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G T Meester

Publications and source records attributed to G T Meester.

At least 19 recordsLinked to original sources
PubMed1987

The role of the personal computer in the cardiac catheterization laboratory: an integrated approach to information management.

A personal computer-based data management system for the cardiac catheterization laboratory is described. This is a cooperative effort on the part of the Dutch academic hospitals, through the Interuniversity Cardiology Institute, to put in place a more uniform structure for data collection and reporting in the context of cooperative studies. The major design criteria included the necessity that the system provide a clear and present benefit to the users in terms of their day-to-day work. This requires a practical data entry package together with a full reporting capability, including management tools for supervision of the catheterization laboratory in general. Ancillary activities include quantitative analysis of ventriculograms and an elementary statistics package with graphics. To facilitate supportability of the system, commercially available packages for data base management, text processing, and communications have been used to advantage. After a prototype test phase involving two centers, five other centers have been equipped with similar systems and used successfully in the majority.

Cardiac Catheterization↗
PubMed1986

Quantitative assessment of regional left ventricular motion using endocardial landmarks.

In this study the hypothesis is tested that the motion pattern of small anatomic landmarks, recognizable at the left ventricular endocardial border in the contrast angiocardiogram, reflects the motion of the endocardial wall. To verify this, minute metal markers were inserted in the endocardium of eight pigs with a novel retrograde transvascular approach. Marker motion was subsequently recorded with roentgen cinematography and compared with the motion of the landmarks on the endocardial contours detected from the contrast ventriculogram with an automated contour detection system. Linear regression analysis of the directions of the systolic metal marker and endocardial landmark pathways yielded a correlation coefficient of 0.86 and a standard error of the estimate of 10.3 degrees. Landmark pathways were also measured in 23 normal human left ventriculograms. Normal left ventricular endocardial wall motion during systole, as observed in the 30 degrees right anterior oblique view, is characterized by a dominant inward transverse motion of the opposite anterior and inferoposterior walls and a descent of the base toward the apex. The apex itself is almost stationary. On the basis of these observations, a widely applicable model for the assessment of left ventricular wall motion is described in mathematical terms.

Animals↗
PubMed1985

Vaporization of atherosclerotic plaques by spark erosion.

An alternative to the laser irradiation of atherosclerotic lesions has been developed. A pulsed electrocardiogram R wave-triggered electrical spark erosion technique is described. Controlled vaporization of fibrous and lipid plaques with minimal thermal side effects was achieved and documented histologically in vitro from 30 atherosclerotic segments of six human aortic autopsy specimens. Craters with a constant area and a depth that varied according to the duration of application were produced. The method was confirmed to be electrically safe during preliminary in vivo trials in the coronary arteries of seven anesthetized pigs. The main advantages of this technique are that it is simpler to execute than laser irradiation and potentially more controllable.

Aged↗
PubMed1978

Computer analysis of oximetry data in cardiac catheterization.

An on-line computer technique is described for the detection and quantitation of left-to-right shunts. The computer used Student's t test to evaluate the probability that variations in right heart oxygen saturations were due to left-to-right shunts. The computer method was found to compare favorably to the present step-up method of detecting left-to-right shunts. The computer also calculated pulmonary blood flow, systemic blood flow, their ratio, and shunt blood flow as accurately as standard methods, as evidenced by correlation coefficients of 0.98, 0.94, 0.95, and 0.71 between the computer and hand calculations.

Cardiac Catheterization↗
PubMed1978

Direct method for determining regional myocardial shortening after bypass surgery from radiopaque markers in man.

A new method is described for determining localized epicardial shortening in regions newly perfused after saphenous vein bypass grafting. Four to six radiopaque markers are sutured to the ventricular epicardium in pairs, 2 cm apart and 0 to 3 cm distal to the coronary anastomosis. Shortening fraction and time to onset of shortening are reported in 56 patients examined noninvasively with use of cinefluorography 1 week to 6 months after operation. The right coronary bypass region showed the greatest improvement in shortening fraction in 6 months (from 10.1 to 16.7 percent); the left anterior descending region showed the least (but still significant) improvement (from 8.6 to 11.5 percent). Paradoxical systolic expansion occurred predominantly in the region of the left anterior descending coronary bypass (95 percent of all such occurrences). Measurement error, observer variability and beat to beat variability were less important than the physiologic changes in the postoperative period. This technique is a direct method providing heretofore unavailable follow-up information on localized shortening in newly perfused myocardium after coronary bypass grafting.

