Final answer:
The described symptoms of a cyanotic neonate suggest a congenital heart defect, possibly Tetralogy of Fallot, which involves a ventricular septal defect among other anomalies, leading to 'blue baby' syndrome. Surgical intervention is the standard treatment to correct the anatomical anomalies of Tetralogy of Fallot.
Step-by-step explanation:
A cyanotic neonate with ECG showing left axis deviation and small or absent R waves in precordial leads, as well as decreased pulmonary markings on X-ray, is indicative of certain congenital heart defects. The correct diagnosis and treatment option for a neonate with these symptoms should align with the individual conditions of congenital heart diseases.
Tetralogy of Fallot is characterized by four anomalies: pulmonary infundibular stenosis, overriding aorta, ventricular septal defect, and right ventricular hypertrophy. These defects lead to cyanosis, a heart murmur, and other symptoms such as dyspnea and clubbing of fingers and toes. Surgical correction, including the use of stents, valve replacement, and patches, is the typical treatment. This condition is manifested by a mix of oxygen-poor and oxygen-rich blood due to the ventricular septal defect, causing cyanosis and accounting for the 'blue baby' phenomenon.
Pulmonary atresia is another condition requiring immediate attention. In cases where the pulmonary valve is completely closed, treatment includes an infusion of Prostaglandin E1 to keep the ductus arteriosus open, allowing for a bypass of the blood flow that would normally go through the pulmonary valve.