[The PhD program "Multimorbidity in Old Age and Selected Care Problems" Center for Human and Health Sciences of the Charité-Universitätsmedizin Berlin]

The PhD Program concerns the care of multimorbid geriatric patients. It takes a multidisciplinary approach in combining different perspectives on delivering care to the elderly. Students have completed courses of studies such as nursing, social education, sociology, psychology, or public health. Likewise, doctoral projects are overseen by members of various disciplines including medicine. These disciplines are represented in the Center for Human and Health Sciences of the Charité-Universitätsmedizin Berlin, where the PhD Program is located. The doctoral projects are grouped into three main topics--Care Problems and Interventions, Quality of Life and Self-Determination, and Care Structures and Quality.

[Requirements of a future-oriented social medicine]

With the new national licensing regulations for physicians subsections of the social medicine became discrete subjects. The question arises, which contents the social medicine can have in the future, with consideration of important basic conditions. Such are the progress of medical knowledge, the representation of social medicine at medical faculties, changes of the medical supply, the transformation of jobs and the globalization. On a long-term basis effects of the demographic development, changes of the family structure and the financing of health and illness are important too. The social medicine should promptly make quality-assured contents available with consideration of the Internet. Such contents could be the comprehensive consultation, investigation and control of patient careers as well as the consultation and investigation from health problems in municipalities and in the society. In addition an inductive and practical oriented curriculum should be compiled, using the subject catalogue of the social medicine as well as a new basic textbook of social medicine.

Comparison of image compression viability for lossy and lossless JPEG and Wavelet data reduction in coronary angiography

BACKGROUND

Lossless or lossy compression of coronary angiogram data can reduce the enormous amounts of data generated by coronary angiographic imaging. The recent International Study of Angiographic Data Compression (ISAC) assessed the clinical viability of lossy Joint Photographic Expert Group (JPEG) compression but was unable to resolve two related questions: (A) the performance of lossless modes of compression in coronary angiography and (B) the performance of newer lossy wavelet algorithms. This present study seeks to supply some of this information.

METHODS

The performance of several lossless image compression methods was measured in the same set of images as used in the ISAC study. For the assessment of the relative image quality of lossy JPEG and wavelet compression, the observers ranked the perceived image quality of computer-generated coronary angiograms compressed with wavelet compression relative to the same images with JPEG compression. This ranking allowed the matching of compression ratios for wavelet compression with the clinically viable compression ratios for the JPEG method as obtained in the ISAC study.

RESULTS

The best lossless compression scheme (LOCO-I) offered a mean compression ratio (CR) of 3.80:1. The quality of images compressed with the lossy wavelet-based method at CR = 10:1 and 20:1 was comparable to JPEG compression at CR = 6:1 and 10:1, respectively.

CONCLUSION

The study has shown that lossless compression can exceed the CR of 2:1 usually quoted. For lossy compression, the range of clinically viable compression ratios can probably be extended by 50 to 100% when applying wavelet compression algorithms as compared to JPEG compression. These results can motivate a larger clinical study.

American College of Cardiology/European Society of Cardiology International Study of Angiographic Data Compression Phase III: measurement of image quality differences at varying levels of data compression

OBJECTIVES

We sought to investigate up to which level of Joint Photographic Experts Group JPEG) data compression the perceived image quality and the detection of diagnostic features remain equivalent to the quality and detectability found in uncompressed coronary angiograms.

BACKGROUND

Digital coronary angiograms represent an enormous amount of data and therefore require costly computerized communication and archiving systems. Earlier studies on the viability of medical image compression were not fully conclusive.

METHODS

Twenty-one raters evaluated sets of 91 cine runs. Uncompressed and compressed versions of the images were presented side by side on one monitor, and image quality differences were assessed on a scale featuring six scores. In addition, the raters had to detect pre-defined clinical features. Compression ratios (CR) were 6:1, 10:1 and 16:1. Statistical evaluation was based on descriptive statistics and on the equivalence t-test.

RESULTS

At the lowest CR (CR 6:1), there was already a small (15%) increase in assigning the aesthetic quality score indicating "quality difference is barely discernible-the images are equivalent." At CR 10:1 and CR 16:1, close to 10% and 55%, respectively, of the compressed images were rated to be "clearly degraded, but still adequate for clinical use" or worse. Concerning diagnostic features, at CR 10:1 and CR 16:1 the error rate was 9.6% and 13.1%, respectively, compared with 9% for the baseline error rate in uncompressed images.

CONCLUSIONS

Compression at CR 6:1 provides equivalence with the original cine runs. If CR 16:1 were used, one would have to tolerate a significant increase in the diagnostic error rate over the baseline error rate. At CR 10:1, intermediate results were obtained.

American College of Cardiology/ European Society of Cardiology international study of angiographic data compression phase III. Measurement Of image quality differences at varying levels of data compression

OBJECTIVES

We sought to investigate up to which level of Joint Photographic Experts Group (JPEG) data compression the perceived image quality and the detection of diagnostic features remain equivalent to the quality and detectability found in uncompressed coronary angiograms.

BACKGROUND

Digital coronary angiograms represent an enormous amount of data and therefore require costly computerized communication and archiving systems. Earlier studies on the viability of medical image compression were not fully conclusive.

