Ann Thorac Surg 1998;65:1453-1455
© 1998 The Society of Thoracic Surgeons
Case Reports
Successful Thrombolysis of an Occluded Modified Blalock Shunt Three Days After Operation
Torsten K. Malm, MD, PhDa,
Catarina Holmqvist, MDb,
Carl-Gustav Olsson, MD, PhDc,
Jens Johansson, MDa,
Ann-Kristin Olsson, MD, PhDd,
Staffan Sandström, MDb,
Rolf Bennhagen, MDe,
Peeter Jögi, MDa
a Division of Pediatric Cardiac Surgery, Department of Cardiothoracic Surgery, University Hospital, Lund, Sweden
b Department of Radiology, University Hospital, Lund, Sweden
c Department of Internal Medicine, University Hospital, Lund, Sweden
d Department of Anesthesiology, University Hospital, Lund, Sweden
e Department of Pediatrics, University Hospital, Lund, Sweden
Accepted for publication December 5, 1997.
Address reprint requests to Dr Malm, Division of Pediatric Cardiac Surgery, Department of Cardiothoracic Surgery, University Hospital, S-221 85 Lund, Sweden
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Abstract
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A 10-day-old boy with pulmonary atresia received a right-sided aortopulmonary polytetrafluoroethylene shunt. Three days after the operation he became cyanotic and was reintubated. Shunt occlusion was confirmed with angiography. Recombinant tissue plasminogen activator was given locally into the proximal end of the shunt. The thrombus was completely resolved after 2 days. When administration of recombinant tissue plasminogen activator was stopped, heparin infusion was started for 5 days. Shunt patency was demonstrated by angiography at 3 months postoperatively.
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Introduction
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A male neonate, delivered at term (birth weight, 3,430 g) after an uneventful pregnancy, became hypoglycemic and cyanotic at 5 hours after birth. Duct-dependent pulmonary circulation was diagnosed, and after intravenous prostaglandin administration was initiated, he was referred to our hospital. Investigation with echocardiography and angiography revealed a pulmonary atresia with intact ventricular septum, hypoplastic right ventricle, and multiple sinusoids connecting the right coronary artery and the right ventricle. The pressure in the right ventricle was suprasystemic. There was unrestricted communication over a large atrial septal defect. Sepsis developed with coagulase-negative staphylococci, and he was treated with cloxacillin and ceftazidime. He was stable on prostaglandin with an oxygen saturation around 80%.
After 1 week on antibiotic treatment, with all infectious parameters normalized, he underwent a modified Blalock-Taussig shunt operation with a 4-mm polytetrafluoroethylene graft performed through a right-sided thoracotomy. The external diameters of the right pulmonary artery and the right subclavian artery were 5 mm and 3.5 mm, respectively. After opening of the shunt, oxygen saturation improved from 66% to 96% and stabilized around 85% to 90% in the intensive care unit. The prostaglandin infusion was discontinued. No heparin was given, according to our protocol.
The early postoperative period was uneventful, and he was extubated the day after the operation. Chest radiography showed pulmonary congestion, and administration of diuretics was started. On the second day after the operation, echocardiography showed good shunt function.
During the night between the second and the third postoperative days, an atelectasis of the right upper lung lobe developed. Desaturation occurred. Later a metabolic acidosis developed. The patient was reintubated and reconnected to the ventilator. A color-coded Doppler study could not demonstrate proper shunt flow. Prostaglandin was restarted and arterial oxygen saturations improved. When the patient’s condition deteriorated, septicemia was also suspected. Blood cultures showed growth of Candida albicans. Oral administration of fluconazole was initiated together with intravenous vancomycin because of a positive culture of coagulase-negative staphylococci at the insertion site of a central venous line. Angiography of the subclavian artery showed shunt occlusion starting 1 cm below the proximal anastomosis. There was no flow through the graft (Fig 1). The duct was open, and there were no localized obstructions of the pulmonary artery adjacent to the shunt.
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Fig 1. Angiogram of the right subclavian artery showing the occlusion of the polytetrafluoroethylene shunt about 1 cm distal to the anastomosis to the right subclavian artery. The catheter is placed in the right subclavian artery with the tip at the proximal end of the shunt.
