Durability of Prosthetic Heart Valves

Accelerated fatigue testing of clinical heart valves has been performed at cyclic rates of 33 to 35 cycles per second at 37° using water for non-biological valves and glutaraldehyde solutions for tissue valves. Flows were in the physiological range, and the pressure difference across each valve during closure was 100 ± 25 mm Hg. The results showed that major fatigue occurred for the Starr-Edwards 2320 at 150 million cycles, the Hufnagel trileaflet at 124 million cycles, the Björk-Shiley Delrin disc at 140, the Björk-Shiley Pyrolite disc at 973, the Beall 103 at 60, the Hancock porcine at 62, the Carpentier-Edwards porcine at 34, and the Ionescu-Shiley porcine pericardial prosthesis at 65 million cycles. The Lillehei-Kaster was removed after 762 million cycles without discernible wear.Three facts emerged from the testing data: (1) the component worn in vitro wears in vivo; (2) the sites of in vitro fatigue on the component are identical to clinical specimens; and (3) those valves that have high durability in vitro have given similar performance in patients. The in vitro and clinical data for tissue valves do not correlate. The possible reasons for the discrepancy are discussed, and a note of caution is made regarding realistic expectations of clinical durability of tissue valves.     

Preliminary Experience with Aspirin for Anticoagulation in Children with Prosthetic Cardiac Valves

Twenty-four children (ages 1 to 18 years, mean 12.2 years) underwent 27 operations for aortic, mitral, or combined aortic and mitral valve replacement. There was 1 operative death. Of the 23 operative survivors (12 aortic, 8 mitral, 3 combined valve replacement), only 5 were given warfarin for long-term anticoagulation. The remaining 18 (10 aortic, 8 mitral valve replacement) were given aspirin (plus dipyridamole in 5). Twelve of the 18 had at least one mechanical valve (11 Björk-Shiley and Beall valves; 1 Björk-Shiley valve was replaced with a Beall disc valve as the child grew).These 18 patients were followed for 1 to 59 months (mean, 20.4 months). There was no thrombotic, embolic, or bleeding complications. There were 2 late deaths (one cardiac).Review of the available literature indicates that in children with prosthetic cardiac valves, aspirin (with or without dipyridamole) provides adequate protection against thromboemboli and avoids the hemorrhagic complications associated with warfarin.     

Strut Fracture and Disc Embolization of a Björk-Shiley Mitral Valve Prosthesis: Localization of Embolized Disc by Computerized Axial Tomography

The case of a patient who survived strut fracture and embolization of a Björk-Shiley mitral prosthetic disc is presented. Prompt surgical treatment was directly responsible for survival. In addition, computerized axial tomography of the abdomen aided in localizing and retrieving the embolized disc, which was lodged at the origin of the superior mesenteric artery. A review of similar case reports from the literature supports our conclusions that the development of acute heart failure and absent or muffled prosthetic heart sounds in a patient with a Björk-Shiley prosthetic heart valve inserted prior to 1978 should raise the possibility of valve dysfunction and lead to early reoperation.     

Early Results of Valve Replacement with the Björk-Shiley Convexoconcave Prosthesis

The Björk-Shiley convexoconcave prosthetic valve has design characteristics that may result in a lower incidence of thromboembolic complications than the conventional spherical Björk-Shiley prosthesis. We evaluated the results of valve replacement with the convexoconcave prosthesis in 248 patients receiving 301 prosthetic valves between March, 1979, and June, 1981. One hundred thirteen patients had aortic valve replacement (AVR), 73 had mitral valve replacement (MVR), and 62 had multiple valve replacement. Two hundred nine (84%) were in New York Heart Association Class III or IV. The median duration of follow-up was 13 months, and follow-up information was available for 246 (99%) of the patients. The actuarial incidence of freedom from thromboembolism at two years was 98% in the AVR group, 97% in the MVR group, and 87% in the group having multiple valve replacement. There were no documented episodes of valve thrombosis or mechanical failure and no fatal thromboembolic complications. The absence of valve thrombosis is in marked contrast to the results reported with the spherical disc valve. Although longer follow-up is necessary, it appears that the convexoconcave design represents a major improvement in the Björk-Shiley prosthesis.     

