Asian Cardiovasc Thorac Ann 1998;6:91-94
© 1998 Asia Publishing EXchange Pte Ltd
Thrombolytic Therapy for Stuck Prosthetic Valves: Phenomenon of Delayed Opening
Chaganti Venkateswara Rao, MD, DM,
Tirumalai Nallan Chakravarthi Padmanabhan, MD, DM,
Damera Seshagiri Rao, MD, DM,
Prabhala Rajagopal, MS, MCh1,
Sadasivan Jaishankar , MD, DM
Department of Cardiology
1 Department of Cardiothoracic Surgery Nizam's Institute of Medical Sciences Hyderabad, India
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For reprint information contact:Chaganti Venkateswara Rao, MD, DMDepartment of CardiologyNizam's Institute of Medical SciencesPunjaguttaHyderabad 500082, IndiaTel:91 40 339 6538Fax:91 40 331 0076
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ABSTRACT
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Thrombolytic therapy for left-sided prosthetic valve occlusion is a viable alternative to surgery. The phenomenon of delayed opening of a bileaflet valve is a peculiar feature of thrombolytic therapy. Of 64 patients who received thrombolytic therapy and presented on 71 occasions, partial success was observed in 28 patients on completion of treatment. Of these 28 patients, delayed opening of the leaflets was observed in 14 (50%) over a period of 3 to 12 months. We suggest that this unique feature of bileaflet valves might delay or avoid reoperation. The need for frequent follow-up of patients with partially successful thrombolytic therapy is emphasized.
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INTRODUCTION
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Thrombotic occlusion of mechanical prosthetic valves is a potentially life-threatening complication. Thrombolytic therapy has been identified as a potent alternative to surgery in treating this complication. The overall success rate of thrombolytic therapy in this setting varied from 73% to 100% in different series.1–5 We have previously reported an overall success rate of 89%.6 In most series, success implied complete opening of one or both leaflets depending on the type of the valve. The phenomenon of delayed opening of the valve leaflets is hitherto unreported. We report the details of this phenomenon from our 6-year experience.
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MATERIALS AND METHODS
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During the period from March 1990 to October 1996, 64 patients presented on 71 occasions with thrombotic occlusion of left-sided mechanical prosthetic valves. All patients were prospectively evaluated. The adequacy of anticoagulation was assessed by prothrombin time on admission. All patients underwent baseline transthoracic echocardiography and cinefluoroscopy. Prosthetic valve occlusion was diagnosed on clinical, echocardiographic, and fluoroscopic criteria as reported earlier.6 Patients who fulfilled these criteria received thrombolytic therapy with either streptokinase or urokinase administered as a bolus infusion of 250,000 units over 30 minutes followed by infusion of 100,000 units per hour. The total dose was individually based on the clinical response, echocardiographic and fluoroscopic data. Thrombolytic therapywas followed by heparin infusion of 1000 units per hour, which was continued until adequate anticoagulation was achieved with nicoumalone or warfarin. Adequate anticoagulation was defined as a prothrombin time 1.5 times the control value. All patients received dipyridamole at a dose of 300 to 400 mg daily from the day of admission.
The results were categorized as success or failure in relation to the clinical outcome and cineradiographic indication of complete opening of the valve leaflet (both leaflets in the case of bileaflet prosthetic valves). Immediate success was defined as complete when both leaflets of the bileaflet prosthesis were open or when the disc of a tilting disc prosthesis was open. It was defined as partial if only one of the two leaflets of a bileaflet prosthesis was open (normal opening angle) at the time of discharge, with the other leaflet being still stuck (opening angle less than 75% of that expected). Delayed opening of the partially stuck leaflet (restoration of the normal opening angle) any time after the departure of the patient from hospital was considered a delayed success. All patients with partial success were followed up every month with clinical, echocardiographic, and fluoroscopic examinations. The adequacy of anticoagulation was regularly assessed.
