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R Brennecke

Publications and source records attributed to R Brennecke.

At least 73 records · Page 4Linked to original sources
PubMed1988

[Current complication rate of percutaneous transluminal coronary angioplasty in stable and unstable angina].

During a four-year period (1983-1986) percutaneous transluminal coronary angioplasty (PTCA) was performed on 930 patients with stable or unstable angina with a mortality rate of 0.4%. A transmural myocardial infarct developed in 1.1% and 1.0% of patients required an urgent aorto-coronary bypass. Thus the total rate of severe cardiac complications was 2.5%. Compared with the years 1983-1985, there was in 1986 a significant fall in the number of deaths and of myocardial infarcts from 2.2% to 0.5% (P less than 0.05), while there was a nonsignificant increase in emergency coronary bypass surgery from 0.7 to 1.3%. Patients with unstable angina compared with those with stable angina had a significantly higher mortality rate (1.0% vs. 0.2%; P less than 0.05), incidence of infarction (2.0% vs. 0.6%; P less than 0.05), and emergency operations (2.0% vs. 0.5%; P less than 0.05). The total risk of a severe cardiac complication was 1.2% for stable and 5.2% for unstable angina (P less than 0.001).

Aneurysm↗
PubMed1988

Requirements on resolution of digital imaging equipment in the cardiac catheterization laboratory.

We evaluated the requirements on spatial resolution of digital imaging equipment in the cardiac catheterization laboratory. Fifty cinefilms of the heart as the biological object and one film of a lead-ladder-pattern as an objective test were used. The patient films were examined for the visibility of the left ventricular angiogram, coronary arterial tree, coronary artery lesions, branching of septal arteries and the number of septal arteries. All films were viewed three times: with a 625 line TV-system, with a 1249 line TV-system and with a cineprojector. It was found that two application areas with different demands on the spatial and temporal resolution can be distinguished: 1) low spatial resolution and high temporal resolution, e.g. left ventriculography; and 2) high spatial resolution and low temporal resolution, e.g. coronary arteriography. For the diagnostic assessment of the state of the coronary system, the spatial resolution provided by the 1249 line TV-system was sufficient. Exceeding this resolution by using cinefilm quality provided no additional diagnostic information. A frame rate lower than 50 frames per second for coronary arteriography seems possible.

Angiography↗
PubMed1988

The effect of balloon dilatation on post-stenotic myocardial perfusion before and after stimulation of coronary flow reserve: evaluation by the densitometric parameter 'mean rise time'.

From densitometric evaluation of digital subtraction cineangiocardiograms the parameter 'Mean Rise Time' (MRT), defined as the time from the onset of local myocardial contrast medium opacification to the point of maximal opacification can be derived; this parameter revealed a close correlation with the results on myocardial perfusion obtained by Thallium-201 scintigraphy. A prolonged 'Mean Rise Time' was indicative of an impairment of myocardial perfusion. We have developed a heart-phase gated real-time digitization procedure and computer-supported method for the densitometric estimation of the MRT to obtain information about the effect of coronary balloon dilatation on myocardial perfusion before and after stimulation of coronary flow reserve by Moxaverin. In 22 patients with single vessel coronary artery disease Moxaverin caused a significant prolongation of the post-stenotic MRT (2.3 +/- 1.2s (mean +/- s.d.) vs. 2.9 +/- 1.1s, p less than 0.05), while after successful dilatation of the obstructive lesion a significant shortening of the MRT was found after stimulation of the coronary flow reserve (2.5 +/- 1.2s vs. 1.9 +/- 0.9s, p less than 0.05). A highly significant decrease in MRT after Moxaverin was measured post-dilatation in comparison to the initial pre-dilatation results (2.9 +/- 1.1s vs. 1.9 +/- 0.9s, p less than 0.005); this shows that the effect of successful balloon dilatation on the post-stenotic myocardial perfusion can be described very well by this parameter. These results demonstrate that information about post-stenotic myocardial perfusion during interventional heart catheterization can be obtained from digital densitometry.

Adult↗
PubMed1988

[Social medicine in the curriculum of universities of West Germany. Recommendations for developing topics and organization].

At German universities and colleges social and community medicine is mainly taught by lecturers from various medical fields. Accordingly a great variety of topics are presented and different focuses are set. Thus orientation becomes more difficult for the students. The present paper was elaborated by experienced lecturers. It contains proposals for the organization of the lessons. With regard to the topics a list of priorities is presented and criteria for the qualification of the lecturers are formulated.

