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An Anomalous Left Coronary Artery Originating from the Pulmonary Artery in a 72-Year-Old Woman: Diagnosis by Color Flow Myocardi
February 2002
An anomalous origin of the left coronary artery arising from the pulmonary artery (ALCAPA) is an uncommon congenital coronary abnormality, occurring in fewer than 0.01% of patients undergoing diagnostic cardiac catheterization.1,2 Also termed Bland-White-Garland syndrome,2 ALCAPA is characterized by blood flow passing from a dilated right coronary artery to the left coronary arteries by collateral vessels and then passing retrograde to exit the anomalous left main artery into the pulmonary artery.
Usually identified during infancy or early childhood, ALCAPA is clinically manifest as ischemic chest pain, congestive heart failure or potentially fatal arrhythmias.3 Since mortality nears 90% in infancy with untreated ALCAPA,2,4 early recognition and surgical correction are paramount. Using both echocardiography and coronary arteriography, we describe an elderly survivor of uncorrected ALCAPA and review contemporary methods for the diagnosis and management of this particular coronary anomaly.
Case Report. A 72-year-old female was referred for cardiology consultation for a heart murmur and presumed valvular heart disease. For 6 months preceding her evaluation, she noted increasing fatigue and dyspnea with exertion. She denied exertional chest pain or discomfort, palpitations or syncope. Despite her symptoms, she remained physically active with routine exercise.
Her past medical history was remarkable only for an uncharacterized heart murmur since 1947, which physicians had attributed to rheumatic heart disease despite her denial of any childhood illness. Except for her age and post-menopausal status, she had no significant risk factors for coronary artery disease.
Physical examination revealed mild systolic hypertension with a blood pressure of 150/54 mmHg, equal in both arms. The jugular venous pressure was estimated at 15 centimeters of water. The apical impulse was discrete. The first heart sound was normal with narrow but physiologic splitting of the second heart sound. The pulmonic closure (P2) was accentuated. There was an audible fourth heart sound but no third heart sound. A non-radiating grade II/VI continuous murmur was audible over the left sternal border and did not vary with respiration. The remainder of the physical examination was unremarkable.
A complete blood count and serum chemistries were within normal limits. Electrocardiogram revealed normal sinus rhythm with left anterior fascicular block, bi-atrial enlargement and left ventricular hypertrophy.
Transthoracic echocardiography demonstrated normal left ventricular function with mild mitral regurgitation and aortic sclerosis. There was mitral annular calcification, but no evidence of mitral or aortic stenosis. The coronary arteries were dilated, and color Doppler showed prominent flow within the ventricular septum (Figure 1). An abnormal Doppler flow pattern was also observed near the bifurcation of the pulmonary artery and was interpreted as either a patent ductus arteriosus or a coronary fistula. Exercise stress testing with technicium-99m Myoview imaging revealed no fixed or reversible perfusion abnormalities. The patient exercised to stage 1 according to Bruce protocol for 2 minutes, 30 seconds. Her peak heart rate was 125 beats/minute and blood pressure was 206/69 mmHg. The patient was limited by severe dyspnea and palpitations, but experienced no chest pain. First pass analysis of the left ventricle showed a rest ejection fraction of 45%, which decreased to 32% with ventricular dilatation during exercise. There was mild apical and inferior hypokinesis interpreted as exercise-induced ischemia.
Because of the abnormal stress test and echocardiogram results, the patient underwent left and right heart catheterization via the right femoral artery and vein. Right heart catheterization using a 7 French (Fr) pulmonary wedge catheter (Medtronic AVE, Santa Rosa, California) demonstrated a right atrial pressure of 12 mmHg, right ventricular pressure of 55/15 mmHg and pulmonary artery pressure of 55/30 mmHg (mean, 43 mmHg). Left ventricular pressure was 170/24 mmHg. Right ventricular oxygen saturation was 71% and the pulmonary artery saturation was 78%. A left to right shunt ratio (Qp/Qs) of 1.2:1 was calculated.
Left ventriculography (6 Fr pigtail catheter, Cordis Corporation, Miami Lakes, Florida) demonstrated normal left ventricular size and function (ejection fraction, 60%) with mild mitral valve prolapse and no mitral regurgitation. The coronary arteries, however, appeared markedly dilated with ventriculography, and contrast was seen to fill the pulmonary artery during the late phases of the ventriculogram. The right coronary arteriogram (6 Fr Judkins right coronary catheter; Cordis Corporation) demonstrated a dilated coronary artery with retrograde flow through the left coronary tree via extensive septal collaterals (Figure 2). Contrast from the left main artery exited into the main pulmonary artery. The conus artery, which had an origin separate from the main right coronary artery, had a fistulous connection to the main pulmonary artery. There was no angiographic evidence of atherosclerotic coronary artery disease.
