Mobile health in adults with congenital heart disease: current use and future needs

Objective

Many adults with congenital heart disease (CHD) are affected lifelong by cardiac events, particularly arrhythmias and heart failure. Despite the care provided, the cardiac event rate remains high. Mobile health (mHealth) brings opportunities to enhance daily monitoring and hence timely response in an attempt to improve outcome. However, it is not known if adults with CHD are currently using mHealth and what type of mHealth they may need in the near future.

Methods

Consecutive adult patients with CHD who visited the outpatient clinic at the Academic Medical Center in Amsterdam were asked to fill out questionnaires. Exclusion criteria for this study were mental impairment or inability to read and write Dutch.

Results

All 118 patients participated (median age 40 (range 18–78) years, 40 % male, 49 % symptomatic) and 92 % owned a smartphone. Whereas only a small minority (14 %) of patients used mHealth, the large majority (75 %) were willing to start. Most patients wanted to use mHealth in order to receive more information on physical health, and advice on progression of symptoms or signs of deterioration. Analyses on age, gender and complexity of defect showed significantly less current smartphone usage at older age, but no difference in interest or preferences in type of mHealth application for the near future.

Conclusion

The relatively young adult CHD population only rarely uses mHealth, but the majority are motivated to start using mHealth. New mHealth initiatives are required in these patients with a chronic condition who need lifelong surveillance in order to reveal if a reduction in morbidity and mortality and improvement in quality of life can be achieved.

Interstudy reproducibility of the second generation, Fourier domain optical coherence tomography in patients with coronary artery disease and comparison with intravascular ultrasound: a study applying automated contour detection

Recently, Fourier domain OCT (FD-OCT) has been introduced for clinical use. This approach allows in vivo, high resolution (15 micron) imaging with very fast data acquisition, however, it requires brief flushing of the lumen during imaging. The reproducibility of such fast data acquisition under intracoronary flush application is poorly understood. To assess the inter-study variability of FD-OCT and to compare lumen morphometry to the established invasive imaging method, IVUS. 18 consecutive patients with coronary artery disease scheduled for PCI were included. In each target vessel a FD-OCT pullback (MGH system, light source 1,310 nm, 105 fps, pullback speed 20 mm/s) was acquired during brief (3 s) injection of X-ray contrast (flow 3 ml/s) through the guiding catheter. A second pullback was repeated under the same conditions after re-introduction of the FD OCT catheter into the coronary artery. IVUS and OCT imaging was performed in random order. FD-OCT and IVUS pullback data were analyzed using a recently developed software employing semi automated lumen contour and stent strut detection algorithms. Corresponding ROI were matched based on anatomical landmarks such as side branches and/or stent edges. Inter-study variability is presented as the absolute difference between the two pullbacks. FD-OCT showed remarkably good reproducibility. Inter-study variability in native vessels (cohort A) was very low for mean and minimal luminal area (0.10 ± 0.38, 0.19 ± 0.57 mm², respectively). Likewise inter-study variability was very low in stented coronary segments (cohort B) for mean lumen, mean stent, minimal luminal and minimal stent area (0.06 ± 0.08, 0.07 ± 0.10, 0.04 ± 0.09, 0.04 ± 0.10 mm², respectively). Comparison to IVUS morphometry revealed no significant differences. The differences between both imaging methods, OCT and IVUS, were very low for mean lumen, mean stent, minimal luminal and minimal stent area (0.10 ± 0.45, 0.10 ± 0.36, 0.26 ± 0.54, 0.05 ± 0.47 mm², respectively). FD-OCT shows excellent reproducibility and very low inter-study variability in both, native and stented coronary segments. No significant differences in quantitative lumen morphometry were observed between FD-OCT and IVUS. Evaluating these results suggest that FD-OCT is a reliable imaging tool to apply in longitudinal coronary artery disease studies.

