Non-invasive assessment by Doppler ultrasound of 155 patients with bioprosthetic valves: a comparison of the Wessex porcine, low profile Ionescu-Shiley, and Hancock pericardial bioprostheses.

One hundred and fifty five patients with 167 bioprosthetic valves (68 Wessex porcine, 54 Hancock pericardial, and 45 low profile Ionescu-Shiley pericardial valves) were studied by Doppler ultrasound. Valve gradients were calculated from the mitral and aortic flow velocities by the modified Bernoulli equation. Mean mitral gradients were significantly smaller across the Ionescu-Shiley valves than across the Wessex porcine or Hancock pericardial valves. Mitral pressure half time was, however, significantly longer in the Hancock pericardial than in the Wessex porcine or Ionescu-Shiley valves. No significant differences were seen among the groups of aortic bioprostheses, though the comparable size of Wessex porcine valves showed significantly higher gradients. Bioprosthetic regurgitation was detected in 13 of 103 mitral and 11 of 59 aortic valves, though it was suspected clinically in only 12 mitral and six aortic bioprostheses. Doppler ultrasound is a repeatable non-invasive method of acquiring haemodynamic information in vivo from a variety of bioprostheses and it can detect bioprosthetic regurgitation at an early stage.     

Flow characteristics of bioprosthetic heart valves

A review of the in vivo and in vitro fluid dynamic performance of three bioprosthetic heart valves is presented. Data on Hancock porcine valves (standard models 242 aortic and 342 mitral and modified orifice model 250 aortic), Carpentier-Edwards porcine valves (model 2625 aortic and 6625 mitral), and the Ionescu-Shiley pericardial valve are reviewed. These valves were chosen because of their past or present popularity in clinical use and because of the variation in fluid dynamic performance reported by different investigators. The flow parameters that are reported include in vivo and in vitro mean pressure drop, cardiac output or cardiac index, regurgitant volume, effective orifice area, and performance index. These data provide a framework for differentiation of normal and abnormal bioprosthetic valve function.     

Errors in pressure gradient measurement by continuous wave Doppler ultrasound: type, size and age effects in bioprosthetic aortic valves

The accuracy of continuous wave Doppler ultrasound in deriving pressure gradients across bioprosthetic heart valves was evaluated in an in vitro pulse duplicator. Simultaneous pressure transducer and Doppler measurements were made in new and explanted aortic bioprosthetic valves of several sizes and four types: Carpentier-Edwards, Ionescu-Shiley, Hancock standard and Hancock modified. The mean and peak gradients calculated by the modified Bernoulli equation from Doppler velocity measurements were always greater than those measured manometrically, despite corrections for location dependence of the manometric gradient (or pressure recovery). The relation between manometric and ultrasonically determined gradient was found to be statistically dependent on the valve type (mean gradient p less than 0.0001; peak gradient p = 0.0003) and size (mean gradient p = 0.0089; peak gradient p = 0.0107). Effects of implantation were observed, but were not shown to be significant. It is concluded that the continuous wave Doppler velocity data overestimated prosthetic valve pressure gradient in all cases, even when pressure recovery was taken into account. Clinicians should be wary of Doppler data when making major diagnostic or therapeutic decisions.     

A mid-term clinical and hemodynamic evaluation of the Wessex and Hancock II bioprostheses]

