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Surgical treatment of thrombosed Björk-Shiley aortic valve prosthesis
Surgical treatment of thrombosed Bjork-Shiley aortic valve prosthesis Massive thrombosis of a Bjork-Shiley aortic valve prosthesis occurs with significant frequency when adequate anticoagulation has not been attained. The converse is also true: This complication is extremely rare in patients receiving anticoagulant therapy. Therefore, we recommend anticoagulants for all patients with Bjork-Shiley aortic valve prostheses. Once a diagnosis of a thrombosed prothesis is made, however, immediate operation is indicated. Declotting of the valve without removal of the disc is adequate treatment. After thrombectomy, it is extremely important to evaluate the entire prosthesis critically, with particular attention to the area of the hinge and the occluder. If any wear is observed, the entire prosthesis should be replaced. Excellent long-term results can be expected if the patient is maintained on adequate anticoagulation postoperatively.
Laman A. Gray, Jr., M.D.,* Robert L. Fulton, M.D.,* Tribeni N. Srivastava, M.D., ** and Nancy C. Flowers, M.D.,** Louisville, Ky.
A rosthetic valvular replacement for the treatment of aortic stenosis and insufficiency has become a routine procedure. As yet, artificial valves have not reached the ideal form and function. The problems of hemolysis and thromboembolism have led to multiple variations in valve design and construction. To date, no valve has been produced which is completely free of associated thromboembolism. An even more catastrophic event is the thrombosis of the valve itself. This causes a malfunction of the prosthesis leading to massive aortic insufficiency and stenosis. If the diagnosis is not promptly made and an urgent reoperation performed, the patient will die. Case history A 55-year-old man underwent aortic valve replacement in December, 1972, with a Bjork-Shiley size 27 (Pyrolyte carbon disc) prosthesis for severe calcine aortic stenosis. Following operation, he did extremely well and was asymptomatic for 2 years. Approximately 4 weeks before admission, he developed sudden onset of shortness of breath and dyspnea on exertion. The patient did not seek medical advice at this time but treated himself with strict bedrest. His From The University of Louisville School of Medicine, Health Sciences Center, Louisville, Ky. 40202. Received for publication July 10, 1975. *Section of Thoracic and Cardiovascular Surgery, The Department of Surgery. **Section of Cardiology, The Department of Medicine.
condition did improve somewhat. However, on the day of his admission, his symptoms became acute. Pertinent physical findings at the time of admission showed diffuse rales throughout both lung fields. The chest roentgenogram confirmed the diagnosis of pulmonary edema. Examination of the heart revealed a Grade 4/6 ejection systolic murmur along the upper left sternal border. In addition, there was a Grade 5/6 early diastolic decrescendo murmur in the third intercostal space to the left of the sternum. The normal prosthetic closing sound was absent. Following admission to hospital, an echocardiogram and a phonocardiograph both demonstrated that the disc was not moving properly. The patient then underwent cardiac catheterization; a supravalvular injection revealed severe aortic insufficiency, with the prosthetic disc fixed at approximately a 45 degree angle (Fig. 1). The patient was taken immediately to the operating room where, with the use of cardiopulmonary bypass, the aorta was opened. Examination of the prosthetic valve disclosed that the poppet was fixed at a 45 degree angle (Fig. 2). A dense clot, involving the hinge mechanism on the side of the poppet with the smaller opening, extended on the aortic and the ventricular sides of the hinge. Because of the location of the thrombus, the disc could neither open nor close. The clot was easily debrided from the occluder without removal of the disc from the hinge. In removing the clot, we were extremely careful not to injure the disc or the hinge. To facilitate removal of the clot from the ventricular side, we rotated the valve mechanism within its sewing ring. After removal of the clot, the disc moved freely and appeared perfectly normal. There was no evidence of any wear of either the disc or the hinge. The sewing ring was well endothelialized, and there were no peri valvular leaks. The postoperative course was uncomplicated. The patient
429
430
Gray et al.
The Journal of Thoracic and Cardiovascular Surgery
Fig. 1. Supravalvular injection demonstrating aortic insufficiency with the valve open wide.