METHODS

Twenty-one raters evaluated sets of 91 cine runs. Uncompressed and compressed versions of the images were presented side by side on one monitor, and image quality differences were assessed on a scale featuring six scores. In addition, the raters had to detect pre-defined clinical features. Compression ratios (CR) were 6:1, 10:1 and 16:1. Statistical evaluation was based on descriptive statistics and on the equivalence t -test. Results At the lowest CR (CR 6:1), there was already a small (15%) increase in assigning the aesthetic quality score indicating "quality difference is barely discernible-the images are equivalent.' At CR 10:1 and CR 16:1, close to 10% and 55%, respectively, of the compressed images were rated to be "clearly degraded, but still adequate for clinical use' or worse. Concerning diagnostic features, at CR 10:1 and CR 16:1 the error rate was 9.6% and 13.1%, respectively, compared with 9% for the baseline error rate in uncompressed images.

CONCLUSIONS

Compression at CR 6:1 provides equivalence with the original cine runs. If CR 16:1 were used, one would have to tolerate a significant increase in the diagnostic error rate over the baseline error rate. At CR 10:1, intermediate results were obtained.

[A standardized documentation structure for data documentation in echocardiography. Work Team on Standards and LV Function of the Work Group on Cardiovascular Ultrasound of the German Society of Cardiology, Heart and Circulation Research]

Presently, there are no well-defined standards for documentation of echocardiographic studies. Nevertheless, standards are essential to provide comparability of data and to realize electronic communication, both essential for quality management in echocardiography. Therefore, the working group "Standards and LV function" of the German Society of Cardiology developed a consensus for documentation of echocardiographic studies. In the present paper this consensus is presented and illustrated by typical clinical examples. Additionally, a prototype of a user-oriented software based on this data set is presented. The complete data set for transesophageal and transthoracic echocardiography and the software prototype can be downloaded at http:@echo.ma.uni-heidelberg.de.

Ten-year outcome after coronary angioplasty in patients with single-vessel coronary artery disease and comparison with the results of the Coronary Artery Surgery Study (CASS)

The 10-year results of randomized trials comparing percutaneous transluminal coronary angioplasty (PTCA) in patients with single-vessel coronary artery disease (CAD) with coronary artery bypass grafting (CABG) and medical treatment are not available yet. The aim of this evaluation was to compare our 10-year follow-up results after PTCA in patients with single-vessel CAD with the 10-year follow-up results after CABG and medical treatment in the Coronary Artery Surgery Study (CASS) trial. We evaluated the clinical outcome of 509 patients with single-vessel CAD 10 years after coronary angioplasty. The data were compared with the results of 214 patients with single-vessel CAD after CABG or medical treatment from the CASS trial. End points were defined as death and myocardial infarction. Statistical evaluation was performed by life-table analysis and 2-sided Fisher's exact test. The rate of survival was 86% 10 years after PTCA compared with 85% after CABG and 82% after medical treatment in patients from the CASS trial (p = NS). Survival free from myocardial infarction was 77% after coronary angioplasty, 70% after CABG, and 72% after medical treatment (p = NS). Thus, in patients with single-vessel CAD, infarct-free survival 10 years after coronary angioplasty compared favorably with the results after bypass surgery or medical treatment from the CASS trial.

Predictors of adverse outcome 10 years after coronary angioplasty

To determine which factors before percutaneous transluminal coronary angioplasty (PTCA) predict long-term outcome, we evaluated the clinical follow-up data from 535 patients 10 years after single-vessel PTCA. Events were defined as death, myocardial infarction, bypass surgery or repeat PTCA. During the follow-up period 79 patients (15%) died, 59 patients (11%) suffered a myocardial infarction, 107 patients (20%) had coronary artery bypass surgery and 141 patients (26%) underwent a redilatation. To determine the predictors of 10-year follow-up, 12 patient-related and 9 lesion parameters were analyzed by logistic regression analysis. Mortality was independently increased in patients with diabetes, with multi-vessel disease, after a previous myocardial infarction and in smokers. The presence of multi-vessel disease, symptoms of a higher angina class and younger age increased the risk for undergoing bypass surgery. In the statistical model with lesion parameters, the risk of bypass surgery was decreased if the stenosis was located in the distal segment of the coronary vessel and by a higher minimal luminal diameter before PTCA.

CONCLUSION

Logistic regression analysis identified multi-vessel disease, diabetes, smoking and a previous myocardial infarction as independent clinical predictors of an adverse outcome 10 years after coronary angioplasty. Lesion parameters before PTCA seem to be less important with regard to the long-term outcome after PTCA.

[Berlin-Brandenburg-Saxony Rehabilitation Research Group]