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We decided to start fibrinolytic treatment with recombinant human tissue-type plasminogen activator (rt-PA), initially given locally at 0.1 mg/kg into the proximal end of the shunt twice, and repeated at 0.2 mg/kg after 10 minutes without any effect, followed by a systemically given continuous infusion of 1 mg · kg-1 · 24 h-1. The levels of activated partial thromboplastin time, prothrombin time, platelet count, and fibrinogen were followed up every 3 hours. A repeated angiogram was performed 13 hours later without any significant change of the thrombus. The catheter was then placed into the shunt and rt-PA was given locally as a continuous infusion first as 1 mg · kg-1 · 24 h-1 and then increased to 2 mg · kg-1 · 24 h-1 according to the monitoring of the fibrinogen level. Angiography 10 hours later showed partial lysis of the thrombus (Fig 2). The catheter could be moved further into the thrombus, and the rt-PA infusion was continued but was changed to 1.5 mg · kg-1 · 24 h-1 according to the fibrinogen levels. Repeat angiography was performed after 12 hours and showed complete resolution of the thrombus and no obstruction in either anastomosis (Fig 3). During the 2-day procedure a 3F introducer was left in place in the right femoral artery. No bleeding occurred during the rt-PA treatment. The catheter was removed and a heparin bolus was given intravenously before a continuous infusion was started at 15 IU · kg-1 · h-1, aiming for an activated partial thromboplastin time of 50 to 70 seconds. On the chest radiograph the following day a right-sided pleural effusion was noted, and 70 mL of hemorrhagic pleural fluid was aspirated. The patient was given heparin for 5 days; on the fourth day aspirin administration was started at 5 mg · kg-1 · day-1. The patient recovered well, with oxygen saturation between 80% and 90%. He was discharged from the hospital 12 days after the thrombolysis treatment.
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Fig 2. Selective angiogram showing partial thrombolysis of the occluded polytetrafluoroethylene shunt 10 hours after the start of thrombolysis treatment. The catheter is pushed further down in the shunt.
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Fig 3. Selective angiogram of the shunt. The thrombolysis is complete after 22 hours of recombinant tissue plasminogen activator infusion.
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Comment
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If shunt occlusion occurs in a case of shunt-dependent pulmonary circulation, there are a few options, especially if the duct can be reopened pharmacologically: surgical shunt revision, shunt exchange, a new shunt on the other side, or thrombolysis with rt-PA. Thrombolysis is considered to be a risky procedure because of bleeding problems. The rt-PA has the advantage of being short-acting; the dominating plasma half-life time is 4 to 5 minutes, and less than 10% of the original plasma concentration remains 20 minutes after the infusion has been stopped. Because of the hemorrhage risk, rt-PA traditionally has not been recommended during the first 10 postoperative days. The effect of rt-PA has to be monitored carefully. Monitoring is achieved with analyses of plasma fibrinogen levels every 3 hours. Thrombolytic therapy should be stopped if plasma fibrinogen levels are less than 0.8 g/L [1]. In the reported case, fibrinogen levels varied only between 2.3 and 3.0 g/L (fibrinogen reference interval, 2.0 to 4.0 g/L) before, during, and after thrombolytic therapy. Hemoglobin levels and chest radiographs daily are essential for monitoring of eventual hemorrhage.
According to our protocol for the modified Blalock-Taussig shunt, we did not use any heparin infusion postoperatively. In the neonate we usually perform a right-sided 4-mm polytetrafluoroethylene shunt sutured with 8.0 polypropylene (Davis & Geck, Goseport, England). If a prostaglandin infusion is running, this is stopped in the operating theater as soon as the shunt flow is established. In many cases we use a dopamine infusion, 5 µg · kg-1 · min-1, during the first postoperative night. Seventy-one shunt operations have been done in the last 3 years without any shunt occlusion with this protocol. There was no early mortality.
Ries and associates [2, 3] reported a successful thrombolysis in an infant with shunt occlusion 4 days postoperatively. Our case report confirms the findings from this group. However, an occluded modified Blalock-Taussig shunt should only be considered for thrombolytic therapy if there is no evidence of an inexpedient surgical result. In this case we found an open anastomosis at the proximal end and no evidence of pulmonary artery distortion at the distal end on angiograms. The reason for occlusion was unclear, but infection might have triggered the thrombus formation. If the patient was in a state of hypercoagulability, the logical treatment would be thrombolysis followed by anticoagulation instead of surgical intervention.
In conclusion, in selected patients with thrombosed shunts, thrombolysis can be accomplished with local continuous infusion of rt-PA. The treatment has to be monitored carefully and the dose accordingly titrated to decrease the risk of hemorrhage. Repeat angiography is necessary to follow up the effect of the treatment. If there is any suspicion of a mechanical reason for shunt occlusion, surgical intervention is the first choice of treatment.
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References
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- Duckert F., Müller G., Nyman D., et al. Treatment of deep vein thrombosis with streptokinase. Br Med J 1975;1:479-481.
- Ries M., Singer H., Hofbeck M. Thrombolysis of a modified Blalock-Taussig shunt with recombinant tissue plasminogen activator in a newborn infant with pulmonary atresia and ventricular septal defect. Br Heart J 1994;72:201-202.[Abstract/Free Full Text]
- Klinge J., Hofbeck M., Ries M., Shaf J., Singer H., von der Emde J. Thrombolyse von modifizierten Blalock-Taussig-Shunts im Kindesalter mit rekombinanten Gewebeplasminogenaktivator. Z Kardiol 1995;84:476-480.[Medline]
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Abstract
Introduction
