Interactive Cardiovascular and Thoracic Surgery 2:592-594(2003)
© 2003 European Association of Cardio-Thoracic Surgery
Thrombolysis of a prosthetic mitral valve in a 50-day-old child
Max Baghai*,
Nelson Alphonso,
Prem Sundar and
Conal Austin
Department of Congenital Heart Disease, Guy's Hospital, St Thomas’ Street, London, SE1 9RT, UK
* Corresponding author. Centre for Cardiovascular Biology and Medicine, The Rayne Institute, St. Thomas’ Hospital, London, SE1 7EH, UK. Tel.: +44-7798-661661; fax: +44-207-5810604
maxbaghai{at}hotmail.com
Received April 28, 2003;
received in revised form July 16, 2003;
accepted July 23, 2003
 |
Abstract
|
|---|
This case report demonstrates both an implantation of a prosthetic mitral valve in a 50 day-old infant, and also the subsequent successful thrombolysis of an obstructive thrombus in the early postoperative period.
Key Words: Case report; Infant; Mitral valve; Thrombosis; Thrombolytic therapy
|
1. Introduction
|
|---|
The use of a mechanical valve in a young infant would only be considered if the native valve is severely dysplastic or there is failure of the initial repair. Thrombosis is an unfortunate complication of mechanical valve prostheses, and is associated with a mortality of up to 20% with even prompt treatment [1,2], The treatment of thrombosed valves with a thrombolytic agent as a first line treatment is relatively new, even in the adult population [3]. There are only a handful of cases of thrombolysis in infants under the age of 2 months who have had a mitral valve replacement [4,5].
|
2. Case report
|
|---|
A 20-day-old baby girl (3.2 kg, non-Down's) was diagnosed with a complete atrioventricular septal defect (AVSD) and a hypoplastic aortic arch. The child progressively deteriorated in spite of optimum medical therapy and the decision was taken to proceed with surgery on the 30th day.
The hypoplastic arch was repaired using an extended end-to-end anastamosis under deep hypothermic circulatory arrest. The AVSD was closed using a double patch technique and the cleft in the left atrioventricular (AV) valve was repaired using the Carpentier ‘figure of eight’ stitch. The patient easily weaned off cardiopulmonary bypass in sinus rhythm. Intraoperative trans-oesophageal echo (TOE) showed only mild left AV valve regurgitation. However, serial echoes performed over the next 2 weeks showed progressive left AV valve regurgitation. Due to her inability to wean off the ventilator, the patient underwent a second surgical repair.
At operation, dehiscence of the left AV valve repair was re-repaired using pericardial pledgets after further mobilising of the bridging leaflets. An echocardiogram a few hours later demonstrated failure of the repair. A third attempt to repair the valve using a triangular piece of autologous pericardium to enlarge the leaflets was attempted. During this process it became rapidly apparent that the likelihood of success was low and due to the accumulating ischaemic time a decision was made to replace the valve. The valve leaflets were excised and a 17-mm St-Jude bi-leaflet aortic valve was reversed and placed in the left AV canal using interrupted horizontal mattress sutures. Great care was taken not to narrow the left ventricular outflow tract. The post-operative echocardiogram showed a normal functioning mechanical prosthesis with no left ventricular outflow tract obstruction. A heparin infusion was commenced during the first post-operative night, and over the next few days the patient was loaded on warfarin. Dual chamber pacing was commenced for atrioventricular dissociation for a period of 2 weeks at which time there was spontaneous reversion back into sinus rhythm.
On the 14th post-operative day the patient presented with acute cardiac failure and frank pulmonary oedema. An echocardiogram demonstrated an immobile posterior valve leaflet with a thrombus protruding through the valve (Fig. 1). The INR at the time of presentation was 2.5 with an activated partial thromboplastin time (APTT) three times normal. The thrombotic screen was normal. As the infant had already undergone two previous surgical procedures it was decided to thrombolise the patient with t-PA using a dosage protocol of 0.3 mg/kg per hour for a period of 48 h [5]. This treatment resulted in complete lysis of the thrombus, as well as normal leaflet mobility. Five days later, thrombus was again identified on the posterior leaflet of the prosthetic valve. The t-PA was recommenced for a further 48 h at a dose of 0.4 mg/kg per hour. Full heparinisation was instituted prior to the cessation of the t-PA. Echocardiography showed resolution of the intra-cardiac thrombus and a normally functioning prosthetic valve (Fig. 2).