The principal subject of the Rehabilitation Research Network of Berlin, Brandenburg and Saxony (BBS) is "the theoretical and practical bases of the organisation and economics of rehabilitation". What is involved is a nation-wide analysis of the rehabilitation system, i.e. obtaining empirical information on the question as to what organisational forms are currently used to carry out rehabilitation and what results are achieved. This empirical stocktaking also includes economic aspects as far as possible. This study is to serve as a basis for developing, testing and implementing steps to rationalise steering mechanisms in the rehabilitation system. The first aspect to be studied is "national steering problems in institutionalised forms of rehabilitation". The focus is on projects on information management and performance and quality management in rehabilitation sciences as well as on the actual work of a number of bodies paying for rehabilitation (Bundesversicherungsanstalt für Angestellte, Landesversicherungsanstalten) as well as rehabilitation facilities (clinics etc.). The two other focuses of the study will examine "rehabilitative adjustment to remedies and technical aids/prostheses" and problems facing "family members in the context of rehabilitation". In studying these two areas, we are particularly interested in examining the interaction between institutionalised aspect of rehabilitation and informal factors both inside and outside the system. The BBS approach is supported by close co-operation with the regional pension insurance institutes (BfA, LVAs) with regard to both the data model and steps being taken. The principal instrument of co-operation is the "Gesellschaft für Rehabilitationswissenschaften e.V." (Society for Rehabilitation Sciences). In Berlin the BBS co-operates with Free University, the Technical University and the Robert Koch Institute and in Saxony with the universities in Dresden and Leipzig. Responsibility for scientific questions in the BBS lies with the Institute for Rehabilitation Sciences of Berlin's Humboldt University.

Impact of routine angiographic follow-up after angioplasty

BACKGROUND

There is an ongoing controversy as to whether repeat coronary angiography should be routinely performed after successful percutaneous transluminal coronary angioplasty (PTCA).

METHODS

We examined the 10-year outcome in 400 patients who had or had not undergone an angiographic control 6 months after successful PTCA and a subsequent event-free 6-month period. Our comparison was based on data gathered by questionnaire and telephone interview in 315 patients with (group A) and 85 patients without (group B) a routine 6-month angiographic control. Multivariate analysis (Cox model) was performed to identify predictors of adverse events.

RESULTS

During the 10-year follow-up period, 22 (7%) of the 315 patients in group A died, compared with 16 (19%) patients in group B (P= .003). In groups A and B, respectively, acute myocardial infarction occurred in 28 (9%) and 10 (12%) patients (not significant [NS]); coronary artery bypass grafting (CABG) was performed in 42 (13%) and 14 (16%) patients (NS); repeat PTCA was performed in 89 (28%) and 11 (13%) patients (P= .012); and serious adverse events (death, myocardial infarction, CABG) occurred in 76 (24%) and 32 (38%) patients (P= .02). Absence of a 6-month angiographic follow-up was identified as an independent predictor of death associated with a 2.7 times higher mortality rate during the 10-year follow-up period. Previous myocardial infarction increased the risk of death 2.5 times. Any increase of residual diameter stenosis by 10% was combined with a 1.4 times higher mortality rate. The chance of bypass surgery was higher in patients with multivessel disease (2.9 times), in patients with unstable angina (2.1 times), and in case of an increase of residual diameter stenosis by 10% (1.3 times). No predictor for the risk of myocardial infarction was found. Angiographic follow-up increased the likelihood of PTCA 2.5 times.

CONCLUSIONS

A routinely performed angiographic control 6 months after successful PTCA is associated with a significantly higher rate of repeat PTCA but, most important, is correlated with a significantly lower mortality rate during the 10-year follow-up period.

Impact of restenosis 10 years after coronary angioplasty

AIMS

The aim of the study was to compare the 10-year follow-up results of patients with or without restenosis following single-vessel percutaneous transluminal coronary angioplasty (PTCA).

METHODS AND RESULTS

A total of 313 patients with successful PTCA (> or = 20% reduction in luminal diameter narrowing without acute complications) and a control angiography 6 months after PTCA were included in the study. Events during the follow-up period were defined as death, myocardial infarction, bypass surgery, or repeat PTCA. Statistical evaluation was performed by the Fisher test, logistic regression, and life-table analysis. Restenosis (loss of > 50% of the initial gain and diameter stenosis of 50%) was found in 87 (28%) patients. During follow-up, 11 patients (5%) without restenosis (group A) and 11 (13%) patients with restenosis (group B) died (P < 0.05). In group A, 17 (8%) patients and in group B, 11 (13%) patients suffered myocardial infarction (ns); 17 group A (8%) patients and 25 (29%) group B patients had bypass surgery (P < 0.0001), and 34 (15%) group A patients and 55 (63%) group B patients underwent repeat PTCA (P < 0.0001). Logistic regression analysis identified restenosis as an independent risk factor that increases the risk of death 2.8-fold (P = 0.02), bypass surgery 5.6-fold (P < 0.0001), and repeat PTCA 10-fold (P < 0.0001).

CONCLUSION

We conclude that patients with restenosis had a poorer long-term outcome than patients without restenosis. Although most patients with restenosis underwent repeat PTCA, the survival rate without any serious adverse events was only 59%, compared with 83% in patients without restenosis (P < 0.0001).

In vitro examination of the coronary artery wall after balloon angioplasty using intracoronary ultrasound

After autopsy 12 human coronary arteries were investigated by intracoronary ultrasound in order to measure the vessel wall dimensions and to detect damage on the vessel wall architecture after balloon angioplasty. Histology revealed artherosclerosis in 11/12 arteries. A total of 41 representative coronary segments were selected for further off-line ultrasound and histological analysis. Intracoronary ultrasound and histological measurements of the vessel wall thickness after balloon dilatation demonstrated a good correlation between the maximum thickness of the intima (histology 0.62 mm vs. intracoronary ultrasound 0.65 mm, r = 0.87) and the intima-media complex (0.80 mm vs. 0.83 mm, r = 0.87), in contrast to a weak one between the minimum thickness (r = 0.46 and r = 0.37). A total of 21 cases of damage occurred during angioplasty; intracoronary ultrasound detected 17. Further analysis showed that it imaged 10 of 11 cases of damage involving more than 30 degrees of the vessel circumference and 7 of 10 cases of damage involving less than 30 degrees of the vessel circumference. After balloon angioplasty of diseased coronary arteries, intracoronary ultrasound is therefore reliable in measuring the maximum wall thickness and in imaging damage involving more than 30 degrees of the vessel wall circumference.