The purpose of this study is to compare clinically and hemodynamically the Wessex and Hancock II porcine bioprostheses. We compared functional class and data from echo-Doppler in 34 Wessex bioprostheses (group A) with those in 42 Hancock II bioprostheses (group B). We subdivided group A into A1 and A2. A1 was made up of 23 Wessex manufactured since 1986. A2 constituted 11 Wessex made before 1986 which belonged to a series with some variations in the manufacturing process, and in which some early dysfunctions have been described. We compared data from these sub-groups between each other as well as with those of group B. The groups were homogeneous in age, sex, patients body surface and the time elapsed since the prosthetic implant. The mean mitral gradient, the mitral area, the peak aortic gradient and the regurgitation incidence were similar in groups A and B. In A2 the mean mitral gradient was significantly superior to that of group B (7.1 +/- 1.1 mmHg vs 5.4 +/- 1.4 mmHg; p less than 0.01), and the mitral area showed a tendency to be inferior, although with no statistical significance. The functional class of the patients was similar in all the groups. We conclude that the Wessex bioprosthesis presents hemodynamic data and functional class similar to those of the Hancock II, with the exception of a sub-group of Wessex manufactured before 1986 which presents mean mitral gradients superior to the others and which would warrant further studies.     

An emergency physician's guide to prosthetic heart valves: identification and hemodynamic function

We describe methods for identifying the type and size of seven commonly used prosthetic heart valves and how these features influence the hemodynamics of flow through the valve. The four mechanical heart valves reviewed are Starr-Edwards silicone rubber ball valves (Models 1200/1260 aortic and 6120 mitral valves), Bjork-Shiley tilting disc valves (60 degrees standard spherical model and the 60 degrees convexo-concave model), Medtronic-Hall (Hall-Kaster) tilting disc valve, and St Jude Medical bileaflet valve. The three bioprostheses reviewed are Hancock porcine valve, Carpentier-Edwards porcine valve, and Ionescu-Shiley bovine pericardial valve. These valves were chosen because of their past or present popularity and therefore are the ones most apt to be implanted in patients seen in the emergency department.     

Doppler hemodynamic evaluation of prosthetic (Starr-Edwards and Bj?rk-Shiley) and bioprosthetic (Hancock and Carpentier-Edwards) cardiac valves

One hundred thirty-four patients with prosthetic or bioprosthetic heart valves were investigated with Doppler echocardiography to determine normal values for commonly used prosthetic valves and to test the specificity of abnormal Doppler findings. In 70 patients the aortic valves had been replaced and in 64 the mitral valves had been replaced. Gradients across prostheses in the aortic position were calculated from maximal velocity. Peak calculated aortic transvalvular gradients in normal subjects were 22 +/- 10 mm Hg in 33 Bj?rk-Shiley valves, 23 +/- 10 mm Hg in 27 porcine valves and 29 +/- 13 mm Hg in 6 Starr-Edwards valves. Mild aortic regurgitation was seen in 42% of Bj?rk-Shiley valves, 26% of porcine valves and 2 of 6 Starr-Edwards valves. Mitral valve orifice was calculated by the pressure half-time method. In clinically normal patients with mitral valve prostheses, the effective mitral valve orifice was 2.5 +/- 0.8 cm2 in 35 Bj?rk-Shiley valves, 2.1 +/- 0.7 cm2 in 17 porcine valves, and 2.0 +/- 0.3 cm2 in 10 Starr-Edwards valves. Mitral regurgitation was found in 11% of Bj?rk-Shiley valves, 19% of porcine valves and 30% of Starr-Edwards valves. Repeat studies at 2 weeks to 14 months revealed no difference in 8 aortic and 14 mitral prostheses. Seven aortic and 4 mitral valves functioned abnormally as determined by Doppler, and the abnormal function was confirmed in each at surgery or at cardiac catheterization.(ABSTRACT TRUNCATED AT 250 WORDS)     

Platelet adherence to bioprosthetic cardiac valves

Tissue from porcine aortic bioprosthetic valves (Hancock) and bovine pericardial valves (Ionescu-Shiley) were incubated with platelets tagged with chromium-51. There was a significantly decreased platelet-collagen adhesion reaction in both porcine and bovine glutaraldehyde-treated valves compared with reactions in fresh porcine aortic valve and fresh bovine pericardium (p less than 0.001). There was no significant difference in the platelet-collagen reaction between porcine aortic valve and bovine pericardium, whether treated with glutaraldehyde or in the fresh state (p greater than 0.05). The addition of aspirin did not significantly decrease the platelet-collagen reaction on glutaraldehyde-treated or fresh valves (p greater than 0.05). Rinsing fresh valves in plasma appeared to offer more protection against platelet adhesion than rinsing them in saline solution (p less than 0.01). It is concluded that there is no difference in platelet adherence to porcine aortic valve or bovine pericardium and that glutaraldehyde, and perhaps plasma, offers a protective effect against platelet adhesion.     

