Post-Operative Care of Congenital Heart Disease

Patients

A brief pediatrics perspective

Electrolytes

• Severe electrolyte abnormalities– Cause: Pump solutions, saline solutions, fluid

shifts.– Most important are those with effects on heart

• Potassium (arrhythmogenic)• Calcium (affects contractility and arrhythmias)• Magnesium (same as Ca)

– Also, but less important• Sodium and phosphate

Glucose

• Hyperglycemia (outside of neonatal period)

• Causes:– Stress response

• Endogenous steroids

• Epinephrine

– Steroids given for bypass

• Tx: Incr sedation & pain control

Renal Effects

• All due to decr MAP and non-pulsatile flow.• Release of

– Angiotensin• Causes HTN

– ADH• Causes retention of free water leading to hyponatremia

– Catecholamines• Causes HTN and faster heart rate.

• Tx: Antihypertensives, Lasix.

Renal Effects, cont.

• Acute Renal Insufficiency (incidence 8%)– Oliguria– Incr creatinine– Fluid retention

• Tx:– MUF– Lasix

Pulmonary Effects

• Causes– Leukocyte & complement activation– Surfactant loss

• Results:– Capillary leak… pulmonary edema.– Atelectasis

• Tx: ventilation with increased PEEP

Pulmonary, cont.

• Pulmonary Hypertension– Constriction of pulm vascular bed– Leads to poor oxygenation– Caused by acidosis & high CO2– Tx: Hyperventilation.

• Reperfusion injury– Unique to Pulmonary Stenosis

• Very common in pediatric CHD (esp. ToF)• Related to procedure itself, not bypass.• Presents as pulmonary edema

– Tx: Diuretics.

Coagulopathy

• Causes:– Activation of clotting factors in tubing– Real clotting to stop surgical bleeding– Hemodilution– Heparin in pump

• Tx:– FFP– Protamine

Hemodynamic Effects

• Tissue ischemia, capillary sludging due to low MAP and non-pulsatile flow.

• Leads to Lactic Acidosis.– May exacerbate electrolyte disturbances

• Potassium driven into cells with acidosis

– Worse with longer bypass duration.

• Tx: shorten bypass time, bicarb, vent.

Hemodynamics, cont.

• Hemodilution from pump priming solutions, iv fluids & renal insufficiency.

• Result worsens HCT than just surgical blood loss.

• Tx:– Modified Ultrafiltration (MUF)– Lasix– PRBC

Hemodynamics, cont.

• Myocardial dysfunction– Usually Right Ventricle in children (unlike

adults)– Increased CVP, decreased Bp and UOP

• Tx:– Dopamine– Epinephrine– Dobutamine

Hemodynamics, Cont.

• Capillary leak… diffuse edema– Caused by inflammatory mediators activated

against tubing of bypass.– Worse in children than adults

• Length of tubing is longer in relation to the length of the child’s vascular system.

– Tx: Lasix, limiting of IV fluids.

Conclusions

• Overall the pathophysiology of bypass is similar to Systemic Inflammatory Response Syndrome seen in patients with sepsis.

• Similar derangements in coags, capillary permeability and tissue ischemia occur in both.

• Bottom line: minimize the pump time!