The diagnostic value of intracoronary optical coherence tomography

Optical coherence tomography (OCT) is a novel light-based imaging modality for application in the coronary circulation. Compared to conventional intravascular ultrasound, OCT has a ten-fold higher image resolution. This advantage has seen OCT successfully applied in the assessment of atherosclerotic plaque, stent apposition, and tissue coverage, heralding a new era in intravascular coronary imaging. The present article discusses the diagnostic value of OCT, both in cardiovascular research as well as in potential clinical application.The unparalleled high image resolution and strong contrast between the coronary lumen and the vessel wall structure enable fast and reliable image interpretation. OCT makes it possible to visualize the presence of atherosclerotic plaque in order to characterize the structure and extent of coronary plaque and to quantify lumen dimensions, as well as the extent of lumen narrowing, in unprecedented detail. Based on optical properties, OCT is able to distinguish different tissue types, such as fibrous, lipid-rich, necrotic, or calcified tissue. Furthermore, OCT is able to cover the visualization of a variety of features of atherosclerotic plaques that have been associated with rapid lesion progression and clinical events, such as thin cap fibroatheroma, fibrous cap thickness, dense macrophage infiltration, and thrombus formation. These unique features allow the use of OCT to assess patients with acute coronary syndrome and to study the dynamic nature of coronary atherosclerosis in vivo and over time. This permits new insights into plaque progression, regression, and rupture, as well as the study of effects of therapies aimed at modulating these developments.Today's OCT technology allows high detail resolution as well as fast and safe clinical image acquisition. These unique features have established OCT as the gold standard for the assessment of coronary stents. This technique makes it possible to study stent expansion, peri-procedural vessel trauma, and the interaction of the stent with the vessel wall down to the level of individual stent struts, both acutely as well as in the long term, where it is has proven extremely sensitive to the detection of even minor amounts of tissue coverage. These qualities render OCT indispensable to addressing vexing clinical questions such as the relationship of drug-eluting stent deployment, vascular healing, the true time course of endothelial stent coverage, and late stent thrombosis. This may also better guide the optimal duration of dual anti-platelet therapy that currently remains unclear and relatively empirical.In the future, OCT might emerge, parallel to its undisputed position in research, as the tool of choice in all clinical scenarios where angiography is limited by its nature as a two-dimensional luminogram.

Late thrombotic occlusion of a malapposed stent 10 months after intracoronary brachytherapy

We report a patient who received a stent following intracoronary 3-irradiation. Despite a good initial angiographic result, the stent appeared to be not fully expanded on intravascular ultrasound imaging at 6-month follow-up. Four months later, sudden thrombotic occlusion occurred shortly after aspirin cessation.

Three-dimensional echocardiography paves the way toward virtual reality

The heart is a three-dimensional (3-D) object and, with the help of 3-D echocardiography (3-DE), it can be shown in a realistic fashion. This capability decreases variability in the interpretation of complex pathology among investigators. Therefore, it is likely that the method will become the standard echocardiography examination in the future. The availability of volumetric data sets allows retrieval of an infinite number of cardiac cross-sections. This results in more accurate and reproducible measurements of valve areas, cardiac mass and cavity volumes by obviating geometric assumptions. Typical 3-DE parameters, such as ejection fraction, flow jets, myocardial perfusion and LV wall curvature, may become important diagnostic parameters based on 3-DE. However, the freedom of an infinite number of cross-sections of the heart can result in an often-encountered problem of being "lost in space" when an observer works on a 3-DE image data set. Virtual reality computing techniques in the form of a virtual heart model can be useful by providing spatial "cardiac" information. With the recent introduction of relatively low cost portable echo devices, it is envisaged that use of diagnostic ultrasound (US) will be further boosted. This, in turn, will require further teaching facilities. Coupling of a cardiac model with true 3-D echo data in a virtual reality setting may be the answer.

