PubMed Health⌕ Search

Biomedical subjects

T Cochrane

Publications and source records attributed to T Cochrane.

31 records · Page 2Linked to original sources
PubMed1983

Computer simulation of the cardiac conduction system.

A discrete computer model simulating the operation of the cardiac impulse transmission apparatus and the electropotential changes of the heart musculature has been developed on a NORD-100 minicomputer. The model is written in NORD-FORTRAN and allows description of practically all basic pathologies of the transmission apparatus. A simulated ECG curve is produced in each case. The current version of the model is especially suited for studies of heart rhythms. Pacemaker descriptions (of most important pacemaker types) have been introduced into the model and the computer computations make it possible to assess the effects of different pacemaker modes under different pathological situations. The principles on which the model is based is described and the paper shows concisely several examples in the form of simulated ECG records.

Arrhythmias, Cardiac↗
PubMed1983

Cardiac electrophysiological studies: computer analysis using a digitiser and interactive visual display unit.

Recording of localised intracardiac electrical potentials provides useful and important information on conduction disease in man. Analysis of intracardiac recordings involves measurement of large numbers of timing intervals representing the sequence of activation of the various part of the cardiac conduction system. In this paper we describe a semi-automatic computer based analysis system tailored to the specific requirements of cardiac electrophysiological measurement. A digitising tablet is used in conjunction with a visual display oriented data handling package to input data directly to computer memory for sorting and further analysis. Particular attention is paid to providing the user with a system that is simple to learn yet is robust and flexible in use. The computer software is written entirely in the high level FORTRAN language. It is modular in design and is therefore easily adapted for the changing needs of a research oriented department.

Arrhythmias, Cardiac↗
PubMedDate not supplied

Software control of sensing and stimulation for cardiac electrophysiological study.

A software-controlled cardiac stimulator for clinical investigations is described. The stimulator is programmed by the user at a keyboard, while current status and values of parameters are presented on a visual display screen. A menu of predefined cardiac electrophysiological tests is available for user selection. Validity checks on data keyed in by the user and internal checks on safe pacing limits are incorporated in case of malfunction or user error. The system consists of a separate relatively simple isolated sensing and stimulation unit which communicates, via a standard digital input output interface, with a controlling microcomputer. All timing and control functions are performed in software by the computer. The use of high-level FORTRAN as the main programming language provides the system with a high degree of adaptability.

Computers↗
PubMedDate not supplied

A comparison of the effects of xylometazoline on nasal airflow, and on blood flux as measured by laser Doppler flowmetry.

The purpose of this study was to examine whether changes in mucosal blood flow measured directly by laser Doppler flowmetry corresponded to changes in turbinate blood volume measured indirectly as changes in nasal airflow. Fifteen healthy subjects underwent active anterior rhinomanometry and laser Doppler flowmetry prior to and following the topical application of 100 micrograms of xylometazoline to each nostril. A significant decrease in nasal resistance occurred in the probe nostril (p less than 0.001) and the non probe nostril (p less than 0.005) following xylometazoline. A significant fall in blood flux occurred with xylometazoline (p less than 0.05). There was no correlation between the percentage change in airflow (rhinomanometry) and the percentage change in blood flux (laser Doppler) following xylometazoline. These results suggest that laser flowmetry and rhinomanometry measure different parts of the inferior turbinate vascular bed.

Adult↗
PubMedDate not supplied

A comparison of the effects of two commonly used vasoconstrictors on nasal mucosal blood flow and nasal airflow.

This study compared two commonly used vasoconstrictors, cocaine and xylometazoline. Non-invasive techniques of measurement were utilised, with active anterior rhinomanometry indirectly assessing changes in nasal mucosal blood volume, and laser Doppler flowmetry assessing changes in nasal mucosal blood flow. Twelve healthy volunteers received 0.1 ml of the topical vasoconstrictor at the anterior end of both inferior turbinates. Following the application of xylometazoline, a significant rise in nasal airflow (p less than 0.005), and a significant fall in blood flux occurred in the probe nostril (p less than 0.05). Following the application of cocaine, no significant change in nasal airflow occurred (p less than 0.05), but a significant fall in blood flux occurred in the probe nostril (p less than 0.02). A comparison of the paired data for the same subject demonstrated no significant difference in the change in blood flux produced by xylometazoline and cocaine, but a significant difference in the change in airflow produced by the two vasoconstrictors (p less than 0.005).

Adrenergic alpha-Agonists↗
PubMedDate not supplied

A microcomputer-controlled cardiac stimulator.

Detailed investigation of abnormal heart rhythms requires electrical stimulators that can deliver sophisticated sequences of stimuli to the heart under controlled laboratory conditions. A dual-channel stimulator that provides an appropriate hardware interface between a controlling microcomputer and the patient is described. The computer gives the system power and flexibility and, most importantly, provides a suitable user interface. The hardware interface is designed to have an ergonomic division between set-up and run-time tasks. Both software and hardware are discussed, and clinical examples of typical usage of the stimulator are given.

Cardiac Pacing, Artificial↗
PubMedDate not supplied

Some aspects of computer modelling in cardiac electrophysiology.

A computer model simulating the electrical activity of the heart is described. The model is designed for use in clinical cardiological research. Its implementation is based on the methods of discrete process simulation. The simulation program is written in FORTRAN, has approximately 12,000 lines and requires 160 kilobytes of memory to run. The whole heart is modelled, including a realistic description of the conduction system and a 'hollow shell' structure with a central plane representing the atrial, ventricular and septal components of the cardiac musculature. The myocardium itself is represented by simple hexagonal elements, which are pieced together to form the 'hollow shell'. The ideas used to develop the model are briefly described, but emphasis is given to clinical applications. The model is first validated by examining its output under well-known pathological conditions. Clinical applications, including predictive value, testing of hypotheses, and evaluation of pacemaker function, are then described, results being presented in the form of orthogonal lead projections.

Computers↗