Relationship between Exercise Hemodynamic and Cardiopulmonary Indices as Measured in Cardiac Patients by Two Separate and Specific Tests

Journal of Clinical and Basic Cardiology 2010; 13 (1-4): 4-7

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Keywords: cardiopulmonary exercise testing,  impedance cardiography,  ischaemic heart disease

Background: Direct non-invasive hemodynamic evaluation becomes more and more familiar due to the relatively new impedance cardiography (ICG) test. On the other hand, the cardiopulmonary exercise test (CPET) is well-known as a reliable physiological test for indirect hemodynamic evaluation through CPET indices and the Fick formula. Aim of Study: To correlate and cross-match between direct and indirect hemodynamic indices as measured during exercise by the 2 tests, the ICG and the CPET, separately. Material and Methods: 30 cardiac male patients (pts), aged 41–74 yrs, with documented IHD, who underwent both, ICG and CPET separately and up to 2 weeks apart, were included in the study. Linear correlations were done between all the indices of both tests. Values of R > 0.6 and p < 0.05 were considered statistically significant. Results: Significant correlations were found between peak-HR of the CPET and the following ICG indices: Peak-CI (Cardiac Index) – R = 0.74; p < 0.0001; Peak-CO (Cardiac Output) – R = 0.72; p < 0.0001; Peak-SI (Stroke Index) – R = 0.72; p < 0.0005. Other specific correlations were shown between: Peak-CI and Peak-VO2: R = 0.82; p < 0.0001; Peak-CO and Peak-VO2: R = O.72; p < 0.001; Peak-SI and Peak-O2P: R = 0.76; p < 0.001; Peak-SV and Peak-O2P: R = 0.76; p < 0.001. Conclusions: Such significant and crossover correlations between the indices of both above tests may validate the ICG indices as reliable for non-invasive hemodynamic evaluation and may further establish the CPET indices for similar, though indirect, physiological assessment.