Quantitative measurements of in-stent restenosis: A comparison between quantitative coronary ultrasound and quantitative coronary angiography

While quantitative coronary angiography (QCA) remains the standard used to assess new interventional therapies, intracoronary ultrasound (ICUS) is gaining interest. The aim of the study was to determine the relationship between QCA and quantitative coronary ultrasound (QCU) measurements after stenting. Sixty-two consecutive patients with both QCA and QCU analysis after stent implantation were included in the study. The mean luminal diameter (QCU vs. QCA) were 2.74 +/- 0.46 mm and 2.41 +/- 0.49 mm (P < 0.0001), the minimal luminal diameter (MLD) 2.08 +/- 0.44 mm and 1.62 +/- 0.42 mm (P < 0. 0001), and the projected QCU MLD 1.90 +/- 0.42 mm (P < 0.0001 with respect to QCA). Percentage obstruction diameter (QCU vs. QCA) were 41.53% +/- 10.78% and 43.15% +/- 12.72% (P = NS). The stent diameter (QCU vs. QCA) were 3.54 +/- 0.65 mm and 3.80 +/- 0.37 mm (P = 0. 0004). Stent length measured by QCU were longer at 31.11 +/- 13.54 mm against 28.63 +/- 12.75 mm, P < 0.0001 with respect to QCA. In conclusion, while QCA and QCU appear to be comparable tools for measuring corrected stent diameters and stent lengths, smaller luminal diameters were found using QCA. This is of particular relevance to quantitative studies addressing absolute changes in vascular or luminal diameters. Cathet. Cardiovasc. Intervent. 48:133-142, 1999.

Dynamic imaging of coronary stent structures: an ECG-gated three-dimensional intracoronary ultrasound study in humans

Three-dimensional (3D) intracoronary ultrasound (ICUS) systems allow dynamic 3D reconstruction of coronary segments after stent deployment, but motion artifacts are frequently present. The use of an electrocardiographic-gated ICUS image acquisition workstation and a dedicated pullback device may overcome this problem. In the present study, we evaluated the potential of dynamic 3D reconstruction of intracoronary stents in 51 patients. Two different types of stent designs were investigated: (1) the Wallstent (mesh type; n = 36) and (2) the Cordis Coronary stent (coil type; n = 15). There was a tendency for imaging of the mesh stent type to be better than imaging of coil type stents (p = 0.06). Differences in the orientation of the stent struts (mesh:longitudinal; coil:transversal) most likely explain this difference. These in vivo observations were tested and confirmed in in vitro experiments. In conclusion, dynamic 3D ICUS reconstruction of the entire stent architecture in vivo was feasible for stents of mesh type, while stents of coil type were incompletely visualized.

ECG-gated versus nongated three-dimensional intracoronary ultrasound analysis: implications for volumetric measurements

The quantitative analysis of a three-dimensional (3-D) intracoronary ultrasound (ICUS) image data set permits a more comprehensive assessment of coronary arterial segments. The 3-D image sets are generally acquired during continuous motorized pullbacks. However, the cyclic changes of vascular dimensions and the cyclic spatial displacement of the ICUS transducer relative to the vessel wall can result in characteristic image artifacts, which may limit the applicability of quantitative automated analysis systems. This limitation may be overcome by an ECG-gated image acquisition. In the present study we acquired in vivo (1) nongated and (2) ECG-gated 3-D ICUS image sets of 15 human atherosclerotic coronary arteries and performed a computer-assisted contour detection of the lumen and total vessel boundaries. Total vessel and lumen volumes measured significantly larger in the nongated versus ECG-gated end-diastolic image sets (753+/-307 mm3 vs. 705+/-305 mm3; 411+/-154 mm3 vs. 388+/-165 mm3, both: P < 0.05). Both end-diastolic and systolic measurements were available in nine arteries, showing a larger total vessel and lumen volume at systole (664+/-221 mm3 vs. 686+/-227 mm3, P=0.03; 384+/-164 mm3 vs. 393+/-170 mm3, P=0.08). The differences observed may be of particular interest for volumetric ICUS studies, addressing presumably small differences in vessel or lumen dimensions.

ECG-gated three-dimensional intravascular ultrasound: feasibility and reproducibility of the automated analysis of coronary lumen and atherosclerotic plaque dimensions in humans

BACKGROUND

Automated systems for the quantitative analysis of three-dimensional (3D) sets of intravascular ultrasound (IVUS) images have been developed to reduce the time required to perform volumetric analyses; however, 3D image reconstruction by these nongated systems is frequently hampered by cyclic artifacts.

