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Biomedical subjects

E C DeLand

Publications and source records attributed to E C DeLand.

At least 19 recordsLinked to original sources
PubMed1988

A personal computer-based arrhythmia generator based on mathematical models of cardiac arrhythmia.

A personal computer-based arrhythmia generator has been developed based upon mathematical models of modulated parasystole and the related equations. A system of nonlinear difference equations is used to generate the time series of RR intervals of ECG that contain normal as well as ectopic QRS waves. The ECG waveform is synthesized according to the computed RR interval and the type of QRS wave and output via DA converter in a real-time base. Various types of ECGs with ventricular ectopic beats and those with very long periods were generated by selecting values for a small number of model parameters. This method requires neither large RAM nor external memory for storing a library of arrhythmic ECGs. The theory, hardware design, software implementation on a personal computer, and experimental reconstruction of clinical ECGs based on the model are discussed.

Arrhythmias, Cardiac↗
PubMed1978

Acute response to acid-base stress.

A method previously established in the experimental animal for predicting the acute response to either metabolic stress (bicarbonate administration) or respiratory stress(manipulation of oxygenator gas during cardiopulmonary bypass) has been extended to man. The method is based on a single nomogram. The accuracy of the nomogram is demonstrated using data from 13 patients on cardiopulmonary bypass. Similar agreement obtains between the nomogram and data reported by others. The nomogram can be used to estimate the therapeutically required dose of bicarbonate.

Acid-Base Imbalance↗
PubMed1978

Optimizing myocardial supply/demand balance with alpha-adrenergic drugs during cardiopulmonary resuscitation.

In 14 dogs the determinants of myocardial blood supply and metabolic demands were assessed during cardiopulmonary resuscitation (CPR) and under steady-state conditions in fibrillating hearts on cardiopulmonary bypass. During open chest cardiac massage (nine dogs), coronary diastolic blood pressure and blood flow were low. Vasopressor infusion (methoxamine or epinephrine) raised diastolic pressure from 33 +/- 3 to 55 +/- 3 mm. Hg and increased coronary blood flow (CBF) 124 percent (from 38 +/- 3 to 85 +/- 11 c.c. per 100 Gm. per minute. Comparison of these drugs in fibrillating hearts on cardiopulmonary bypass showed that epinephrine increased the "vigor of fibrillation" (intraventricular balloon pressure rose 24 percent and oxygen uptake increased 42%) but impeded subendocardial flow 53% (endocardial/epicardial flow ratio fell from 0.79 to 0.48). In contrast, methoxamine did not significantly change intraventricular balloon pressure, oxygen uptake, coronary flow, or its distribution. We conclude that augmentation of diastolic pressure with alpha adrenergic drugs during CPR improves coronary perfusion and that inotropic drugs may worsen myocardial ischemia during CPR by raising oxygen demands while simultaneously impeding subendocardial blood supply.

Animals↗