Fig. 2. The aortic prosthesis is held open at a 45 degree angle secondary to massive thrombosis involving both the aortic and ventricular sides of the hinge. Note that the thrombus is located on the smaller opening of the valve. was discharged on adequate anticoagulant therapy and has continued to do well. Discussion The incidence of thromboembolism from the Bjork-Shiley valves is important. Messmer and coworkers7 reported a series of 100 cases in which the Bjork-Shiley aortic valve prosthesis was used. In this group, 29 patients required double or triple valve replacements. These authors reported a 2.5 per cent early emboli rate and a 2.5 per cent late emboli rate in
patients taking anticoagulants. One patient not taking anticoagulants had massive thrombosis of the aortic prosthesis. Similar results were found by Fernandez and colleagues6 in reviewing 110 consecutive aortic valve replacements with Bjork-Shiley prostheses. There were three hospital deaths, a mortality rate of 2.7 per cent, and five late deaths, for a late mortality rate of 4.5 per cent. In this series, 2 patients or 1.8 per cent experienced nonfatal cerebral embolic episodes during the follow-up period of from 3 to 20 months. One of these emboli was secondary to a calcium embolus at the
Volume 71 Number 3 March, 1976
time of operation. The other patient developed a cerebral embolus 9 months after operation. One additional patient developed a thrombosis of the valve prosthesis which resulted in death. One of the significant advantages of the Bjork-Shiley aortic valve prosthesis as compared to other prostheses is the central-flow design which produces a large inner diameter and a greater central flow.2 This is regarded not only as a hemodynamic advantage but also as a way of washing away any tiny thrombi that might have been formed on the valve. In 1971, Cokkinos and others5 described a patient with acute thrombosis of a Bjork-Shiley aortic prosthesis. The patient died before emergency operation could be performed. At postmortem examination, heavy fibrosis was found on the prosthesis on both the aortic and ventricular sides of the hinge. The authors suggested that thrombus formation was secondary to eddy currents caused by the asymmetrical opening of the valve. In 1972, Bozerand Karamehmetoglu4 reported 2 additional cases of thrombosis of Bjork-Shiley aortic prostheses. Again, at postmortem examination, the thrombus was present on the less mobile portion of the disc. Thrombosis had extended to cover approximately two thirds of the valve in a curtain-like fashion. In all of these reported cases, location of the thrombus was exactly the same. The authors suggested this was a result of the design of the valve. The disc opens at approximately a 60 degree angle in relation to the sewing ring. Therefore, there is both a large and a small aperture through which blood can pass. The volume of blood going through the smaller part of the valve is less than the volume passing through the larger section. Therefore, relative stasis occurs around the hinge mechanism. They suggested that the asymmetrical opening of the disc with its relative stasis promoted the thrombosis. Bjork and Henze3 first suggested that the treatment of choice for a thrombosed Bjork-Shiley valve was the declotting of the valve. They have reported 2 cases of thrombosed aortic valves in a total of 300 patients. Neither of these patients received anticoagulant therapy. The first patient had massive thrombosis with the valve in the open position. She developed symptoms of acute, marked aortic stenosis and incompetence. The patient died suddenly before an operation could be carried out. The second patient was a 60-year-old woman who developed symptoms of malfunction of the valve 3 months after insertion. At operation, the Pyrolite disc was removed and the valve declotted. Following removal of the thrombi, the Pyrolite disc was reinserted. This patient has done well. The authors believe complete thrombectomy
Bjork-Shiley aortic valve prosthesis
43 1
could be carried out after removal of the disc; however, they do not recommend this procedure because of the possible damage to the struts. Therefore, if the surgeon is not experienced in the proper removal of the disc, they recommend complete removal of the clotted prosthesis and insertion of a new valve. In a series of 121 patients receiving Bjork-Shiley aortic valve prostheses, Ben Zvi and co-authors1 had 7 cases or a 5 per cent incidence of massive thrombosis of the prosthesis. These thrombi occurred 3 to 19 months after insertion of the prosthesis. Of the 7 patients, only one had adequate anticoagulation at the time of diagnosis. Two patients died before operation could be performed. Of the 5 patients operated upon, 4 survived. In all 4 of these patients, the original Bjork-Shiley prosthesis was left in place, and a thrombectomy with debridement of the valve was performed. Good endothelialization of the sewing ring was noted, and the disc appeared normal without any variance. The Bjork-Shiley aortic prosthesis is not free of embolic complications, as was once thought. It is difficult to determine the exact incidence, because some of the patients in the series have received anticoagulants and others have not. Probably, the incidence of thromboemboli forming on this valve with adequate anticoagulant therapy is 1 to 2 per cent. Ample evidence exists that all patients receiving Bjork-Shiley aortic prostheses should be administered anticoagulants. In reviewing the literature, we found that all but one of the patients who had a thrombosed valve were not receiving adequate anticoagulation. There is no question as to the desirability of prophylactic anticoagulation. In any patient with a valve prosthesis who has been doing well and suddenly develops symptoms, the possibility of valve malfunction should be considered. Malfunction is clinically confirmed by the absence of the closing click of the valve and the appearance of the prominent systolic and diastolic aortic murmurs. Once a diagnosis has been confirmed by cinearteriography, the patient should be taken immediately to the operating room. The operation of choice is declotting of the valve. Thrombectomy can be carried out without removing the disc from the struts. It is extremely important to examine the struts and the disc carefully to be certain that there is no wear. In addition, the sewing ring has to be scrutinized closely to make sure that there is no underlying cause for the thrombus. When this procedure is carried out and the patient is prescribed long-term anticoagulant therapy postoperatively, an excellent long-term result can be expected.