METHODS AND RESULTS

We used an ECG-gated 3D IVUS image acquisition workstation and a dedicated pullback device in atherosclerotic coronary segments of 30 patients to evaluate (1) the feasibility of this approach of image acquisition, (2) the reproducibility of an automated contour detection algorithm in measuring lumen, external elastic membrane, and plaque+media cross-sectional areas (CSAs) and volumes and the cross-sectional and volumetric plaque+media burden, and (3) the agreement between the automated area measurements and the results of manual tracing. The gated image acquisition took 3.9+/-1.5 minutes. The length of the segments analyzed was 9.6 to 40.0 mm, with 2.3+/-1.5 side branches per segment. The minimum lumen CSA measured 6.4+/-1.7 mm2, and the maximum and average CSA plaque+media burden measured 60.5+/-10.2% and 46.5+/-9.9%, respectively. The automated contour-detection required 34.3+/-7.3 minutes per segment. The differences between these measurements and manual tracing did not exceed 1.6% (SD<6.8%). Intraobserver and interobserver differences in area measurements (n=3421; r=.97 to.99) were <1.6% (SD<7.2%); intraobserver and interobserver differences in volumetric measurements (n=30; r=.99) were <0.4% (SD<3.2%).

CONCLUSIONS

ECG-gated acquisition of 3D IVUS image sets is feasible and permits the application of automated contour detection to provide reproducible measurements of the lumen and atherosclerotic plaque CSA and volume in a relatively short analysis time.

Electrocardiogram-gated intravascular ultrasound image acquisition after coronary stent deployment facilitates on-line three-dimensional reconstruction and automated lumen quantification

OBJECTIVE

This study evaluates the feasibility, reliability and reproducibility of electrocardiogram (ECG)-gated intravascular ultrasound (IVUS) image acquisition during automated transducer withdrawal and automated three-dimensional (3D) boundary detection for assessing on-line the result of coronary stenting.

BACKGROUND

Systolic-diastolic image artifacts frequently limit the clinical applicability of such automated analysis systems.

METHODS

In 30 patients, after successful angiography-guided implantation of 34 stents in 30 target lesions, we carried out IVUS examinations on-line with the use of ECG-gated automated 3D analyses and conventional manual analyses of two-dimensional images from continuous pullbacks. These on-line measurements were compared with off-line 3D reanalyses. The adequacy of stent deployment was determined by using ultrasound criteria for stent apposition, symmetry and expansion.

RESULTS

Gated image acquisition was successfully performed in all patients to allow on-line 3D analysis within 8.7 +/- 0.6 min (mean +/- SD). Measurements by on-line and off-line 3D analyses correlated closely (r > or = 0.95), and the minimal stent lumen differed only minimally (8.6 +/- 2.8 mm2 vs. 8.5 +/- 2.8 mm2, p = NS). The conventional analysis significantly overestimated the minimal stent lumen (9.0 +/- 2.7 mm2, p < 0.005) in comparison with results of both 3D analyses. Fourteen stents (41%) failed to meet the criteria by both 3D analyses, all of these not reaching optimal expansion, but only 7 (21%) were detected by conventional analysis (p < 0.02). Intraobserver and interobserver comparison of stent lumen measurements by the automated approach revealed minimal differences (0.0 +/- 0.2 mm2 and 0.0 +/- 0.3 mm2) and excellent correlations (r = 0.99 and 0.98, respectively).

CONCLUSIONS

ECG-gated image acquisition after coronary stent deployment is feasible, permits on-line automated 3D reconstruction and analysis and provides reliable and reproducible measurements; these factors facilitate detection of the minimal lumen site.

Simpson's rule for the volumetric ultrasound assessment of atherosclerotic coronary arteries: a study with ECG-gated three-dimensional intravascular ultrasound

BACKGROUND

Volumetric intravascular ultrasound (IVUS) assessment provides complementary information on atherosclerotic plaques. The volumes can be calculated by applying Simpson's rule to cross-sectional area data of multiple IVUS images, acquired with a fixed sample spacing, which is the distance (along the vessel's axis) between two images.

