Management of Cyanotic Heart Disease

Indications for Therapeutic Phlebotomy

The American Heart Association recommends that therapeutic phlebotomy should only be performed when hemoglobin exceeds 20 g/dL AND hematocrit exceeds 65%, accompanied by symptoms of hyperviscosity, and only after confirming the patient is not dehydrated or anemic 1
Therapeutic phlebotomy is indicated when hemoglobin is greater than 20 g/dL and hematocrit is greater than 65% 1
The presence of hyperviscosity symptoms, such as headache, fatigue, and poor concentration, is a criterion for therapeutic phlebotomy 2
The absence of dehydration is a necessary condition for therapeutic phlebotomy 1, 3
The absence of iron deficiency is a necessary condition for therapeutic phlebotomy 1

Repeated routine phlebotomies are explicitly contraindicated due to the risk of iron depletion, decreased oxygen-carrying capacity, and increased stroke risk 1, 3
Iron deficiency from repeated phlebotomy creates rigid, microcytic red cells with reduced oxygen-carrying capacity 1, 4
Iron-deficient microcytic cells are the strongest independent predictor of cerebrovascular events—not the hematocrit level itself 2

Evaluation of hydration status is necessary, as dehydration is the most common cause of symptomatic hyperviscosity 1, 2
Checking iron stores, such as serum ferritin and transferrin saturation, is necessary to avoid worsening symptoms 1, 3
Screening for intercurrent illness, such as infection or fever, is necessary to avoid increasing metabolic demands 2

Only 1 unit (250-500 mL) of blood should be removed 1
The removed blood should always be replaced with an equal volume of normal saline or dextrose to prevent further hemoconcentration 1, 3
The goal of phlebotomy is temporary symptom relief, not hematocrit reduction per se 1

Iron deficiency must be avoided, even in the presence of severe erythrocytosis, as it increases stroke risk more than elevated hematocrit 1, 2
If iron deficiency is confirmed, cautious oral iron supplementation should be initiated with close hemoglobin monitoring 1, 3
Oral iron frequently causes rapid, dramatic increases in red cell mass 1
Hemoglobin should be monitored weekly during initial supplementation 1
Iron supplementation should be discontinued once ferritin and transferrin saturation normalize 1
If oral iron is not tolerated, pulses of intravenous iron should be used instead 1

A peripheral blood smear showing microcytosis is indicative of iron deficiency 1
Serum ferritin below the normal range is diagnostic of iron deficiency 1, 3
Transferrin saturation below the normal range is diagnostic of iron deficiency 1, 3