Biomedical subjects

M Haugh

Publications and source records attributed to M Haugh.

23 records · Page 2Linked to original sources

PubMedDate not supplied

Heterogeneous effect of quinidine on the ventricular depolarization process assessed by the spatial velocity electrocardiogram of the QRS complex. Preliminary report of a new investigative method.

The negative conduction effect of quinidine on each of the successive phases of the ventricular depolarization was investigated using an original noninvasive method: the spatial velocity electrocardiogram of the QRS complex (SVECG-QRS). We performed a randomized placebo-controlled trial in 10 healthy subjects with a single oral dose of quinidine (330 mg) or placebo. Electrocardiographic acquisition and processing (220 recordings for the complete trial) were performed using the Lyon vectorcardiographic program. For each SVECG-QRS curve, the position of seven specific points from A (onset of QRS) to G (end of QRS) were determined precisely. The six successive time intervals between these points (AB-FG) and five velocity values (B-F) were then calculated. The QRS complex was longer under quinidine than placebo (102.4 +/- 1.6 vs. 100.3 +/- 1.5 ms). The difference was at the periphery of statistical significance (p = 0.05), and this lack of statistical difference may be mainly due to the low serum levels of quinidine obtained at the peak of the concentration (1.46 +/- 0.4 mg/1). All six QRS time intervals were longer under quinidine, but only the BC interval was significantly different (9.3 +/- 1.1 vs. 18.8 +/- 1.1 ms; p < 0.05) suggesting a more pronounced negative conduction effect at the onset of ventricular depolarization. No significant modifications were observed for the velocity values. We conclude that (1) the negative conduction effect of quinidine is heterogeneous, but a further study with a higher dose of quinidine (concentration-dependent effect) is required to confirm this hypothesis and (2) the spatial velocity electrocardiogram of the QRS complex allows a detailed analysis of the ventricular conduction phases. The results of the measurement were found to be reproducible. This noninvasive tool could be used in clinical practice to assess effects of antiarrhythmic drugs on successive ventricular depolarization phases.

Administration, Oral↗

PubMedDate not supplied

[The problem of therapeutic efficacy indices. 1. Elements of the problem].

Efficacy indices measure the efficacy of therapies. They derive, by definition, from two quantities, the basal or control risk of event, Rc, observed in the control group, and the on-treatment risk, Rt, observed in the treated group. In clinical trials and meta-analyses, each is an unbiased measure of efficacy. Although they are a combination of frequencies, these indices are used in clinical practice to predict the benefit in treated patients. Their relevance to express efficacy depends on the type of clinical condition, and is better for acute diseases than for chronic diseases. In order to be useful for prescribers, they should meet certain specifications. In addition, they should be considered in the more general framework of effect models.

Clinical Trials as Topic↗

PubMedDate not supplied

[The problem of therapeutic efficacy indices. 2. Description of the indices].

The four indices for a binary outcome or therapeutic objective are: the odds ratio, the relative risk, the absolute benefit and the number of patients to treat. For a continuous outcome, the effect size is the best choice. The odds ratio approximates the relative risk. The difference may be large in some instances. The number of patients to treat is the reciprocal of the absolute benefit. Although they are built on the same two quantities, they are not interchangeable and should not be considered in the same way. Moreover, their meaning is not straightforward and they can be misused.

Clinical Protocols↗

PubMedDate not supplied

[Outline of the problem of indices of therapeutic efficacy. 4. Expression of efficacy when the underlying illness is incurable. Study Group for the Indices of Efficacy].

In chronic illness, when death or a non-fatal event can occur at any time, the current efficacy indices are no longer appropriate to express the effect of the treatment on the potential therapeutic objectives. The inappropriateness is not dependent on the effect model. Clues for solutions are proposed.

Chronic Disease↗

PubMedDate not supplied

[The problem of therapeutic efficacy indices. 3. Comparison of the indices and their use].

Efficacy indices do not contain the same information although they are all combinations of the same two quantities. Therefore, one should choose the proper index. Actually, none is entirely appropriate. Each more or less meets the specifications, depending on the underlying effect model for the therapy considered. However, one can say that the absolute benefit is more appropriate from the patient's point of view, the relative from the scientific point of view and the number of patients to treat from the policy maker's point of view. Nevertheless, this classification needs to be considered with caution. Finally, it emerges from the review that none is fully relevant to express the efficacy of a therapy, even in the most suitable condition, the acute illness.

Drug Evaluation↗