Search PubMed⌕ Search

Biomedical subjects

H Todt

Publications and source records attributed to H Todt.

At least 37 records · Page 2Linked to original sources
PubMed1991

Ventricular arrhythmias after reperfusion: is there a correlation with infarct size?

The aim of this investigation was to examine whether any correlation exists between enzymatically estimated infarct size and arrhythmias arising in response to coronary reperfusion. Four hour occlusion of the left anterior coronary artery followed by reperfusion was carried out in conscious dogs. Serum creatine phosphokinase (CPK) analysis and planimetric determination of infarct size were performed. The Holter monitoring technique was used to analyze the arrhythmias. A good correlation was observed between the number of premature ventricular complexes (PVC) occurring during 4-h coronary artery occlusion and peak serum CPK values (CPKmax; r = 0.74). While PVC in the early 2-h reperfusion phase and on days 1 and 2 of the late reperfusion phase did not show a correlation with CPKmax nor with occlusion arrhythmias, arrhythmic activity on day 3 of the late reperfusion phase correlated well with CPKmax (r = 0.71) and occlusion arrhythmias (r = 0.75). Whereas it cannot be ruled out that arrhythmias on days 1 and 2 are related to coronary reperfusion as well as to the established infarction, we speculated that arrhythmias on day 3 are delayed arrhythmias in response to the occlusion procedure and not a consequence of reperfusion. Providing that arrhythmias occurring in the early reperfusion phase are almost exclusively induced by the arrhythmogenic phenomenon of reperfusion, we conclude that in contrast to occlusion arrhythmias, reperfusion arrhythmias are not markers of infarct size. Thus, a higher number of arrhythmias after reperfusion is not necessarily associated with a larger infarct size.

Animals↗
PubMed1990

[Cardiovascular pharmacology. An example of the need of clinically relevant pharmacological research].

Like all other scientific disciplines, preclinical pharmacological research is subject to permanent changes. New measuring devices and the possibility of continuous on line data acquisition have markedly influenced basic research in this field. Another aim of modern cardiovascular pharmacology is the testing of promising drugs in clinically relevant animal models of disease, particularly under conditions, referring to the everyday situation in patients, e.g. physical activity. Investigations carried out in this way allow an exact assessment of the clinical efficacy of new drugs, and are, thus, clearly indispensable, also from the ethical point of view, before primary evaluation of the drug in man.

Angina Pectoris↗
PubMed1990

Programmed electrical stimulation after myocardial infarction and reperfusion in conscious dogs.

The hemodynamic and electrophysiologic variables and the inducibility of arrhythmias were studied before coronary artery occlusion (CAO, 4h) and on days 4, 14, and 28 of the late reperfusion phase in conscious, chronically instrumented dogs. Despite a lack of significant changes in the hemodynamic and the electrophysiologic variables, the response to programmed electrical stimulation (PES) before and after CAO with subsequent reperfusion varied substantially. Before intervention arrhythmias such as sustained ventricular tachycardia (SVT) or ventricular fibrillation (VFib) could not be induced by PES via ultrasonic crystals located subendocardially (LAD and LCX region) or via common stimulation electrodes (right ventricle) in any of six instrumented animals. All six animals were inducible after CAO and reperfusion. Five animals showed SVT and one animal showed VFib in response to stimulation on days 4 and 14 of the late reperfusion phase after CAO. On day 28 four animals showed SVT, and two showed VFib. Antiarrhythmic drug testing carried out in the late reperfusion phase with lidocaine (1 mg/kg bolus followed by continuous infusion) revealed 50% efficacy at a dosage of 40 micrograms/kg/min, 100% at 80 micrograms/kg/min, and 67% at 120 mu/kg/min. The persistent inducibility of arrhythmias for the entire experimental period of 24 days may be attributable to the following features of our model: 1. Electrical stimulation carried out from three different locations. 2. The use of up to three extrastimuli in the PES studies. 3. The use of conscious dogs during CAO, reperfusion, and PES. This novel experimental approach thus promises to be of clinical relevance for the investigation of new antiarrhythmic drugs.

Animals↗
PubMed1990

Antiarrhythmic efficacy of labetalol as assessed by programmed electrical stimulation.

1. The purpose of the present study was to investigate the haemodynamic, electrophysiological and antiarrhythmic effects of labetalol in the late reperfusion phase after myocardial infarction in conscious dogs. 2. Labetalol was administered in cumulative doses (0.5, 1 and 3 mg kg-1 90 min-1, i.v.). Compared to control the systolic blood pressure was significantly decreased 20 min after 0.5, 1 and 3 mg kg-1 and up to 30 min after 3 mg kg-1 labetalol. The diastolic blood pressure was significantly decreased 20 and 30 min after 0.5 and 3 mg kg-1 but was not significantly altered after 1 mg kg-1 labetalol. 3. Labetalol significantly increased the PQ, QRS, QT and QTc intervals, the 2:1 AV-conduction point, the ventricular effective refractory periods and the intraventricular conduction time from the apex of the right ventricle to the infarcted LAD-area. With the exception of the alterations in the PQ interval and 2:1 AV-conduction point the effects described above were dose-dependent. 4. Labetalol was active against arrhythmias induced by programmed electrical stimulation. This effect was already present after the lowest dose (0.5 mg kg-1). 5. The good antiarrhythmic activity of labetalol in this study can be explained by the adrenoceptor blocking properties and both the class I and III activity of this drug. Labetalol may be of potential benefit in controlling arrhythmias arising following myocardial infarction.

