Fracture of the outlet strut of a Björk-Shiley mitral prosthesis: Emergency operation with survival

Acute aortic regurgitation secondary to disk embolization of a Björk-Shiley prosthetic aortic valve

Having passed the 30th anniversary of the first implantation of a Björk-Shiley convexo-concave tilting mechanical valve, recognition of the life-threatening complication of strut fracture is not widespread. The authors report the case of a 48-year-old man with acute-onset chest pain and dyspnea found to have strut fracture and disk embolization of a 26-year-old Björk-Shiley prosthetic aortic valve. The value of echocardiography in the diagnosis of this condition is discussed.

Disk embolization of a Björk-Shiley convexo-concave mitral valve: a cause of sudden cardiovascular collapse and mesenteric ischemia

Strut fracture and disk embolization of a Björk-Shiley convexo-concave valve is uncommon, but it should always be considered as a cause of sudden cardiovascular collapse in patients with such valves. Recognition of this clinical scenario is essential, given the importance of early diagnosis and the prevalence of these valves worldwide. We present a fatal case of disk embolization of a mitral prosthesis presenting with cardiogenic shock and mesenteric ischemia.

Medical device tracking: results of a case study of the implantable cardioverter defibrillator

Case reports were received of a fatal tachycardia caused by a malfunction of an implantable cardioverter defibrillator (ICD), a device that is subject to the tracking regulations of the Food and Drug Administration's Center for Devices and Radiological Health. The case reports led to a decision to notify 5,604 patients of the need for reprogramming of their ICDs to prevent the tachycordia. In the first 60 days, a total of 98.7% of the patients were successfully located and their devices reprogrammed. Multiple logistic regression analysis was conducted to examine an extensive array of factors that might have been related to the time to reprogramming. Patient-specific factors such as age, sex, and ejection fraction did not serve as a barrier to reprogramming in the first week (p = NS). Patients whose regular physician had >5 patients with the ICD subject to the recall were significantly more likely to have their ICDs reprogrammed in the first week (odds ratio [OR] 2.11, 95% confidence interval [CI] 1.85 to 2.43, p<0.001). Patients who changed physicians were significantly less likely to undergo reprogramming in the first week (OR 0.73, 95% CI 0.63 to 0.86, p<0.001). The experience of the recall of this tracked device is highly encouraging because it demonstrates that most tracked device recipients can be successfully located and receive medical intervention. Although tracking devices is a manufacturer's responsibility, the clinical community plays a critical role in its success. This report highlights the importance of understanding that role among physicians.

Radiographic detection of strut separations in Björk-Shiley convexo-concave mitral valves

BACKGROUND

The outlet struts of Björk-Shiley convexo-concave heart valves can occasionally fracture. By December 31, 1994, 564 complete strut fractures had been reported to the manufacturer, approximately two thirds of which were fatal. There are no reliable diagnostic methods to detect valves that may be at risk for strut fracture. The outlet strut has two legs, and one leg often appears to break before the other, potentially permitting detection of the single-leg separation while the valve is still functionally intact.

METHODS

We used high-resolution cineradiography and defined valve profiles to evaluate 315 patients selected on the basis of their having mitral convexo-concave valves with an estimated fracture rate of 0.46 percent or higher per year. Two examinations were scheduled six months apart, with early reimaging performed when initial ratings were indeterminate.

RESULTS

Three patients had unsatisfactory studies, the most recent examinations in 277 patients were rated as apparently normal, 23 had findings considered minimally suspicious, and 1 had findings termed suspicious. The number of false negative results in this study group is unknown. Eleven cineradiograms were rated as showing probable or definite single-leg separations. All five "definite" ratings and five of the six "probable" ratings were confirmed by removal of the valves. One valve with a "probable" rating was intact. Two complete outlet-strut fractures occurred three and seven months after apparently normal radiographic examinations. Unsuspected new positive findings were not found at six months among 288 patients who completed the examination cycle.

CONCLUSIONS

Cineradiographic imaging can detect some single-leg separations in mitral convexo-concave valves and may help the estimated 41,000 patients with these valves worldwide and their physicians decide about elective valve removal.

Management of patients with Björk-Shiley prosthetic valves

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Digital acoustical analysis of normal and bimodal Björk-Shiley 60 degrees convexo-concave heart valves

Fracture of the outlet strut of the Björk-Shiley 60 degrees convexo-concave (BS60CC) valve has been attributed to a bimodal closing pattern in certain valves in which the closing disk rotates about the inlet strut, causing upward displacement of the outlet strut and its eventual fracture. This article reports the in vivo studies of the normal BS60CC valve and the in vitro studies of the normal and bimodal BS60CC valves, using a digital acoustical signal processing technique, in which the individual collisions (impact history) of the occluder disk with the components of the valve body are revealed during each closing cycle. In vitro analysis of the closing acoustical signals of normal BS60CC valves showed impact history cluster width (IHCW) means of 2.07 +/- 0.85 ms (standard error), not significantly different from those of 1.86 +/- 0.58 ms (standard error) observed in 38 clinically normal patients with BS60CC valves (p greater than 0.1). The bimodal valves showed IHCW of 6.14 +/- 0.98 ms (standard error), in vitro, which was significantly greater than those observed in the normal in vitro valve group and in the normal patient population (p less than 0.0001).