Considerations in Selection and Management of Patients Undergoing Valve Replacement with Glutaraldehyde-Fixed Porcine Bioprostheses

From November, 1973, through June, 1978, 428 operations in 425 patients were performed for replacement of aortic, mitral, or aortic plus mitral valves, utilizing 277 Hancock and 180 Carpentier-Edwards bioprostheses. Actuarially determined survival at 36 months was similar for all three groups and compared favorably with our experience with the Björk-Shiley prosthesis. Certain patient-related variables influencing late survival were identified by multivariate analysis and included previous operation for congenital heart disease, coronary artery bypass grafting in nonaortic valve replacement, race (black), age at operation, and New York Heart Association Functional Class. A small but definite incidence of thromboembolism occurred in all three groups, again similar to our experience with the Björk-Shiley prosthesis. Multivariate analysis identified four factors influencing risk of thromboembolism: previous cardiac operation, age, double-valve replacement, and rhythm at discharge. Valve degeneration occurred, primarily in children and young adults. Over the medium term, the porcine bioprosthesis compared favorably with mechanical prostheses in terms of survival, function, and thromboembolism. Certain patient-related variables affecting survival may be modified by earlier surgical intervention.     

Surgical treatment of annuloaortic estasia: experience in 7 consecutive patients.

Seven patients with annuloaortic ectasia were treated according to the method described by Bentall and De Bono. A Björk-Shiley valve in a composite graft was the prosthesis of choice and was used in all patients except 1, who received a Starr-Edwards valve. Profound topical cooling without selective coronary perfusion was applied in 5 patients for myocardial preservation during aortic occlusion.There was 1 operative death and 1 late death, the latter from cerebral thromboembolism. Five survivors have been followed from 1 year 5 months to 2 years 10 months with an average follow-up of 2 years. Excellent results were obtained in all survivors, their physical capabilities putting them in Class I of the New York Heart Association Functional Classification. Postoperative aortograms showed no signs of kinking or compression of vascular prostheses nor abnormalities of prosthetic valves. A modified technique to secure graft fixation is discussed.     

Mitral disc-valve variance

This report deals with a rare complication of disc-valve prosthesis in the mitral area. A significant disc poppet and struts destruction of mitral Beall valve prostheses occurred 20 and 17 months after implantation. The resulting valve incompetence in the first case contributed to the death of the patient. The durability of Teflon prosthetic valves appears to be in question and this type of valve probably will be unacceptable if there is an increasing number of disc-valve variance in the future.     

Heterograft aortic valve replacement: initial follow-up studies

Twenty-three patients have had calf or pig heterograft aortic valve replacements. Eight of these patients have required Starr-Edwards mitral ball-valve prostheses for associated mitral valve disease. There have been two hospital deaths and one late death. The 20 surviving patients have shown symptomatic improvement. Clinical evidence of incompetence is present in one patient. Pre-operative and post-operative ciné-aortograms show valve mobility with a wide central orifice. Heterografts have the advantages of homografts in being free from thromboembolism and from the need for anticoagulants; they exhibit some resistance to infection as compared with prosthetic valves. We think that heterografts, because of their wider range of size, can offer a better haemodynamic result with little clinical aortic incompetence. The long-term fate of aortic valve heterografts is not known with certainty, although the durability of homografts is better known. There is a possibility of late degeneration or rupture. If the valve continues to function normally, then it would be justifiable to recommend operation at an earlier stage in the progression of the patient's disease. At present, despite encouraging early results, we think the use of heterografts should be limited, like that of other prostheses, to those patients who show severe cardiac disability.     

Operative results of tricuspid valve replacement with St. Jude Medical prosthesis

Since 1974, 14 patients underwent tricuspid valve replacement (TVR) with prosthetic heart valves. Hardy's operation was undergone in 2 patients with Ebstein's anomaly and mitral valve surgery or multiple valve surgery were undergone in 9 patients with rheumatic valvular disease, concomitantly. Four types of prosthetic heart valves were used in the tricuspid position, i.e. 2 Starr-Edwards prostheses, 1 Hancock xenograft, 1 Bj?rk-Shiley prosthesis and 12 st. Jude Medical prostheses. The operative mortality rate was 14.3% (2/14) and 2 hospital deaths were due to low cardiac output syndrome. Twelve survivors have been followed with a maximum follow-up of 13 years and the mean of 4.7 years. There were 3 late deaths due to congestive heart failure and prosthetic valve endocarditis (PVE) of the aortic Bj?rk-Shiley prosthesis. There was 1 PVE of the tricuspid Starr-Edwards prosthesis and 1 thrombosis of the tricuspid Bj?rk-Shiley prosthesis, but no thrombosis and no other valve-related complications of SJM prostheses in the tricuspid position. The post-operative NYHA function class improved satisfactorily in 9 survivors. Judging from our relatively satisfactory post-operative results in TVR cases using SJM prostheses, SJM prosthesis in the tricuspid position is one of advisable prosthesis to get satisfactory hemodynamic improvement post-operatively.     