432
The Journal of Thoracic and Cardiovascular Surgery
Gray et al.
REFERENCES 1 Ben-Zvi, J., Hildner, F. J., Chandraratna, P. A., and Samet, P.: Thrombosis on Bjork-Shiley Aortic Valve Prosthesis: Clinical, Arteriographic, Echocardiographic and Therapeutic Observations in Seven Cases, J. Cardiol. 34: 538, 1974. 2 Bjork, V. O., Henze, A., and Carlstrom, A.: Haematological Evaluation of the Bjork-Shiley Tilting Disc Valve Prosthesis in Isolated Aortic Valvular Disease, Scand. J. Thorac. Cardiovasc. Surg. 8: 12, 1974. 3 Bjork, V. O., and Henze, A.: Encapsulation of the Bjork-Shiley Aortic Disc Valve Prosthesis Caused by the Lack of Anticoagulant Treatment, Scand. J. Thorac. Cardiovasc. Surg. 7: 17, 1973.
4 Bozer, A. Y., and Karamehmetoglu, A.: Thrombosis Encountered With Bjork-Shiley Prosthesis, J. Cardiovasc. Surg. 13: 141, 1972. 5 Cokkinos, D. V., Voridis, E., Bakoulas, G., Theodossiou, A., and Skalkeas, G. D.: Thrombosis of Two High-flow Prosthetic Valves, J. THORAC. CARDIOVASC. SURG. 62: 947,
1971.
6 Fernandez, J., Morse, D., Maranhao, V., and Gooch, A. S.: Results of Use of the Pyrolitic Carbon Tilting Disc Bjork-Shiley Aortic Prosthesis, Chest 65: 640, 1974. 7 Messmer, B. J., Hallman, G. L., Liotta, D., Martin, C . and Cooley, D. A.: Aortic Valve Replacement: New Techniques, Hydrodynamics, and Clinical Results, Surgery 68: 1026, 1970.
Laman A. Gray, Jr., M.D.,* Robert L. Fulton, M.D.,* Tribeni N. Srivastava, M.D., ** and Nancy C. Flowers, M.D.,** Louisville, Ky.
A rosthetic valvular replacement for the treatment of aortic stenosis and insufficiency has become a routine procedure. As yet, artificial valves have not reached the ideal form and function. The problems of hemolysis and thromboembolism have led to multiple variations in valve design and construction. To date, no valve has been produced which is completely free of associated thromboembolism. An even more catastrophic event is the thrombosis of the valve itself. This causes a malfunction of the prosthesis leading to massive aortic insufficiency and stenosis. If the diagnosis is not promptly made and an urgent reoperation performed, the patient will die. Case history A 55-year-old man underwent aortic valve replacement in December, 1972, with a Bjork-Shiley size 27 (Pyrolyte carbon disc) prosthesis for severe calcine aortic stenosis. Following operation, he did extremely well and was asymptomatic for 2 years. Approximately 4 weeks before admission, he developed sudden onset of shortness of breath and dyspnea on exertion. The patient did not seek medical advice at this time but treated himself with strict bedrest. His From The University of Louisville School of Medicine, Health Sciences Center, Louisville, Ky. 40202. Received for publication July 10, 1975. *Section of Thoracic and Cardiovascular Surgery, The Department of Surgery. **Section of Cardiology, The Department of Medicine.