Doppler echocardiography assessment of prosthetic heart valves

Transthoracic Doppler echocardiography is an accurate noninvasive method for the evaluation of prosthetic valve function. The flow characteristics and pressure gradients of normally functioning mechanical and bioprosthetic valves have been, in general established. Normal functioning mitral valve prostheses have a valve area > 1.8 cm² with the St. Jude valve having the largest effective valve area and normally functioning aortic prosthetic valves have a peak instantaneous gradient of < 45 mmHg, with the Starr-Edwards valves (Starr-Edwards, Irvine CA) showing the highest gradients. The incidence of minimal or mild regurgitation is approximately 15% to 30% in the mitral position and 25% to 50% in the aortic position, with the higher incidence of regurgitation seen with mechanical compared to bioprosthetic valves. Transthoracic Doppler echocardiography can accurately detect patients with prosthetic valvular stenosis. The presence of prosthetic aortic regurgitation can also generally be accurately assessed, except in the presence of both prosthetic aortic and mitral valves. Assessment of prosthetic mitral regurgitation remains limited due to significant attenuation of the ultrasound beam by the prosthesis and the frequent underestimation of severity of regurgitation. Other limitations of transthoracic studies include assessment of leaflet morphology, detection of vegetations and valve abscesses, and differentiation between valvular and paravalvular regurgitation.     

Effect of prosthetic aortic valve design on the Doppler-catheter gradient correlation: an in vitro study of normal St. Jude, Medtronic-Hall, Starr-Edwards and Hancock valves.

To evaluate the normal range of Doppler-derived velocities and gradients, their relation to direct flow measurements and the importance of prosthetic valve design on the relation between Doppler and catheter-derived gradients, five sizes of normal St. Jude bileaflet, Medtronic-Hall tilting disc, Starr-Edwards caged ball and Hancock bioprosthetic aortic valves were studied with use of a pulsatile flow model. A strong linear correlation between peak velocity and peak flow, and mean velocity and mean flow, was found in all four valve types (r = 0.96 to 0.99). In small St. Jude and Hancock valves, Doppler velocities and corresponding gradients increased dramatically with increasing flow, resulting in velocities and gradients as high as 4.7 m/s and 89 mm Hg, respectively. The ratio of velocity across the valve to velocity in front of the valve (velocity ratio) was independent of flow in all St. Jude, Medtronic-Hall, Starr-Edwards and Hancock valves when the two lowest flow rates were excluded for Hancock valves. Although Doppler peak and mean gradients correlated well with catheter peak and mean gradients in all four valve types, the actual agreement between the two techniques was acceptable only in Hancock and Medtronic-Hall valves. For St. Jude and Starr-Edwards valves, Doppler gradients significantly and consistently exceeded catheter gradients with differences as great as 44 mm Hg. Thus, Doppler velocities and gradients across normal prosthetic heart valves are highly flow dependent. However, the velocity ratio is independent of flow.(ABSTRACT TRUNCATED AT 250 WORDS)     