Intravascular haemolysis after valve replacement: comparative study between Starr-Edwards (ball valve) and Björk-Shiley (disc valve) prosthesis.

Seventy-four patients with single prosthetic valves (Björk-Shiley or Starr-Edwards) in the mitral or aortic position and 18 controls with rheumatic valvar heart disease were investigated for evidence of intravascular haemolysis. Serum lactate dehydrogenase (LDH) was used as the most sensitive indicator of haemolysis. Raised concentrations were found in a third of 39 patients with Björk-Shiley prostheses (mean 281 IU/l) and in all 35 patients with Starr-Edwards prostheses (mean 859 IU/l. Values were considerably higher in patients with Starr-Edwards prostheses and particularly in those with aortic prostheses (mean 927 IU/l). Eight out of 12 patients with haemosiderinuria had Starr-Edwards valves. Intravascular haemolysis was of little clinical significance in patients with Björk-Shiley prostheses, but some patients with Starr-Edwards prostheses became iron deficient as a result.     

Twelve-year experience with mitral valve replacement.

Between 1962 and 1974, 203 mitral prostheses were implanted in 201 patients. Of the 102 survivors, 29 have Beall, 25 Kay-Shiley, 22 Starr-Edwards (SE) 6000, and 27 SE 6320 valves. Full rehabilitation was achieved in 25 patients with Beall and 23 with SE 6320 valves. Sixteen with SE 6000 valves remain normally active. Only 8 with Kay-Shiley prostheses have resumed normal activities. Systemic embolization occurred with the following frequencies per 1,000 patient-months: 13.7 for those receiving the Kay-Shiley valve; 7.2 in the SE 6000 group; 4.3 after SE 6320 implantations; and 3;1 for the Beall group. Other prosthesis-related complications that were much less frequent included detachment (10), bacterial endocarditis (5), and hemolysis (10). Three Kay-Shiley valves malfunctioned. Life table analyses reveal the following survival rates: 33% after 11 years in the SE 6000 patients, 50% after 7.5 years in the Kay-Shiley group, 69% 2.5 years after SE 6320 implantation, and 65% 3.5 years after replacement with a Beall valve. Evidence is presented to support the extension of operative treatment to patients with less advanced valvular heart disease. Postoperative anticoagulation remains an unresolved issue despite lower rates of thromboembolism. More cumulative analyses of survival and morbidity and follow-up hemodynamic data are needed to assess the Beall and SE 6320 prostheses now employed in our valve replacement program.     

Failure of Hancock xenograft valve: importance of valve position (4- to 9-year follow-up)

To evaluate long-term durability of Hancock valves, we reviewed our results in 107 hospital survivors (120 valves) who were operated on during 1974 through mid-1979. Mitral valve replacement was done in 63 patients, aortic valve replacement in 20, and mitral valve replacement combined with other procedures in 24. The 7-year survival was 84 +/- 4% (standard error of the mean) for 91 patients and 97 valves. During a follow-up of 590 patient-years, 15 (12 mitral and 3 aortic) of 120 valves at risk (87 mitral, 32 aortic, 1 tricuspid) were removed from 14 patients. Six valves (3 mitral and 3 aortic) were removed because of bacterial endocarditis. One mitral valve was removed because of thromboembolism. Eight mitral valves were removed because of valve structural failure, which occurred at a mean follow-up of 42 months. These valves showed extensive calcification, leaflet perforation, or cusp tear. Structural failure was unrelated to valve size, year of implantation, or valve shelf-life. Structural failure was not seen after aortic valve replacement. Results show that structural failure of the Hancock xenograft valve in the mitral position is related primarily to valve position. After aortic valve replacement, valve failure is predominantly due to endocarditis. Although medium-term (mean, 6-year) durability of this xenograft valve compares satisfactorily with prosthetic valves, its high failure rate in the mitral position indicates the necessity for improvement in valve mounting, design, and preservation.     