Angiocardiographic digital still images compressed via irreversible methods: concepts and experiments

We defined, implemented and tested two new methods for irreversible compression of angiocardiographic still images: brightness error limitation (BEL) and pseudo-gradient adaptive brightness and contrast error limitation (PABCEL). The scan path used to compress the digital images is based on the Peano-Hilbert plane-filling curve. The compression methods limit, for each pixel, the brightness errors introduced when approximating the original image (i.e. the difference between the values of corresponding pixels as grey levels). Additional limitations are imposed to the contrast error observed when considering along the scan path consecutive pixels of both the original and the reconstructed image. After previous testing on angiocardiographic images selected as clinically significant from 35 mm films, we enlarged our experiment to a set of 38 coronary angiograms digitally acquired. BEL and PABCEL methods were experimented according to several values of the implied thresholds. Up to a compression ratio of 9:1 for the BEL method and 10:1 for the PABCEL method, no deterioration of the reconstructed images were detected by human observers. After a visual evaluation, we performed a quantitative evaluation. The visualization of pseudo-colour difference images showed the capability of BEL and PABCEL for preserving the most significant clinical details of the original images. For comparison, we applied the JPEG (joint photographic experts group) image-compression standard to the same set of images. In this case, pseudo-colour difference images showed a homogeneous distribution of errors on the image surface. Quantitative compression results obtained by testing the different methods are comparable, but, unlike JPEG, BEL and PABCEL methods allow the user to keep under his direct control the maximum error allowed at each single pixel of the original image. These different behaviors are confirmed by the values obtained for the considered numerical quality quantifiers.

Comparison of QCA systems

AIMS

Excellent agreement between different 'second generation' systems for quantitative coronary arteriography (QCA) has been found in in vitro measurements. To verify the quality and stability of QCA when used in clinical practice, three QCA systems (AWOS, Cardio, and CMS) were used in a representative set of coronary artery lesions.

METHODS AND RESULTS

This set consisted of angiographic stenosis images of 57 patients which varied in stenosis severity and morphology. The process of image acquisition, calibration, and measurement was strictly standardized to eliminate procedural sources of error. Three observers performed QCA five times in each lesion with each QCA system. Interobserver variability was low (Dnorm 0.01-0.05 mm, Dmin 0.01-0.02 mm, %stenosis 0.3-0.7%). Values of system precision were excellent (Dnorm 0.11-0.13 mm, Dmin 0.04-0.06 mm, %stenosis 2.1-2.6%). Comparison of measurements between three QCA systems revealed good agreement (range of mean differences for Dnorm 0.03-0.12 mm, Dmin 0.04-0.11 mm, and %stenosis 0.5-3.6%) and high correlation (corr 0.902-0.977). There was a tendency to measure smaller values for Dmin and consequently to identify more severe stenoses with the AWOS system than with the Cardio and CMS systems. All QCA results were compared to measurements done with the Brown Dodge method to reveal failure of the QCA measurements. These results showed excellent agreement without any systematic deviation (mean differences for Dnorm 0.01-0.08 mm, Dmin 0.02-0.06 mm, and %stenosis 1.3-1.8%). None of the differences were statistically significant.

CONCLUSION

We therefore conclude that using the defined version of the AWOS, Cardio, and CMS systems, there is no difference in precision or accuracy when used for QCA of coronary artery lesions.

[Effect of qualitative stenosis characteristics on the quality of measurements of various QCA systems]

Reproducibility and accuracy of in vitro measurements are very high using recently developed QCA systems. We analyzed the impact of lesion characteristics ad the image quality on the quality of measurements under clinical conditions. For the study we selected 57 coronary artery lesions which had a clinically relevant distribution for stenosis severity, lesion characteristics, and image quality. Every effort was made to eliminate procedural sources of error. Three investigators measured each lesion five times with each of three QCA systems (AWOS, Cardio and CMS). Only the measurements of the minimal stenosis diameter were analyzed. The precision of all the measurements was high with the AWOS (0.04 mm), the Cardio (0.05 mm), and the CMS systems (0.06 mm). Variability of measurements increased for the following criteria: Ambrose-III morphology (CMS 0.082 mm), surface irregularities (Cardio 0.069 mm, CMS 0.073 mm), TIMI I (Cardio 0.084 mm, CMS 0.0121 mm), and moderate image quality (CMS 0.07 mm). There were no differences in the precision of the measurements in the other groups of lesion characteristics. There were no relevant differences in any of the measurements between the systems (AWOS-Cardio -0.07 mm, AWOS-CMS-0.11 mm, Cardio-CMS-0.04 mm). Smaller diameters were measured with the AWOS system than with the CMS and the Cardio systems when the lesion was calcified (AWOS-Cardio-0.109 mm, AWOS-CMS-0.161 mm). This was only a trend, however, and did not reach statistical significance, which was also true for the other differences found between the systems according to various lesion characteristics. In summary, we found that the measurement quality of the QCA systems used in this study is not altered by the underlying lesion characteristics or the image quality.

