Medication Summary
Diuretics are now the mainstay of medical therapy for infants and children with large ventricular septal defects (VSDs), large left-to-right shunts, and symptoms of CHF. Current debate is ongoing concerning the use of digoxin. In certain situations, the addition of afterload reduction may also be beneficial. Hemoglobin levels should be normal.
As previously mentioned, be aware that ACE inhibitors have a potassium-sparing effect; when these are used, spironolactone or supplemental potassium should be avoided or judiciously used.
Diuretics
Class Summary
These agents relieve ventricular volume load and peripheral and pulmonary congestion.
Furosemide (Lasix)
Furosemide increases the excretion of water by interfering with the chloride-binding cotransport system, which, in turn, inhibits sodium and chloride reabsorption in the ascending loop of Henle and distal renal tubule.
Spironolactone (Aldactone)
Spironolactone is used for the management of edema resulting from excessive aldosterone excretion. It competes with aldosterone for receptor sites in the distal renal tubules, increasing water excretion while retaining potassium and hydrogen ions.
Afterload Reducers
Class Summary
These drugs decrease systemic afterload and may decrease left-to-right shunting through a large ventricular septal defect (VSD). They are used to improve preoperative or postoperative cardiac output, reducing systemic vascular resistance and increasing systemic blood flow resulting from myocardial dysfunction.
Enalapril (Vasotec)
Enalapril is a competitive inhibitor of ACE; it reduces angiotensin II levels, decreasing aldosterone secretion.
Captopril
Captopril prevents the conversion of angiotensin I to angiotensin II, a potent vasoconstrictor, resulting in lower aldosterone secretion.
Inotropic Agents
Class Summary
These agents augment ventricular contractility. Positive inotropic agents increase the force of contraction of the myocardium and are used to treat acute and chronic CHF. Some may also increase or decrease the heart rate (ie, positive or negative chronotropic agents), provide vasodilatation, or improve myocardial relaxation. These additional properties influence the choice of drug for specific circumstances. Cardiac glycosides are used predominantly for their inotropic effects.
Digoxin (Lanoxin)
Digoxin is a cardiac glycoside with direct inotropic effects; it also has indirect effects on the cardiovascular system. Digoxin inhibits sodium- and potassium-activated adenosine triphosphatase (NaK-ATPase), which causes intracellular calcium in the sarcoplasmic reticulum of cardiac cells to increase.