Long-term Results in 1375 Patients Undergoing Valve Replacement with the Starr-Edwards Cloth-covered Steel Ball Prosthesis

The two principal considerations with prosthetic valves are durability and thromboembolism. With the widespread interest in recently developed prosthetic valves (porcine, tilting disc, Cooley), the long-term results at one institution with a single prosthesis were considered of particular importance. Accordingly, a 97% follow-up has been completed on 1375 patients (pts) undergoing prosthetic valve replacement with the Starr-Edwards cloth-covered steel ball prosthesis at New York University between October 1967 and December 1975. Operative procedures were as follows: aortic valve replacement (AVR): 470 pts; mitral valve replacement (MVR): 362 pts; combined AVR and MVR: 129 pts; other combined procedures: 414 pts. Overall operative deaths were 13.7%, 9% for AVR, 10.8% for MVR, and 18.6% for combined AVR and MVR. At seven years, AVR survival was 64%, and MVR survival 64.5%. There has been widespread pessimism, usually without significant data, about the cloth-covered prosthesis, because of concern of cloth wear, hemolysis and other complications. Therefore, a particularly significant finding by actuarial analysis was that 85% of surviving patients with isolated AVR remained free of emboli for five years. In pts surviving isolated MVR, 80% remained free of emboli for five years. Of those having embolic episodes, 33% were not on anticoagulants. Fatal hemorrhage from anticoagulants occurred in 0.8% of pts. Endocarditis occurred in 5.7% of the entire group, with 1.3% requiring reoperation. Clinically significant hemolysis occurred in 5.1% of the group, with only 0.2% requiring reoperation. Hence, the total frequency of clinically significant cloth-wear was less than 0.5%. These data indicate both the reliability and the limitations of the Starr-Edwards cloth-covered steel ball valve and can be used in comparing experiences with the more recently developed prostheses.     

Premeditated reoperation after mitral valve replacement with a Starr-Edwards ball valve for young women who desire to bear a child: Report of two cases

There are many difficulties for young women with a Starr-Edwards ball valve who want to attempt pregnancy. There is no consensus regarding whether they should maintain anticoagulation therapy throughout pregnancy with the risk of a thromboembolism or to undergo a reoperation with bioprosthetic heart valves, followed by a third operation when the valve deteriorates. This report presents two cases of young women who underwent mitral valve replacement (MVR) with Starr-Edwards ball valves (model 6120: 1M) during their childhood. Although they did not have any cardiac symptoms, transthoracic echocardiography and cardiac catheterization data demonstrated that both the patients had asymptomatic mild relative mitral stenosis. They both wished to bear a child. After the patients and their family provided thorough informed consent, redo MVRs were preformed safely with biological prostheses. The presence of significant pannus formation along the strut and sewing ring of the excised valves could also have a positive impact on the decision to undergo reoperation.     

Comparative analysis of long-term results with porcine-aortic, bovine pericardial and tilting disc valves

The three series with the first-generation valve prostheses were reviewed for long-term clinical evaluation in isolated aortic and mitral valve replacement. Hancock porcine xenograft was implanted in 71 patients from 1977 to 1979, ionescu-Shiley pericardial xenograft (standard model) in 271 patients from 1979 to 1983, and Bjork-Shiley tilting disc valve in 194 from 1978 to 1986. In aortic position, no any significant difference among three valve types could be demonstrated in the actuarial survival and freedom from thromboembolism and valve infection, while the actuarial freedom from valve dysfunction in lonescu-Shiley valve was significantly lower than that in other two valves. Bj?rk-Shiley valve in mitral position showed satisfactory clinical performance in terms of valve-related complications and survival in comparison with two types of bioprosthetic valves. In our conclusion at present time, Bj?rk-Shiley valve is suitable for the first choice of both aortic and mitral valve prostheses. In case of valve replacement with a bioprosthesis, however, porcine aortic valve is a better choice for aortic, and bovine pericardial valve likely for mitral replacement.     

Platelet survival in patients with homograft and prosthetic heart valves: Correlation with incidence of thromboembolism

Manohitharajah, S. M., Rahman, A. N., Donnelly, R. J., Deverall, P. B., and Watson, D. A. (1974).Thorax, 29, 639-642. Platelet survival in patients with homograft and prosthetic heart valves. Investigations in the past have demonstrated shortened platelet survival time in patients with prosthetic heart valves. This suggested that platelets contribute to thromboembolism in this group. Homograft valves and the newer models of the Starr-Edwards prosthesis have proved less thrombogenic than those previously employed, but platelet survival studies in patients with these valves are lacking. In this study platelet function, survival, and its relation to haemolysis were determined in 28 patients following mitral valve replacement and in two patients following mitral valvotomy: 14 patients had a frame-mounted homograft aortic valve; 13 patients had a Starr-Edwards prosthesis model 6310 or 6320, and one had a Starr-Edwards prosthesis model 6000. Normal platelet function and survival was found in both the homograft and the Starr valve groups. The patient with the earlier model of the Starr valve (model 6000) had a shortened platelet survival time. The two patients following mitral valvotomy had normal platelet survival. The fact that platelet abnormalities were not demonstrable in our patients with homograft valves and newer Starr-Edwards prostheses may explain the low incidence of thromboembolism in this group. Platelet survival studies are a useful parameter to determine the potential thrombogenic nature of prosthetic valves. Platelet survival time was not influenced by the presence or severity of haemolysis.     

