Impaired myocardial performance is known to be associated with electrical and mechanical beat-to-beat alternans phenomena. The alternans in blood pressure and heart rate and their interdependency in idiopathic dilated cardiomyopathy (IDC) were studied. The arterial blood pressure and the electrocardiograph (ECG) were continuously recorded in 22 patients suffering from IDC (age 49 +/- 13 years, ejection fraction 0.33 +/- 0.13, left ventricular diameter of 67 +/- 8 mm) and in 21 healthy controls (age 52 +/- 15 years). The beat-to-beat variations of the interbeat intervals (IBI) and of the blood pressure amplitudes (AMP) were measured. An alternans beat was defined as a beat preceded and followed by beats that had higher or lower values in the respective modality. The percentages of singular and repetitive alternans patterns, and the interdependency of the alternans patterns in AMP and IBI were assessed. The study found significantly more singular and repetitive alternans patterns in the IDC group compared to the control group both in the analysis of AMP and IBI (singular alternans in IBI: 55 +/- 11 vs 47 +/- 7%, P < 0.01; singular alternans in AMP: 61 +/- 15 vs 45 +/- 6%, P < 0.01; triple alternans in IBI: 29 +/- 18 vs 16 +/- 9%, P < 0.01; triple alternans in AMP: 34 +/- 24 vs 12 +/- 7%, P < 0.01). The amplitudes of the AMP alternans patterns were higher in IDC compared to controls (9 +/- 7 vs 4 +/- 2% of AMP, P = 0.01) whereas they did not differ in IBI. The correlation analysis revealed a significant interdependency of the alternans pattern in IBI and AMP in 18 of 22 IDC patients and in 12 of 21 controls (r = 0.50 +/- 0.21 [IDC]; r = 0.26 +/- 0.05 [controls]). The slope of the linear regression (delta AMP vs delta IBI) was steeper in the IDC group compared to the control group (62 +/- 50 vs 20 +/- 22 mmHg/s, P < 0.01). The percentages of alternans patterns appearing in IBI and AMP were positively correlated to the left ventricular diameter (r = 0.70 in the IBI, and r = 0.30 in the AMP). The blood pressure amplitude and the heart rate did not differ between the two groups. Patients suffering from IDC have a higher prevalence, stability, amplitude, and interdependency of alternans patterns in IBI and AMP compared to the control group. The amount of alternans patterns indicates the stage of disease. The alternans analysis may have impact on the functional assessment of patients suffering from heart failure.

No abstract

The beat-to-beat variability of the diastolic blood pressure induces small variations in the afterload of the left ventricle. These variations influence myocardial contractility, and thus blood pressure amplitude. We assessed the interdependence of blood pressure and changes in the afterload. We continuously recorded blood pressure (duration 200 s, at rest) in 20 patients with dilated cardiomyopathy (ejection fraction 32 +/- 13%, left ventricular diameter 67 +/- 8 mm) and in 20 healthy volunteers. Interbeat intervals, diastolic pressures, systolic pressure amplitudes and mean slopes of systolic pressure amplitudes were measured. Correlation coefficients (r) were calculated to assess the interdependence of blood pressure amplitudes/mean systolic slopes and the preceding diastolic pressures/interbeat intervals, respectively. In healthy volunteers we found a strong interdependence between blood pressure amplitude and the preceding diastolic pressures (r = 0.62 +/- 0.21 and 0.47 +/- 0.22). Higher diastolic pressures were followed by higher blood pressure amplitudes, and by steeper slopes of the systolic peaks. In patients with dilated cardiomyopathy, such interdependence was significantly lower (r = 0.33 +/- 22 and r = 0.28 +/- 0.35), and in patients with severely reduced left ventricular function (ejection fraction < 32%) was only marginal (r = 0.23 +/- 0.27 and 0.21 +/- 0.44, respectively). The forces of the isovolumetric contraction necessary to initiate the ejection phase of the left ventricle depend on the afterload, i.e. on the diastolic pressure. The responses of amplitude and slope of the systolic blood pressure to small changes in the afterload make it possible to assess left ventricular contractility. The latter is impaired in dilated cardiomyopathy.

Pregnancy has impact on autonomic control. Since hypertensive pregnancy disorders are a major cause of maternal mortality we investigated the baroreflex sensitivity (BRS) in chronic hypertensive pregnant women (CH), normotensive pregnant (PRE) and non-pregnant (NPRE) women. In addition to the traditional 'sequence method' we used joint symbolic dynamics (JSD). BRS was significantly reduced in all pregnancies compared with NPRE (p < 0.00001) but there was no significant difference between CH and PRE. Contrary, the JSD measures revealed significant differences (p < 0.00001) in the heart rate and blood pressure interactions between PRE and CH. In conclusion, JSD measures uncovered a different gestation related adaptation of autonomic regulation in women with chronic.

Sl ; MMAKV. Wo hypolhcsi/ecl that a hing recruitment m;mcu\cr lias positive influence on hemodynamic Parameters in nicchanical ventilated patienls. \Yo mvcstigated paticnts of the Intensive Care Unit with hoalthy lungs Hut posl operative atelectasis ander nicchanical Ventilation. ECG and conlinuous blood prcssure were recorded during 30min before and after thc recruitment maneuver, respectively. ßaroreflex scnsiiivity and number of baroreflex fluctuations were ealculated using the sequence method. Furthermore, we computed linear and non-linear measures of heart rate and blood pressure variability. \Vhereas baroreflex sensitivity remained unchanged, the number of baroreflex fluctuations was significantly rcduced after the recruitment maneuver. Blood pressure ampliuide was increased and complexity (non-linear Parameter) of blood pressure time series was decreased. Number of baroreflex activations after the recruitment maneuver is comparable with healthy spontaneous breathing subjects. The improved oxygenation increases contractility of the heart and blood pressure adoption is less frequently necessary. This study shows that a hing recruitment maneuver has a sigmficant positive influence on patients hemodynamics.EINLEITUNG