Mortality and pathology following aortic valve replacement with the Björk-Shiley tilting disc valve

Metallurgic and design development in response to mechanical dysfunction of Björk-Shiley heart valves

In 16 years' experience with the Björk-Shiley tilting disc valve, the failures encountered have been disc-related. A. Obstruction of the disc movement in the aortic area has been due to faulty implantation technique, i.e. a suture cut too long and caught between the disc and the valve ring. Immediate reexploration, with cutting of the suture, has restored function. Disc obstruction in the mitral area has also been attributable to technique--leaving chordae tendineae too long. The author utilizes the universal sewing ring, which prevents the suture from encroaching on the disc. B. Disc escape by strut dislocation or strut fracture is a risk which can be reduced by care during valve implantation, always using only the valve holder to orient the valve. Forceful use of forceps, or use of the disc itself as a handle, may produce a crack in the weld which can propagate a strut fracture in the course of a year. When a patient's condition suddenly deteriorates, with dyspnea and tachycardia, immediate referral to the heart surgeon can be life-saving. Stethoscopy and chest X-ray suffice to reveal disc location and/or outflow strut fracture. Other investigations waste crucial time, as only reoperation with ex-change of the valve can save the patient. To strengthen the valve and avoid a weld, a mono-outflow strut has now been used for three years at the Karolinska Hospital, with no mechanical dysfunction and with excellent hemodynamic results.

Long-term results of cardiac valve replacement with the Delrin-disc model of the Björk-Shiley valve prosthesis

One hundred two Björk-Shiley valve prostheses with the Delrin-disc occluder were implanted in 83 patients between January, 1971, and July, 1972. Fifty-eight were in the mitral position, 42 in the aortic, and 2 in the tricuspid. Complete follow-up until 1981 was obtained in 93% of the patients (mean follow-up, 66.8 months). Hospital mortality was 18% and late mortality, 19%. Survival according to actuarial methods was 84.8% at 5 years and 78.1% at 9 years after operation. Thromboembolism was detected in 8.8% of patients but caused no deaths. The incidence was 1.2% and 1.5% per year in those patients treated with Coumadin and antiplatelet agents, respectively. Reoperation was necessary in 13% of the patients. Most survivors (72%) are in New York Heart Association Functional Class I, despite a preoperative status of Class III or IV in 57% of the patients. Hospital mortality may be due to poorer understanding of patient management and less refined techniques of myocardial protection. Long-term survival with this prosthesis is similar to that in more recent studies, and rates of thromboembolism and malfunction compare favorably with other prosthetic valves.

Dysfunction of the Björk-Shiley prosthesis. Report of 32 cases

We present 32 cases of dysfunction of the Björk-Shiley valvular prosthesis, representing 3.01% of the 1,063 BS prostheses implanted at this clinic. The complications observed were thrombosis of the prosthesis, suture dehiscence with or without endocarditis and disc-suture interference. In selected, favourable cases, we prefer thrombectomy with generous washing of the prosthesis and rotation of the disc, without removal of the disc from the prosthesis. Furthermore, when the dehiscence does not exceed 1/3 of the circumference of the ring, we have achieved very good results with single sutures supported on Teflon patches. Subsequent failures of this procedure were not of a technique nature, but rather due to the poor condition of the patients. In situations of clinical emergency, the diagnosis of valvular dysfunction may suffice as indication of surgery, further diagnostic measures being postponed in view of the data of the physical exploration.

Aortic valve replacement in patients over 70 years

Twenty-seven patients 70 years of age or more were operated upon with aortic valvular replacement with an early mortality rate of 7%. No more patients died during a mean follow-up period of 28 months. The Björk-Shiley standard tilting disc valve was implanted in 15 cases and the new convexo-concave model in 12 cases. Sixty-seven per cent of the patients had narrow aortic roots (21 and 23 mm prosthesis diameters) compared with 40% of younger patients. Thrombo-embolic complications occurred in 2 patients who had not received anticoagulant treatment. No such complications were recorded in the remaining 23 surviving patients treated with anticoagulants. All the surviving patients (except one who was re-operated because of a thrombotic encapsulation of the disc) were markedly improved postoperatively. High age alone is no longer an absolute contra-indication for aortic valve replacement. The convexo-concave Björk-Shiley tilting disc prosthesis is suitable in these patients because of its low resistance of flow at small diameters. The importance of anticoagulant treatment even in elderly patients is emphasized.

