| Dilated cardiomyopathy in children has an incidence in several countries of approximately 0.5-0.75/100,000 population. It is characterized by a dilated left ventricle with primarily systolic dysfunction. In the most severe cases, children present with signs and symptoms of heart failure including diaphoresis, dyspnea at rest or with exertion, orthopnea, exercise intolerance, abdominal pain and pallor. Young children often have poor appetites and growth failure. Sinus tachycardia, gallop rhythm, hepatomegaly and mitral regurgitation are common though ventricular arrhythmias may also be present. The etiology is genetic in 20-35% of cases and post viral myocarditis in up to 25%. Despite an identifiable etiology in perhaps 50% or more of cases, therapy for left ventricular dysfunction is generally supportive in nature rather than specific. Furthermore, evidence-based clinical trial data validating therapeutic approaches is generally based upon adult clinical trials that may not necessarily be valid for children. Patients with acute decompensated heart failure require intensive therapy, typically including intravenous medications, intubation and mechanical ventilation and, in some cases mechanical support via LVAD or ECMO. The use of milrinone, nesiritide and vasopressin, along with diuretics may be preferable to high dose beta-adrenergic inotropes such as epinephrine, dopamine or dobutamine. The need for aggressive inotropic support often indicates the potential need for a mechanical device. Use of inotropes increases the metabolic demands of the myocardium and tends to lead to arrhythmias that can result in sudden death. Levosimendan, a new agent that increases myofilament responsiveness to endogenous calcium, provides improved systolic function and arterial vasodilation without increased myocardial oxygen demand.Once clinical improvement occurs, transition to oral therapy with ACE inhibition, e.g.captopril, enalapril, lisinopril and beta blockers (carvedilol, metoprolol) plus oral diuretics should proceed. Digoxin may also be helpful. However, proven effectiveness in children is lacking. Ventricular assist devices are being used increasingly as a bridge to transplant but in some patients may result in reverse remodeling sufficient to allow recovery of ventricular function and discontinuation of mechanical support. In this regard, improvement in systolic function has been associated with reversibility of dystrophin disruption. |
