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The assessment of myocardial viability is a major diagnostic challenge in patients with coronary artery disease (CAD) after myocardial infarction. Novel threedimensional current density (CD) imaging algorithms use high-resolution magnetic field mapping to determine the electrical activity of myocardial segments at rest. We, for the first time, compared CD activity obtained with several algorithms to 18-F-fluoro-deoxyglucose positron emission tomography (FDG-PET) in evaluation of myocardial viability. Magnetic field maps were obtained in nine adult patients (pt) with CAD and a history of infarction. The criterion for non-viable myocardium was an FDG-PET uptake with less than 45% of the maximum in the respective segments. CD imaging was applied to the left ventricle by using six different methods to solve the inverse problem. Mean CD activity was calculated for a close meshed grid of 90 locations of the left ventricle. A cardiologist compared bull's eye plots of CD and FDG-PET activity by eye. Spearman's correlation coefficients and specificity at a given level of sensitivity (70%) were calculated. Bull's eye plots revealed a significant correlation of CD/PET in 5 pt and no correlation in 3 pt. One pt had a negative correlation. The six different CD reconstruction methods performed similar. While CD reconstruction has the principal potential to image viable myocardium, we found that the reconstructed CD magnitude was low in scar segments but also reduced in some segments with preserved metabolic activity under resting conditions. New vector measurement techniques, the use of additional stress testing and advances in mathematical methodology are expected to improve CD imaging in future.

Background: Autonomic regulation analysis is useful in risk stratification of ventricular tachycardia and sudden cardiac death in chronic heart failure (CHF). Heart rate variability (HRV) reflects the condition of autonomic regulation. For analyzing the autonomic control the whole cardiovascular system has to be considered. Therefore, the aim of our study was to assess the influence of peripheral arterial disease (PAD) on the autonomic regulation. Methods: In 53 men (age: 67 ± 11 years) from the cardiovascular unit we compared standard HRV parameters in 27 with (ankle brachial index, ABI 0.9) PAD as well as with 12 healthy subjects as reference. High-resolution electrocardiograms were recorded over 30 minutes under resting conditions. Pulse wave velocity as well as ABI was estimated using the vascular screening system VASERA. Results: In cardiac patients with PAD, we found both significant differences in linear and nonlinear HRV parameters. Higher increase of low-than high-frequency components indicated higher elevated sympathetic than vagal activation. Altered autonomic control can be interpreted as a compensatory mechanism for diminished vascular arteriolar vasodilator capacity in PAD. To maintain the arterial blood pressure, an elevated setpoint of sympathovagal balance is required. Conclusions: Our data indicate PAD alters the HRV in cardiaovascular patients. PAD should be considered in the assessment of cardiac autonomic regulation especially in risk stratification.

Background: Early and late restenosis in up to 30% remains a major problem for long-term success after percutaneous coronary intervention (PCI). Compared to bare metal stents, the use of drug-eluting stents reduces restenosis below 10%, but implant coasts have to be considered. In restenosis noninvasive testing lacks diagnostic power. We applied a new approach to identify patients with a high risk for restenosis after PCI by combining heart rate (HR) and blood pressure variability (BPV) analyses. Methods: In 52 patients with clinical suspicion of restenosis and history of PCI, we investigated patterns of cardiovagal autonomic regulation prior to cardiac catheterization. The patients were separated in (i) patients with restenosis (CAD+R) and (ii) patients without restenosis (CAD−R), where restenosis is defined as a stenosis greater than 75% of luminal diameter in at least one main vessel. The following parameters/methods were evaluated: Canadian Cardiovascular Society grade (CCS-grade), vessel disease score (CAD-level), left ventricular ejection fraction (LVEF), heart rate variability (HRV), BPV, baroreflex sensitivity (BRS), as well as HR turbulence and blood pressure (BP) potentiation caused by premature ventricular complexes. Results: Whereas age, LVEF, CAD-level, CCS-grade, and mean BP did not differ between CAD+R and CAD−R, significant differences were found in (i) BPV: diastolic LF/P, systolic, and diastolic UVLF, (ii) in BRS: slope of tachycardic sequences, and (iii) in extrasystolic parameters: heart rate turbulence onset (HRTO) and potentiation of systolic BP (SBPP). Standard HRV parameters did not show significant differences between the groups. Using the two parameters diastolic LF/P (threshold >0.2) and HRTO (threshold >0) restenosis were predicted in 83.4%. Conclusions: These results demonstrate that indicators of sympathetic activation or vagal depression identify restenosis in patients after PCI, thus opening a perspective for a new noninvasive monitoring.