Björk-Shiley strut fracture and disc escape: literature review and a method of disc retrieval

Embolization of a prosthetic valve poppet is a rare but life-threatening event. It was reported sporadically before the introduction of the Björk-Shiley 70-degree convexoconcave prosthesis in 1980. Since that time, there have been a large number of reported mechanical failures with disc escape. The rate for the 29-mm to 33-mm mitral valves is estimated as 5.2%. In 29 of 35 patients (including the 2 presented here) in whom the site of disc lodgment could be determined, the disc was in the descending or abdominal aorta. Fifteen of these patients died. Six survivors had the disc removed at the same operation and 6 at a later operation. In 2 patients, the disc was not removed. In 2 patients in whom the disc was not removed initially, it was thought to contribute to postoperative complications. Two more cases of structural failure of the Björk-Shiley convexoconcave prosthesis are presented. A transpericardial approach to the descending aorta on bypass is described. It allows easy removal of the disc and eliminates the need for a second operation.

Strut fracture and disc embolisation of a Björk-Shiley aortic prosthesis: emergency operation with survival. Case report

Strut fracture with disc embolisation from a Björk-Shiley prosthesis in the aortic position is extremely rare, and almost invariably fatal. We report a case in which the patient survived emergency surgery for this complication. The pathogenesis of strut fracture, its prevention, diagnosis and management are discussed.

Outlet strut fracture of the Björk-Shiley 60 degrees Convexo-Concave valve: current information and recommendations for patient care

Mechanical failure of artificial heart valves can be a catastrophic event. The problem of outlet strut fracture of the Björk-Shiley 60 degrees Convexo-Concave tilting disc prosthesis has received much attention in the medical literature and generated both concern and confusion among patients and physicians. Analysis of current data from the manufacturer, as well as a review of the medical literature, suggests that the overall risk of outlet strut fracture is low and that elective explantation of a well functioning Björk-Shiley 60 degrees Convexo-Concave valve prosthesis is not warranted. Diagnostic features of outlet strut fracture can be seen with overpenetrated chest X-ray films so that diagnosis can be established promptly. Early operation to replace the fractured prosthesis is essential for patient survival.

Echocardiographic demonstration of outlet strut fracture of a Björk-Shiley mitral prosthesis

Fracture of the outlet strut of the Björk-Shiley mitral valve prosthesis has been recognized with increasing frequency, prompting recall of unimplanted valves manufactured before March 1982. Presenting dramatically with acute severe pulmonary edema and low cardiac output, strut fracture is frequently a fatal complication. This case report documents the first reported echocardiographic demonstration of occluder disc dislodgment secondary to outlet strut fracture with survival after emergency valve replacement.

Disc dislodgment in Björk Shiley mitral valve prosthesis: two successfully operated cases

Two patients with Björk Shiley mitral valve replacement had migration and embolization of the occluding disc. One patient suffered migration of the disc a few hours after surgery and the other had a strut fracture with disc translocation six years after the initial operation. Clinical signs in both cases were pulmonary edema, cardiogenic shock, and absence of prosthetic sounds. Both patients were reoperated on an emergency basis, recovering after a complicated postoperative course. They are on functional Class I, 8 and 1 years later, respectively, with their dislodged discs still in the abdominal aorta. The only hope for survival in these patients is emergency reoperation, once the prosthetic mitral valve dysfunction is confirmed.

Long-term follow-up of Björk-Shiley mitral valve replacement. 10 years' experience

Retrospective analysis was made of 176 patients who received a Björk-Shiley mitral valve replacement in the period 1973 through 1982. Actuarial cumulative curves showed the 10-year and 5-year survival rates to be 79 +/- 3.4%. The functional status at follow-up was better than preoperatively in 77.1% of the patients. The hospital mortality was 9.1% and the late mortality was 3.6/100 patient years. Early complications included disc entrapment against the ventricular wall in three cases, wedging of chorda between disc and valve rim in two and posterior perforation of the left ventricle in three patients. There was no structural valve damage. Calculated per 100 patient years, the incidence of thromboembolism was 2.5, endocarditis 1.4 and prosthetic leak 1.8. One thrombosed valve was successfully replaced by a new prosthesis 11 years after the initial implantation. Jamming of the disc by tissue over-growth necessitated a new valve implantation in one case. The incidence of early valve-related complications was high, but the long-term results were comparable with those from other mechanical valves. One early complication--disc entrapment against the ventricular wall--may be avoided by use of a sufficiently small valve if the ventricle is small and thickened.

