The performance of the Braunwald-Cutter aortic prosthetic valve

The Caged-Ball Prosthesis 60 Years Later: A Historical Review of a Cardiac Surgery Milestone

Sixty years ago, 2 cardiac operations dramatically influenced the survival of patients with valvular heart disease. The replacement of an aortic valve by Dwight Harken and of a mitral valve by Albert Starr with mechanical caged-ball valves, both in 1960, was a true milestone in the history of cardiac surgery and the beginning of a long journey toward prosthetic valve replacement full of expectations, hopes, and dreams fulfilled. Caged-ball prostheses underwent numerous modifications in design and materials to improve reliability and prevent specific mechanical and thrombogenic complications. Clinical and pathologic experience gained during the past 6 decades has enabled the development of safe, durable, and minimally thrombogenic mechanical prostheses.

"It Will Work": The Story of Nina Starr Braunwald and the First Successful Mitral Valve Replacement

Cardiothoracic surgery is a clinical and scientific discipline that has evolved enormously over the last decades. Cardiac problems that were historically death sentences can now be addressed with approaches that only continue to improve. In the late 1950s, while cardiothoracic surgery was still a nascent field, Nina Starr Braunwald emerged as a pioneer for this exponential improvement. As the first woman cardiac surgeon in an era in which general surgery and surgical specialties were dominated by men, Dr Braunwald not only made revolutionary contributions to cardiothoracic surgery, but also did so while balancing roles as a dedicated mother and supportive partner.

15 years experience with 615 homograft and autograft aortic valve replacements

Homograft valve replacement of the diseased aortic valve with a homologous aortic valve inserted in the sub-coronary position was first performed in July 1962 (Ross 1962). The procedure of transferring the patients autologous pulmonary valve to the aortic position has been used since 1967 (Ross 1967).

The long term performance of homograft valves has not been regarded as satisfactory in some centres (Cope-land 1977, Anderson & Hancock 1977) whereas others have shown it to be an excellent valve replacement (Barratt-Boyes, 1977, Bodnar et al 1979).

The differing experiences may be the results of alternative methods of sterilization, preservation and surgical insertion. This paper presents information on isolated aortic valve replacements with either homograft or autograft valves over a 15 year period.

Normal function of a 43-year-old Braunwald Cutter heart valve

We present the case of a 72-year-old woman diagnosed with rheumatic fever at the age of 6. In 1972, she was diagnosed with mitral valve insufficiency and mitral valve stenosis, then in 1974, a decision was made to perform mitral valve replacement surgery with a 32-mm Braunwald-Cutter ball cage prosthesis. An echocardiogram performed in 2014 revealed normal biventricular systolic function, mechanical prosthesis in mitral position with maximum speed of 1.9 m/s, maximum gradient of 15 mmHg, mean gradient of 6 mmHg, severe tricuspid valve insufficiency, inferior vena cava measuring 15 mm with more than 50% collapse and pulmonary artery systolic pressure of 40 mmHg. We report the use of the 32-mm Braunwald-Cutter ball cage prosthesis with the longest longevity that remains functional after more than 43 years of implantation.

Prosthetic heart valves: Types and echocardiographic evaluation

In the last five decades multiple different models of prosthetic valves have been developed. The purpose of this article is to provide a comprehensive source of information for the types and the echocardiographic evaluation of the prosthetic heart valves.