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RESULTS
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Of the 64 patients presenting on 71 occasions with left-sided prosthetic valve occlusion, 57 had a prosthetic valve in the mitral position and the others had a prosthesis in the aortic position. All 64 patients had thrombolytic therapy. Partial success after thrombolytic treatment was observed in 28 of the 64 patients. Delayed opening of the partially stuck valve was observed in 14 of these 28 patients. There were 9 men and 5 women aged between 15 and 53 years. The duration of symptoms at admission ranged from 3 to 60 days. Twenty-three patients presented within 2 weeks of the onset of symptoms. The main symptom was acute pulmonary edema in patients who presented within 2 weeks and subacute pulmonary edema in the 5 who presented after 2 weeks from the onset of symptoms. All of these patients had a CarboMedics bileaflet prosthetic valve (CarboMedics Canada Ltd., Calgary, Canada) in the mitral location. All received thrombolytic therapy with streptokinase in individual total doses ranging from 1.5 to 9 million units.
At follow-up, delayed opening of a partially stuck leaflet was observed over a period of 3 to 12 months (Figures 1A, 1B, and 1C
). In 5 of the 14 patients with initial partial success, the prosthetic valve became stuck again and repeat thrombolytic therapy was given. One of these patients responded with completely opened leaflets. Two patients had partial success after the repeat thrombolysis. Thrombolysis failed in 2 other patients and both died. In 2 patients with initial partial success, reocclusion of the prosthesis was treated by redo mitral valve replacement. Three patients with initial partial success were asymptomatic after 2 years of follow-up and 4 patients were lost to follow-up.
Of the 14 patients with the delayed success, 2 developed reocclusion of the prosthetic valve. One patient (no. 3) developed the symptoms 3 months after the delayed opening and responded to repeat thrombolytic therapy of 2 million units of urokinase with complete success. In the second patient (no. 6), the prosthetic valve was repeatedly occluded (on 5 occasions) over a period of 2.5 years. The first reocclusion was treated with 4 million units of urokinase as the patient had been given streptokinase within the previous year. The patient responded with complete success. The subsequent reocclusions were treated with heparin infusion for varying periods of 1 to 4 days. Each of these episodes responded to heparin infusion with complete relief.
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DISCUSSION
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Thrombotic occlusion continues to be a dreaded complication of mechanical prosthetic valves and surgery remains the primary modality of therapy. Thrombolytic therapy is a viable alternative to surgery with high success rates reported by a number of centers including ours.1–6 The response to thrombolytic therapy can be complete success with complete opening of the leaflets, or partial success with partial opening of the leaflets. We observed partial success in 43% of 64 patients presenting on 71 occasions. In contrast, Roudat and colleagues2 reported partial success in only 2 of 64 patients.
In our series, we did not observe any difference in the efficacy of the two thrombolytic agents (streptokinase and urokinase). Urokinase was chosen for patients who had received streptokinase within the previous year. The occurrence of delayed opening of the leaflets of bileaflet valves has been reported earlier by our group.6 However, this interesting phenomenon has not been indicated in other major series. In this study, delayed success was noted in 50% of patients who initially had partial success after thrombolytic therapy. The majority of these patients presented within 2 weeks of the onset of symptoms and in most cases the level of anticoagulation was inadequate at presentation.
Partial and delayed success was noted only in valves in the mitral position. The incidence of thrombotic occlusion in aortic prostheses is lower because of flow dynamics across the aortic valve and all the aortic prostheses responded with complete success to thrombolytic therapy in our series. The time of delayed opening is difficult to predict; we found it varied from 2 to 12 months. The mechanism of delayed opening is conjectural. It might be due to delayed dissolution of a residual thrombus by the intrinsic fibrinolytic system. Whether this phenomenon is observed only in bileaflet valves remains to be established. Ideally, patients with a partial response to thrombolytic therapy should undergo early valve replacement. However, the patients in this series declined a second valve replacement for socioeconomic reasons.
Since delayed opening of the valve leaflets in patients with partial success from thrombolytic therapy seems to be a feature of bileaflet valves, this factor should be considered in the timing of redo surgery in this subset of patients. The varied time frame of this phenomenon emphasizes the need for repeated short-term follow-up in such patients.
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Acknowledgments
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We thank Mr. Appaiah, Mr. J.L.N Varma, and the catheter laboratory staff for photographic work and for typing the manuscript.
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REFERENCES
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ABSTRACT
INTRODUCTION
