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Rafal Baranowski

Publications and source records attributed to Rafal Baranowski.

8 recordsLinked to original sources
PubMed2006

Autonomic information flow improves prognostic impact of task force HRV monitoring.

Heart rate variability (HRV) represents the cardiovascular control mediated by the autonomic nervous system and other mechanisms. In the established task force HRV monitoring different cardiovascular control mechanisms can approximately be identified at typical frequencies of heart rate oscillations by power spectral analysis. HRV measures assessing complex and fractal behavior partly improved clinical risk stratification. However, their relationship to (patho-)physiology is not sufficiently explored. Objective of the present work is the introduction of complexity measures of different physiologically relevant time scales. This is achieved by a new concept of the autonomic information flow (AIF) analysis which was designed according to task force HRV. First applications show that different time scales of AIF improve the risk stratification of patients with multiple organ dysfunction syndrome and cardiac arrest patients in comparison to standard HRV. Each group's significant time scales correspond to their respective pathomechanisms.

Adult↗
PubMed2006

Analysis of complex physiological systems by information flow: a time scale-specific complexity assessment.

In the last two decades conventional linear methods for biosignal analysis have been substantially extended by non-stationary, non-linear, and complexity approaches. So far, complexity is usually assessed with regard to one single time scale, disregarding complex physiology organised on different time scales. This shortcoming was overcome and medically evaluated by information flow functions developed in our research group in collaboration with several theoretical, experimental, and clinical partners. In the present work, the information flow is introduced and typical information flow characteristics are demonstrated. The prognostic value of autonomic information flow (AIF), which reflects communication in the cardiovascular system, was shown in patients with multiple organ dysfunction syndrome and in patients with heart failure. Gait information flow (GIF), which reflects communication in the motor control system during walking, was introduced to discriminate between controls and elderly patients suffering from low back pain. The applications presented for the theoretically based approach of information flow confirm its value for the identification of complex physiological systems. The medical relevance has to be confirmed by comprehensive clinical studies. These information flow measures substantially extend the established linear and complexity measures in biosignal analysis.

Adult↗
PubMed2006

Complex autonomic dysfunction in cardiovascular, intensive care, and schizophrenic patients assessed by autonomic information flow.

BACKGROUND: The cardiovascular control system is mediated by mechanisms acting at different time scales, such as heart period, vagal, sympathetic, and other slower controllers. Since these elements are interrelated in a complex manner, classical control theory fails and information-based description, based on autonomic information flow (AIF) functions, is appropriate. We investigated the hypothesis that AIF functions of typical time scales specifically characterize autonomic dysfunction and prognosis. MATERIALS AND METHODS: Holter recordings of patients with multiple organ dysfunction syndrome (MODS) (26 survivors, 10 non-survivors), heart failure (13 low risk, 13 high risk of cardiac arrest), idiopathic dilated cardiomyopathy (IDC) (26 low risk, 11 high risk), after abdominal aorta surgery (AAS) [32 with length of stay in hospital (LOS) >7 days; 62 with LOS < or =7 days] or with schizophrenia (n=20) were assessed and compared to 20 control subjects. RESULTS: We found different AIF time scales discriminating risk. AIF measures of heart beat period had predominant prognostic value in heart failure patients, those of vagal communication in MODS and IDC, and those of long-term communication after AAS. Schizophrenic patients were discriminated from controls by vagally mediated communication. CONCLUSION: Different time scales of AIF represent specific pathophysiological aspects of altered complex autonomic control (communication) and consequently have predictive implications.

Autonomic Nervous System↗
PubMed2005

Prognostic impact of autonomic information flow in multiple organ dysfunction syndrome patients.

BACKGROUND: Multiple organ dysfunction syndrome (MODS) is the sequential failure of several organ systems after a trigger event, like cardiogenic shock or decompensated heart failure. Mortality is high, up to 70%. Autonomic dysfunction (AD) may substantially contribute to the development of MODS. In cardiology, it has recently been shown that nonlinear parameters could predict mortality. Our study aimed at 1. characterising the complex characteristics of AD of critically ill MODS patients by the nonlinear parameters of autonomic information flow (AIF), 2. comparing AIF with autonomic function of healthy controls, and 3. characterising the accuracy of this parameter in predicting mortality in MODS. METHODS: We enrolled 43 score-defined MODS patients who were consecutively admitted to a twelve-bed medical intensive care unit in a university centre into this prospective outcome study. Additionally, we assigned 50 healthy controls to the study. AIF was assessed as a complexity function of AD using 24-h ECG. Measures of AIF were introduced according to the standard HRV concept. The patients were followed up for 28-day mortality. RESULTS: MODS causes a disorganisation of short term AIF in favour of an enhanced (rigid) long term AIF. Concerning prognosis increased short term AIF was associated with survival. Short term AIF discriminated between MODS survivors and non-survivors at the level of APACHE II score. CONCLUSIONS: This is the first study providing evidence that complex AD of MODS patients is specifically assessed by AIF time scales and that AIF has significant prognostic impact.

Adult↗
PubMed2005

Reduction of the QT interval dispersion after aortic valve replacement reflects changes in electrical function rather than structural remodeling.