Mechanical heart valves: 50 years of evolution

The past 50 years have witnessed remarkable progress in the development of safe, hemodynamically favorable mechanical heart valves. Starr-Edwards aortic and mitral ball valves introduced in the mid-1960s, continue to be used successfully worldwide. More than 100,000 Omniscience and Omnicarbon tilting-disc valves have been implanted since 1978 with essentially no mechanical failure; similar results have been obtained with more than 300,000 Hall-Kaster and Medtronic-Hall tilting-disc valves over the past 25 years. Pyrolytic carbon, originally used to encapsulate nuclear fuel rods, has been adapted for the fabrication of discs, leaflets and the housings for more than 2 million mechanical valves. The St. Jude bileaflet valves, totally fabricated from pyrolytic carbon, have remained virtually unchanged in design since their introduction in 1977. More than 1.3 million of these valves have been implanted worldwide with virtually no reported failures of the carbon leaflets or housings. Similarly, pyrolytic carbon bileaflet Carbomedics valves have been implanted in more than 500,000 patients since 1986. Now, 50 years after Dr Gibbon's seminal achievement, patients with debilitating valve disease can have elective valve replacement (mechanical or tissue) with an operative mortality approaching 1% to 2% and a low lifetime complication rate.

Prophylactic replacement of Björk-Shiley convexo-concave valves at risk of strut fracture. Björk-Shiley Study Group

OBJECTIVE

Prophylactic replacement of Björk-Shiley convexo-concave valves (Shiley, Inc., Irvine, Calif.) has been advised for selected groups of patients. If prophylactic replacement is considered, risks of postoperative morbidity and mortality have to be weighed against benefits of replacement. Here we report the results of prophylactic replacement of Björk-Shiley convexo-concave valves at risk of strut fracture in The Netherlands.

METHODS

We reviewed medical records of 36 patients undergoing prophylactic replacement of their Björk-Shiley convexo-concave valves before August 1995. Replacement was judged to be prophylactic if the risk of strut fracture outweighed that of death from reoperation, or the patient wished to have the valve replaced although it was not recommended. The procedure was also considered to be prophylactic if a concomitant pathologic condition, not likely to require cardiac surgery in the near future, was present or if preoperative examination revealed an unexpected cardiac pathologic condition.

RESULTS

Twenty-two 70-degree and 16 60-degree Björk-Shiley convexo-concave valves and one spherical valve were replaced (25 aortic and 14 mitral, including three double-valve replacements). Early mortality was 2.8% (1/36) (exact 95% confidence interval [CI] 0.1 to 14.5). Mean follow-up was 33 months. One- and 3-year survivals were 94% (95% CI 79% to 99%) and 91% (95% CI 74% to 97%), respectively. All three deaths were sudden.

CONCLUSIONS

If special care is taken in selecting patients, the risk of prophylactic replacement is comparable to that of primary valve replacement. More data are needed to assess whether the risk of sudden death is possibly increased.

Reoperation on prosthetic heart values. Patient-specific estimates of in-hospital events

Reoperation on prosthetic heart valves is increasingly under consideration for both clinical and prophylactic indications. To determine the correlates of hospital events, including in-hospital mortality, new persisting neurologic deficit, and length of postoperative stay, a three-institution study of 2246 consecutive prosthetic valve reoperations performed on 1984 patients between 1963 and 1992 was undertaken. The combined experience ranged from high-risk patients coming moribund to the operating room to an important number of well individuals undergoing prophylactic reoperations on potentially failing valves. The risk-unadjusted hospital mortality was 10.8%, neurologic deficit at hospital discharge 1.1%, and length of stay 10 days (median). Multivariably determined correlates of outcome included age at reoperation, degree, severity, and acuity of impairment of cardiac function, extensiveness of valvular heart disease, coexisting morbid conditions, number of previous heart operations, and concomitant procedures. The risk-adjusted hospital mortality for the first elective reoperation in a good-risk patient was 1.3% (90% confidence limits 0.3% to 4.4%), neurologic deficit 0.3% (90% confidence limits 0.02% to 1.8%), and length of postoperative stay 7 days (90% confidence limits 4 to 13), emphasizing the wide variance in outcome events. Equations were developed to permit wide application of the results of the study for quantitatively estimating the risk of outcome events based on individual preoperative patient characteristics. These estimates should be useful for informed patient consent, considerations of prophylactic valve replacement, and cost and resource use.

