Search

OBJECTIVE Altered autonomic activity has been implicated in the development of cardiac dysfunction during seizures. This study investigates whether intervening in seizure progression with diazepam will reduce seizure-induced cardiomyopathy. Second, this study examines the hypothesis that combining atenolol with diazepam, as an intervention after seizure onset, will combat cardiac injury during status epilepticus. METHODS Male Sprague-Dawley rats were implanted with electroencephalographic/electrocardiographic electrodes to allow simultaneous recordings during seizures induced by intrahippocampal (2 nmol, 1 μL) kainic acid (KA). Subcutaneous saline, atenolol (5 mg·kg-1 ), diazepam (5 mg·kg-1 ), or atenolol and diazepam (n = 12/group) were administered at 60 minutes post-KA and daily for 7 days, at which point echocardiography, susceptibility to aconitine-induced arrhythmias, and histology were evaluated. RESULTS Seizure activity was associated with immediately increased heart rate, QTc interval, and blood pressure (BP; 10%-30% across indices). Seven days postseizure, saline-treated animals were found to have reduced left ventricular function, increased fibrotic scarring, and an elevated risk of aconitine-induced arrhythmias. Diazepam treatment significantly reduced cumulative seizure behaviors by 79% compared to saline-treated animals but offered no cardiac protection. Diazepam significantly raised BP (35%) and increased the risk of bigeminal arrhythmias (36%) compared to saline-treated animals. Atenolol administration, either alone or with diazepam, reduced heart rate, QTc interval, and BP back to control levels. Atenolol also preserved cardiac morphology and reduced arrhythmia risk. SIGNIFICANCE Attenuation of seizure with diazepam offered no cardiac protection; however, coadministration of atenolol with diazepam prevented the development of seizure-induced cardiac dysfunction. This study demonstrates that atenolol intervention should be strongly considered as an adjunct clinical treatment to reduce cardiomyopathy during seizures.

Seizures are associated with altered autonomic activity, which has been implicated in the development of cardiac dysfunction and structural damage. This study aimed to investigate the involvement of the autonomic nervous system in seizure-induced cardiomyopathy. Male Sprague-Dawley rats (320–350 g) were implanted with EEG/ECG electrodes to allow simultaneous telemetric recordings during seizures induced by intrahippocampal (2 nmol, 1 μl/min) kainic acid and monitored for 7 days. Seizure activity occurred in conjunction with increased heart rate (20%), blood pressure (25%), and QTc prolongation (15%). This increased sympathetic activity was confirmed by the presence of raised plasma noradrenaline levels at 3 h post-seizure induction. By 48 h post-seizure induction, sympathovagal balance was shifted in favor of sympathetic dominance, as indicated by both heart rate variability (LF/HF ratio of 3.5 ± 1.0) and pharmacological autonomic blockade. Functional cardiac deficits were evident at 7 and 28 days, as demonstrated by echocardiography showing a decreased ejection fraction (14% compared with control, P < 0.05) and dilated cardiomyopathy present at 28 days following seizure induction. Histological changes, including cardiomyocyte vacuolization, cardiac fibrosis, and inflammatory cell infiltration, were evident within 48 h of seizure induction and remained present for up to 28 days. These structural changes most probably contributed to an increased susceptibility to aconitine-induced arrhythmias. This study confirms that prolonged seizure activity results in acute and chronic alterations in cardiovascular control, leading to a deterioration in cardiac structure and function. This study further supports the need for modulation of sympathetic activity as a promising therapeutic approach in seizure-induced cardiomyopathy.

