Impedance cardiography is a noninvasive technique for estimation of stroke volume, systolic time intervals, and some other cardiovascular indices. These estimations require error-free detection of the B, C, and X points of impedance cardiogram (ICG), as markers of aortic valve opening, peak aortic blood velocity, and aortic valve closure, respectively. Based on an empirical examination of the morphological variations in the ICG waveforms, a technique for automatic beat-to-beat detection of these points is developed. It uses wavelet-based denoising for suppression of respiratory artifacts to avoid restrictions on breathing during the recording. It uses R peaks of ECG as reference points to avoid inter-cycle smearing and multiple time-domain waveform features to reduce errors due to morphological variations. The technique is evaluated on simultaneously acquired and time-aligned ICG, ECG, and Doppler echocardiogram recordings from subjects with normal-health and subjects with cardiovascular disorders. Compared to the earlier techniques, the proposed technique detects the points with low bias and precision errors. The means of differences, as referred to the mean R-R interval, in the estimation of R-C, R-B, R-X, and B-X intervals with the corresponding measurements from Doppler echocardiograms as the reference were 0.5%, 0.3%, 0.5% and 3.0% respectively. The corresponding standard deviations of differences were 1.3%, 1.3%, 5.8% and 6.0%. The proposed technique may help in improving the acceptability of impedance cardiography for diagnosis of cardiovascular disorders.

No abstract

Impedance cardiography is a noninvasive technique for monitoring the variation in thoracic impedance during cardiac cycle. Estimation of the stroke volume and other cardiovascular indices using impedance cardiography requires error-free detection of characteristic points in the impedance cardiogram (ICG). A technique for automatic detection of ICG characteristic points using R peaks in ECG as reference is presented. It does not require pre-processing of the ICG signal for baseline correction and adjustment of detection parameters. The technique is validated using Doppler echocardiography as a reference technique, by recording ICG and ECG signals simultaneously along with velocity profile of blood flow at the level of left ventricular outflow tract. Application of the technique on the recordings from healthy subjects in pre-exercise and post-exercise conditions and from cardiac patients under rest condition showed a very low detection error.

A 50-year-old man was admitted with high-risk acute coronary syndrome with enzyme elevation. A coronary angiogram revealed a critical 90% stenosis of the proximal left anterior descending artery. The lesion was predilated and a 3 mm × 18 mm bare metal stent was deployed at 14 atm. After stent deployment, balloon passage inside the stent was difficult. For better visualization of the stent, StentBoost (Philips Medical Systems, Netherlands) was used. With the balloon markers located within the stented segment, roughly 40 frames of digital cine were acquired without injection of contrast at 15 frames/s. StentBoost-augmented images (Figure 1) revealed that the stent had fractured into two pieces, which was not apparent on ordinary cine angiography. Subsequently, a second stent was deployed across the fractured stent.Stent strut fracture is a rare but important complication that can lead to serious consequences, such as stent thrombosis, if it is not treated in time. Stent fracture is a rare but important cause of restenosis in the drug-eluting stent era (1). In the present case, StentBoost enabled the diagnosis of this complication, which could then be treated. Stent strut fracture has been diagnosed previously by means of intravascular ultrasound (1), multislice computed tomography (2) and optical coherence tomography (3).StentBoost is a novel fluoroscopic stent visualization technique that creates a high-quality image of deployed stents by superimposing motion-corrected acquisition frames, thus giving a clearer image of the stent. The balloon markers must be in the frame. StentBoost does not require any additional expensive hardware and it can give important information about stent position, placement and complications, as illustrated in the present case. imageS in cardiology

No abstract