Late outcome of patients with Braunwald-Cutter mitral valve replacement

Eighty patients who underwent mitral valve replacement (MVR) with Braunwald-Cutter prostheses (54, single valve replacement; 26, multiple valve replacement) between December, 1972, and September, 1975, are discussed. The period of follow-up ranged from 72 to 120 months with a mean of 84.6 months. For the hospital survivors, actuarial survival at ten years was 73 +/- 6.7% for patients with MVR alone and 30 +/- 17.5% for those with multiple valve replacement. The linearized rate of embolic complications in patients with MVR was 3.2% per year and in patients with multiple valve replacement, 1.5% per year. These low rates of embolism allow a favorable comparison of the Braunwald-Cutter valve with other mechanical prostheses. There was no evidence of serious poppet wear or poppet escape after ten years of the valve in the mitral and tricuspid positions. Thus, elective replacement of the Braunwald-Cutter valve from the atrioventricular position because of this potential problem is not considered necessary. In the aortic position, escape of the poppet from the valve has occurred as late as 101 months. The overall morbidity for the group was high. Only 34% of the patients having MVR and 12% of those with multiple valve replacement are expected to be alive and to remain free from any major complication ten years after operation.

Five-year clinical experience with the Omniscience cardiac valve

Clinical data on the Omniscience cardiac valve prosthesis (sizes 19 to 31 mm) were obtained from 326 patients (155, aortic valve replacement [AVR]; 125, mitral valve replacement [MVR]; and 46, double-valve replacement) during a five-year period (650 patient-years) with 96% accountability. Mean age was 56 +/- 12 years, and 40% (130) of the patients were 61 years old or older. Thirty-one percent (101) had prior or concomitant coronary artery bypass grafting procedures, 9% (28) had a previous malfunctioning prosthesis, and 17% (57) had other cardiac surgical procedures. Eighty percent were in New York Heart Association (NYHA) Functional Class III or IV preoperatively. Early mortality was 10% (34). Five-year actuarial thrombus-free rate is 96% for patients who underwent AVR and 95% for patients having MVR. Postoperatively, 89% (172/193) were in NYHA Class I or II, and 84% (163/193) improved by at least one Functional Class. A significantly high proportion of the postoperative hematological values fall within normal ranges: red blood cell count, 94% (176/187); hematocrit, 88% (166/188); and hemoglobin, 93% (176/190). Ninety-eight percent (287/292) are free from clinical anemia. Four of the 5 patients with clinical anemia had a preoperative history of this condition. Levels of lactic dehydrogenase in 3 patients suggested the probable presence of clinically significant hemolysis, although all 3 have normal hematological values. Actuarial five-year survival for patients who underwent AVR or MVR are similar (82% and 80%, respectively), indicating satisfactory and comparable levels of safety and performance.(ABSTRACT TRUNCATED AT 250 WORDS)

Nine years' experience with the Björk-Shiley prosthetic valve: early and late results of 932 valve replacements

Between November, 1970, and December, 1977, 932 consecutive patients received the standard Björk-Shiley prosthesis. Operative mortality was 4.6% for aortic valve replacement (AVR; N = 364), 5.1% for mitral valve replacement (MVR; N = 313); 11.3% for multiple valve replacement (N = 194), and 13.7% for valve replacement combined with coronary artery bypass grafting (CABG; N = 51). Factors influencing hospital mortality included type of valve replacement, age at operation, whether the valve replacement was done as an emergency, and year of implantation. Complete follow-up (mean, 3.7 years) was achieved in 95% of the survivors. Actuarial survival was 82% for AVR patients at 8 years, 83% for MVR patients at 7 years, 72% for multiple valve replacement patients at 7 years, and 76% for those who had valve replacement with CABG at 3 years. No significant difference in late survival was found between patients with mitral insufficiency alone (p greater than 0.2) or aortic insufficiency alone (p greater than 0.9) and those with stenotic lesions only. Thromboembolic complications occurred at an incidence of 1.17% per patient-year, and Dicumarol-induced hemorrhages occurred at an incidence of 2.11% per patient-year. Twelve out of 13 patients survived operation for prosthetic valve thrombosis, indicating that this complication is not as catastrophic as many believe. The incidence of reoperation in anticoagulated patients was 0.63% per patient-year. All of these results are compared with data from the recent literature.