Adult↗
PubMed1977

Automatic data processing in the cardiac catheterization laboratory.

A review of automatic data processing in the cardiac catherization lab is presented. The emphasis placed on on-line manometry, indicator dilution and off-line quantitative ventriculography. The system organization is described and several specific examples given to illustrate the level of detail necessary to specify such a system. The clinical use of the system is described together with an evaluation of the original design goals in terms of the actual performance of the system. A few unexpected benefits have emerged with respect to quality control and reliability, but one of the original design goals, speeding up the catheterization procedure, has proven to be unrealistic. The next logical steps in the software and hardware evolution are described with the emphasis placed on making the system a more effective tool for the clinician.

Cardiac Catheterization↗
PubMed1976

Orthotopic canine heart transplantation: left ventricular contractility during chronic rejection.

Myocardial left ventricular contractility is assessed in 8 orthotopic heart-transplanted dogs during chronic rejection by a noninvasive method. The mean circumferential velocity of shortening (Vcf) is calculated from endocardial marker motion on cinefilms. A model for chronic rejection after cardiac transplantation was obtained by histocompatibility matching in DLA identical Beagle littermates. No immunosuppressive treatment was used. All dogs eventually died of chronic rejection; mean survival time was 112.5 days. LV contractility shows the following pattern: Chronic rejection causes an important contractility decrease (P less than 0.001) with two significant drops: (1) from the week preoperative to the first week after transplantation (P less than 0.02) and (2) from week terminal minus one to the terminal week (P less than 0.01). This study describes the technique and the changes in Vcf observed over a period of time in a predictable model.

Animals↗
PubMed1975

Quantification of ventricular performance: a computer-based system for the analysis of angiographic data.

A computer-based quantitative angiography system for the acquisition and analysis of ventriculographic data has been developed. In addition to the apparatus normally required for angiography and left ventricular pressure recording, a digitizing tablet, PDP 11/20 mini computer, and TV monitor with a hard-copy device is employed. Four modes of operation are currently in use: data acquisition, analysis, mini cine, and data tape editor. Data acquisition facilitates forming a magnetic tape record of the digitized pressure, timing, and event identification, together with anywhere from 4 to 100 digitilized LV contours. A number of error checks and feedbacks are incorporated to provide some measure of quality control. In the event an error is written onto the magnetic tape record, the data tape editor can be used to review the record and correct most errors. Analysis of the generated data tape consists of several options which include: pump function, muscle function, pressure derived indices of contractility and systolic time intervals, and contour pattern recognition which is still under development. If the complete analysis option is chosen, a summary of the analysis, referred to as the quick-sight list, is also presented. The so called mini cine option employs a separate and independent acquisition-analysis program. This requires only the end-diastolic (with a segment of wall) and end-systolic contours (without pressure data) to extract the most essential parameters (EDV, EF, CI, HR, and wall mass). As a result of the relative straightforward processing and inherent simplicity, the mini cine option is most frequently used. This system has done much to reduce the time required for analysis of angiographic data, while at the same time maintaining and even improving the quality of the results. Other less tangible benefits include: the possibility to build a readily accessible library of patient data files facilitating a posteriori studies, precise and uniform definition of the rules to input and analyze data, and finally providing a useful step towards fully automatic ventriculographic processing.

Angiocardiography↗
PubMed1975

A fully automatic device for compensating for artifacts in conventional catheter-manometer pressure recordings.

A device is described which detects the resonant artifacts in clinical cathetermanometer systems and automatically sets a notch filter so as to provide some measure of compensation. The equalised response characteristic does visibly improve transient response by removing resonant artifacts due to the uneven transfer function characteristic in these systems. Artifacts due to knocking of the catheter by the heart, external vibrations induced in the manometer, its mechanical support, or the catheter are reduced, but not eliminated. Nevertheless, the system described here has provided a solution to an important class of artifacts in conventional fluid filled catheter-manometer pressure recordings.

Automation↗