Importance of calibration for diameter and area determination by intravascular ultrasound

BACKGROUND

Intravascular ultrasound (IVUS) permits quantitative assessment of the lumen diameter and area of coronary arteries. The experimental study was performed to evaluate the accuracy of diameter and area measurements.

METHODS AND RESULTS

Lumen quantitation (lumen diameter D and cross-sectional area A) in lucite tubes (lumen diameter 2.5 to 5.7 mm, Plexiglas) was performed using a mechanical IVUS system (HP console, 3.5 F catheter, Boston Scientific, 30 MHz). The influence of fluid type (blood, water and saline solution), fluid temperature (20 degrees C/37 degrees C), catheter to catheter variation, gain setting and ultrasound frequency (12, 20 and 30 MHz) was determined. In blood at 20 degrees C there was a constant deviation of the measured diameter from the true luminal diameter of -0.29 +/- -0.04 mm (p < 0.06). In water and saline solution at 20 degrees C the mean deviation from true diameter was -0.21 +/- -0.06 mm (p < 0.06). At 37 degrees C, the deviation in blood was greater than at 20 degrees (-0.34 +/- -0.02 mm) which is > 10% in a 3 mm tube (p < 0.06). Three of the ten catheters tested in water at 20 degrees C underestimated true diameter by more than -0.3 mm. The deviation from true diameter (5 mm tube) with varying gain settings was -0.14 mm to -0.23 mm compared to -0.19 mm at standard settings (p > 0.288). At 12 MHz diameter measured was over-estimated. The error in absolute area estimation increased with increasing diameter tested in blood at 37 degrees C (-1.21 to -2.72 mm2), whereas the relative error ([Measured Area-True Area]/True Area x 100 [%]) was more striking at smaller diameters (up to -25% in the 2.5 mm tube).

CONCLUSION

Luminal diameters and areas are underestimated by this particular IVUS system. When IVUS imaging and measurements are made during coronary interventions this error should be taken into account with regard to appropriate sizing of the device and the assessment of the postprocedure result. Because systematic errors might also occur in other IVUS system (not tested in this study), it is advisable to ensure that each system is validated prior to clinical use, especially when exact measurements are required.

[Development of standards for quality management in interventional cardiology]

Standardization is one of the fundamental methods for quality management. Standards describe first requirements for adequate delivery of diagnostic and therapeutic services (e.g. in the format of guidelines and protocols), second they define core data sets for documentation of real clinical outcome and of process and structure quality or third they define normal values (standards in the strict sense) or thresholds for critical parameters. This standardization is increasingly performed by the professional societies in international collaboration. We report on the parallel development of methodology. Presently standards for documentation and guidelines are being developed for the areas of cardiac interventional and surgical therapy. Three main methods are described. First, the common approach to guideline definition becomes more formalized as exemplified by the consensus approaches of the RAND group and of physicians in The Netherlands. Second, the definition of core data sets for quality assurance is increasingly based on the statistical evaluation of large interventional databases with the goal of developing predictive models of outcome. Since some of these methods are not yet fully reliable, it is still necessary to combine the results of predictive modelling with consensus on clinical practice. Figure 1 describes one of these approaches to data standards definition. These methods are currently developed within the new Cardiovascular Data Standards Initiative of the American College of Cardiology (ACC) that is open for international collaboration. Figure 2 describes a parallel approach for standardization of digital image communication in angiocardiography. As shown in Figure 3, these data set standards and imaging standards will be applied not only in quality assurance, but also in shared care. Third, the PRESTIGE project of the European Commission is developing computerized tools that support terminology support, guideline authoring, guideline dissemination and protocol-directed care. We show that the elements described can be put to use within the unifying framework depicted in Figure 4. This guideline approach that is fully integrated into daily care delivery provides the physician with instant feedback from the guideline and, in addition, with periodic quality reports based on a comparison of the local clinical reality with the recommendations from the guideline. In our extended concept, these deviations are in addition symmetrically used to trigger, where necessary, the process of evaluation of the guideline. The often poor acceptance of guidelines should be improved both by integrating them into daily practice and by providing a feedback to the guideline authoring committee. We conclude that standardization activities are now entering into a new era due to increased involvement of physicians, international collaboration, integrated approaches to quality management, and improved computerized tools.

Intravascular ultrasound detected classification of coronary lesions as a predictor of dissections after balloon angioplasty

Dissection after balloon angioplasty of coronary arteries may give rise to an unfavourable early outcome. Compared with coronary angiography, intravascular ultrasound (IVUS) allows more detailed characterisation of dissections. We investigated the incidence and type of dissections after balloon angioplasty in calcified coronary lesions. IVUS was performed in 43 patients with 48 lesions before and after percutaneous balloon angioplasty. Significant calcification was defined as an arc of more than 90 degrees with typical acoustic shadowing. Dissections were classified as type A when the media was not involved by the dissection and as type B when media involvement had occurred. In the group with significant calcification dissection was observed in 79% of the cases vs 38% in the control group (p < 0.03). Type B dissection was present in 71% of the dissections in the calcified lesions vs. 15% in the control group (p < 0.02). The balloon diameter and the ratio of balloon area to vessel area was not different in both groups but the required pressure for the first complete balloon inflation was significantly greater in the group with calcified lesions (9.46 +/- 3.6 atm vs. 6.65 +/- 2.6 atm; p < 0.001). Thus balloon angioplasty in calcified coronary lesions is more likely to lead to dissection with frequency involve the media.