condition did improve somewhat. However, on the day of his admission, his symptoms became acute. Pertinent physical findings at the time of admission showed diffuse rales throughout both lung fields. The chest roentgenogram confirmed the diagnosis of pulmonary edema. Examination of the heart revealed a Grade 4/6 ejection systolic murmur along the upper left sternal border. In addition, there was a Grade 5/6 early diastolic decrescendo murmur in the third intercostal space to the left of the sternum. The normal prosthetic closing sound was absent. Following admission to hospital, an echocardiogram and a phonocardiograph both demonstrated that the disc was not moving properly. The patient then underwent cardiac catheterization; a supravalvular injection revealed severe aortic insufficiency, with the prosthetic disc fixed at approximately a 45 degree angle (Fig. 1). The patient was taken immediately to the operating room where, with the use of cardiopulmonary bypass, the aorta was opened. Examination of the prosthetic valve disclosed that the poppet was fixed at a 45 degree angle (Fig. 2). A dense clot, involving the hinge mechanism on the side of the poppet with the smaller opening, extended on the aortic and the ventricular sides of the hinge. Because of the location of the thrombus, the disc could neither open nor close. The clot was easily debrided from the occluder without removal of the disc from the hinge. In removing the clot, we were extremely careful not to injure the disc or the hinge. To facilitate removal of the clot from the ventricular side, we rotated the valve mechanism within its sewing ring. After removal of the clot, the disc moved freely and appeared perfectly normal. There was no evidence of any wear of either the disc or the hinge. The sewing ring was well endothelialized, and there were no peri valvular leaks. The postoperative course was uncomplicated. The patient
429
430
Gray et al.
The Journal of Thoracic and Cardiovascular Surgery
Fig. 1. Supravalvular injection demonstrating aortic insufficiency with the valve open wide.
Fig. 2. The aortic prosthesis is held open at a 45 degree angle secondary to massive thrombosis involving both the aortic and ventricular sides of the hinge. Note that the thrombus is located on the smaller opening of the valve. was discharged on adequate anticoagulant therapy and has continued to do well. Discussion The incidence of thromboembolism from the Bjork-Shiley valves is important. Messmer and coworkers7 reported a series of 100 cases in which the Bjork-Shiley aortic valve prosthesis was used. In this group, 29 patients required double or triple valve replacements. These authors reported a 2.5 per cent early emboli rate and a 2.5 per cent late emboli rate in
patients taking anticoagulants. One patient not taking anticoagulants had massive thrombosis of the aortic prosthesis. Similar results were found by Fernandez and colleagues6 in reviewing 110 consecutive aortic valve replacements with Bjork-Shiley prostheses. There were three hospital deaths, a mortality rate of 2.7 per cent, and five late deaths, for a late mortality rate of 4.5 per cent. In this series, 2 patients or 1.8 per cent experienced nonfatal cerebral embolic episodes during the follow-up period of from 3 to 20 months. One of these emboli was secondary to a calcium embolus at the
Volume 71 Number 3 March, 1976
time of operation. The other patient developed a cerebral embolus 9 months after operation. One additional patient developed a thrombosis of the valve prosthesis which resulted in death. One of the significant advantages of the Bjork-Shiley aortic valve prosthesis as compared to other prostheses is the central-flow design which produces a large inner diameter and a greater central flow.2 This is regarded not only as a hemodynamic advantage but also as a way of washing away any tiny thrombi that might have been formed on the valve. In 1971, Cokkinos and others5 described a patient with acute thrombosis of a Bjork-Shiley aortic prosthesis. The patient died before emergency operation could be performed. At postmortem examination, heavy fibrosis was found on the prosthesis on both the aortic and ventricular sides of the hinge. The authors suggested that thrombus formation was secondary to eddy currents caused by the asymmetrical opening of the valve. In 1972, Bozerand Karamehmetoglu4 reported 2 additional cases of thrombosis of Bjork-Shiley aortic prostheses. Again, at postmortem examination, the thrombus was present on the less mobile portion of the disc. Thrombosis had extended to cover approximately two thirds of the valve in a curtain-like fashion. In all of these reported cases, location of the thrombus was exactly the same. The authors suggested this was a result of the design of the valve. The disc opens at approximately a 60 degree angle in relation to the sewing ring. Therefore, there is both a large and a small aperture through which blood can pass. The volume of blood going through the smaller part of the valve is less than the volume passing