Animals↗
PubMed1990

[The value of sleep EEG following sleep deprivation before terminating anticonvulsive therapy in epileptic children and adolescents].

A sleep electroencephalogram was carried out after deprivation of sleep in 70 epileptic children and young people. The EEG was done before an intended reduction of anticonvulsants. Patients who had generalized paroxysmal patterns in the sleep EEG suffered from significantly more frequent relapse after and of therapy than those ones with local paroxysmal activity or electroencephalogram without paroxysmal activity respectively. A sleep EEG after deprivation of sleep should be carried out before a decision is made on the end of the therapy in patients with expected generalized paroxysmal patterns.

Adolescent↗
PubMed1990

[Ptosis as the leading symptom of Kearns-Sayre syndrome. A case report for differential diagnosis of external ophthalmoplegia].

Progressive external ophthalmoplegia has generally been considered a brainstem syndrome, but new investigative techniques have identified a variety of etiologies. We report a 17-year-old girl in whom Kearns-Sayre syndrome presented as unilateral ptosis with progression to bilateral ptosis, and discuss the clinical, biochemical, electrophysiological, histopathological and computerized tomographical findings.

Adolescent↗
PubMed1990

[Multiple sclerosis with early manifestation in children].

From the starting point of cases reported in literature, five of the authors' own cases are reported in which multiple sclerosis had its origins not later than in the fourteenth year of the patient's life. There is no basic difference from adult cases in respect of neurological symptoms, course, and cerebrospinal-fluid condition, but unmistakably, well remitting episodic courses were in the foreground, multilocular failures preponderated, and cerebral symptoms predominated over spinal symptoms. As in adult cases, females were more commonly affected. There were inflammatory changes in the cerebrospinal fluid.

Adolescent↗
PubMed1989

Holter monitoring in conscious dogs. Assessment of arrhythmias occurring during ischemia and in the early reperfusion phase.

Myocardial ischemic episodes of 5 min, 15 min, and 4 hr duration, with interposed reperfusion periods, were induced in the same conscious, chronically instrumented dogs. A drop in systolic blood pressure and an increase in heart rate and in the arrhythmic ratio (AR% = number of ectopic beats x 100/total number of beats, as assessed by Holter monitoring) was registered in response to the induction of myocardial ischemia. Reperfusion-induced salvage after coronary occlusion of 5 and 15 min duration was documented by an immediate return of systolic blood pressure, heart rate, and AR to the preocclusion control level. However, after coronary occlusion lasting for 4 hr, reperfusion induced a further drop in blood pressure and an increase in heart rate and in AR. We conclude that in conscious dogs, reperfusion-induced arrhythmias do not occur after short-lasting myocardial ischemic episodes. Reperfusion after long-lasting ischemia induces marked ventricular ectopic activity, yielding an arrhythmic ratio of more than 80%. Although these reperfusion-induced arrhythmias impair the hemodynamic state, they are well tolerated in the conscious dog and can be assessed by the Holter monitoring technique. This new experimental approach promises to be of clinical relevance for investigations on the therapeutic efficacy of new antiarrhythmic drugs.

Animals↗
PubMed1989

Holter monitoring in conscious dogs. Assessment of arrhythmias occurring in the late reperfusion phase after coronary occlusion.

Arrhythmias occurring in the late reperfusion phase, i.e., up to 3 days after episodes of 5 min, 15 min, and 4 hr of coronary occlusion (CAO), were investigated in six conscious, chronically instrumented dogs using the Holter monitoring technique. The arrhythmic ratio (AR% = number of premature ventricular complexes x 100/total number of beats) of a 24-hr preocclusion control record was 0.004% and did not differ from the values assessed for day 1 (0.004%) and 2 (0.001%) of the late reperfusion phase after 5 min CAO. After 15 min, CAO increased, but insignificantly elevated AR values were registered on days 1 (2.5%), 2 (0.26%), and 3 (0.1%) of the late reperfusion phase. On day 1 of the late reperfusion phase after 4 hr CAO, the AR increased markedly to 75%. On day 2 of this phase, the AR was lower (20%) but still significantly elevated. On day 3, the AR was 3.5%, a value still markedly, although not significantly, above the preocclusion control level. We conclude that in conscious dogs, arrhythmias in the late reperfusion phase do not occur after 5 min CAO. However, after 15 min CAO and, especially, after 4 hr CAO, an increase in arrhythmic activity occurs in the late reperfusion phase and gradually declines towards the preocclusion control level over a period of 3 days. Thus, it could be demonstrated that the long-term assessment of reperfusion arrhythmias by ECG monitoring using the Holter technique is feasible in conscious dogs. This method represents a promising approach to clinically relevant experimental investigations on the therapeutic efficacy of a new antiarrhythmic drugs.

Animals↗
PubMed1986

Termination of anticonvulsive drug treatment and the electroencephalogram.

The value of the EEG in the decision to terminate antiepileptic treatment has been investigated on the basis of longitudinal EEG studies in 433 children and adolescents with epileptic seizure disorders. The data were subjected to uni- and multivariate statistical analysis. Most valuable information concerning the risk of seizure recurrence was derived from the EEG findings obtained just before tapering of medication; the course of EEG after termination of treatment; and the maturation of EEG background activity. Thus, the EEG is a valuable tool in the decision of continuation or termination of antiepileptic treatment.

Adolescent↗