Comparison of myocardial perfusion reserve before and after coronary balloon predilatation and after stent implantation in patients with postangioplasty restenosis

BACKGROUND

Stents provide a scaffold for coronary arteries after angioplasty and inhibit elastic recoil.

METHODS AND RESULTS

In 25 patients with postangioplasty restenosis of the left anterior descending artery, ECG-gated digital subtraction coronary angiograms were recorded at baseline and during hyperemia (12 mg papaverine IC) before and after balloon predilatation (PTCA), after implantation of a Palmaz-Schatz stent, and after 6 months. Densitometric evaluation revealed different time and density parameters to calculate two definitions of myocardial perfusion reserve (MPR1 and MPR2) and maximum flow ratio (MaxFR). Poststenotic MPR1 increased from 1.57 +/- 0.14 to 2.59 +/- 0.86 after PTCA and to 3.10 +/- 0.41 after stenting, with 2.90 +/- 0.65 at follow-up (ANOVA, P < .05), while reference MPR1 remained unchanged at 3.10 +/- 0.40. Poststenotic MPR2 increased from 1.36 +/- 0.28 to 2.50 +/- 1.20 and to 3.40 +/- 0.58, respectively, with 3.20 +/- 0.92 at follow-up (ANOVA, P < .05), while reference MPR2 remained unchanged at 3.40 +/- 0.60. MaxFR was 2.13 +/- 0.53 after PTCA, elasticity 2.83 +/- 0.35 after stenting, and 2.73 +/- 0.58 at follow-up (ANOVA, P < .05). A good correlation was found between minimal stenotic luminal diameter and MPR1 or MPR2 (r = .87 and r = .94) and between luminal gain and MaxFR (r = .75). A negative correlation was measured between recoil and MPR1, MPR2, and MaxFR (r = -.80, r = -.86, and r = -.83). At follow-up, a steeper correlation was found between MPR and minimal stenosis diameter (MPR1: slope, 0.52 versus 0.91; MPR2: slope, 1.48 versus 1.95) and between MaxFR and net lumen gain (slope, 0.78 versus 1.27).

CONCLUSIONS

Coronary stent implantation in patients with postangioplasty restenosis normalized poststenotic myocardial perfusion immediately as a result of a larger postprocedural lumen and a more pronounced inhibition of elastic recoil. After 6 months this benefit was sustained despite progressive lumen loss.

[Long term course over 10 years after balloon dilatation in stable and unstable angina pectoris]

OBJECTIVE

To assess the cardiac status of patients ten years after percutaneous transluminal coronary artery angioplasty (PTCA).

PATIENTS AND METHODS

Data of 534 patients (436 men, 98 women; mean age 53.2 +/- 8 years) in whom a PTCA had been performed between 1983 and 1986 were analysed, based on a questionnaire answered 121 +/- 11 months after the initial procedure. At the time of PTCA 184 patients (35%) had unstable angina, 350 (65%) stable angina.

RESULTS

116 patients (63%) with unstable angina and 164 (47%) with stable angina had at least one cardiac event after the initial PTCA (repeat PTCA, bypass operation, myocardial infarction, death). None of these events occurred in 68 patients (37%) with unstable or in 186 (53%) with stable angina (P < 0.001). After 10 years 196 of the 302 surviving patients with stable angina (65%) and 104 of the 153 surviving patients with unstable angina (68%) were symptom-free.

CONCLUSIONS

Ten-year follow-up after PTCA has shown that cardiac events are significantly more frequent in patients who had had unstable angina than in those with stable angina. This difference already develops in the first year post-PTCA, with no increase later. Symptoms are lastingly improved after 10 years in both groups of patients.

[Normalization of myocardial perfusion reserve after coronary stent implantation in comparison with balloon angioplasty alone]

Stents scaffold coronary arteries after angioplastic treatment and inhibit elastic recoil resulting in a larger and more circular focal lumen. In 25 patients with significant stenoses of the left anterior descending coronary artery, presenting no collaterals or myocardial infarction, EKG-gated digital subtraction angiograms were recorded at baseline and during hyperemia induced by intracoronary injection of 12 mg papaverine before and after balloon angioplasty, and after adjunct implantation of a single Palmaz-Schatz stent. Densitometric evaluation revealed the time parameters contrast medium appearance time (MCAT) rise time (RT) and mean transit time (MTT) and maximum intensity (Imax). Myocardial perfusion reserve (MPR1) was calculated as the ratio of baseline MCAT and hyperemic MCAT multiplied by the ratio of hyperemic Imax and baseline Imax while MPR2 was calculated as the ratio of baseline RT and hyperemic RT. Maximum flow ratio (MaxFR) was calculated as the ratio of preprocedural hyperemic MTT and postprocedural hyperemic MTT. Post-stenotic MPR1 increased from 1.36 +/- 0.28 to 2.50 +/- 1.20 and to 3.40 +/- 0.58 (ANOVA p < 0.05), while reference MPR1 remained unchanged with 3.40 +/- 0.60. Post-stenotic MPR2 increased from 1.57 +/- 0.14 to 2.59 +/- 0.86 after balloon angioplasty and to 3.10 +/- 0.41 after stenting (ANOVA p < 0.05), while reference MPR2 remained unchanged with 3.10 +/- 0.40. MaxFR was 2.13 +/- 0.53 after balloon angioplasty and 2.83 +/- 0.35 after stenting (p < 0.05). A good correlation was found between minimal stenosis diameter and MPR1 or MPR2 (MPR1: r = 0.94; MPR2: r = 0.87) and between luminal gain and MaxFR (r = 0.75). A negative correlation was measured between recoil, defined as the difference between inflated balloon diameter and resulting minimal stenosis diameter, and MPR1 and MPR2 and MaxFR (MPR1: r = -0.86; MPR2 r = -0.80; MaxFR r = -0.83). In conclusion, adjunct coronary stent implantation normalized post-stenotic myocardial perfusion immediately in contrast to balloon angioplasty alone resulting from a larger postprocedural lumen and a more pronounced inhibition of elastic recoil.