through the larger section. Therefore, relative stasis occurs around the hinge mechanism. They suggested that the asymmetrical opening of the disc with its relative stasis promoted the thrombosis. Bjork and Henze3 first suggested that the treatment of choice for a thrombosed Bjork-Shiley valve was the declotting of the valve. They have reported 2 cases of thrombosed aortic valves in a total of 300 patients. Neither of these patients received anticoagulant therapy. The first patient had massive thrombosis with the valve in the open position. She developed symptoms of acute, marked aortic stenosis and incompetence. The patient died suddenly before an operation could be carried out. The second patient was a 60-year-old woman who developed symptoms of malfunction of the valve 3 months after insertion. At operation, the Pyrolite disc was removed and the valve declotted. Following removal of the thrombi, the Pyrolite disc was reinserted. This patient has done well. The authors believe complete thrombectomy
Bjork-Shiley aortic valve prosthesis
43 1
could be carried out after removal of the disc; however, they do not recommend this procedure because of the possible damage to the struts. Therefore, if the surgeon is not experienced in the proper removal of the disc, they recommend complete removal of the clotted prosthesis and insertion of a new valve. In a series of 121 patients receiving Bjork-Shiley aortic valve prostheses, Ben Zvi and co-authors1 had 7 cases or a 5 per cent incidence of massive thrombosis of the prosthesis. These thrombi occurred 3 to 19 months after insertion of the prosthesis. Of the 7 patients, only one had adequate anticoagulation at the time of diagnosis. Two patients died before operation could be performed. Of the 5 patients operated upon, 4 survived. In all 4 of these patients, the original Bjork-Shiley prosthesis was left in place, and a thrombectomy with debridement of the valve was performed. Good endothelialization of the sewing ring was noted, and the disc appeared normal without any variance. The Bjork-Shiley aortic prosthesis is not free of embolic complications, as was once thought. It is difficult to determine the exact incidence, because some of the patients in the series have received anticoagulants and others have not. Probably, the incidence of thromboemboli forming on this valve with adequate anticoagulant therapy is 1 to 2 per cent. Ample evidence exists that all patients receiving Bjork-Shiley aortic prostheses should be administered anticoagulants. In reviewing the literature, we found that all but one of the patients who had a thrombosed valve were not receiving adequate anticoagulation. There is no question as to the desirability of prophylactic anticoagulation. In any patient with a valve prosthesis who has been doing well and suddenly develops symptoms, the possibility of valve malfunction should be considered. Malfunction is clinically confirmed by the absence of the closing click of the valve and the appearance of the prominent systolic and diastolic aortic murmurs. Once a diagnosis has been confirmed by cinearteriography, the patient should be taken immediately to the operating room. The operation of choice is declotting of the valve. Thrombectomy can be carried out without removing the disc from the struts. It is extremely important to examine the struts and the disc carefully to be certain that there is no wear. In addition, the sewing ring has to be scrutinized closely to make sure that there is no underlying cause for the thrombus. When this procedure is carried out and the patient is prescribed long-term anticoagulant therapy postoperatively, an excellent long-term result can be expected.
432
The Journal of Thoracic and Cardiovascular Surgery
Gray et al.
REFERENCES 1 Ben-Zvi, J., Hildner, F. J., Chandraratna, P. A., and Samet, P.: Thrombosis on Bjork-Shiley Aortic Valve Prosthesis: Clinical, Arteriographic, Echocardiographic and Therapeutic Observations in Seven Cases, J. Cardiol. 34: 538, 1974. 2 Bjork, V. O., Henze, A., and Carlstrom, A.: Haematological Evaluation of the Bjork-Shiley Tilting Disc Valve Prosthesis in Isolated Aortic Valvular Disease, Scand. J. Thorac. Cardiovasc. Surg. 8: 12, 1974. 3 Bjork, V. O., and Henze, A.: Encapsulation of the Bjork-Shiley Aortic Disc Valve Prosthesis Caused by the Lack of Anticoagulant Treatment, Scand. J. Thorac. Cardiovasc. Surg. 7: 17, 1973.
4 Bozer, A. Y., and Karamehmetoglu, A.: Thrombosis Encountered With Bjork-Shiley Prosthesis, J. Cardiovasc. Surg. 13: 141, 1972. 5 Cokkinos, D. V., Voridis, E., Bakoulas, G., Theodossiou, A., and Skalkeas, G. D.: Thrombosis of Two High-flow Prosthetic Valves, J. THORAC. CARDIOVASC. SURG. 62: 947,
1971.
6 Fernandez, J., Morse, D., Maranhao, V., and Gooch, A. S.: Results of Use of the Pyrolitic Carbon Tilting Disc Bjork-Shiley Aortic Prosthesis, Chest 65: 640, 1974. 7 Messmer, B. J., Hallman, G. L., Liotta, D., Martin, C . and Cooley, D. A.: Aortic Valve Replacement: New Techniques, Hydrodynamics, and Clinical Results, Surgery 68: 1026, 1970.