Considering the minimal degree of shunting, the patient’s age and absence of symptoms at rest, the patient and her physicians elected to continue medical therapy with aspirin and improved antihypertensive treatment with an ACE inhibitor.
Discussion. ALCAPA is a very rare congenital coronary abnormality characterized by blood flow passing from a dilated right coronary artery to the left coronary arteries by collateral vessels and then retrograde, exiting the anomalous left main coronary artery into the pulmonary artery. Although its occurrence is uncommon, the presence of ALCAPA is associated with serious clinical consequences in nearly all individuals, including ischemic chest pain, congestive heart failure, and even sudden cardiac death resulting from ventricular arrhythmias. Because symptoms manifest early, survival into adulthood with unrecognized or uncorrected ALCAPA is even more unusual.5,6 These features make the finding of previously unrecognized ALCAPA in a 72-year-old patient quite remarkable.
Although the clinical history and physical examination are critical in raising the suspicion of a coronary anomaly, there are no findings specific for the diagnosis of ALCAPA. Patients with ALCAPA often describe symptoms of dyspnea, chest pain, palpitations or syncope, but many do not have any symptoms prior to sudden cardiac death.4 Similar to the present case, physical examination of patients with ALCAPA often reveals a continuous murmur, which is also common to other abnormalities such as coronary arteriovenous or arteriocameral fistulae, aortopulmonary windows, patent ductus arteriosus, and ruptured sinus of Valsalva aneurysms. Other physical examination findings with ALCAPA include a mitral regurgitation murmur secondary to papillary muscle dysfunction or ventricular dilatation and evidence of left ventricular dysfunction such as an S3 gallop and a diffuse, laterally displaced apical impulse. The electrocardiogram may demonstrate a previous infarction, often in an anterolateral distribution.
Diagnostic methods to identify ALCAPA include echocardiography, magnetic resonance imaging (MRI) and coronary angiography. Because many patients with ALCAPA may have an extensive collateral supply to the left coronary arteries, exercise testing with nuclear perfusion imaging may not detect myocardial ischemia.3 Although the perfusion study in this particular patient did not demonstrate ischemia, first pass radionuclide imaging showed ventricular dilatation and exercise-induced decline in left ventricular function, consistent with ischemia and explaining her symptoms of exertional fatigue and dyspnea. Echocardiography revealed a dilated right coronary artery, and color flow imaging and pulse-wave Doppler identified diastolic retrograde flow from the left main coronary artery into the pulmonary artery. The Doppler color flow pattern seen within the interventricular septum as a myocardial blush was quite unusual and impressive. This echocardiographic finding, undoubtedly due to the abundant retrograde collateral flow within the septal perforator arteries, has not previously been described and may be helpful in the diagnosis of ALCAPA.
MRI has also been useful in defining the anomalous origin of the left main coronary artery from the pulmonary artery.7 Cardiac catheterization, however, remains the standard for the diagnosis of ALCAPA. First, coronary arteriography demonstrates the anatomic abnormality, with flow of contrast from the dilated right coronary artery to septal collateral vessels and then retrograde through the left coronary tree to exit into the pulmonary artery. Second, right heart catheterization quantifies the degree of left to right shunting.
Considering the patient’s age, preserved ventricular function, low shunt fraction and absence of symptoms at rest, medical therapy with aspirin and antihypertensive therapy with an angiotensin-converting enzyme inhibitor was chosen. For most patients, however, treatment of ALCAPA is primarily limited to surgical correction, which results in improved ventricular function and survival.8 Surgical options to establish dual coronary circulation include left main artery ligation with aortocoronary bypass grafting, intra- and extrapulmonary baffling, simple left coronary artery ligation, and direct reimplantation of the left coronary tree into the aorta. Pre-operative risk factors include the severity of mitral regurgitation, degree of left ventricular dysfunction and early age.8–10 Although repair of the anomalous left coronary artery is associated with high operative risk, complications may be reduced with the use of a left ventricular assistance device.8,11
Survival with ALCAPA is dependent upon the extent and adequacy of collateral circulation from the right coronary artery to the left coronary tree.2 At present, only one other septuagenarian survivor of uncorrected ALCAPA has been described.12 For the present case, the survival and preservation of left ventricular function in this 72-year-old patient resulted from early establishment of an extensive collateral circulation to the left coronary arteries and possibly the development of mild pulmonary hypertension to reduce the severity of coronary steal. Early maintenance of elevated pulmonary pressures following the physiologic decrease in pulmonary vascular resistance soon after birth may also be important in limiting the steal of flow from the left coronary arteries into the pulmonary artery. Regardless of these compensatory mechanisms, extended survival into adulthood with untreated ALCAPA is very unusual, making its identification in a 72-year-old individual quite remarkable.
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