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D M Monro

Publications and source records attributed to D M Monro.

14 recordsLinked to original sources

Parallel computation of ECG fields.

A parallel implementation of a finite difference model for computing the electric field of cardiac sources is presented. On a relatively inexpensive SIMD parallel computer, a full-forward solution is obtained in minutes, using accurate thoracic detail including anisotropy if required. Because the computation is based on a volume grid with constant size voxels, it readily accepts anatomical data from classified magnetic resonance imaging scans. By using a variation of the colored successive over-relaxation iteration, our finite difference model takes full advantage of the performance of massively parallel computers. Evaluations of the accuracy and performance of the model show the practicality of using specific anatomical models to recover the electrocardiographic field distributions for individual subjects. A relatively modest parallel machine is capable of assembling and computing a specific direct inverse solution from body surface potentials within an hour of measurement, assuming the magnetic resonance imaging classification has been previously completed.

Electrocardiography

Body surface potential mapping to monitor the effects of thrombolytic therapy following acute myocardial infarction.

The authors demonstrate the value of body surface potential mapping (BSPM) and a limited lead system in monitoring complete ECG evolution following myocardial infarction (MI) and the effects of thrombolytic therapy. They produced ST-segment isopotential maps, which indicate the site and extent of myocardial injury. Pathological Q wave maps were also produced, which intimate the extent of myocardial necrosis. Analysis of a sequence of maps recorded during the acute phase of MI revealed sudden changes attributed to reperfusion, reinfarction or "silent" events.

Adult

Comparison of epicardial and body surface ECG potentials in man.

Simultaneously measured epicardial electrograms and body surface electrocardiograms in human subjects were compared. Unipolar electrograms were recorded from up to three epicardial sites in each of 21 patients one week after aortocoronary bypass surgery. Simultaneously, electrocardiograms were recorded from 37 body surface electrodes. The epicardial electrograms from ventricular sites correlated well during the QRS complex with body surface electrocardiograms at geometrically similar positions. In particular, most posterior epicardial sites correlated best with posterior body surface regions, contrary to model predictions. P waves recorded from the right atrial surface showed a sharp negative deflection not evident in body surface P waves. A large intersubject variation was evident when the magnitude of epicardial potentials was compared with the body surface potentials. The findings are relevant to the interpretation of surface maps, the estimation of epicardial potentials from surface maps, and the positioning of body surface electrodes.

Electrocardiography

A portable integer FFT in FORTRAN.

A radix 2 integer fast Fourier transform is organised for compatibility among small computer systems by simulating binary fraction multiplications and bit reversal as functions in basic FORTRAN. After installation the efficiency can be improved by machine code replacement of some parts.

Computers