Curriculum↗
PubMed1987

Color superposition: a new modality for contrast echocardiography.

To improve the estimation of endocardial borders in echocardiography, a technique has been developed to combine images from contrasted and noncontrasted echocardiograms of the same heart-phase using a color superposition mode. This method allows both experienced as well as less experienced examiners to define the endocardial borders more reproducibly and objectively. This is achieved by displaying tissue structures as gray level images while the ventricular cavity is marked selectively by the color display of the contrast material zone. Results of volume estimations of the left ventricle by different examiners using several imaging modes including color superposition display are presented.

Cardiac Volume↗
PubMed1986

New balloon catheter for prolonged percutaneous transluminal coronary angioplasty and bypass flow in occluded vessels.

A new balloon catheter was developed for continuous perfusion of coronary arteries during angioplasty (CPC catheter). Steerable Grüntzig balloon catheters (3.7 mm) with two lumina were formed. The first lumen was used for balloon inflation. Side holes to the second lumen proximally and distally to the balloon were created for coronary perfusion even during inflation phase. At a perfusion pressure of 120 mmHg, a flow rate of 63 +/- 3 ml/min with 0.9% saline and 43 +/- 1 ml/min with plasma expander were measured. In experiments on five dogs, dilation time until appearance of signs of ischemia could be prolonged in three of five dogs from 30 to 40 s, 120 to 203 s, and 180 to 420 s comparing conventional and CPC balloon catheters. In 11 patients with proximal lesions, dilation time could be increased from 39.5 +/- 23.9 s to 81.1 +/- 36.3 s (p less than 0.01) until appearance of angina pectoris. ST segment changes were observed in 10/11 patients using conventional catheters. Using CPC catheters, no ST segment changes were observed in four patients; time until appearance of ST segment changes was delayed in the other seven patients. The CPC catheter seems to be an alternative catheter in proximal lesions of the left and right coronary artery, allowing the possibility of prolonged dilation and increased safety to the patient. In case of dissection or perforation, the CPC catheter can be used for perfusion of the distal part of the coronary vessel until emergency bypass surgery.

Adult↗
PubMed1985

[Normal values for two-dimensional echocardiography].

In 51 normal subjects (26 men, 25 women, age range 15-38 years), normal values for longitudinal axis and diameters of left and right ventricle and left and right atrium were determined by 2-D echocardiography. Both left parasternal longitudinal and cross-sectional cuts were used. Tolerance values to determine normal range were recorded, in addition to mean values and standard deviations. Diastolic and systolic diameters (DD/DS) in the left parasternal longitudinal and cross-sectional cuts gave similar results to those in the 4-chamber view from the apex: DD 2.7 +/- 0.4 (2.3-3.1) cm/m2, DS 1.8 +/- 0.4 (1.4-2.2) cm/m2, and DD 2.7 +/- 0.4 (2.3-3.1) cm/m2, DS 1.7 +/- 0.3 (1.4-2.0) cm/m2, respectively. Sizes of the right ventricle (1.8 +/- 0.4/1.4-2.2 cm/m2) and right atrium (2.4 +/- 0.5/1.9-2.9 cm/m2) could only be obtained in the 4-chamber view. Values for the left atrium (2.3 +/- 0.7/1.6-3.0 cm/m2) were obtained also in the left parasternal cross-section. Correcting for body surface, differences between males and females were reduced to the extent that there was no significant difference between them. These normal values make it possible to standardize the measurement of intracardiac dimensions by 2-D echocardiography and classify individual values.

Adolescent↗
PubMed1985

Assessment of cardiovascular function by digital angiocardiography.

