Cardiac Ouput – ABC CARDIOL

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Editorial

Continuous Non-Invasive Cardiac Output: Myth or Reality

Cardiac output (CO) is an important cardiovascular system function parameter. Changes in cardiac function are commonly observed as a response to physical training and pharmacological interventions. Unfortunately, the methods for assessing CO are invasive, leading to well-known complications and considered inconvenient in daily practice. For this reason, the search for new noninvasive methods that can accurately detect CO at rest, at physical exertion or as a response to a clinical intervention has become desirable in academic and non-academic circles. The ideal method for measuring CO at rest and during exercise should be noninvasive, safe, reproducible and inexpensive.

The Cardiopulmonary Exercise Testing (CPT) is recommended in the evaluation of cardiorespiratory fitness and exercise tolerance in athletes, the general population and in patients. Briefly, CO and systolic volume can be estimated during CPT through measured VO₂. In 2001, Williams et al. were the first ones to integrate CPT with non-invasive measures of CO using rebreathing (RB) of carbon dioxide, but the technique was quickly abandoned due to its difficulty and inaccuracy. Another non-invasive method is thoracic electrical bioimpedance (TEB), first described in 1966 by Kubicek et al., which measures thoracic resistance as a result of changes in blood velocity during the cardiac cycle and uses an algorithm to calculate the CO.

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Transthoracic impedance compared to magnetic resonance imaging in the assessment of cardiac output

Humberto Villacorta Junior et al. Aline Sterque Villacorta Fernanda Amador Marcelo Hadlich … Denilson Campos de Albuquerque Clerio Francisco Azevedo

BACKGROUND: Cardiac magnetic resonance imaging is considered the gold-standard method for the calculation of cardiac volumes. Transthoracic impedance cardiography assesses the cardiac output. No studies validating this measurement, in comparison to that obtained by magnetic resonance imaging, are available. OBJECTIVE: To evaluate the performance of transthoracic impedance cardiography in the calculation of the cardiac output, cardiac index and stroke volume using magnetic resonance imaging as the gold-standard. METHODS: 31 patients with a mean age of 56.7 ± 18 years were assessed; of these, 18 (58%) were males. Patients whose indication for magnetic resonance imaging required pharmacologic stress test were excluded. Correlation between methods was assessed using the Pearson’s coefficient, and dispersion of absolute differences in relation to the mean was demonstrated using the Bland-Altman’s method. Agreement between methods was analyzed using the intraclass correlation coefficient. RESULTS: The mean cardiac output by transthoracic impedance cardiography and by magnetic resonance imaging was 5.16 ± 0.9 and 5.13 ± 0.9 L/min, respectively. Good agreement between methods was observed for cardiac output (r = 0.79; p = 0.0001), cardiac index (r = 0.74; p = 0.0001) and stroke volume (r = 0.88; p = 0.0001). The analysis by the Bland-Altman plot showed low dispersion of differences in relation to the mean, with a low amplitude of agreement intervals. Good agreement between the two methods was observed when analyzed by the intraclass correlation coefficient, with coefficients for cardiac output, cardiac index and stroke volume of 0.78, 0.73 and 0.88, respectively (p < 0.0001 for all comparisons). CONCLUSION: Transthoracic impedance cardiography proved accurate in the calculation of the cardiac output in comparison to cardiac magnetic resonance imaging.

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Continuous Non-Invasive Cardiac Output: Myth or Reality

Transthoracic impedance compared to magnetic resonance imaging in the assessment of cardiac output

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Electronic Document Format (Vancouver)

Electronic Document Format (ABNT)

Electronic Document Format (APA)

Electronic Document Format (ISO)