Cardiopulmonary exercise testing provides oxygen pulse as a continuous measure of stroke volume, which is superior to other stress-testing methods in which systolic function is measured at baseline and at peak stress. However, the optimal peak oxygen pulse criterion for distinguishing cardiac from noncardiac causes of exercise limitation is unknown.
In comparing several peak oxygen pulse criteria against the clinical standard of cardiopulmonary exercise testing, we retrospectively studied 54 consecutive patients referred for cardiopulmonary exercise testing. These exercise tests included measurement of oxygen consumption, carbon dioxide production, breathing reserve, arterial blood gases at baseline and at peak stress, exercise electrocardiogram, heart rate, and blood pressure response. Results were blindly interpreted and patients were categorized as members either of our Cardiac Group (abnormal result secondary to cardiac causes of exercise limitation) or of our Noncardiac Group (normal or abnormal result secondary to any noncardiac cause of exercise limitation).
The accuracy of the peak oxygen pulse criteria ranged from 50% for univariate criterion (≤15 mL/beat), to 61% for oxygen pulse curve pattern, to 63% for bivariate criterion (≤15 mL/beat for men, ≤10 mL/beat for women), to as high as 81% for a multivariate criterion. All multivariate criteria outperformed oxygen pulse curve pattern, univariate, and bivariate criteria.
This is the first study to evaluate the optimal peak oxygen pulse criterion for differentiating cardiac from noncardiac causes of exercise limitation. Multivariate criteria (especially a criterion incorporating age, sex, height, and weight) should be used preferentially, as opposed to the commonly used univariate and bivariate criteria.
There is growing evidence of a differential etiological basis for thoracic aortic aneurysms (TAA), with ascending (As) TAAs being genetically mediated and descending (Des) TAAs more strongly related to acquired pathologies. A comprehensive literature review of this hypothesis has not been carried out. We carried out a systematic literature review based on the latest guidelines on TAA endorsed by the American Heart Association. The etiologies were classified as genetic and inherited, the studies were tabulated accordingly, and Hill's epidemiological criteria of causality were applied. We found 38 studies addressing the etiology of TAAs. Out of these, 17 were about genetic causes, 9 about acquired causes, and 4 had information regarding both etiologies. Multiple genetic studies showed a strong association of As TAA with different genetic mutations. Contrary to commonly held beliefs, acquired causes, that is, dyslipidemia, diabetes, and atherosclerosis, were negatively associated with As TAA and positively associated with Des TAA. Hypertension was only associated with Des TAA and dissections (TAAD), not with As TAA. Multiple studies fulfilled the criteria of strength of association (n = 4), consistency (n = 9), specificity (n = 5), temporality (24), biological gradient (n = 3), plausibility (n = 38), biological coherence (n = 25), experiment (n = 4), and analogy (n = 6). Our literature review supports the hypothesis that As TAA is genetically mediated and Des TAA is predominantly an acquired pathology, and supports the argument for genetic testing in all cases of As TAA.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.