ABSTRACT
The explanation of physiological mechanisms involved in adaptation of the cardiovascular system to intrinsic and environmental demands is crucial for both basic science and clinical research. Computational algorithms integrating multivariable data that comprehensively depict complex mechanisms of cardiovascular reactivity are currently being intensively researched. Quantitative Complexity Theory (QCT) provides quantitative and holistic information on the state of multi-functional dynamic systems. The present paper aimed to describe the application of QCT in an integrative analysis of the cardiovascular hemodynamic response to posture change. Three subjects that underwent head-up tilt testing under beat-by-beat hemodynamic monitoring (impedance cardiography) were discussed in relation to the complexity trends calculated using QCT software. Complexity has been shown to be a sensitive marker of a cardiovascular hemodynamic response to orthostatic stress and vasodilator administration, and its increase has preceded changes in standard cardiovascular parameters. Complexity profiling has provided a detailed assessment of individual hemodynamic patterns of syncope. Different stimuli and complexity settings produce results of different clinical usability.
ABSTRACT
BACKGROUND: Arterial hypertension might be caused by hemodynamic disturbances such as fluid retention, increased vascular resistance, and hyperdynamic function of the heart. The aim of this study was to estimate the effectiveness of antihypertensive therapy based on hemodynamic assessment by impedance cardiography in a randomized, prospective, controlled trial. MATERIAL AND METHODS: This study involved 128 patients (average age: 42.9 ± 11.1 years) with arterial hypertension, randomized into groups: (1) empiric, and (2) hemodynamic, in which treatment choice considered impedance cardiography results. Evaluation of treatment effects was performed after 12 weeks and included office blood pressure measurement and ambulatory blood pressure monitoring. RESULTS: All final blood pressure values were lower in the hemodynamic group, significantly for office systolic blood pressure (empiric vs. hemodynamic: 136.1 vs. 131.6 mmHg; p=0.036) and diastolic blood pressure (87.0 vs. 83.7 mmHg; p=0.013), as well as night-time systolic blood pressure (121.3 vs. 117.2 mmHg; p=0.023) and diastolic blood pressure (71.9 vs. 68.4 mmHg; p=0.007). Therapy based on impedance cardiography significantly increased the reduction in office systolic blood pressure (11.0 vs. 17.3 mmHg; p=0.008) and diastolic blood pressure (7.7 vs. 12.2 mmHg; p=0.0008); as well as 24-h mean systolic blood pressure (9.8 vs. 14.2 mmHg; p=0.026), daytime systolic blood pressure (10.5 vs. 14.8 mmHg; p=0.040), and night-time systolic blood pressure (7.7 vs. 12.2 mmHg; p=0.032). CONCLUSIONS: Antihypertensive treatment based on impedance cardiography can significantly increase blood pressure reduction in hypertensive patients.