OBJECTIVE

To evaluate the effect of different sample spacings on the results of volumetric IVUS measurements.

METHODS

A stepwise electrocardiographically gated IVUS image-acquisition and automated three-dimensional analysis approach was applied to 26 patients. Twenty-eight coronary segments with mild-to-moderate coronary atherosclerosis were examined. Volumetric measurements of five images per mm (i.e. sample spacing 0.2 mm), representing a complete scanning of the coronary segment, were considered the optimal standard, against which volumetric measurements of three, one, and one-half images per mm (i.e. larger sample spacings) were compared.

RESULTS

The lumen, total vessel, and plaque volumes obtained with five images per mm were 183.3 +/- 2.8, 350.6 +/- 141.6, and 167.3 +/- 89.2 mm3. There was an excellent correlation (r = 0.99, P < 0.001) between these data and volumetric measurements with larger sample spacings. The volumetric measurements with larger sample spacings differed on average only by a little (< 0.7%) from the optimal standard measurements. However, a relatively small, but significant, increase in SD of these differences was associated with the wider sample spacings (< 3.6%, P < 0.05).

CONCLUSIONS

The width of the sample spacing has a relatively small but significant impact on the variability of volumetric intravascular ultrasound measurements. This should be considered when designing future volumetric studies. The electrocardiographically gated acquisition of five IVUS images per mm axial length during a stepwise transducer pull-back is an ideal approach, particularly when addressing with IVUS volumetric changes that are assumed small, such as those expected in studies of the progression and regression of atherosclerosis.

Is quantitative angiography sufficient to guide stent implantation? A comparison with three-dimensional reconstruction of intracoronary ultrasound images

Intracoronary ultrasound (ICUS) frequently reveals stent underexpansion despite a satisfactory angiographic result by visual assessment. Whether on-line quantitative coronary angiography (QCA) alone can guide optimal stent deployment is still unknown. The aim of the study was to assess the usefulness of quantitative coronary angiography in the evaluation of optimal stent expansion, confirmed with a new on-line system of 3-D reconstruction of ICUS. The results obtained with 3-D ICUS were compared with the measurements achieved with QCA analyses in 49 patients (70 stents: 31 Palmaz-Schatz, 22 Wallstent, 7 Cordis, 6 Micro-stent, 2 Gianturco-Roubin, 2 Multi-Link). Following delivery of the stent, high pressure intrastent balloon inflation (14.2 +/- 3.3 atmospheres) was performed in all 70 stents. Optimal stent implantation by QCA was defined as minimal lumen diameter post-stenting > or = 90% of the reference diameter preintervention. Percent diameter stenosis (% DS) post-stenting was defined as minimal lumen diameter divided by the reference diameter post-stenting. The on-line 3-D ICUS reconstructions and measurements were performed processing the images on-line in the catheterization laboratory with an automated contour detection algorithm based on acoustic quantification. ICUS criteria for optimal stent expansion were defined as: 1) complete apposition of stent struts to vessel wall; 2) minimal stent lumen cross-sectional area > or = 80% of the average lumen area of the proximal and distal reference segments; 3) symmetry index (minimum divided by maximum lumen diameter) > 0.7. Ninety-seven percent of the deployed stents met the QCA criteria. Whilst 3-D ICUS documented complete stent apposition to the vessel wall in all cases and a symmetric expansion in 65 of 70 lesions (93%), the stent minimal lumen area was > or = 80% only in 30 out of 70 stents (43%). The diagnostic sensitivity and specificity at 10% residual diameter stenosis provided by QCA for optimal stent expansion compared to 3-D ICUS criteria were 86 and 45%, respectively. In conclusion 3-D ICUS criteria of adequate stent expansion were achieved only in 43% of patients despite the application of aggressive strategies of stent deployment leading to optimal results with quantitative angiography. Ten percent residual diameter stenosis provided by QCA may be an acceptable alternative for optimal stent deployment in clinical practice. The clinical benefit of an ICUS guided approach of stent deployment and of a lower cost strategy using on-line QCA guidance should be compared in large prospective randomized studies.

