Approach Considerations
Medical care for a disease or condition that predisposes children to acute myocardial infarction (AMI) is discussed more fully elsewhere (see Anomalous Left Coronary Artery from the Pulmonary Artery and Kawasaki Disease).
The primary treatment in patients with anomalous left coronary artery (LCA) from the pulmonary artery (ALCAPA) is surgical. Surgical revascularization may also be necessary in patients with Kawasaki disease who develop significant coronary stenoses or occlusion. Percutaneous transluminal coronary angioplasty (PTCA) for proximal coronary stenoses after an arterial switch procedure for dextro-transposition of the great arteries (D-TGA) has been reported.
The severity of myocardial infarction (MI) symptoms at presentation determines whether the patient is admitted to an intensive care unit (ICU) for aggressive medical management of congestive heart failure (CHF) before surgical revascularization.
Short-term use of oral digoxin, diuretics, and angiotensin-converting enzyme (ACE) inhibitors is common after surgical revascularization. Coronary spasm is generally treated with nitrates or calcium channel blockade.
Initial Supportive Measures
Intensive care and acute management of the infant with symptoms of coronary artery ischemia or injury are initially directed at reducing myocardial oxygen demands while administering oxygen, fluids, or blood products, providing endotracheal intubation, and correcting acid-base status and paralysis to reduce the work of breathing.
Treatment of CHF includes careful administration of diuretics, afterload reduction medications, and inotropic drugs. Spontaneous resolution of CHF symptoms is rare. Surgical revascularization is usually necessary in the event of AMI.
Aggressive afterload reduction may be deleterious in patients with ALCAPA. Right coronary artery (RCA) perfusion may be reduced during aggressive afterload reduction, leading to decreased left coronary blood flow.
Conversely, inotropic support may increase myocardial oxygen consumption significantly, which, in the presence of reduced myocardial blood flow, may worsen ischemia.
Surgical Revascularization
Once the patient is stabilized, surgical revascularization is performed to create a patent coronary arterial distribution (see Anomalous Coronary Artery from the Pulmonary Artery: Surgical Perspective).
Oral administration of digitalis, diuretics, and afterload-reducing medications improves cardiac output and reduces preoperative symptoms in patients with CHF. These techniques are frequently used until left ventricular systolic and diastolic functions improve and mitral insufficiency stabilizes.
Cardiac dysrhythmia secondary to preoperative myocardial ischemia or MI is likely. Monitor continuously in the immediate postoperative period.
In a review of NIS data, only 2% of adolescents with AMI underwent coronary artery bypass grafting (CABG), compared with 12-24% of adults with AMI. The higher incidence of subendocardial AMI and coronary vasospasm (possibly related to substance abuse) in adolescents may at least partially account for this difference. [18]
Successful PTCA for proximal coronary stenoses after an arterial switch procedure has been reported in a small number of patients, with apparently excellent results 3-5 years later. [33, 34] Postcatheterization effects that call for precautions include hemorrhage, vascular disruption after balloon dilation, pain, nausea and vomiting, and arterial or venous obstruction from thrombosis or spasm. Possible complications include blood vessel rupture, tachyarrhythmia, bradyarrhythmia, and vascular occlusion.
NIS data suggest that the use of cardiac catheterization and percutaneous coronary interventions (PCIs) may be less in adolescents with AMI (29%) than in adults with AMI (40-50%). Again, this may be due to a higher incidence of coronary vasospasm and subendocardial AMI in adolescents. [18] A recent study on long-term follow-up in Kawasaki disease patients with giant aneurysms reported a 30-year survival of 49% in patients who had an AMI, compared with a 25-year survival of 95% in patients who had undergone coronary bypass grafting, highlighting the importance of consideration for early revascularization in these patients. [21]
Postoperative care
After surgical revascularization, postoperative care includes the use of inotropes, diuretics, and afterload reduction medication to improve cardiac output and eliminate the preoperative symptoms of CHF. Initial postoperative treatment is usually provided in a pediatric ICU until the patient is extubated and no longer requires intravenous (IV) inotropes or antiarrhythmics.
Monitor patients continuously during the immediate postoperative period because, cardiac dysrhythmia secondary to preoperative myocardial ischemia or MI, though unusual, is a risk that should be taken into account.
Complications
Complications are rare. Whether future valve surgery will be needed depends on the occurrence of hemodynamic complications (eg, residual mitral valve insufficiency precipitated by permanent damage of the mitral valve architecture) after surgical treatment.
Late complications related to coronary artery insufficiency are more likely to occur if revascularization was accomplished via any of the following techniques:
-
Surgical ligation
-
Bypass grafting (the grafts may become occluded or stenotic)
-
Intrapulmonary tunneling, which may cause supravalvular pulmonary stenosis or, less commonly, obstruction of the surgically created aortopulmonary window
Although generally unlikely, inadequate growth of the coronary anastomosis may ensue if surgical reimplantation of the LCA is performed. This complication is similar to the rare reports of late coronary artery problems after an arterial switch procedure for D-TGA, which also requires direct coronary transfer and reimplantation.
Diet and Activity
In general, no specific dietary restrictions are necessary. If failure to thrive was noted preoperatively, patients may require increased caloric density postoperatively. Patients with residual CHF may require salt or fluid restriction.
Activity restrictions are directly related to the severity of the left ventricular dysfunction and postoperative mitral valve insufficiency. In patients who are able to participate in exercise or competitive sports or who have residual postoperative hemodynamic problems, consider recommending avoidance of significant isometric activities. Exercise stress testing (eg, with electrocardiography or echocardiography) is advised for assessment of myocardial response to exercise, preparticipation screening, and ongoing monitoring of conditioning effect.
Prevention
Long-term antiplatelet therapy with aspirin may be needed in patients with conditions predisposing to coronary thrombosis, such as Kawasaki disease with significant aneurysm formation. [35] In patients with giant aneurysms, additional anticoagulation with dipyridamole or warfarin may be recommended. A small retrospective study suggested that combination therapy with warfarin and aspirin was associated with a decreased risk of MI in patients with giant aneurysms due to Kawasaki disease. [36]
Consultations
Consultation with an adult interventional cardiologist is indicated because of the wealth of information he or she can provide have regarding proper imaging planes and anatomic variations of the coronary arteries.
A nuclear medicine radiologist or cardiologist may help quantify approximate myocardial injury and recovery potential. Pediatric and adult cardiovascular surgeons may collaborate to effect optimal surgical repair.
Long-Term Monitoring
The clinical status of the patient in relation to residual CHF symptoms determines the frequency of postoperative outpatient follow-up visits.
Most patients do not require frequent cardiac evaluations after surgical revascularization once ventricular function and mitral valve insufficiency have dramatically improved.
For patients with Kawasaki disease, long-term follow-up is recommended, even in cases without evidence of obvious coronary dilatation or aneurysms. Dipyridamole stress scintigraphy may be useful for long-term follow-up and risk stratification in patients with Kawasaki disease. [37] The progression of stenosis in patients with aneurysms impacts prognosis. Dobutamine stress echocardiography may also be useful in providing independent prognostic data over time, as demonstrated in a cohort of 58 patients with coronary artery lesions following Kawasaki disease followed over 15 years. [38]
Patients on coronary vasodilators for coronary artery spasm require long-term follow-up. [19]
-
Myocardial Infarction in Childhood. Electrocardiogram in an infant with anomalous origin of the left coronary artery from the pulmonary artery, demonstrating pathologic Q waves in leads I and aVL and diffuse ST-T wave changes consistent with an anterolateral infarction.
