelets from one patient were normally reactive in vitro and no platelet deposits were seen on the surface of his degenerated mitral bioprosthetic valve. These observations demonstrate that platelets from patients with degenerated porcine bioprosthetic valves show increased reactivity. Our study also showed that the in vivo deposition of platelets onto the surface of degenerated porcine bioprosthetic valves is paralleled by a hyperactive response of the circulating platelets which can be measured in vitro. These results suggest that the porcine bioprosthesis, at least when it is degenerated, may be more thrombogenic than clinical evaluations of the incidence of thromboembolic events in these patients would indicate.

Frequency of the first heart sound in the assessment of stiffening of mitral bioprosthetic valves.

The frequency spectrum of the first heart sound (S1) was measured noninvasively in 54 patients with porcine bioprosthetic valves inserted in the mitral position. Phonocardiograms were recorded on magnetic tape on line with a signal processor with which the frequency spectrum and peak frequency of S1 were determined. In 19 patients with normal natural mitral valves, the apparent peak frequency within the range of measured frequencies of S1 was 46 +/- 2 Hz (mean +/- SEM). In 11 patients with porcine bioprosthetic valves implanted in the mitral position for less than or equal to 11/2 years, the apparent peak frequency of S1 was 43 +/- 3 Hz, which was not significantly different from S1 in patients with normal mitral valves. However, in 33 patients with porcine bioprosthetic valves in place 5-7 years, the apparent peak frequency of S1 was higher, 67 +/- 2 Hz (p < 0.001). In patients in whom the porcine bioprosthetic valve was implanted 5 years or longer, the frequency spectrum of S1 showed a greater proportion of sound energy at frequencies between 50-200 Hz compared with patients in whom the prosthetic valve was implanted 11/2 years or less. changes of the frequency of S1 in these patients may be a manifestation of stiffening of the valve as a result of early degenerative changes.