Late thrombotic malfunction of the Björk-Shiley tilting disc valve in the tricuspid position. Principles for recognition and management

Among 52 consecutive patients surviving tricuspid valve replacement with the Björk-Shiley tilting disc valve, follow-up extends between 1/2-9 years, mean 4.9 years. Four patients suffered thrombotic obstruction of their tricuspid prosthesis on 8 occasions, an incidence of 3.2%/year. Ebstein's anomaly and deficient anticoagulation were identified as likely contributory factors, but the complication remained unexplained in 2/8 instances. Thrombotic malfunction of the tricuspid prosthesis seems to constitute a relatively benign clinical entity with mild manifestations and diagnostic possibilities by non-invasive methods. Relief by means of thrombolytic treatment in the form of streptokinase (Kabikinase) (4) or replacement of the clotted prosthesis (4) involved neither disabling complications nor mortality. Our clinical observations and experimental studies suggest that thrombolytic therapy is effective, provided that prosthetic malfunction is due to a recent red clot, whereas encapsulation of the prosthetic disc by organized white-grey pannus necessitates re-operation. Streptokinase treatment should be attempted before surgery, but it is hardly meaningful to proceed for more than 24 hours. Restored prosthetic function within this time limit indicates the likely resolution of a red clot.

Teflon felt embolism of coronary arteries after cardiac surgery: a case report

A case is presented of fatal coronary embolism of Teflon felt used to buttress sutures in the placement of a Björk-Shiley aortic valve prosthesis. The embolism occurred on the tenth postoperative day, lodging in the left anterior descending branch of the left coronary artery 5.5 cm. from the ostium, causing a large anterior myocardial infarct. The patient died in less than 24 hours following the infarct. A review of the literature indicates that this is the first reported case of clinically significant embolism of Teflon felt used in the placement of a Björk-Shiley aortic valve.

The improved Björk-Shiley tilting disc valve prosthesis

The Björk-Shiley valve has been improved in three respects: (1) Increased strength by making the inlet strut an integral part of the orifice ring and doubling its cross-section area; (2) Improved hydrodynamics; (3) Elimination of the area of stagnant and low flow behind the disc. By utilizing a convexo-concave disc and by moving the pivot point downstream, the disc in open position is moved further out of the orifice ring. The flow through the smaller hole is thus increased by 40%. A significant clearance is obtained between the disc and the valve ring in open position. 234 of these valves have been inserted and followed-up for a maximum period of two years with excellent results.

Late evaluation of patients undergoing valve replacement with the Björk-Shiley prosthesis

This study analyzes 484 patients who survived mitral, aortic, or mitral and aortic valve replacement using the Björk-Shiley prosthesis from January, 1970, through December 31, 1974. Long-term follow-up of 1 1/2 to 6 1/2 years (mean, 3.67 yr) was done on 435 patients (98.2%). Eighty to 85% of the patients have improved noticeably. Thromboembolic problems occurred in 6.9%, representing 1.5 emboli per 1,000 patient-months. Anticoagulant bleeding problems occurred in 6.4% of the patients; late mortality was 15%. Actuarial survival curves showed patients at risk to 6 years having a 79% chance of survival. The same analysis according to preoperative New York Heart Association Functional Classification showed a striking reduction in survival in class IV patients. The Björk-Shiley prosthesis is a good choice for valve replacement today. Earlier diagnosis and treatment are needed to obtain better long-term survival.

Combined aortic and mitral valve replacement with the Björk-Shiley tilting disc valve prosthesis. Early and late results in 75 consecutive patients

This study evaluates the early and late results of combined aortic and mitral valve replacement with the Björk-Shiley tilting disc valve prosthesis in 75 consecutive patients operated upon during a 6-year-period commencing October 1969. The Delrin disc model Björk-Shiley prosthesis was inserted in the first 20 patients and the pyrolytic carbon disc model in the remainder. The opening angle was increased from 50 degrees to 60 degress and the Teflon sewing ring was designed with two flanges in the pyrolytic carbon disc mitral model. The patient material was characterized by marked cardiomegaly, impaired physical working capacity, hypokinetic central circulation, pulmonary hypertension and a 59% incidence of atrial arrhythmias before operation. Surgery was performed during generalized hypothermia to 30 degrees C and selective coronary perfusion, and the mitral valve was always replaced first. There were no intra-operative deaths, although 7/75 patients (9%) died while in hospital. Twelve patients (16%) died in average 19 (2-59) months postoperatively. Thrombo-embolic complications, which were frequently associated with poor anticoagulation, occurred in 9 patients and were fatal in 4 cases, corresponding to an incidence per patient month of 0.005 and 0.002, respecitvely. This risk was not affected by the type of prosthesis. One patient required operative repair of an aortic paraprosthetic leakage. Clinical improvement was found in 88% of the long-term survivors. The maximal working capacity increased in average 41% over the pre-operative value (p less than 0.001) and cardiac enlargement diminished in average by 22% (p less than 0.001). The incidence of atrial arrhythmias decreased slightly to 48%. Haemolysis was mild and without clinical significance. The actuarial curve indicated a 75% survival rate 3 years after operation.