Hemodynamic assessment of the new aortic carpentier-edwards bioprosthesis

Although glutaraldehyde-preserved porcine aortic Hancock heterografts have lower thromboembolism incidence than mechanical aortic valves, Hancock xenografts provide less functional aortic outflow orifices and thereby greater transvalvular gradients than mechanical prostheses. The newly developed aortic Carpentier-Edwards porcine heterografts comprise a thin-walled Elgiloy flexible metal stent covered with Teflon which provides somewhat wider internal orifices than aortic Hancock valves of the same external annulus diameter. Since aortic Carpentier-Edwards xenografts have not been clincially evaluated previously, the present study assessed cardiac function and heterograft performance (1.7 months postoperation) and clinical status (4.2 months postoperation) of 19 patients with severe aortic stenosis and/or regurgitation prior to surgery. Left ventricular end-diastolic pressures decreased (17 to 9 mm Hg), cardiac index remained normal, and clincial symptomatology diminished markedly. Mean peak transxenograft systolic pressure was only 16 mm Hg (valve area 1.73 cm²), without meaningful regurgitation. Thus aortic Carpentier-Edwards bioprostheses provide generally excellent heterograft function which appears more favorable than previous reports of Hancock xenografts.     

Progressive functional deterioration of bioprostheses assessed by Doppler ultrasonography

Doppler echocardiography was used to study the function of bioprosthetic heart valves by noninvasive means in 32 patients aged 29 to 72 years at various postoperative intervals. There were 24 Ionescu-Shiley, four Hancock, and four Carpentier-Edwards prostheses, 19 in the aortic and 13 in the mitral position. Initial studies were performed at a mean of 2.3 years after implantation and were repeated one, two, and three years thereafter. Flow velocities in the mitral orifice, left ventricular outflow tract, and ascending aorta, as well as mitral pressure half-time, were measured from pulsed-wave or continuous-wave Doppler recordings. Mitral and aortic valve areas and aortic pressure gradients were calculated. In aortic prostheses the valve area decreased and pressure gradient increased progressively in relation to the time from implantation. The mean value (+/- SD) of the aortic valve area was 67 +/- 17 percent of the manufacturer's nominal value at the first examination and 57 +/- 20 percent one year later, 51 +/- 14 percent two years later, and 46 +/- 11 percent three years later (overall differences, p less than 0.01). In mitral prostheses, reduction of the valve area was not related to the time from implantation. The mean mitral valve area was 45 +/- 12 percent of the nominal value at rest and increased to 68 +/- 18 percent during exercise at a mean of 45 months after implantation. There was no change in these values at the one-year repeat study. It is concluded that in a population with predominantly pericardial bioprostheses, (1) aortic tissue prostheses showed a progressive functional deterioration demonstrable by Doppler echocardiography, most probably due to degenerative changes; and (2) in mitral tissue prostheses, there was no significant reduction of orifice area in relation to time from implantation. Reduction of mitral valve areas may, to some extent, reflect a less than full opening at rest.     

Clinical results of pericardial xenograft valves: the Ionescu-Shiley and Hancock valves

Between 1979 and 1985, 552 Ionescu-Shiley valves were implanted in 511 patients. The Hancock valve was implanted in 122 patients (129 valves) between 1982 and 1983. Sixty percent of procedures were isolated aortic valve replacements. In the Ionescu series, 59% of these were 19 or 21 mm valves while only 15% of the Hancock valves were of this size. For isolated mitral valve replacement, 76% of Ionescu-Shiley valves were 25 to 27 mm, compared to 36% of the Hancock valves. Patient age, sex, prior operations, concomitant surgery (usually coronary bypass), operative mortality and late deaths were similar for both valves. A mean follow-up of 38 months was obtained for each valve population (99% complete) representing a cumulative 1497 patient-years for the Ionescu-Shiley valve and 375.4 patient-years for the Hancock valve. Actuarial survival for the former was 73 +/- 4% at 72 months, and 65 +/- 14% for Hancock valves at 60 months. The frequency of major events during follow-up (thromboembolism, anticoagulant related hemorrhage, bland perivalvular leak and prosthetic valve endocarditis) were similar, but the frequency of primary tissue valve failure was markedly different for the two valves (1.1% per patient-year for Ionescu-Shiley valves and 5.9% for the Hancock valve). The mean interval to replacement of an Ionescu mitral prosthesis was significantly shorter (23.4 months) than for replacement of an aortic prosthesis (42 months) while the mean interval to replacement of an Ionescu aortic and/or a Hancock aortic or mitral were all similar.(ABSTRACT TRUNCATED AT 250 WORDS)     