Echocardiographic features of aortic ball valve prosthesis malfunction

A case of aortic ball valve prosthesis malfunction is described in which the poppet became alternately stuck in the open and closed position. The patient experienced chest pain followed by pulmonary edema and cardiac arrest. Malfunction of prosthetic valve was diagnosed on echocardiogram and cardiopulmonary resuscitation was carried out until a Bjork-Shiley valve could be inserted in place of the faulty prosthesis. At the time of the operation, poppet migration had occurred and the poppet could not be found. Subsequent Bjork-Shiley aortic valve prosthesis dysfunction was suggested by variation in the intensity of the aortic opening sound and in the duration of the systolic ejection period. Fluoroscopy revealed the missing poppet in the left ventricle. Following surgical removal of the poppet, "normal" Bjork-Shiley valve function was restored.

Durability of pyrolytic carbon-containing heart valve prostheses

To assess abrasive wear of mechanical valve prostheses containing pyrolytic carbon components, we recovered at necropsy or surgery and analyzed by scanning electron microscopy and surface profilometry eight prostheses. Seven were implanted for 30-85 (mean 50 months. Valves included DeBakey aortic (2), DeBakey mitral (1), Beall mitral (2), Bjork-Shiley aortic (1), Cooley-Cutter mitral (1), and Lillehei-Kaster (L-K) tricuspid (1). All carbon occluders had undetectable wear. Carbon cage struts had a superficial burnish. Metallic struts had insignificant wear marks. In contrast, a Teflon Beall Model 104 valve implanted for 34 days and similarly analyzed had considerable material loss from the cage struts. This study suggests that clinically important abrasive wear will not be a late complication of cardiac valve replacement with pyrolytic carbon prostheses.

Late follow-up of the Braunwald-Cutter valve

A retrospective review has been made of 234 patients who received 239 Braunwald-Cutter valves (109 aortic, 130 mitral). For the aortic valve, the thromboembolic rate was very high (10.3 per 100 patient-years). This was associated with severe strut cloth wear in 94.5% of valves and with long strands of fibrin attached to the worn cloth in 58% of valves studied at reoperation or postmortem examination. The aortic poppet showed a mean decrease in volume of 4%, and poppet escape was recognized in 4 patients. The actuarial incidence of poppet escape was less than that predicted in earlier reports. There was a 4% incidence of stenosis of the valve. The hospital mortality associated with removal of the aortic Braunwald-Cutter valve and replacement with another device was 4%. Performance of the mitral Braunwald-Cutter valve appears satisfactory to date (mean follow-up, 42 months). Its electric removal is not recommended.

Bioengineering aspects of heart valve replacement

Biomedical engineering inputs have been important in the design, development and testing of substitute heart valves as well as in the pre- and post-operative management of patients with cardiac valve disease. This paper is a review of heart valve replacement whose goal is the enhancement of future bioengineering contributions. We review the approach to the patient with valvular heart disease, and the sources of early and late postoperative pathology with emphasis on complications of the prostheses used. Major significant problem areas relate to the noninvasive evaluation of cardiovascular function (both before and after surgery), device design, hemodynamics, and the need for thromboresistant and durable materials.

