In cooperation with the Department of Electronic Data Processing Systems we have developed a data processing unit for the analysis of hemodynamic data at the Department of Internal Medicine I. The aim was to design a computer-system for the daily routine in heart-catheterizations as well as for the solution of scientific problems during hemodynamic studies. In the on-line-mode besides the ECG up to four pressures can be analysed simultaneously. Analog and digital tapes can also be processed off-line on demand. The concept of the whole system and the individual steps of computer-handling are adjusted to the problems of data-analysis in praxis from the viewpoint of the examining cardiologist. Since the system is interactive after each measurement and each given command the computer-results are displayed on the video-scope. Because of the modular structure of the program new medical criteria can easily be implemented at any time. Since the computer-system is not effectively used with only one cath-lab other units possibly of different hard-ware configuration can be connected simultaneously to the computer. Each cath-lab shares 16 K out of the total 32 K core-memory. The results are displayed graphically and alpha-numerically on video-scope, x-y-plotter and line printer. The sampling-rate for fluid-filled catheters is 200 Hz and for catheter-tip-manometers 400 Hz. Smothing and differentiation-procedures are adapted to the respective catheter-material. The computer-program calibrates the different pressure amplifiers automatically. After defining the catheter-position the pressure-signals are sampled for 10 s and immediately afterwards analyzed by the computer. The ECG and the corresponding pressure-curves are displayed on the video-scope. The automatically selected representative beat as well as each of the identified and numerated other beats of the sampling-phase can be displayed selectively together with its numerical results. The computer marks the positions within the pressure-curves, where the individual measurements were taken. Besides the systolic and diastolic pressures in valvular stenosis the maximal and mean systolic or diastolic gradients, ejection- or filling-period, valve-flow and valve-area are calculated autonomously. The calculation of cardiac-output, different volume-indices and stroke-work-index are based on Fick-method, thermo- or indicator-dilution technique. The contractility-parameters max dp/dt, t-max dp/dt, max dp/dt/DP, max dp/dt/P, VPM, V40, min dp/dt and the stiffness are computed for the left and on demand also for the right ventricle. Data of the patient and the operating-team, catheter-technique, complications and free comments are transmitted to the computer via terminal together with the actual time. The computer-system was drafted for permanent use. Therefore possible technical defects have been anticipated in the design of hard- and soft-ware. In cases of failure suitable steps allow the immediate restart of the system without loosing information...