14. Congenital Coronary Artery Anomalies and ALCAPA

Anomalous origin of the Left Coronary Artery from the Pulmonary Artery (ALCAPA, or Bland-White-Garland Syndrome) is a life-threatening congenital anomaly that causes severe infantile anterolateral myocardial infarction and ischemic dilated cardiomyopathy.

1. Clinical Presentation & Bedside Evaluation

The "Colicky Infant" with Myocardial Infarction: At $1-3$ months of age (as pulmonary vascular resistance declines), infants present with episodes of crying, diaphoresis, pallor, and dyspnea during feeding, which represent angina pectoris.
Physical Examination: Severe congestive heart failure (tachypnea, grunting, hepatomegaly, cardiomegaly), displaced hyperdynamic apex, and an apical holosystolic murmur of ischemic mitral regurgitation (papillary muscle dysfunction).

2. Electrocardiographic Hallmarks of ALCAPA

Diagnostic Triad of ALCAPA on 12-Lead ECG:

Deep, Broad Pathological $Q$ Waves ($>4\text{ mm}$ deep and $>0.03-0.04\text{ s}$ duration) in leads I, aVL, and $V_4 - V_6$.
ST-Segment Elevation or Depression in lateral leads indicating acute subendocardial ischemia.
Inverted T Waves in leads I, aVL, and $V_5 - V_6$ (persisting beyond neonatal period).
Diminished R Waves in precordial leads ($V_5-V_6$) reflecting anterolateral left ventricular transmural myocardial necrosis.

3. Pathophysiology of Coronary Steal

In utero and early neonatal life, high pulmonary artery pressure perfuses the anomalous left coronary artery with desaturated blood.
As PVR falls after birth, flow in the anomalous LCA reverses (blood flows from the normal RCA $\to$ intercoronary collaterals $\to$ LCA $\to$ low-pressure pulmonary artery). This coronary steal phenomenon produces profound anterolateral left ventricular subendocardial ischemia and infarction.

4. Multimodality Diagnostic Investigations

Echocardiography (TTE): Demonstrates retrograde red Doppler jet entering the main pulmonary artery from the LCA, dilated right coronary artery (compensatory collateralization), severe LV systolic dysfunction (EF $<25-35\%$), and bright echogenic fibroelastosis of the papillary muscles.
Cardiac CT Angiography (CCTA): Confirms anomalous coronary takeoff from the pulmonary trunk and maps coronary branching prior to surgical reimplantation.

5. Evidence-Based Surgical Management

Definitive Surgical Repair:
- Direct Coronary Reimplantation: Transfer of the anomalous LCA button into the ascending aorta (procedure of choice).
- Takeuchi Procedure: Creation of an intrapulmonary baffle from the aortopulmonary window to the ostium of the anomalous LCA when direct reimplantation is anatomically impossible.
Prognosis: With timely surgical revascularization, left ventricular systolic function recovers dramatically over $6-12$ months.