BACKGROUND Neurovegetative and haemodynamic changes impact on the regulation pattern of blood pressure and heart rate in patients with heart failure. We studied these patterns and their interactions in patients with idiopathic dilated cardiomyopathy (IDC) and in healthy subjects (REF). METHODS We continually measured the heart rate and blood pressure (Portapres device) in twenty-five supine IDC patients (age: 51 +/- 13 y; left ventricular end-diastolic diameter 67 +/- 11 mm; ejection fraction 30 +/- 11%) and in twenty-seven REF (age: 50 +/- 11 y) Recording time was 30 minutes. The heart rate (HR) of each beat and the systolic blood pressure (SYS) of the subsequent beat were measured. Code numbers (symbols) were assigned to the beat-to-beat changes in HR and SYS (increase: 1; decrease: 0). The frequencies of the symbols sequences of three successive beats were counted. In this way we obtained a matrix consisting of eight (two to the power of three) HR and SYS combinations: 000, 100, 010, 001, 111, 110, 011 and 101. We then counted the frequencies of the different combinations of the symbol sequences in HR and SYS (2(3) x 2(3) = 64 combinations). The relative frequencies of symbol patterns appearing in HR, SYS and in the combined analysis of HR and SYS, were compared for IDC and REF using the T-test for independent samples. RESULTS Significant differences were seen between IDC and REF. The HR patterns 101 and 010 were more frequent in IDC than in REF patients (11.1 +/- 4.7 vs. 7.7 +/- 2.9%, p = 0.003, and 16.1 +/- 6.3 vs. 11.7 +/- 4.9%, p = 0.008). This finding was even more marked in the analysis of the SYS patterns 101 and 010 (11.0 +/- 7.4 vs. 8.2 +/- 2.9%, p < 0.001, and 11.6 +/- 7.4 vs. 5.4 +/- 2.7%, p < 0.001). Non-alternating patterns were more frequent in REF (e.g. 000HR & 111SYS: 4.6 +/- 3.3 vs. 2.9 +/- 2.4%, p = 0.03). CONCLUSIONS We demonstrated significant interaction of the regulation patterns of blood pressure and heart rate, as also their interactions in IDC. Opposed changes in HR and SYS mediated by the baroreflex, became superimposed by alternans phenomena in IDC. The pattern analysis of changes in HR and SYS detects these disturbances of neurovegetative short-term control.

The aim of this study was to detect pathological changes of the complex autonomous regulation of ecg, blood pressure and respiration (synchronously recordings of 30 minutes) in patients with cardiac diseases. We investigated the cardiovascular and cardiorespiratory linear and nonlinear interactions in 10 patients with dilative cardiomyopathy (dcm) and in 10 patients after myocardial infarction (mi). We compared results from the classical linear correlation function analysis with results from the mutual information method (transinformation) for analysis of nonlinear and linear interactions. Both methods yield high significant parameters (p < 0.01). Thus, we found both linear and nonlinear interactions with partly different specificity in patients with dcm and mi compared to healthy subjects (ref).

