Comprehensive Cardiovascular Assessment Protocol

A whole-body impedance cardiography device (CircMon^R, JR Medical Ltd, Tallinn, Estonia), which records the changes in body electrical impedance during cardiac cycles, was used to determine beat-to-beat HR, stroke volume, cardiac output, and aortic-popliteal PWV [27 (link)]. The mechanism of function, electrode placement, and processing of impedance cardiography data have been previously described [21 (link), 27 (link)–29 (link)]. Briefly, the impedance cardiography method calculates PWV between the level of the aortic root and the popliteal artery by the use of the whole-body impedance signal and the signal measured from the popliteal artery region [27 (link), 28 (link)]. The PWV results obtained using CircMon^R show good repeatability [29 (link)], and normal values for PWV in 799 individuals (age 25–76 years) have been previously published [30 (link)]. We have also shown that the determination of stroke volume using impedance cardiography versus 3-dimensional echocardiography show good correlation [29 (link)]. SVR was calculated from the tonometric radial BP signal and cardiac output measured by the CircMon^R device by subtracting average normal central venous pressure (4 mmHg) from mean arterial pressure and dividing it by cardiac output. Mean arterial pressure was calculated by using the formula: [(systolic BP)/3 + 2 × (diastolic BP)/3]. Cardiac output, stroke volume and SVR were indexed to body surface area (abbreviated as CI, SVI and SVRI, respectively).