(44Kb)Mizzi J, Grech V. Acute modified Blalock-Taussing
shunt obstruction successfully treated with urokinase and heparin. Images
Paediatr Cardiol 2005;24:20-23
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(44Kb) |
Mizzi J, Grech V. Acute modified Blalock-Taussing
shunt obstruction successfully treated with urokinase and heparin. Images
Paediatr Cardiol 2005;24:20-23
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Paediatric Department , St. Luke’s Hospital, Guardamangia, Malta |
| Abnormalities, Multiple/*surgery/ultrasonography | Constriction, Pathologic/ultrasonography | Echocardiography, Doppler, Color/*methods |
| Heart Defects, Congenital/*surgery/ultrasonography | Pulmonary Circulation |
Introduction
The modified Blalock-Tuassig shunt continues to be widely used as a
palliative procedure, and allows staging for further cardiac surgery by
controlling pulmonary blood flow.1 Shunt morbidity is not insignificant2,3
and shunt obstruction due to thrombosis, stenosis or kinking may be life
threatening due to hypoxia. Various modalities have been employed in relieving
such obstruction but the options are severely limited in settings outside
a tertiary center. We report an acutely obstructed shunt that was relieved
in an exclusively non-interventional, pharmacological way, a viable alternative
in virtually all settings.
Patient
Our patient (female) was born in mid-2000 with a birth weight of 2.4
kilograms. She was noted to be cyanosed a few hours after birth and an
echocardiogram revealed situs solitus, concordant atrioventricular connections,
discordant ventriculoarterial connections, a large ventricular septal defect,
pulmonary stenosis and a patent arterial duct. A 4 millimetre Gore-Tex
right modified Blalock-Taussig shunt was implanted in the early neonatal
period at a tertiary center and the duct was closed with a ligaclip.
She remained well after surgery with oxygen saturations in the high 70s to mid 80s. Her only problem was failure to thrive (growing below and parallel to the third centile). She had been started on aspirin post-operatively, but this was stopped by the parents.
At the age of three years, she presented acutely, deeply cyanosed and tachypnoeic (respiratory rate 46/minute). The shunt murmur was not audible and there was a faint systolic murmur at the upper left sternal edge. Echocardiography was performed and the shunt could not be visualized at all. Colour doppler showed some forward flow across the right ventricular outflow, with good ventricular function.
The provisional diagnosis was acute shunt obstruction. The clinical condition deteriorated dramatically. She become confused, deeply cyanosed with saturations in the high 30s and bradycardic. She was given pulmonary embolism loading doses of urokinase (4400 units per kilogram intravenous bolus) and heparin (75 units per kilogram intravenous bolus), followed by a maintenance doses of both (4400 units per kilogram per hour; 20 units per kilogram per hour). This, combined with a fluid bolus, led to improved saturations. Aspirin at a dose of 150 milligrams daily was also commenced. She was never acidotic and gases at this point were: pH 7.334, pCO2 29.2 millimetres of mercury, PO2 28.5 millimetres of mercury, BD –7.9, HCO3 15.7 millimoles per litre.
Oxygen saturation climbed to the 60s over the next four hours. A morphine
infusion was started to calm her down as the saturations dropped to the
40s with struggling. Shunt flow became evident on echocardiography, with
an unimpressive and only systolic murmur (figure 1). Heparin was continued
and the urokinase was stopped. She was transferred to a tertiary center
where she underwent a bi-directional Glenn procedure. She has remained
well after surgery.
References
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