We extracted and quantified high frequency intra-QRS signals in idiopathic dilated cardiomyopathy (IDC). In IDC the analysis of late potentials in the terminal QRS complex often fails in predicting clinical events because of intraventricular conduction abnormalities and the absence of a circumscribed arrhythmogenic substrate. Therefore, new approaches are required to assess the electrical state of the myocardium. We investigated 21 patients suffering from IDC with (n = 14) and without (n = 7) bundle branch block. High resolution 31 lead magnetocardiograms were filtered with a 67 point 4th order Savitzky-Golay filter. The difference of the measured and filtered signals was calculated (67-200 Hz). The spatio-temporal properties and the areas under the curves of the resulting high frequency intra-QRS signals (IQCs) were studied. We detected IQCs in all patients. The patients had individual patterns regarding the temporal and spatial properties of the IQCs during depolarisation. The IQCs predominantly appeared in the initial portion of the QRS. The ratios of the areas under the curves of the IQCs and the measured signals were linearly correlated to the left ventricular enddiastolic diameter (r = 0.71, significance 0.0012). In IDC the ventricular depolarization is accompanied by individual spatial and temporal patterns of high frequency intra-QRS signals. They can be studied non-invasively from body surface mapping data with the algorithm used in this study. This provides access to the assessment of the electrical status in patients with IDC.

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.

Assessment of fluctuations in heart rate (HR) following a premature ventricular complex (PVC) is valuable for identifying patients at high risk of sudden cardiac death. We hypothesised that postextrasystolic potentiation is the main determinant of the regulation patterns of blood pressure (BP) and HR following a PVC. Twelve patients with idiopathic dilated cardiomyopathy (IDC) and 13 control subjects with single PVCs (comparable coupling intervals) were investigated. Non-invasive finger arterial BP and ECGs were analysed. Regulation patterns following a single PVC were quantified using the indices postextrasystolic amplitude potentiation (PEAP) and maximum turbulence slope of five consecutive mean BP values (MBP-TS), and compared with the HR turbulence parameters turbulence slope (HR-TS) and turbulence onset (HR-TO). PEAP was significantly higher in IDC patients compared to controls (48.7 +/- 32.6 vs. 9.8 +/- 5.4 %, P < 0.01), whereas MBP-TS was lower (0.97 +/- 0.60 vs. 2.07 +/- 1.04 mmHg BBI(-1) (BBI, beat-to-beat interval), P < 0.05), as was HR-TS (8.46 +/- 7.90 vs. 30.73 +/- 22.90 ms BBI(-1), P < 0.01). HR-TO was significantly higher in IDC patients (-0.56 +/- 2.19 vs. -5.52 +/- 4.13 %, P < 0.01). In addition, the regulation patterns of BP and HR following a single PVC differed significantly between IDC patients and controls. Specifically, we observed pronounced PEAPs in IDC patients. The baroreflex response initiated by the low pressure amplitude of the PVC was suppressed in IDC patients due to the augmented potentiation of the first postextrasystolic blood pressure. Furthermore, IDC patients displayed impressive postextrasystolic pulsus alternans phenomena, whereas healthy subjects exhibited a typical baroreflex pattern. The pulsus alternans phenomenon seems to be triggered by a PVC.

Arteriovenose Fisteln der Koronararterien sind sehr selten und drainieren meist in den rechten Ventrikel oder rechten Vorhof. Echokardiographie und Koronarangiographie sind etablierte Methoden in der Detektion dieser Anomalien. Es wird uber einen Patienten berichtet, bei dem eine Anomalie mit Dilatation des Ramus circumflexus, Aneurysma und Drainage uber eine arteriovenose Fistel in den rechten Ventrikel vorlag. Mittels Magnetresonanztomographie im Bolustrack-ing-Verfahren konnten Gefasverlauf und Dynamik der Perfusion zusatzlich zur Bildgebung mittels TSE-Sequenz nichtinvasiv dargestellt werden. Durch die Moglichkeit einer mehrfachen Applikation von 2 ml Gd-DTPA eignet sich die Bolustracking-Methode ausgezeichnet zur Bestimmung des individuellen Gefasverlaufes, der Hamodynamik und Drainagerichtung einer Koronaranomalie mit Fistel.

