Congenital anomaly of the left coronary artery.
Anomalous Left Coronary
Artery from the Pulmonary Artery;
1:300,000 live births (0.25-0.5% of all cardiac
Not an inherited disorder.
Because the left coronary artery arises from the
pulmonary trunk, perfusion of the left heart must be provided by the
pulmonary artery or from collaterals of the right coronary artery.
Myocardial perfusion remains normal in the early neonatal period when
pulmonary pressure is high. As pulmonary pressure and resistance decrease by
1 to 2 months of age, myocardial perfusion becomes insufficient and ischemia or
even myocardial infarction with global ventricular failure occurs. Depending
upon the importance of collateral vessels between the right and left
coronary arteries, left-to-right shunting of oxygenated blood from the right
coronary artery to the left coronary artery and into the pulmonary artery
may create a “myocardial steal,” resulting in increased ischemic insult to
the anterolateral myocardium with global left ventricular dilatation and
dysfunction. Papillary muscle infarction and/or mitral annular dilatation
may result in secondary mitral valve regurgitation. Left atrial dilation and
finally pulmonary venous congestion ensue, adding congestive symptoms to
those of angina pectoris.
Infants present with respiratory distress, feeding
intolerance, and failure to thrive. Congestive heart failure in an infant
with either no murmur on auscultation or the murmur of mitral insufficiency
is suspicious for ALCAPA. The electrocardiogram may reveal anterolateral myocardial ischemia or
infarction. Thallium myocardial perfusion scintigraphy or echocardiography
assists in the diagnosis of this specific malformation. Aortic angiography
provides the final confirmation and is a good tool for assessing the
collateral vessels. The diagnosis is generally made during the first year of
life, but occasionally may become manifest later in childhood or even in
adulthood. Sudden death has been reported in these patients following
Rapidly progressive deterioration of physical
condition, including dyspnea, expectorations, perspiration, tachycardia, and
refusal to drink with failure to thrive. The patient may have angina pectoris associated with
feeding. It has been estimated that 90% of untreated patients die in the
first year of life. The lesion is sometimes discovered during investigation
for heart murmur (although a murmur is not a constant finding) or chest pain
in late childhood or adulthood.
Obtain full history of
cardiopulmonary symptoms of the patient. Evaluate cardiac function with electrocardiogram,
chest radiography, echocardiography, left cardiac catheterization, and
coronary angiography (ejection fraction, left ventricular diameter,
pulmonary artery pressure and saturation, arterial saturation).
Symptomatic infants undergoing surgery
to correct their coronary anomaly will have pulmonary venous congestion, a
diminished cardiac output, decreased contractility as a result of chronic
ischemia of the myocardium, and, frequently, myocardial infarction and some
degree of subendocardial fibrosis.
Avoid factors that reduce pulmonary vascular resistance (alkalosis, hypocapia, hyperoxia),
since this may result in increased coronary steal.
There is a high risk of ventricular
arrhythmias. The clinical condition ...