Inhibition of cusp and aortic wall calcification in ethanol- and aluminum-treated bioprosthetic heart valves in sheep: background,mechanisms, and synergism

BACKGROUND AND AIM OF THE STUDY: Calcification of bioprosthetic heart valves fabricated from glutaraldehyde (GA)-pretreated heterograft tissue is frequently responsible for the clinical failure of these devices. Stentless bioprostheses fabricated from GA-fixed porcine aortic valves pose an important challenge in this regard, as pathologic calcification can affect not only the bioprosthetic cusps, but also the aortic wall segment. METHODS: A synergistic approach was used to prevent bioprosthetic cusp and aortic wall calcification. Ethanol pretreatment of bioprosthetic heart valves was shown to inhibit cuspal calcification due to multiple mechanisms, including alterations of collagen structure and lipid extraction. AlCl3 pretreatment of bioprostheses to prevent calcification was also investigated; this alters elastin structure, inhibits alkaline phosphatase, and complexes with phosphoesters, thereby inhibiting aortic wall mineralization. RESULTS: Experimental data from rat subdermal implants and sheep mitral replacements showed successful synergism with co-pretreatment of porcine aortic valve bioprostheses with ethanol and AlCl3. Significant inhibition of both cusp and aortic wall calcification was achieved by differential pretreatments that restrict AlCl3 to only the aortic wall, and not the cusp, accompanied by ethanol cuspal exposure. Sequential exposure of bioprostheses, first to AlCl3 and then to ethanol, led to unexpectedly severe cuspal calcification. CONCLUSION: Differential pretreatment of stentless bioprostheses with ethanol and AlCl3 can effectively inhibit both cuspal and aortic wall calcification.     

The third generation Carpentier-Edwards bioprosthesis: early results

The current status of valve replacement was reviewed by analyzing six groups of 100 consecutive patients, each receiving the standard Carpentier-Edwards bioprosthesis, the Starr-Edwards valve or the Bj?rk-Shiley valve in the mitral or aortic position and operated on by the same surgeons in the same institution during an identical time frame. Data were evaluated for valve failure, reoperation, thromboembolism and valve-related deaths. Long-term results up to 9 years showed the superiority of bioprostheses over mechanical valves in terms of valve-related deaths and thromboembolic and anticoagulant complications for a similar rate of valve failure. Persistent drawbacks associated with valvular bioprostheses, namely, transvalvular gradients, limited durability and tissue calcification in young patients, led to continual improvements in valve design and preservation techniques and the development of the third generation Carpentier-Edwards bioprosthesis: the supraanular porcine valve and pericardial valve. The supraanular porcine valve was designed with the aim of decreasing the transvalvular gradient, decreasing turbulence, increasing longevity and decreasing calcification. The pericardial valve was designed with the aim of improving hemodynamics in small-sized orifices, improving mounting techniques to avoid fixation sutures at the commissures, achieving a flexible stent and improving preservation. Between July 1980 and October 1984, there were 391 supraanular porcine and 61 pericardial valves implanted. The supraanular valves were used for three purposes: isolated aortic, isolated mitral and mitral valve replacement associated with tricuspid anuloplasty. The pericardial valves were used for isolated aortic valve replacement. Short-term results (1 to 4 years) are presented concerning the clinical use of these third generation bioprostheses.     