Requirements for quality assessment in coronary angiograph and angioplasty

The application of formal methods of quality assessment in medicine is a relatively new activity. Interventional cardiology is expected to be one of the fields of clinical medicine adopting formal schemes of quality assessment at a relatively early phase because of its invasive nature, the associated risks, the rapid growth of this treatment and the correspondingly increasing total cost. We therefore aim to compile the requirements for the development of quality assessment schemes in angioplasty and coronary angiography. The rather disparate nature of methodologies applied in previous and present quality initiatives is reviewed, grouping the numerous methods of organizing quality initiatives found in the literature into a few generic schemes. This new classification of methods is provided as a prerequisite for the discussion of general problems inherent in current quality initiatives in the medical field and for the selection of approaches to quality development best suited for the environment of the catheterization laboratory. Here we identify the concrete steps of goal definition, quality indicator selection, definition of standards and thresholds for these indicators and the selection of a quality management scheme for monitoring the aspects of quality previously defined. Because of the limitations of each of the original methodologies of quality assessment, we propose a synthesis of the most important approaches as the basis for new quality initiatives in interventional cardiology.

[Reconstruction methods for 3D imaging and quantification of intracoronary ultrasound cross-sectional images using biplanar fluoroscopy. Initial experiences in vitro and in vivo]

In this investigation, we studied the feasibility of 3D-reconstruction from 2D cross-sectional intracoronary ultrasound images. A computer-aided, automated 3D-reconstruction was used to generate cylindrical and sagittal format of vessels in vitro (n = 9) and in vivo (n = 48). Ultrasound 2D-images were acquired with a 20 MHz mechanical intracoronary ultrasound catheter (Boston Scientific). A slow pullback (about 1 mm/s) of the catheter was performed during continuous recording of the ultrasound images. The recorded 2D-images were then fed to an image processing computer. Correction and scaling of the axial vessel dimensions was performed by the assessment of the catheter position in the simultaneously recorded biplane fluoroscopy. Digitized data were then processed to 3D-images with use of voxel space modeling. The 3D-views from any plane can be reconstructed. The in-vitro study demonstrated that the reconstructed images were able to correctly portray the pathological changes of the vessel wall in all specimen as proved by pathologic examination. In the in-vivo study, 3D-reconstruction provided not only a spatial visualization of the coronary arterial disorders (such as coronary aneurysm, coronary dissection, spontaneous plaque rupture etc.) but also provides the potential to quantify the mass of lesions. By combining sagittal and cylindrical views, 3D-reconstruction enables longitudinal and orthogonal imaging of the both the vessel lumen and vessel wall, therefore, it has the advantage of cross-sectional viewing as obtained from intracoronary ultrasound and the longitudinal viewing as derived from coronary angiography. These preliminary results of the study indicate that 3D-reconstruction of coronary segments is a promising technique for studying coronary artery disease. Analysis can be based not only on single or multiple cross-sectional images but also on vessel segments facilitating serial studies as for instance studies assessing the progression and regression of atherosclerosis.

[Teaching/learning model for the social medicine course in human medicine at the Berlin Free University]

Considering the discussions on the reform in medical education and the Free University of Berlin's plans for a reformed curriculum for medical studies, a new model in teaching and learning for the course "social medicine" was developed and tested. The model deals with students' interests in topics of social medicine and allows inductive access to matters of social medicine by means of exemplary learning. Teacher's task is to be moderator and organizer of learning processes. Experiences show that this procedure leads to improved interest in and more engagement towards the subject "social medicine" within the reach of the course.

Improving the applicability of myocardial densitometry and parametric imaging by extended automated densogram analysis

In clinical applications the analysis of X-ray contrast densograms acquired in regions of interest (ROI's) over the myocardium is disturbed by many complex factors. For this reason we acquire redundant densogram information for quality control before extracting densitometric parameters. In our approach, initially some stable measures of quality for densograms are used to lower the influence of poor quality densograms by a quality weighted averaging. For example a shape quality measure, Q1, is calculated using regions of optimal and minimal acceptable quality defined with respect to a prototype densogram. Not a few myocardial ROI's yield densograms that differ from single-source densograms (SSD's) due to e.g. superposition of different perfusion beds or the position of the ROI relative to the coronary sinus or stenoses. This might result in a densogram shape with oscillating or plateau behavior. For densograms of a such general shape many parameters defined in the usual way do not depend smoothly on the densogram values. The conventional definitions of some parameters (appearance time, rise time) are therefore extended for application to multi-maxima densograms as well as to SSD's. These new methods are evaluated using digitized clinical angiocardiograms and are applied to parametric imaging (pixeldensograms) in a slightly modified way. Taking into account the densogram quality, its shape and its origin results in a considerable improvement both for densitometry and parametric imaging of myocardial perfusion.