A methodology for computerized digital videoangiocardiography is briefly described. Single or biplane projection image series from the cardiovascular system are combined with the corresponding physiologic (electrocardiogram, blood pressure, etc.) reference data, digitized and stored as a block of simultaneously available information representing anatomic and functional aspects of the cardiovascular system. Simple mask mode and more complex modes of digital subtraction, image combination and manipulation techniques, as developed during the last decade, are mentioned. These techniques are primarily useful to separate the contrast bolus from the background, thereby allowing contrast enhancement with less contrast medium injected selectively, or so-called noninvasive intravenous angiocardiography. Ventricular function can be assessed by these simple digital image processing techniques. This has been proved for determining right ventricular volumes and ejection fraction with respect to reproducibility and accuracy using conventional biplane angiocardiography as reference. More complex techniques for the assessment of function, in particular blood flow distributions in the systemic circulation, are described using information from the whole digitized angiocardiographic image series by extracting time and volume parameters from the complete matrix of pixel densograms. Various modes of extraction and display of time parameters allow a generation of parametric images that display heretofore unavailable flow patterns reflecting the progress of the contrast bolus within the arterial tree. Based on an adequate temporal segmentation (for example, time segments of one cardiac cycle) and simultaneous volume determination of the circulatory structure from the area of the densogram, relative and absolute flow as well as regional flow distribution in a branching arterial system can be determined.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiocardiography↗
PubMed1985

Digital angiocardiography and echocardiography: fundamentals and future aspects.

Digital techniques of image data acquisition, processing and analysis were developed relatively early in cardiology but their broad clinical application lags behind the use of similar methods in angiography, even though these techniques have shown their advantages in reducing contrast material and X-ray dose, in quantitative evaluation of circulatory parameters and in high quality real-time electronic image storage. Recent developments in the fields of angiocardiographic image acquisition, in image processing and in the design of advanced digital processors are reported. The possibilities for an integration of echocardiographic imagery (especially of echo contrast studies) into angiocardiographic image processing are discussed. Medical and technological research is needed to define still more precisely the medical needs and to improve the technical means for digital angiocardiography and echocardiography.

Angiocardiography↗
PubMed1983

[Digital function angiography. A method of measuring arterial blood flow].

Digital image processing techniques can be effectively used for the quantitative evaluation of angiograms. In this study, the principle of parameter extraction from digitized image series was utilized. The procedure of parametric analysis was based on mathematical calculations of density-time-curves of the contrast medium according to each picture element of a digital image matrix (256 x 256 picture elements). Flow measurements were calculated from time parameter data and the subsequent segmentation of vessels indicating the propagation of the contrast medium within given time intervals. Flow velocity and volume flow studies will provide additional quantitative information to the evaluation of conventional angiograms.

Angiography↗
PubMed1982

Quantitative analysis of structure and function of the cardiovascular system by roentgen-video-computer techniques.

A survey of the evolution of roentgen-video-computer techniques is given which was initiated by the development of videodensitometry by Wood and his associates. Following fundamental studies of the usefulness and limitations of x-ray equipment for quantitative measurements and the applicability of the Lambert-Beers law to x-ray absorption, videodensitometry has been used experimentally and clinically for various circulatory studies and has proved to be particularly valuable for the quantitation of aortic, pulmonic, and mitral valvular regurgitation. The second offspring of these techniques, so-called videometry, uses dimensional measurements from single and biplane angiocardiograms for the assessment of size, shape, and contraction pattern of the heart chambers. Volumes of the right and left ventricles can be determined clinically with a standard error of estimate below 10%. On the basis of these studies, normal values have been derived for all age groups, and they depict geometric changes of the growing heart. Cardiac index and ejection fractions proved to be age-independent biologic constants. Finally, methods for complete digital processing of video-image sequences in an off-line and real-time mode are described which allow digital image storage and documentation, dynamic background subtraction for contrast enhancement, and intravenous angiocardiography, in addition to functional imaging by parameter extraction from a matrix of pixel densitograms. Wall thickness and motion determinations, regional flow distribution measurements, and various image-composition techniques are also feasible.

Absorptiometry, Photon↗
PubMed1981

Assessment of arterial blood flow measurements by digital angiography.

A system for computerized processing of video image series was utilized for the real-time digitization of arteriograms. There were 256 x 256 picture elements (pixels) per image with a resolution of 256 gray levels. Temporal changes in x-ray absorption at each pixel as induced by contrast media were computed for the extraction of regional blood flow parameters. Four steps of processing included: (a) vascular masking, (b) time parameter extraction, (c) segmentation of vessels, and (d) segmental volume and flow determinations. The results were displayed pictorially as angiographic parameter images. Measurement of the regional blood flow was tested at the abdominal arteries in nine pigs. Flow distribution values at the renal and iliac arteries were accurate within +/- 5% of the total abdominal aortic flow. The method may also be applicable to quantitative circulatory studies of the cerebral, pulmonary, and possibly, coronary arteries.

Angiography↗