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)     

Causes of failure and pathologic findings in surgically removed Ionescu-Shiley standard bovine pericardial heart valve bioprostheses: emphasis on progressive structural deterioration

Twenty-three Ionescu-Shiley standard bovine pericardial bioprostheses (15 aortic, seven mitral, and one tricuspid) removed at surgery from 21 adults, 28 to 75 years old (mean 55 at reoperation), were examined after functioning for as long as 84 months (mean 26). Reoperation was necessitated by active or healed endocarditis (10 valves), paravalvular leak (three), structural deterioration (eight), and other causes (two). Valves with degenerative dysfunction functioned 32 to 84 months (mean 68). Six had intrinsic cuspal calcification, one with stenosis, and there was regurgitation through secondary cuspal defects in five. Six valves had cuspal defects clearly associated with commissural sutures ("alignment stitches") unique to this valve design. One valve had a large basal cuspal tear. Other prominent pathologic features included gross cuspal thickening and mild stretching and microscopic deep fluid insudation, separation of collagen bundles, and mononuclear inflammation. Thus, structural disruption due to calcific tissue degeneration and design-related cuspal tears or commissural perforations are the predominant modes of degenerative failure of Ionescu-Shiley standard bovine pericardial valves.     

Early stenosis and calcification of glutaraldehyde-preserved porcine xenografts in children

Thirty-four glutaraldehyde-preserved porcine aortic valves have been implanted in children at the Center of Thoracic and Cardiovascular Surgery in G?ttingen since 1972. Severe stenosis of the right ventricular outflow tract (RVOT) due to massive calcification of the bioprosthetic valve was detected 15 to 76 months after surgery in 2 of 3 children with hospital-made, and in one of 25 children with commercially available valved conduits. The results with Hancock xenograft valves in mitral position were even more alarming. Five out of 6 children, aged 5 to 15 years (mean 9 years) presented similar massive calcification patterns of the bioprosthesis, necessitating reoperation from 23 to 63 months (mean 38.8 months) after implantation. Focal calcium deposits were found mostly in the central layers of the cusps; severe stenosis and regurgitation were due to immobilization of the leaf-lets which were fixed in a semi-open position. The causes for early valve dysfunction and calcification of glutaraldehyde-fixed porcine aortic bioprostheses in children remain to be further investigated. Degenerative changes have been shown to commence early after implantation, resulting in collagen disruption as early as 2 years later (3, 7, 19). There is evidence that these lesions could be predisposing factors for calcification, leading to accelerated calcification rats in children and patients with a high-calcium-turnover. The use of bioprostheses in children and adolescents must therefore be questioned since they appear to carry a high prospect to early valve deterioration.     

Serial Doppler Gradients Are Predictive of Future Bioprosthetic Valve Degeneration

Doppler echocardiography and color flow imaging are helpful techniques in evaluating the functional status of a bioprosthetic valve. The aim of this study was to determine whether serial Doppler gradients are predictive of future bioprosthetic valve degeneration. We performed serial echo-Doppler studies over a 6-year period (1988–1994) on 228 patients who had undergone mitral (n = 112) or aortic (n = 116) bioprosthetic valve implantation between 1973 and 1994. Thirtynine mitral prostheses and 30 aortic prostheses became dysfunctional and required reoperation. A serial rise in mean gradient of 5 mmHg or more across the mitral valve and 25 mmHg or more across the aortic valve was significantly associated with increased valve degeneration (odds ratio 3.40 and 16.11 and 95% confidence intervals 1.31 and 8.80 and 13.6 and 72.13 for the mitral and aortic valve, respectively). Both aortic and mitral valves began to degenerate after 8 years. Serial echo-Doppler studies showed a rise in transvalvular gradients around the same time. Closer evaluation for prosthetic valve dysfunction should be considered in patients 8 or more years status post surgery, especially those with high transvalvular gradients.     

