Hypercoagulable states

Hypercoagulable states or thrombotic disorders indicate— (a) deficiency of anti-coagulant factors, (b) excess of pro­coagulants, or (c) relative stasis of blood flow due to any cause, e.g.

Etiologically, hypercoagulable states may be hereditary or acquired (Table 19.27). Acquired disorders, e.g. presence of a vascular catheter, is the commonest cause of thromboembolic episodes in childhood.

Clinical spectrum of thromboembolic complications depends on the severity of defect and primary etiology, ranging from acute purpura fulminans to localized and/or recurrent thromboembolic episodes, e.g. deep vein thrombosis, cerebrovascular strokes, pulmonary embolism, renal thrombosis, etc.

Diagnosis of thrombotic episodes depends on the suspected site. While Doppler studies are commonly

TABLE 19.27: Hypercoagulable states in children

• Inherited procoagulant defects

- Protein C#8725;S, plasminogen or AT-III deficiency

- Protein C resistance (Mutant _fV Leiden)

• Acquired defects (more common)

- Sepsis and DIC

- Cyanotic CHDs

- Nephrotic syndrome

- Malignancy

- Vasculitis syndromes, e.g. SLE, homocysteinuria

- Prolonged vascular catheterization/immobilization

used for diagnosis of peripheral thromboembolic episodes, venographic studies may be required for doubtful cases of organ thrombosis.

Management of thromboembolic episodes includes treatment of primary cause and removal of thrombus either by thrombolytic therapy (Urokinase, Streptokinase, recombinant Plasminogen activator) or thrombectomy, along with low molecular weight heparin or LMWH (SC 1-1.5 mg/kg BD) during acute phase to prevent the spread of thrombus. LMWH should be avoided in kidney dysfunction.

Recurrent episodes may necessitate use of prophylactic anticoagulant therapy to maintain an INR between 2 to 3, starting with low molecular weight heparin (SC 0.5­0.75 mg/kg/dose OD), followed by oral warfarin or direct-acting anticoagulants till the risk persists.

Purpura fulminans is a life-threatening condition, characterized by acute hemorrhagic infarction/necrosis of skin due to severe protein C and/or S deficiency.

Etiologically, It may be seen in newborns (hereditary homozygous deficiency) or as an acquired defect in severe sepsis (Staph. aureus, Pseudomonas), menigococcemia or viral infections, e.g. chicken pox.

Clinical and hematological picture in these cases resembles DIC with predominant skin involvement.

Treatment is largely supportive, including elimination of primary infection along with heparin or steroids in selected cases.

19.15