Preoperative criteria predictive of late survival following valve replacement for severe aortic regurgitation

Forty-five patients underwent aortic valve replacement (AVR) for severe isolated aortic regurgitation from 1973 to 1979. There were two (4.4%) hospital deaths, both functional class IV. Six patients with mechanical prosthesis not receiving anticoagulants were excluded from further analysis. These data relate to 39 patients; the two operative deaths, 35 patients with mechanical prosthesis receiving anticoagulants, and two with bioprosthesis. There were three late cardiac deaths with 5-year survival 85%; average annual mortality rate of 3%. The 5-year survival with pre-AVR left ventricular (LV) ejection fraction greater than or equal to 0.45 was 87% vs 54% less than 0.45, (p less than 0.04); cardiac index greater than or equal to 2.5 L/min/m2 92% vs 66% less than 2.5 (p less than 0.04); mean VCF greater than or equal to 0.75 vs less than 0.75 circ/sec (p less than 0.09); end-diastolic pressure less than or equal to 20 vs greater than 20 mm Hg (p less than 0.08). Late survival was not significantly different between pre-AVR functional class I and II vs class III and IV; LV end-diastolic volume index greater than or equal to 210 vs less than 210 ml/m2; LV end-systolic volume index greater than or equal to 110 vs less than 110 ml/m2; and LV mass greater than or equal to 240 vs less than 240 gm/m2. With ejection fraction greater than or equal to 0.50 there was only one operative death (functional class IV) and no late cardiac deaths. Thus late survival following aortic valve replacement for severe isolated aortic regurgitation is better predicted preoperatively by the LV systolic pump function variables of ejection fraction and cardiac index than by LV diastolic parameters and clinical status.

Aortic valve replacement: a 9-year experience

Experience with aortic valve replacement over a 9-year period is reviewed. Hospital mortality was 5.0%, with an additional late mortality of 15.0% during a mean follow-up period of 4.3 years. There was a 7.5% mortality among the 93 patients who were operated on using direct coronary perfusion. There were no early deaths among the 48 patients operated on using cold cardioplegic arrest. Paravalvular leaks developed in 20 patients, and 9 had reoperation. There were no early deaths following elective reoperations for prosthetic valve dysfunction, but urgent reoperation was associated with a 40% mortality. Eighty percent of all patients are still alive at a maximum follow-up of 9 years. Eighty-six percent of the survivors who were in New York Heart Association Functional Class III or IV before operation are now in Class I or II. Hypothermic cardioplegic arrest was found to be preferable to coronary perfusion as a method of myocardial protection during aortic valve replacement. Patients with paravalvular leaks who have a history of left ventricular failure prior to aortic valve replacement should be considered candidates for early elective reoperation, owing to the significantly greater mortality associated with urgent reoperation.

Hemodynamic evaluation of patients with combined mitral and aortic prostheses

Complete hemodynamic evaluation of patients with combined aortic and mitral mechanical valve prostheses presents a difficult technical problem. Yet such patients with cardiac symptoms postoperatively often require this evaluation to determine the diagnosis and the advisability of reoperation. A 4 year experience with 22 patients requiring such evaluation is reviewed. Eight patients (36 percent) required reoperation for malfunction of the prosthesis. Four (18 percent) had major complications of the cardiac catheterization study, but no fatalities or residual permanent defects resulted. In 17 cases transthoracic left ventricular needle entry was used. A standardized procedure of this type for both pressure measurement and angiographic studies has evolved, providing reasonable efficiency and a relative degree of safety. The patient is positioned in the right anterior oblique position for optimal needle entry into the left ventricular apex and angiographic visualization of mitral prosthetic incompetence and the myocardial contractile pattern. A 16 gauge needle with side holes but no end hole allows ventriculography to be performed after chamber entry using the prostheses as reference points under fluoroscopic guidance. Retrograde catheterization of the aortic prosthesis, transseptal left atrial catheterization with anterograde crossing of the mitral prosthesis and transapical pressure measurement with a similar needle, combined with quantitative left atrial angiography, are alternative choices for study.