The prevalence of late potentials after myocardial infarction depends on the site of the infarction. This may be caused by the different activation onsets of the anterior and inferior myocardial segments. Therefore, in anterior infarcts the high frequency signals may be concealed within the QRS whereas in the inferior infarcts they last beyond the end of the QRS. We compared the timing and the spatial patterns of high frequency intra-QRS signals (IQSs) in the different infarction sites. We investigated 14 patients with anterior infarcts, 17 patients with inferior infarcts, and 10 healthy subjects. 31-lead magnetocardiograms were recorded in left precordial position and averaged. The QRS signals were smoothed with a Savitzky-Golay filter. The smoothed QRS signals were subtracted from the measured ones. The difference of the signals (frequency band of about 60-200 Hz) representing the high frequency components was quantified. The percentage of the high frequency signals was calculated for the entire QRS, for the first and for the second half, respectively. We found that in patients with anterior infarcts the high frequency components predominantly appeared in the first half of the QRS whereas in inferior infarcts these components predominantly appeared in the second half of the QRS. The different infarction sites were associated with different spatial patterns of the high frequency signals on the body surface. In healthy subjects there was not such a preferential association of time intervals and high frequency signals. Late potentials are the special case of high frequency signals appearing in the terminal QRS. It is the general property of the myocardium to generate high frequency signals associated with the depolarization of infarcted tissue. The timing of such signals and the spatial distribution patterns on the body surface may help to identify the location of the sources.

Objective: In this paper we present an attempt at noninvasive imaging of distributed myocardial electrical activity in patients suffering from myocardial infarction and in healthy subjects. Although advances have been made, noninvasive three-dimensional imaging of cardiac electrophysiological activity is still in its infancy and extending our knowledge of cardiac electrophysiological properties may be a valuable guide in the treatment of patients with coronary artery disease. Methods: Magnetic field mapping data formed the input for an inverse solution that is based on a multiple dipole model. The lead field normalized minimum norm least square criterion was applied to predefined myocardial source geometry. Current density distributions were calculated for the left ventricle during ventricular depolarization. Images from two patients with previous myocardial infarction were compared to images from two healthy subjects. Results: Low regional and global current density was found in the infarction patients. Regions of low current density corresponded to infarcted segments. The images of the healthy subjects displayed less marked areas of low current density. Conclusion: The proposed multiple dipole model may be able to distinguish viable from scarred myocardium. A prospective clinical study should be undertaken to investigate the spatial resolution and the diagnostic performance of this method.

Amiodarone is widely used in ventricular tachyarrhythmias and atrial fibrillation, known to prolong QT-intervals. Concurrent administration of drugs prolonging QT- time can induce life-threatening ventricular tachyarrhythmia.QT-interval changes following use of Iohexol contrast-medium for coronarangiography were observed comparing 21 patients taking long-term amiodarone therapy with 21 controls not taking amiodarone or QT-prolonging drugs retrospectively.Concurrent use of Iohexol and amiodarone was associated with significant prolongation of QTc-interval (433, 95%CI: 419-448 ms vs. 480, 95%CI: 422-483 ms, P0.001) the day after coronarangiograpgy. 6/21 patients showed severe prolonged QTc-interval of500 ms.Caution is advised until more is known about pro-arrhythmic effects of Iohexol.

Heart rate variability (HRV) is a marker of autonomous activity in the heart. An important application of HRV measures is the stratification of mortality risk after myocardial infarction. Our hypothesis is that the information entropy of HRV, a non-linear approach, is a suitable measure for this assessment. As a first step, to evaluate the effect of myocardial infarction on the entropy, we compared the entropy to standard HRV parameters. The entropy was estimated by compressing the tachogram with Bzip2. For univariate comparison, statistical tests were used. Multivariate analysis was carried out using automatically generated decision trees. The classification rate and the simplicity of the decision trees were the two evaluation criteria. The findings support our hypothesis. The meanNN-normalized entropy is reduced in patients with myocardial infarction with very high significance. One entropy parameter alone exceeds the discrimination strength of multivariate standards-based trees.