Ankle-brachial index (ABI) and pulse volume recordings (PVR) are non-invasive tests used in diagnosis of peripheral arterial disease (PAD). The Dopplex Ability is an automated ABI/PVR device utilising air plethysmography, offering easy and rapid PAD diagnosis. The accuracy and repeatability of the Dopplex were assessed in comparison to the Doppler/air plethysmography-based Parks Flo-Lab system.Sixty-six patients (n = 129 lower limbs) were assessed with both Dopplex and Parks systems. For Dopplex ABI and PVR to be deemed accurate, it had to be within ±10% of the Parks ABI, and the PVR grade (1-4) had to be equal. The coefficient of variation (CV) was calculated from three repeat ABI/PVR readings to assess repeatability.The Dopplex and Parks devices correlated poorly for ABI (R2 = 0.17) with only 43% of ABIs and 69% of PVRs meeting the accuracy criteria compared to the Parks values. The specificity and sensitivity were 56% and 82%, respectively for ABI, and 91% and 89%, respectively for PVRs. The Dopplex showed a significantly higher CV for both ABIs and PVRs compared to the Parks.We found the Dopplex device to demonstrate suboptimal accuracy and repeatability in assessing ABI/PVR, and it was deemed unsuitable for use in our community.

Two studies, concerned with the use of process control computer-generated information for production management decision making, are discussed. One study which has been completed, used data from a large primary steel products company to study and propose a process control/business control interface. The other study deals with the use of process generated information as a basis for automatic decision making at the lower levels of production management.

Using data from a large primary steel products company, two industrial dynamics simulation models were constructed to study the effects of process control computer-generated information on management control systems. The first model represented the existing system, the other a proposed process control/business control interfaced system. The research provides an initial step in the solution of the problem of integrating process control and management control systems by investigating the relationship between process information and control decisions at the operating level of management. The proposed system model indicated much less fluctuation in inventory levels following changes in demand, lower backlog ratios, higher inventory ratios, lower delivery delay ratios, and higher levels of customer satisfaction. The proposed system was also fairly insensitive to changes in the time between transmissions from the process control system to the management control systems once the interface was effected.

“Applications Reviews” is a guide to accomplished or partial MS/OR applications, cited in articles appearing in many of the major journals of the field. We cover only applications—except for the occasional brief mention of a survey article or special issue—and so do not claim to cover all the best articles in MS/OR. The abstracts are purposely kept short to emphasize breadth of coverage over depth; we try to tell you what modeling approach has been applied to what problem, and if possible the size and character of the improvements achieved as a result.

An overview of latest results published elsewhere: —Decision Sciences (AIDS), Vol. 9, No. 4, October 1978; —Management Science (TIMS), Vol. 24, No. 11, July 1978; —Management Science, Vol. 24, No. 12, August 1978; —Management Science, Vol. 24, No. 13, September 1978; —MIS Quarterly (SMIS), Vol. 2, No. 3, September 1978; —Operations Research, Vol. 26, No. 5, September–October 1978; —Policy Analysis, Vol. 4, No. 4, Fall 1978.

A machine shop falls victim to the exacting analysis of an “operations researcher”; the results of the research indicate that the small company must drop several of the items currently being produced and sold. “There are more catalog items than constraints”, the O.R. type explains, “If you only had more constraints on your production!” The manager's response to the thought of seeking to identify more constraints than already existed is omitted in the interests of good taste. A manufacturer of injection-molded dinnerware allowed a group of graduate students in industrial engineering to do a study of their production-inventory system. One of the results was a series of recommendations relating to economic lot size production runs for the various items being produced.

“Applications Reviews” is a guide to accomplished or partial MS/OR applications cited in articles appearing in many of the major journals of the field. We cover only applications—except for the occasional brief mention of a survey article or special issue—and so do not claim to cover all the best articles in MS/OR. The abstracts are purposely kept short to emphasize breadth of coverage over depth; we try to tell you what modeling approach has been applied to what problem, and if possible the size and character of the improvements achieved as a result. If an issue of one of our regularly covered journals contains no applications articles, we give the one-line citation for the issue with no articles shown under it. Readers who know of applications articles we may have missed or improperly slighted are invited to let us know. “Applications Reviews” is cosponsored by the TIMS College on Public Programs and Processes, the TIMS College on Marketing, and the ORSA Military Applications Section.