Increased risk of central venous line
thrombosis in tiny premature infants occurs because the size of the
catheter relative to the cross-sectional area of the vessel is large, decreased plasma levels of
plasminogen and
antithrombin III, and relative low flow of the infusate through the
catheter, in comparison with larger infants. A potentially fatal complication of
central venous catheters is an intracardiac
thrombus. The yield of detecting right atrial thrombi by routine echocardiographic monitoring is very low. Persistent positive blood cultures in infants with central venous lines, in spite of appropriate
antibiotic therapy, or signs of
catheter occlusion, may increase the yield of echocardiographic detection of intracardiac thrombi. Surgical removal of intracardiac thrombi in infants weighing less than 1500 gm carries a high mortality rate because of the need to use
cardiopulmonary bypass with total circulatory arrest and profound
hypothermia during surgery. It is in these infants that thrombolysis with
urokinase should be considered. A successful therapy with
urokinase of a complete occlusion of the right pulmonary artery by an
embolus originating from the right atrium is described in a premature infant. For thrombolysis, a loading dose of
urokinase of 4400 U/kg followed by 4400 to 8800 U/kg/hr for a few days was used. The thrombolytic effect was manifested by decreased
thrombus echogenicity followed by its disappearance, by increased
fibrinogen split products, and by decreased plasma
fibrinogen.
Urokinase therapy may cause massive
bleeding, dislodge an intracardiac
thrombus causing obstruction of cardiac valves or main vessels or causing embolization to the pulmonary or systemic circulation.(ABSTRACT TRUNCATED AT 250 WORDS)