BACKGROUND AND AIM OF THE STUDY: Factors related to changes of QT dispersion (QTd) after aortic valve replacement (AVR) in patients with aortic stenosis were analyzed. METHODS: The prospective group comprised 121 consecutive patients (45 women, 76 men; mean age 58 +/- 11 years; range: 24-77 years) with significant aortic valve stenosis. Data (clinical, echocardiographic and electrocardiographic) were collected before and at least 16 months after AVR. QTd was measured in the standard ECG. RESULTS: Before AVR, the mean QTd was 60 +/- 24 ms (QT(max) 424 +/- 40 ms). QTd was > 50 ms in 68% of patients, and > 70 ms in 30%. During postoperative follow up the mean QTd was 54 +/- 19 ms (QT(max) 368 +/- 36 ms) for all patients, and was > 50 ms in 58% of cases and > 70 ms in 13%. Postoperatively, QTd was decreased to < 70 ms in 27% of patients with a normalized left ventricular mass index (LVMI), and in 27% of those without any clinically significant reduction in left ventricular (LV) hypertrophy. In the multivariate analysis, QTd reduction was weakly related to the reduction in LV wall thickness (p = 0.09) and LVMI (p = 0.05). The reduction in QTd was more related to changes in T-wave amplitude in lead V5 (p = 0.004). CONCLUSION: Following AVR for aortic stenosis, a decrease in QTd was observed, notably among patients with QTd > 70 ms. This reduction was only weakly related to the degree of reduction in cardiac hypertrophy, but a more important relationship was observed with changes in T-wave amplitude. These findings suggest that a reduction in QTd after AVR is reflective of changes in electrical function rather than structural remodeling.

Adult↗
PubMed2004

Influence of ACE I/D genotypes on left ventricular hypertrophy in aortic stenosis: gender-related differences.

BACKGROUND AND AIM OF THE STUDY: Factors responsible for cardiac hypertrophy in patients with aortic stenosis (AS) are not well defined. The study aim was to examine the relationship between angiotensin-converting enzyme (ACE) I/D polymorphism and the degree of cardiac hypertrophy in patients with AS. METHODS: A total of 392 white patients (159 women, 233 men; age range: 32-82 years) with AS was analyzed, with clinical data, echocardiographic parameters and ACE I/D polymorphism being assessed. RESULTS: Left ventricular mass index (LVMI) and wall thickness (LVWT) were greater in men than in women (226 +/- 66 versus 200 +/- 68 g/m2, p <0.0001; and 28.4 +/- 4.5 versus 27.3 +/- 4.1 mm, p = 0.02, respectively). In all patients, LVMI was significantly correlated with the maximal aortic gradient, ejection fraction and gender, whereas LVWT was dependent upon maximal aortic gradient, ejection fraction, gender and history of hypertension. In women, cardiac hypertrophy increased with age. Hypertrophy in women aged <66 years correlated with an absence of the DD genotype. In men, a reverse correlation of both LVMI and LVWT with age was observed (higher in younger patients). The presence of a DD genotype in men seemed to have a significant impact on the degree of cardiac hypertrophy. CONCLUSION: The degree of left ventricular hypertrophy in patients with AS was higher in men than in women. ACE I/D polymorphism appeared to have a modulating impact on cardiac hypertrophy in patients with AS, notably those aged <66 years. A higher degree of cardiac hypertrophy was seen in men with the DD genotype, and in women without the DD genotype.

Adult↗
PubMed2003

QT interval dispersion analysis in patients with aortic valve stenosis: a prospective study.

BACKGROUND AND AIM OF THE STUDY: QT interval dispersion (QTd) was analyzed in patients with aortic valve stenosis, and the relationship investigated between QTd, age, gender, hypertension, presence of significant coronary artery stenosis and left ventricular (LV) hypertrophy assessed by echocardiography. Results were also compared between survivors and patients who had cardiac arrest or died before, during or soon after cardiac surgery. METHODS: The group comprised 535 consecutive patients (217 women, 318 men; mean age 59 +/- 11 years; range: 20-81 years) with significant aortic valve stenosis before valve replacement. The control group comprised 35 healthy subjects (12 women, 23 men; mean age 51 +/- 11 years; range: 28-74 years). RESULTS: Mean QTd was 29 +/- 10 ms in controls and 59 +/- 24 ms in patients (p < 0.001). Gender had no impact on QTd. QTd was increased in men with significant coronary artery stenosis, and independently related strongly with ECG parameters (QTmax, heart rate) and weakly with age and degree of LV hypertrophy. In patients with cardiac arrest or those who died (n = 14), QTd was increased compared to that in survivors (71 +/- 22 versus 59 +/- 24 ms; p = 0.05), and QTd >70 ms was observed more frequently (p = 0.02; odds ratio 3.4, 1.16-10.0). CONCLUSION: QTd is abnormally increased in two-thirds of patients with aortic valve stenosis, and is increased in men with concomitant coronary artery disease. QTd >70 ms significantly increased the risk of cardiac arrest or death perioperatively. QTd was only weakly related with age and degree of LV hypertrophy, but QTmax and heart rate had a greater impact. QT dispersion analysis has limited clinical value in patients with aortic stenosis.

Adult↗