Postextrasystolic potentiation mainly effects short term regulation of blood pressure and heart rate. The objective of our study was to verify how changes in systolic blood pressure (/spl Delta/SBP) from the preextrasystolic to the postextrasystolic beat characterize the pathological behavior in patients with idiopathic dilated cardiomyopathy (IDC). This measure was compared with mean blood pressure turbulence slope (BPTS) and heart rate turbulence onset (HRTO). Therefore, we analyzed the non-invasively recorded finger arterial blood pressure during single premature ventricular complexes (PVC) in IDC (n=10) and healthy subjects (CON; n=7). Although all parameters revealed significant differences (Mann-Whitney test) between IDC and CON (/spl Delta/SBP: 10.7/spl plusmn/9.7 vs -5.1/spl plusmn/1.9 %, p

The inverse solution of the single equivalent current dipole model obviously fails in the explanation of more complex source structures like a distributed myocardial activation wavefront. For this reason we applied depth normalized minimum norm estimation with anatomical constraints in patients with myocardial infarction and known regions of large myocardial damage. Current density was calculated for several hundred myocardial support points using lead field normalized minimum norm least square estimates and overlayed with 3D-MR-images as color coded surfaces. In 55% of 40 patients/normals investigated, MCI had complete correspondence with the other cardiological findings, in 27% we found partly correspondence and 18% MCI failed to provide correct diagnosis. Myocardial current imaging (MCI) is a new and promising method for assessing of myocardial viability.

Patients with decreased left ventricular function due to either acute myocardial infarction or idiopathic dilatative cardiomyopathy are known to have an increased risk of sudden death due to malignant ventricular arrhythmias. The heart rate variability (HRV) representing the influence of the autonomic nervous system on the heart is one parameter for risk stratification in these conditions, since decreased HRV correlates with increased risk for sudden death. The authors investigate: 1) whether there is a comparable sensitivity in HRV sampling ECG systems with either high (1000 Hz) or low (200 Hz) sampling rate during simultaneously short time measurements (10 minutes) and; 2) if there are differences in HRV parameter after short time measurements (10 minutes) and long time measurements (24 hours) on behalf of its usefulness for risk stratification.

Dilated cardiomyopathy (DCM) is a serious heart disease, characterized by dilatation and impaired contraction of the left or both ventricles. These pathophysiological changes were already studied by various techniques, but no complex investigations have been made concerning the peripheral noninvasive blood pressure. We hypothesize that the influence of DCM on cardiac hemodynamics can be derived by the analysis of the noninvasive finger blood pressure waveform. Therefore, a set of 25 parameters was developed, describing typical time intervals, slopes and areas. We analyzed the blood pressure contour in 20 patients with DCM and 20 healthy subjects as controls. Age and heart rate were matched in both groups. The data, recorded by a Portapres M2 device, were computed on a beat-to-beat basis. The calculated values were averaged over a period of 200 s. Ejection related time in patients with DCM was significantly shorter than in controls. It was also measured that the area under the blood pressure curve was significantly reduced in DCM patients, compared with controls. These effects may be caused by a decreased heart efficiency. This introduced new noninvasive method may lead to a more detailed analysis of pathophysiological changes in DCM patients.

Magnetocardiography was introduced to clinical cardiologists in the early 1970’s. The measurement devices were technically unreliable, signal-to-noise ratio was poor and measurements were time consuming. Most measurements were performed in ambient environment without any shielding. Patient material studied included at first normals and myocardial infarction patients. Electromagnetic activity produced by the His-Purkinje conduction system also drew a lot of attention. Later on, pregnant women (fetal MCG), patients with ventricular hypertrophy, Wolff-Parkinson-White (WPW) Syndrome patients as well as patients with tachycardias were studied. The analysis of MCG signals in those days was rather primitive: mostly descriptive, qualitative, and morphological data was published. In order to be useful in the clinic there were many things to be improved: low signal-to-noise ratio, limited mapping and analysis possibilities, and the measurement systems were mostly located outside hospital.

