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Biomedical subjects

M Kirchner

Publications and source records attributed to M Kirchner.

At least 55 records · Page 3Linked to original sources
PubMed1988

On-line interval measurement during invasive cardiac electrophysiologic testing.

A microprocessor-based timer has been developed for routine and research use in cardiac electrophysiologic studies. The cycle length (A-A) and the conduction times through the right atrium (A(HRA)-A(HIS], the AV node (A-H) and the His-Purkinje system (H-V) can be automatically measured beat-to-beat in real-time both during sinus rhythm and during atrial pacing. The design has been refined during three years of use in over 80 clinical studies. A comparison between manual and automatic measurements has been executed for randomly chosen portions of 10 studies. With the manual measurements as reference procedures the sensitivities of the automatic measurements of the A, H and V waves were 0.98, 0.88 and 0.92, respectively, while the specificities were 0.93, 0.92 and 0.93, respectively. For the true positive measurements the correlation coefficients of the intervals were r(A-A) = 0.9998, r(A-H) = 0.987 and r(H-V) = 0.988. The statistical analysis of the differences between manual and automatic readings for the intervals A-A, A-H and H-V yielded mean values of -1 ms, -0.8 ms and 0.6 ms and standard deviations of 3 ms, 4 ms and 4 ms which are smaller than the accuracy of the common manual measurements.

Ajmaline↗
PubMed1984

Real-time beat-to-beat measurement of conduction intervals during cardiac electrophysiological studies.

The conduction times through different myocardial structures have been measured in real-time during clinical intracardiac investigations by means of a low-cost microprocessor-based system. Two endocavitary electrograms, a surface ECG and a pacemaker stimulus are analysed to detect the stimulus as well as atrial, His and ventricular waves and to measure, beat to beat, the time intervals between them. Measurements have been made in the course of 40 clinical studies, randomly chosen from about 500, and including different conditions such as sinus rhythm, acute drug tests and programmed atrial pacing. Our results show that the real-time measurement of the conduction intervals is feasible and may offer several advantages: it allows immediate data analysis which enables the investigator to better make decisions during the study; it reduces the time and effort required to perform and analyse the study; and it increases the quantity and quality of information gained on the cardiac status of the patient.

Adolescent↗