The patient's anticoagulation was optimised using warfarin (INR 3.0–3.5) prior to discharge. There were no bleeding complications secondary to the thrombolysis treatment. The patient remains well at 12 months with a normally functioning prosthetic valve.
|
3. Discussion
|
|---|
The successful use of a mechanical prosthesis in an infant under the age of 2 months has only been documented a few times before in the literature [4,6]. The limited data available on this group of patients shows not only a high early and late mortality, but also a fair degree of morbidity [6–8]. The main problems are the mechanical valve's inability to grow with the infant, the limitation on sizes of valves available for the paediatric population and the obvious disadvantages of anticoagulation from infancy. The valve's inflexibility and design not only affects the way the ventricle functions, but also has been reported to obstruct the flow of blood through the heart and coronary arteries [7]. The maintenance of adequate and steady anticoagulation in this group of patients is both difficult and at times, unpredictable [9]. The recurrence of thrombus on the prosthetic valve in this case is a good example of its erratic nature.
The use of t-PA in neonates has been shown to be an effective first-line therapy in a range of cardiovascular thrombi [5]. Our institutions guidelines are consistent with those published by Weiner and colleagues, which included: exclusion of previous intraventricular haemorrhage or cerebral ischaemic changes; baseline laboratory assessments and cranial ultrasound; correction of hypertension; limit t-PA dose to 0.5 mg/kg per hour; maintain fibrinogen level >150 mg/dl; daily cranial ultrasounds during and after treatment [5]. As an addition we prefer to have an APTT of three times normal prior to the termination of thrombolysis. The incidence of bleeding complications during thrombolysis appears to be high among the very young infants, especially cerebral haemorrhage which can be as high as 2–4% [10]. This incidence is relatively low when compared to the risk of re-operation in the critically ill infant who had already undergone three major procedures and would not have had a favourable outcome from further surgery.
The incidence of prosthetic valve thrombosis in the very small infant is high because of the unpredictability of the anticoagulation and the low cardiac output leading to the inevitable haemodynamic stasis. Close monitoring is essential to ensure prompt diagnosis and adequate thrombolysis.
|
Appendix A
|
|---|
ICVTS on-line discussion
Author: Dr. Sameh Sersar, Assistant Lecturer, Cardiothoracic Surgery, Mansoura University, Mansoura, Egypt
Date: 03-Sep-2003
Message: As a substitute for Mechanical valve replacement, what about Kabbani S. operation (Pulmonary autograft in the mitral position) in such a young patient? What about putting a larger valve in a tilting supraannular position attached to the left atrial tissues rather than the mitral ring? When do you usually expect LVOTO as regards the mitral prosthesis? What is the size of mitral prosthesis that you expect LVOTO to occur?
doi:10.1016/S1569-9293(03)00167-1
|
References
|
|---|
- Vongpatanasin W, Hillis LD, Lange RA. Prosthetic heart valves. N Engl J Med. 1996;(6):407–416
- Deviri E, Sareli P, Wisenbaugh T, Cronje SL. Obstruction of mechanical heart valve prostheses: clinical aspects and surgical management. J Am Coll Cardiol. 1991;(3):646–650
- Manteiga R, Carlos Souto J, Altes A, Mateo J, Aris A, Dominguez JM, Borras X, Carreras F, Fontcuberta J. Short-course thrombolysis as the first line of therapy for cardiac valve thrombosis. J Thorac Cardiovasc Surg. 1998;(4):780–784
- Smith JA, Desai K, Bernstein D, Reitz BA. Successful thrombolysis of a thrombosed St Jude Medical mitral prosthesis in a two-month-old infant. J Thorac Cardiovasc Surg. 1994;(1):187
- Weiner GM, Castle VP, DiPietro MA, Faix RG. Successful treatment of neonatal arterial thromboses with recombinant tissue plasminogen activator. J Pediatr. 1998;(1):133–136
- van Doorn C, Yates R, Tsang V, deLeval M, Elliott M. Mitral valve replacement in children: mortality, morbidity, and haemodynamic status up to medium term follow up. Heart. 2000;(6):636–642
- Alexiou C, Galogavrou M, Chen Q, McDonald A, Salmon AP, Keeton BK, Haw MP, Monro JL. Mitral valve replacement with mechanical prostheses in children: improved operative risk and survival. Eur J Cardiothorac Surg. 2001;(1):105–113
- Gunther T, Mazzitelli D, Schreiber C, Wottke M, Paek SU, Meisner H, Lange R. Mitral-valve replacement in children under 6 years of age. Eur J Cardiothorac Surg. 2000;(4):426–430
- Michelson AD, Bovill E, Andrew M. Antithrombotic therapy in children. Chest. 1995;(4):506S–522S
- Gupta AA, Leaker M, Andrew M, Massicotte P, Liu L, Benson LN, McCrindle BW. Safety and outcomes of thrombolysis with tissue plasminogen activator for treatment of intravascular thrombosis in children. J Pediatr. 2001;(5):682–688
|
|
Top
Abstract
1. Introduction