Comparative study of primary tissue valve failure between Ionescu-Shiley pericardial and Hancock porcine valves in the aortic position

From August 1977 to June 1981, 221 patients received a Hancock porcine valve and 133 an Ionescu-Shiley bovine (I-S) pericardial valve as aortic valve substitutes. No special selection or randomization was used and no patient with either of these types of valves was excluded. Preoperative data show no differences between the groups influencing the appearance of primary tissue failure. Hospital survivors were followed until June 1984 and those with an uneventful history at least 36 months. Patients who died late postoperatively or who underwent reoperation for causes other than primary dysfunction were considered at risk until death or reoperation. Primary tissue failure occurred in 8 patients in the I-S group from 36 to 70 months postoperatively and in 6 patients of the Hancock group from 24 to 83 months. Linearized rates of primary failure were 0.61 valves per 100 patient-years for the Hancock and 1.70 valves per 100 patient-years for the I-S group. Mean age of patients with failing valves was 38 years (range 25 to 55) for Hancock valves and 39 years (range 15 to 62) for I-S valves. Actuarial analysis shows a lower rate of primary dysfunction in the Hancock group since the fourth year, which is statistically significant in the sixth and seventh years (96.5 +/- 1.5% vs 79.6 +/- 7.6% in the sixth year and 93.1 +/- 3.6 vs 79.6 +/- 7.6% in the seventh year). Microscopically, calcium and collagen degeneration were consistently associated and present on failing bioprostheses.(ABSTRACT TRUNCATED AT 250 WORDS)     

Doppler echocardiography in assessing mechanical and biological heart valve prostheses

The study was performed to assess Doppler echocardiographic features of mitral and aortic prosthetic valves of different types with both normal and abnormal function. Two hundred and twenty-three patients with 250 prostheses were studied. Two hundred eight valves (111 mitral, 95 aortic and 2 tricuspid) were considered to be functioning normally after clinical examination, phonocardiography and M-mode and 2D echocardiography. This group enabled us to define normal Doppler echocardiographic findings for different types of prosthesis. In mitral position, peak (p) and mean (m) gradients were lower for disc prostheses and higher for ball and biological prosthetic valves; values of effective orifice area (A), calculated by pressure half-time method, were lower for biological and ball prostheses and higher in disc valves. Results were as follows: St. Jude (p 10.6 mmHg, m 3.9 mmHg, A 2.7 cm2), Duromedics (p 10.6, m 4.3, A 2.8), Bj?rk-Shiley (p 10.4, m 4, A 2.3), Omniscience (p 14.2, m 6.2, A 2.1), Starr-Edwards (p 15.9, m 5.4, A 2.1), Hancock (p 14.7, m 6, A 2), Carpentier (p 13.2, m 5.4, A 1.9). Mild regurgitation, considered "physiological", was found in 2/8 Carpentier valves and in 3/34 St. Jude prostheses. In aortic valves lower peak gradients were found in Lillehei (18.3 mmHg), St. Jude (23.8 mmHg), Bj?rk-Shiley (26 mmHg), Duromedics (27 mmHg) and higher values in Starr-Edwards (30.2 mmHg), Hancock (30 mmHg) and Omniscience (35.5 mmHg) prostheses. Mild regurgitation, considered "physiological", was found in 17% of Omniscience valves, 21% of Hancock, 33% of Duromedics, 45% of St. Jude, 60% of Bj?rk-Shiley prostheses. Hancock mitral valves implanted for over 7 years had a mean gradient higher than valves with a shorter period of implantation (7.6 vs 4.85 mmHg, p less than 0.1), whereas the effective orifice area was similar. Hancock aortic valves implanted for over 7 years had a peak gradient slightly higher than the other group (implantation less than 7 years previously), but the difference was not statistically significant. Forty-two valves (19 aortic and 23 mitral) were considered to be malfunctioning. Regurgitation Doppler signals of malfunctioning valves appeared different from those of "physiological" reverse flow; in the former cases forward gradient was higher than normal prostheses. In stenotic aortic prostheses, peak systolic gradient was greatly increased; in stenotic mitral prostheses, a very significant increase in mean gradient and a great decrease in effective orifice area were found. In 14 patients who underwent surgical re-operation and in the patient who died before operation, Doppler echocardiographic findings were confirmed.(ABSTRACT TRUNCATED AT 400 WORDS)