Early clinical evaluation of a new Björk-Shiley valve prosthesis with integral monostrut

We evaluated preliminary results of valve replacement with a new Björk-Shiley valve prosthesis with integral monostrut. Sixty-five valves were implanted in 56 patients (18 aortic, 30 mitral, 7 double, 1 triple). The age of the patients ranged from 30 to 62 years, and they were followed up for 7-17 months (mean, 12.5 months). There were three operative deaths (5.3%) not related to the prosthesis and no late deaths. Minor cerebral thromboembolism occurred in one patient 2 weeks after surgery despite anticoagulant therapy. Intraoperative transvalvular pressure gradients across the 23-mm aortic and 27-mm mitral valve prostheses were insignificant. Real-time two-dimensional echocardiography revealed no regurgitation at the moment of valve closure in 20 randomly selected patients. Though the data accumulated so far are still relatively incomplete and the follow-up periods short, the clinical results obtained here were satisfactory, warranting further use of this new Björk-Shiley valve prosthesis with integral monostrut for longer follow-up studies.

Experience with outlet strut fracture of the Björk-Shiley convexoconcave mitral valve prosthesis

Within a period of 15 months, we encountered five patients with outlet strut fracture of the Björk-Shiley convexoconcave mitral valve prosthesis. All of the patients had acute failure of the left side of the heart and pulmonary edema. The diagnosis was made by review of the chest roentgenogram which showed features of pulmonary edema; both the outlet strut and the tilting disc were missing from the mitral prosthesis. The "missing" components might be found in the left side of the heart or in the course of the thoracic aorta. Emergency reoperation was carried out on three patients, and there were two survivors. It is essential to recognize this potentially fatal complication and undertake immediate surgical intervention. We performed the original valvular replacement operations in four of the five patients. The probability of outlet strut fracture occurring in our series of 237 patients with a Björk-Shiley convexoconcave mitral valve prosthesis is 1.69%, or 0.076 per 100 patient months.

Hemodynamic evaluation of the integral monostrut Björk-Shiley prosthesis in the aortic position

Between May, 1983, and November, 1984, the new integral monostrut Björk-Shiley prosthesis was used for aortic valve replacement in 62 patients. The prosthesis is machined from a solid piece of cobalt alloy and has no welded joints. The traditional U-shaped outlet strut has been replaced by a projecting metal finger that holds the disc in place. The disc opens to 70 degrees and is convexoconcave. Successful transseptal heart catheterization was performed in 23 patients an average of 6 months following operation to evaluate the hemodynamic performance of the prosthesis. The mean peak-to-peak gradient was 7.73 +/- 7.49 mm Hg (+/- standard deviation). In five valves it was 0, and in only three was it higher than 15 mm Hg. Significant peak gradients were directly related to the valve index (valve area/body surface area). Mean systolic gradient at rest was 12.7 +/- 6.27 mm Hg and did not increase after exercise. Effective orifice areas were adequate, and the discharge coefficient ranged from 0.77 for the 21-mm prosthesis to 0.48 for the 29-mm prosthesis. Minimal regurgitation, which was washed out on the next systole, was observed with all sizes of the prosthesis. Disc opening was maximal (70 degrees) in all but one of the observed instances. Longer clinical follow-up is required, but the new integral monostrut Björk-Shiley prosthesis, with its important design changes and excellent hemodynamic performance, appears to be a promising aortic valve substitute.

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.

Current status of valve prostheses

The deterioration in cardiac function caused by a valvular lesion frequently can be halted or reversed by timely surgery. This article discusses the principles used to decide when surgery is beneficial and briefly reviews current indications for operation in the more common acquired and congenital valve lesions. The factors influencing the choice of a valve prosthesis are also discussed.

Mechanism of late failure of the Alvarez disc valve prosthesis

An Alvarez disc valve prosthesis had been implanted in the mitral and tricuspid positions in 15 patients between 1964 and 1967 in this hospital. Of these 15 patients, only three survived longer than 10 years, all three dying unexpectedly between 16 and 18 years postoperatively. Two deaths were a direct result of disruption of the Alvarez prosthesis. The third patient was not examined at necropsy, but in retrospect the history was highly suggestive of valve malfunction. Cross sectional and pulsed Doppler echocardiography made valuable contributions to the diagnosis in both cases of valve disruption and, when available, should be part of the primary investigation of suspected prosthetic heart valve failure. The Alvarez valve prosthesis is liable to erosive wear which may cause late detachment of the disc from the valve ring with abrupt and catastrophic haemodynamic consequences.

Disc and strut embolisation after minor strut fracture in a Björk-Shiley mitral valve prosthesis

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