There is a list of conditions that come under cono-truncal anomaly(CTA) in CHD. TOF is the classical example. CTA are group of genetically determined fusion defects between developing right ventricle , septum and the outflows .Many components of outflow are outsourced from cranially located neural crest . In fact, improper migration and fusion of this secondary heart field to the primary is most common cause of many complex heart disease. Microdeletion on chromosome 22, specifically in the 22q11.2 is a major documented gene defect. Traditionally CTA list often includes PA with VSD. This table compares the anatomical and embryological basis of TOF & PA with VSD. You can decide whether to call both as part of cono-truncal anomaly or not.
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One important difference is missing in the above table. It is about presence and absence of PDA. In TOF true PDA may be present in early days or months . In PA with VSD , PDA or (MAPCAS mimicking a PDA ) can be part of collateral .A persistent controversy is, how to differentiate a PDA from MAPCAS .That can be challenging. Further, to label a vessel as PDA it should drain into normally formed left pulmonary artery, which is rarely likely.
Dr.S.Venkatesan MD 