Mechanical Aortic Valve Without Anticoagulation For Twenty-Six Years
A Ozler, M Dumantepe, A Tarhan, K Atalan, T Denizalt?
Keywords
anticoagulation, aortic valve replacement, mechanical valvular prostheses, risk of thrombosis
Citation
A Ozler, M Dumantepe, A Tarhan, K Atalan, T Denizalt?. Mechanical Aortic Valve Without Anticoagulation For Twenty-Six Years. The Internet Journal of Thoracic and Cardiovascular Surgery. 2013 Volume 16 Number 1.
Abstract
Objective: Mechanical valvular prostheses have the advantage of longevity but carry a risk of thrombosis, which is dependent from valve design, materials and host-related interface. Anticoagulation is known as essential for mechanical heart valves to prevent lethal complications such as valve thrombosis and systemic embolism.
Method: A 47-year-old man had an aortic valve replacement in 1985. His native valve was incompetent from infective endocarditis. He discontinued warfarin a few months after the surgery and presented 26 years later with palpitations and dyspnea on exertion for one month. On auscultation, mechanical valve sounds were absent. Transthoracic echocardiography and angiography revealed that the mechanical aortic valve was dysfunctional. Furthermore, echocardiography showed tilting disc of the prosthetic valve was entirely immobile with a mobile soft tissue mass, 5 mm in diameter, was detected at the obstructed leaflet. The patient was re-operated for to replace the dysfunctional valve.
Results: At the time of surgery, tilting disc aortic valve, which was implanted at an anatomical orientation, was obstructed at the open position with fresh thrombi. We decided upon replacement with a 23 mm St Jude Medical prosthetic aortic valve. Postoperative period was uneventful and medication consisted of warfarin plus low molecule weight heparine.
Conclusion: It is unusual that a functioning mechanic aortic valve is present without anticoagulation for over twenty-five years. The potential factors underlying in the normal valvular mechanics in our patient remains unclear. Prompt diagnosis and emergency surgical intervention are essential for a successful outcome.
Introduction
Mechanical valvular prostheses have the advantage of longevity but carry a risk of thrombosis, which is dependent from valve design, materials and host-related interface. These prostheses composed of metal or carbon alloys have the advantage of long-term durability, but they carry an increased risk of thrombo-embolism as well as definite risk of bleeding secondary to anticoagulation (1).
Anticoagulation is known as essential for mechanical heart valves to prevent lethal complications such as valve thrombosis and systemic embolism. Current guidelines necessitate varying degrees of long-term anticoagulation in patients with mechanical heart valve(s) to prevent thrombotic and embolic complications.
We report the case of a patient has a Bjork-Shiley tilting disc mechanic valve in the aortic position without anticoagulation during 26 years event free and now presented with valve disfunction.
Case Report
A 47-year-old man had an aortic valve replacement in 1985-a Björk Shiley mechanical heart valve had been implanted. His native valve was incompetent from infective endocarditis. After surgery, he did not have any problems. He discontinued warfarin a few months after the surgery and presented 26 years later with palpitations and dyspnea on exertion for one month. On auscultation, mechanical valve sounds were absent.
Transoesophageal echocardiography showed thrombotic material adjacent to the prosthesis. A cross sectional view through the aortic root revealed thrombi (Figure 1A) localized at the prosthetic ring protruding into the lumen. A long axis view of the ascending aorta showed flow exclusively across the major orifice by color Doppler.
The patient was then taken to surgery. We instituted cardiopulmonary bypass with systemic hypothermia, and began antegrade infusion of cold blood cardioplegia. Then we performed aortotomy, making a high aortic incision, and explored the aorta and the prosthetic aortic valve. The Björk Shiley mechanical heart valve which was implanted at an anatomical orientation was covered almost entirely with fibrotic tissue and obstructed at the open position with fresh thrombi (Figure 1B). The valve was immobile-fixed open about 0.5 cm. We decided upon replacement with a 23 mm St Jude Medical prosthetic aortic valve. Postoperative period was uneventful and medication consisted of warfarin plus low molecule weight heparin.
Figure 1
(A) Transoesophageal echocardiography showed thrombotic material adjacent to the prosthesis. A cross sectional view through the aortic root revealed thrombi (arrowed) localized at the prosthetic ring protruding into the lumen. (B) The thrombotic prosthesis was excised and replaced with bileaflet aortic valve prosthesis.
Discussion
Thromboembolism and bleeding under anticoagulants account for 75% of all mechanic valve complications (1). These complications occur most frequently during the first six months after surgery. Until appropriate dose of the anticoagulant is achieved, several fluctuations of the INR levels may occur, and most of the complications ensue during this period patient's compliance is one of the main problems while anticoagulation is established.
Prosthetic valve thrombosis and subsequent systemic embolization are well-known complications of mechanical valves, which mandate the patient to receive long-term anticoagulant therapy. However, most results of antithrombotic prophylaxis are from non-randomized case series without controls (2). Uncomplicated functioning without anticoagulation of various mechanical valves including Bjork–Shiley (B-S), Star–Edwards (S-E) and Lillehei-Kaster (L-K) in aortic or mitral positions have been reported (3-8). It is observed that mechanical valves at aortic position are durable without anticoagulation irrespective of type of valve used as Bjork–Shiley, Starr–Edwards or St Jude Medical as in our case (2–7).
Interestingly, Andersen and Alstrup followed 43 patients who discontinued anticoagulation after 12 months of isolated mechanical aortic valve replacement and were followed for a mean period of 7.2 years without anticoagulation (3). They noted after 10 years, 41% incidence of thromboembolic events and 17% mortality.
Here, We report the case of a patient has a Bjork-Shiley tilting disc mechanic valve in the aortic position without anticoagulation during 26 years event free and now presented with valve disfunction. Although it seems impossible for metallic heart valves to function without any medication, a few contradictory examples to this widely known fact were present in the literature (3-8) How these valves were protected so long is unknown.
It is unusual that a functioning mechanic aortic valve is present without anticoagulation for over twenty-six years. The potential factors underlying in the normal valvular mechanics in our patient remains unclear. Prompt diagnosis and emergency surgical intervention are essential for a successful outcome.