Cardiac changes after SCUBA diving: the evasive shape of right ventricle

We have read with interest the paper by Obad et al. (2007), ‘The effects of acute oral antioxidants on diving-induced alterations in human cardiovascular function’, recently published in The Journal of Physiology. We were somewhat puzzled by the method used to calculate right ventricular volumes. As is known, radionuclide angiography is still considered the most reliable method for evaluating right ventricular volumes and function. Previous attempts of obtaining a two-dimensional echocardiographic estimate of right heart volumes were based on multiple cardiac views and complex mathematical formulas (Starling et al. 1982) and, more recently (Pasipoularides et al. 2003), a 3-D echo approach has been successfully applied. Contrary to this, Simpson's method, already validated for the calculation of left ventricular volumes, does not seem applicable to a cavity with such a complex three-dimensional geometry like the right ventricle. The scarce reliability of the method used in the paper by Obad et al. (2007) appears evident if one considers the large difference between left and right ventricular stroke volumes evinced in Table 3 (93.1 ml for left ventricle versus about 37 ml for right ventricle, simply considering mean values of right ventricular diastolic and systolic volumes).

Even if the paper contains a number of interesting new data on the physiology of diving, we think that anatomical and functional characterization of right heart requires a more reliable methodological approach.