Data from simulations of the anterior myocardial infarction (AMI) and inferior myocardial infarction (IMI) are presented. One infarct located in the anterior section of the left ventricle and a second one in the inferior wall of the left ventricle were modeled. A high-resolution finite element model of a heart and torso was used in this study. Differences in the normal and infarcted fields were computed. The authors data suggest that the infarcted region contribution to the total magnetic field can be accounted for by an equivalent current dipole. It might also be possible to detect an infarct from these difference fields constructed for different cases of myocardial infarction. More simulations are needed to determine the relations between infarct sizes and locations and magnetic fields. These relations might then be used to detect various cases of myocardial infarction.

Chronic heart failure (CHF) alters heart rate and blood pressure variability (HRV, BPV). Additional prospective studies are needed to clarify their role in cardiac risk stratification. The aim of this study was to prove the value of BPV analysis for risk stratification in CHF compared to HRV. In 88 patients with CHF high-resolution ECG (22 bit resolution, 1600 Hz sampling frequency) and continuous non-invasive blood pressure (NIBP, 22 bit, 500 Hz) were recorded over 30 minutes. Based on volume clamp method the peripheral arterial blood pressure was measured via finger cuff. From the ECG recordings, time series of beat-to-beat intervals were extracted to analyze HRV and from the NIBP recordings, time series of systolic as well as diastolic blood pressure values were extracted to analyze BPV. To get ‘normal-to-normal’ beat time series (NN), ventricular premature beats and artefacts within the time series were detected and replaced by interpolated normal heartbeats. Standard HRV and systolic as well as diastolic BPV parameters were evaluated for patients with ejection fraction above and below 40% (EF+ and EF-) and for 5-year follow up (cardiac death and worsening of NYHA class). Only one HRV parameter (MEAN NN) but six BPV indices separated EF+ from EF-. In the 5-year follow up systolic BPV but not ejection fraction and HRV predicted worsening of NYHA class with 15% positive and 91.2% negative predictive value. Cardiac death was predicted in 81.8% by using the two best diastolic BPV parameters (dLF/HF and dSDNN). We conclude BPV analysis may be useful in medium range risk stratification in patients with CHF. The analysis of autonomic control should focus more on blood pressure regulation.

A wide range of cardiac imaging procedures is available to assess left-ventricular function, geometry, perfusion, and altered metabolism. There is no non-invasive imaging procedure to detect electrically unstable myocardium. We assessed the electrical function of the myocardium by biomagnetic imaging of high-frequency depolarisation signals in a patient aged 70 years who had non-sustained ventricular tachycardia that developed after anterior left-ventricular myocardial infarction and apical aneurysm. Imaging was done on the basis of magnetic-field measurement and inverse computation of the magnitudes of 1200 left-ventricular endocardial dipoles regularly spaced (mean distance 3 mm). Such endocardial activity images have been computed for the unfiltered depolarisation signal (QRS) and for the last 40 ms of the bidirectional 30 Hz highpass filtered depolarisation signal (LP). In theory, three types of QRS/LP image pairs could appear. If areas of high dipole magnitude of LP and QRS images match, LP generators can be taken to lie in the intact myocardium. If areas of high dipole magnitude in LP images match areas of low dipole magnitude in QRS images, LP generators may belong to the area infarcted and, therefore, display properties of the surviving subendocardial layer. If no correlation of LP and QRS is seen, it will not fit into the concepts of arrhythmogenesis after infarction. By comparison of LP and QRS images (figure), we observed regional mismatch of dipole magnitudes. The QRS image shows low dipole magnitudes in the apical segment of the left ventricle (the apical aneurysm) with a loss of electrically active myocardium. The opposite has appeared in the LP image with high dipole magnitudes in the segments infarcted. This finding could be an indication of fragmented delayed intraventricular conduction in this region. We conclude that this method supports the imaging of delayed high-frequency depolarisation signals, which are known to correlate with conduction disturbances and, therefore, risk of arrhythmia. Our findings may help in assessing patients with malignant tachyarrhythmias after myocardial infarction.

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.