Central haemodynamics at rest and during exercise before and after combined aortic and mitral valve replacement with the Björk-Shiley tilting disc valve prosthesis

Pre- and postoperative haemodynamics were compared in 36 patients with combined aortic and mitral valvular disease. These patients suffered from markedly restricted cardiac function in terms of cardiomegaly, low physical working capacity, hypokinetic central circulation and pulmonary hypertension. Valve replacement was performed with the Björk-Shiley Delrin disc (10) and pyrolytic carbon disc (26) prostheses and followed by subjective improvement in the majority of patients. Heart volume decreased and working capacity increased in average significantly, but were not restored to normal. The main response to surgery was a shift towards a normokinetic circulation, although many patients remained hypokinetic. There was also regression of pulmonary hypertension as a result of reduced left atrial pressure and pulmonary vascular resistance. In spite of a significant decrease in left atrial mean pressure, it remained elevated with prominent v-waves in many patients, particularly during exercise. Marked v-waves in the right atrial pressure curves were also noted in one third of the patients. Only one patient, however, suffered from clinically manifested tricuspid incompetence. This study shows the benefits of combined aortic and mitral valve replacement, even in patients with longterm haemodynamic burden on the myocardium. Although the central haemodynamics were almost normalized at rest, abnormal responses persisted during exercise.

Combined multiple-valve procedures: a five-year experience with 125 patients

One hundred twenty-five patients underwent 128 operations for combined multiple-valve procedures, with an overall early mortality of 16%. Highest mortality was associated with mitral and tricuspid valve disease (28.5%), followed by triple-valve disease (18.2%) and aortic and mitral valve disease (14%). Left ventricular end-diastolic pressure, cardiac index, mean pulmonary artery pressure, pulmonary artery wedge pressure, and arteriovenous oxygen difference were all significantly different in patients with regard to early mortality. Late follow-up of 94% has been achieved in 105 early survivors, with a late mortality rate of 11.2%. Analysis of late functional results reveal that 85% of survivors improved at least one Functional Class. Actuarial 5-year survival of 75% was achieved for early survivors of operation.

Treatment of infective endocarditis: a 10-year comparative analysis

The results of surgical and non-surgical treatment of active infective endocarditis in 182 patients over a 10-year period were analyzed. Heart failure, annular and myocardial abscesses, heart block, and coronary embolism, seen most frequently with staphylococcal and fungal endocarditis, were the primary causes of death in both native valve endocarditis (NVE) and prosthetic valve endocarditis (PVE). In NVE, surgery significantly improved the survival in patients with moderate or severe heart failure (P less than 0.05) and in all patients with staphylococcal endocarditis (P less than 0.03). In PVE, surgery significantly influenced survival in patients with moderate or severe heart failure (P less than 0.05) and in the entire group with late PVE (P less than 0.01). Early surgery is recommended for patients with native valve endocarditis and moderate or severe heart failure; those patients with staphylococcal NVE, regardless of hemodynamic state, should undergo early valve replacement. Early surgery is recommended for PVE patients with moderate or severe heart failure. We also recommend early valve replacement for early and late staphylococcal PVE.

The problem of valve prosthesis-patient mismatch

Valve prostheses have played an important part in the past two decades in the management of patients with valvular heart disease. However, many of the devices used in valve replacement have introduced new clinical problems. This paper deals with some of the problems associated with valve replacement, including one not previously emphasized--valve prosthesis-patient mismatch, which may cause obstruction to ventricular outflow and/or inflow.

Tetralogy of Fallot with subpulmonary ventricular septal defect

Among a total of 608 patients with tetralogy of Fallot, 35 with tetralogy and subpulmonary ventricular septal defect (VSD) have undergone intracardiac repair at the Children's Hospital, Buenos Aires. The crista supraventricular was absent in 62.9% of these patients; it was hypoplastic in 37.1%. Only 3 patients (8.6%) were severely cyanotic and required operation in infancy. The main and left and right pulmonary arteries were relatively large in all but 1 patient. Nevertheless, patch-graft enlargement across the pulmonary valve ring was necessary in 20 (57.1%). We believe that closure of the subpulmonary VSD increase the apparent severity of the pulmonary stenosis and necessitates patch-graft enlargement in patients in whom the appearance of the right ventricular outflow tract before repair would not have suggested its need.