Starr-Edwards valves at the aortic and mitral positions implanted for 39 years

Cloth-covered Starr-Edwards caged ball valves implanted in the aortic and mitral valve positions for 39 years were extracted. Both showed valve dysfunction resulting from pannus overgrowth. The metal cages of the Starr-Edwards valves were covered with worn cloth. This case indicates the extended durability of Starr-Edwards valves and the importance of the design and materials of prosthetic heart valves to avoid pannus overgrowth and prosthetic valve abrasion.     

Surgical treatment of the prosthetic valves in reoperation

Surgical treatment and problems in patients required reoperation for malfunctioning prosthetic valves are reviewed in our institute. The cinefluoroscopy and pulse doppler echocardiography were helpful for diagnosis of artificial valve dysfunction. In recent two decades valve replacement were performed in 382 cases and number of re-implanted valve were 469. Among them the cases of reoperation were 21 and reimplanted valves were 25 (5.6%); 4.7% in aortic, 5.0% in mitral, 6.7% in tricuspid position. Three cases of those patients had three operations. Main causes of reoperation were primary tissue failure in Carpentier-Edwards porcine xenograft (6 cases, 23%) and cloth wear in Starr-Edwards ball valve (9 cases, 38%) and thrombosis in St. Jude Medical bi-leaflet valve (3 cases, 15%). In most cases St. Jude Medical valve were chosen for the alternative prosthetic valve in reoperation. We applied IABP support to seven patients for severe low cardiac output syndrome after the operation and overall mortality was 24% in reoperation. It concluded that St. Jude Medical valve may be most reliable because of low incidence of postoperative complication in our institute.     

Long-term results after Starr-Edwards mitral valve replacement in children aged 5 years or younger

BACKGROUND: Mitral valve replacement with prosthetic valves in infants and children requires consideration of multiple variables. When we examined our late follow-up, the effect of the growth of the patient relative to the size of the prosthesis placed was the most important variable predicting late successful results. We reviewed our experience with mitral valve replacement using the Starr-Edwards ball valve in children aged 5 years or younger, focusing on the effect of valve prosthesis-patient mismatch on the long-term results in the growing patient. METHODS: From August 1974 to June 1986, 8 patients aged 5 years or younger underwent mitral valve replacements using the Starr-Edwards prosthesis size OM in 3 patients and 1M in 5 patients. Model 6320 was used in 1 patient and Model 6120 in the remaining 7 patients. RESULTS: Follow-up was 100% from 15 to 27 years (mean, 20 years). No valve-related complications of thromboembolism, anticoagulant-related hemorrhage, or prosthetic valve endocarditis were seen. All patients normally developed to adult size. The range of the valve area index of the 3 patients who received the smaller Starr-Edwards valve (size OM) was 0.97 to 1.24 cm2/m2. Although this size valve was adequate for patient growth to adolescence, in each case valve replacement with a larger valve was required. CONCLUSIONS: Our long-term review of Starr-Edwards ball valve mitral valve replacement in children aged 5 years or younger shows that the Starr-Edwards ball valve (Models 6320 [1 patient] and 6120 [7 patients]) showed excellent durability, no thromboembolism, and no anticoagulant-related complications. Size OM valves required replacement for hemodynamic reasons because of patient growth; larger size 1M valves remained hemodynamically satisfactory in spite of patient growth.     

Strut Fracture and Disc Embolization in Björk-Shiley Mitral Valve Prostheses: Diagnosis and Management

Mechanical failure of the Björk-Shiley tilting disc prosthesis is a rare but catastrophic complication of the valve. Several previously reported cases of major strut fracture with disc embolization led to improvements in the structure of the prosthesis. A case of minor strut fracture in the improved convexoconcave model of the Björk-Shiley mitral valve prosthesis is described. The literature on mechanical failures in the Björk-Shiley mitral valve prosthesis is reviewed, and recommendations for recognition and management of this problem are made.