Theoretical aspects of multiple deconvolution analysis for quantification of left to right cardiac shunts

A new method for quantification of left to right cardiac shunts by Bourguignon et al based on multiple deconvolution analysis is critically analysed within the framework of a simple mathematical model. Underlying assumptions are explicitly stated and their validity discussed. It turns out that some reinterpretation of the method is necessary. Using the same ideas as in multiple deconvolution analysis, a new relation for the pulmonary to systemic flow ratio is proposed on a theoretical basis. This technique may be useful when diagnosing left to right cardiac shunts with radiocardiographic methods.