[Responsibilities and problems in national health reporting]

Complaints about the inadequate data situation in public health services are not new. However, during the course of the past few years there have been significant developments: the board of experts for concerted action in the public health services requested an improvement to the situation and the Federal Government promoted a preliminary study on the establishment of a national health reporting system (GBE) in Germany. Under the responsibility of the Federal Statistics Office, a national GBE is currently being established through further promotion by the Federal Ministry for Research and Technology (BMFT) and the Federal Health Ministry (BMG); the standard users of this system will be both the general public as well as the bodies responsible for health policy and scientific research. In the public health services there exist complete, but improveable data sources or incomplete sources requiring selection; also, new data sources must be won. In establishing the GBE, it is being assumed that public health services participants willing to cooperate already have at their disposal extensive data that does not need to be newly acquired, but does need improved mutual co-ordination. The GBE can be established on this. Further supplementary data acquisition is only being considered for a later stage.(ABSTRACT TRUNCATED AT 250 WORDS)

Variations in acoustical beam properties of intracoronary Doppler catheters

The limitations of coronary angiography in assessing the functional significance of coronary obstructions is well known. While the critical variable of coronary blood flow cannot be readily measured, intraluminal Doppler sonography offers useful related functional information on blood flow velocity. In order to fully evaluate Doppler signals it is essential to have exact knowledge of the transducer transmission characteristics and of the ultrasound beam topology. In an experimental set-up, the transmitter-receiver characteristics of five commonly used Doppler catheters were investigated. In comparing the beam characteristics we found inhomogeneities in the lateral beam spread. At a penetration depth of 3.0 mm the beam shape varied from a minimum of 1.25 mm up to a maximum of 3.5 mm. The mean was 2.25 mm. The different beam profiles of the investigated Doppler transducers cause an error in measuring the blood flow velocity. The blood flow velocity tends to be underestimated the more the vessel diameter and the blood flow velocity increase. Contrary to transducer design optimized for imaging, for spectral analysis of the Doppler signal it would be advantageous to have as broad a beam as possible in order to illuminate the entire vessel lumen.

[Incidence of psychiatric diseases in the patient sample of a general practitioner--a case study of ambulatory management of psychiatric patients]

A prevalence study carried out in Berlin aimed at determining the incidence and distribution of psychiatric diseases among the patients treated by a general practitioner. A questionnaire had to be completed by the patient and by the physician at every consultation. This form comprised not only questions regarding the patient's main concern and self-assessment in respect of physical and mental complaints, but also a list of actual signs and symptoms of physical and mental disorders as well as questions on demographic and social variables. The physician was asked to state details on findings, principal and secondary diagnoses, kinds of therapy and also the time the consultation lasted. The results show clearly that psychiatric diseases occur in the general practitioner's consultation-room and in his practice in a proportion that is large indeed; and that the patients' self-assessment regarding the predominantly" or exclusively" mentally conditioned nature of their complaints and the formulation of their main mental concern of frequent affirmative answers in the list of mental complaints largely correlated with the statements regarding mental or psychiatric findings or principal diagnosis made by the physician. There were also clear interrelations with demographic and social variables, particularly in connection with the kinds of therapy that had been selected. On the whole, this study showed once again clearly that mentally diseased patients do not receive all the satisfactory and appropriate treatment of which they stand in need.

Intravascular ultrasound imaging of arterial wall architecture

Intravascular ultrasound (IVUS) is a promising new technique for assessing vascular morphology and structure. Controversy exists whether the three-layer appearance of the arterial wall correctly reflects the histologic structures of the intima, media, and adventitia. We performed an experimental study to clarify the three-layer appearance. The vessel wall architecture was analyzed by IVUS on eight different kinds of plastic cylinders, 24 normal blood vessels from pigs, and 59 human arterial segments. A distinct three-layer appearance was observed on all the plastic cylinders when the ultrasound beam was perpendicular to the wall. A three-layer appearance was also seen in the arterial wall, in the muscular (iliac, femoral artery) and elastic types (aorta), when the echo beam was perpendicular to the vessel wall. The three-layer pattern was even observed on the arterial wall when the intima was removed. Furthermore, the removed intima itself provided a three-layer image. Histologic examination showed that there was no correspondence between the IVUS three-layer appearance and the intima, media, and adventitia. Moreover, we also performed IVUS on nine patients who suffered from aortic dissection. Intravascular ultrasonic visualization of the dissected intima showed a distinct three-layer pattern. The pattern disappeared when: (1) the echo beam was not perpendicular to the vessel wall; (2) there was connective tissue around the vessel wall; (3) there was arterial wall calcification; or (4) the vessel wall was too thick or the distance between the ultrasound transducer and the vessel wall was too large.(ABSTRACT TRUNCATED AT 250 WORDS)