On-line three-dimensional intracoronary ultrasound for guidance of catheter based interventions

Intracoronary ultrasound (ICUS) provides valuable information on the distribution and composition of atherosclerotic plaque. For this reason its use for guidance of interventional procedures has been advocated. Recently, on-line systems of three-dimensional reconstruction have been introduced and offer great potential for guidance of interventional procedures since valuable details on longitudinal architecture of the plaque under treatment are obtained. In this article we review the current clinical application of three-dimensional (3-D) ICUS and report our experience with the use of an on-line 3-D ICUS system for guidance of interventional procedures. In our experience 3-D reconstruction of ICUS proved to be a feasible method facilitating device selection and guidance of catheter based interventions.

Three-dimensional intracoronary ultrasound imaging. Methodology and clinical relevance for the assessment of coronary arteries and bypass grafts

Three-dimensional (3-D) reconstruction of intracoronary ultrasound (ICUS) images has an increasing application as the applicability of systems of on-line analysis provides a superior guidance by coupling the advantages of a high-resolution cross-sectional imaging with an overview of stenosis and reference segments. Detection of the external contour of the vessel which is a prerequisite for measurements of coronary plaques is currently not provided by the algorithms for automated on-line analysis. Thus, off-line reconstruction is required for studies aiming at the assessment of progression/regression of atherosclerosis and of mechanisms of interventions or restenosis. Various 3-D reconstruction methods with specific advantages and limitations are able to meet the different requirements concerning applicability, quality of visualization, and accuracy of quantification. The use of 3-D ICUS in the assessment of cardiac transplant recipients permits a more reliable and accurate quantification of intimal hyperplasia as seen in cardiac allograft arteriopathy. In patients undergoing bypass surgery it may influence the therapeutic decision, since it allows to determine the longitudinal extent of calcification and frequently discovers atherosclerosis in angiographically normal segments. Vessel stenoses both of native coronary arteries and bypass grafts can be studied by 3-D ICUS and additional information can be obtained during catheter based interventions. Despite some remaining technical limitation 3-D reconstruction of ICUS images has the potential of becoming a practical tool to simplify the interpretation and quantification of ICUS images.

Three-dimensional reconstruction of coronary arteries with intravascular ultrasound

Three-dimensional (3D-) reconstruction of intravascular ultrasound (IVUS) images is a recently introduced technical method which has rapidly grown in science and clinical practice. In the catheterization laboratory it is particularly important to obtain the 3D-reconstruction on-line, since the dimensions measured and the plaque attributes displayed may guide the therapeutic decision. Off-line reconstruction, however, provides very accurate and reproducible area and volume measurements of lumen and plaque and is thus exceptionally qualified for studying progression/regression of atherosclerosis or restenosis after catheter-based interventions. Complementary 3D-reconstruction methods, revealing specific advantages and limitations, meet the requirements by slightly different technical approaches, but each 3D-reconstruction of two-dimensional IVUS images requires some basic procedural steps. The IVUS images can be acquired during continuous or ECG-gated withdrawals of the IVUS imaging catheter. The latter permits even to visualize the cyclic pulsation of the reconstructed arteries. As an alternative approach a sensing device recognizes the insertion depth of the IVUS catheter and permits reliable measurements even during manual handling of the IVUS catheter. A discrimination between the blood-pool and structures of the vascular wall, performed in the digitized images, can be achieved by the application of different techniques. This processing step which is called segmentation and the image acquisition are particularly crucial with regards to the final quality of the 3D-reconstruction. Currently there are still limitations of 3D-IVUS, but a new approach combining data obtained from 3D-IVUS and biplane angiography offers a promising potential to solve most of the remaining problems in the future. Thus, three-dimensional IVUS offers a great clinical and scientific potential since it provides spatial visualization of vascular pathology, longitudinal and volumetric measurement of luminal and plaque dimensions, and facilitated guidance of catheter-based interventions. Assuming a technical development similar to the progress of the previous years. 3D-IVUS has a realistic chance to gain significant importance and to become a routine technique in the future.

Three dimensional reconstruction of cross sectional intracoronary ultrasound: clinical or research tool?

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