Choosing a substitute cardiac valve: type, size, surgeon

Certain ideal characteristics of substitute cardiac valves are analyzed for each of the four basic types of available substitute cardiac valves. Of the four, the caged disc prosthesis is the least desirable: it obstructs, it clots and it degenerates. Each of the other three types of substitute cardiac valves has more favorable characteristics. Ideally, the caged ball prosthesis might be limited to patients with predominantly regurgitant lesions because of the problem of prosthetic disproportion. The tilting disc has favorable hemodynamic and wear characteristics, but long-term anticoagulant therapy is essential, as with the caged ball and caged disc types of prosthesis. The porcine xenograft appears to be desirable, but patients with sufficient implantation time (more than 5 years) for proper evaluation are just beginning to be studied and, therefore, final judgment must be reserved. Assuming that valve replacement is to be carried out in a large medical center by a surgical team experienced in this procedure, the results of this operation today are dependent more on the type and size of substitute valve inserted than on the surgeon who inserts the valve. It is therefore important for the cardiologist to become more informed about the various types of prosthetic cardiac valves and to become a member of the team deciding which type and size of cardiac valve are most suitable for his (or her) patient.

Management of the patient with a prosthetic heart valve

Approximately 20,000 heart valve prostheses are inserted yearly in the United States. Even after successful heart operations, the patients who receive them cannot be regarded as healthy individuals but are a special group with special problems who need close medical attention for the rest of their lives. They are susceptible to many unusual complications because of their implanted foreign body, and it is a challenge to all physicians in contact with them to be aware of their peculiar problems in order to prevent complications if possible and to treat them immediately if they occur. General therapy, surgical complications, infection, and mechanical problems are reviewed, with means for management outlined. These difficulties can be dealt with only by careful follow-up and well-coordinated teamwork between the family physician and the institution where the operation was performed.

Coronary ostial stenosis: a complication of aortic valve replacement of coronary perfusion

Coronary ostial stenosis developing after aortic valve replacement is a clinically well-recognized entity. This non-atheromatous intimal proliferation may be limited to the proximal part of the coronary artery, probably as a complication of intra-operative coronary perfusion. It may also occur in association with widespread intimal thickening in the aortic root, presumedly as a reaction to turbulence around aortic ball valve prostheses. We have encountered this process in 2/508 patients (0.4%), who underwent aortic valve replacement with the Björk-Shiley tilting disc valve prosthesis. The coronary perfusion technique was identical in all the operations.

Current status of the Beall, Bjork-Shiley, Braunwald-Cutter, Lillehei-Kaster and Smeloff-Cutter cardiac valve prostheses

The Starr-Edwards ball valve prosthesis is generally the standard by which other cardiac valve substitutes are compared. This report reviews information pertaining to several prostheses--the Beall mitral valve and the Bjork-Shiley, Braunwald-Cutter, Lillehei-Kaster and Smeloff-Cutter aortic and mitral valves--considered by some to have specific advantages over the Starr-Edwards valves. Hospital and late mortality rates after valve replacement are comparable for the four aortic valve prostheses reviewed and depend more on patient selection than on the specific prosthesis utilized. Extensive clinical experience with the Bjork-Shiley aortic valve indicates that this prosthesis offers hemodynamic advantages over ball valve prostheses, especially in patients with a small aortic root. Clinical experience with the Lillehei-Kaster pivoting disc prosthesis has been less extensive, but this model provides theoretical hemodynamic advantages similar to those of the Bjork-Shiley aortic valve prosthesis. Problems associated with cloth wear and the unexpectedly slow rate, in man, of tissue ingrowth into the fabric of the Braunwald-Cutter aortic valve prosthesis have been discouraging, although this prosthesis has been associated with a very low thromboembolic rate in patients receiving anticoagulant therapy. The Smeloff-Cutter aortic prosthesis is hemodynamically similar to the Starr-Edwards prosthesis and has been proved to be a reliable and durable aortic valve substitute over the past several years. Mortality after mitral valve replacement is also largely influenced by factors other than prosthetic valve design. On the basis of postoperative data, the five mitral valve prostheses reviewed do not appear to have substantial hemodynamic differences. For patients with a small left ventricular cavity the low profile prostheses, such as the Beall, Bjork-Shiley and Lillehei-Kaster, may be advantageous. Most available evidence indicates that patients receiving aortic or mitral valve prostheses should be given anticoagulant therapy postoperatively.

Aortic valve replacement with the Björk-Shiley tilting disc valve prosthesis. Clinical experiences in 50 cases

Single aortic valve replacement with the Björk-Shiley tilting disc valve prosthesis has been performed in 50 patients since April 1971. None of the total of six deaths (12.0%) was attributable to malfunction of the prosthesis or to embolic complications. Follow-up examination showed insignificant or moderate prosthetic regurgitation in two patients and moderate paravalvular leakage in one patient. A slight intravascular haemolysis was found in two cases, one of them without marked regurgitation, and a slight reversible cerebral thrombo-embolism in two. Clinical improvement was observed in 43 of the 44 survivors during the 6 to 12 months of follow-up. Objective evidence of improvement was verified by cardiac catheterization following the replacement of aortic valve with the Björk-Shiley tilting disc prosthesis.