[The importance of multivariate statistical procedures in the diagnosis of acute radiation injuries in man]. / Die Bedeutung multivariater statistischer Verfahren für die Diagnostik von akuten Strahlenschäden am Menschen (Kurzmitteilung).

Data published in international papers were analyzed and submitted to a multidimensional variate and discriminant analysis. In this analysis, information on prodromal symptoms and on hematological alterations 24 hours after irradiation was considered. As a result of the analysis it was pointed out that by means of a discriminant function the classification of persons to the four degrees of radiation sickness is possible with a computed false rate of classification of nearly 20% and a dose-effect-relation exists between discriminant scores and computed whole-body doses.

A new principle of rate adaptive pacing in patients with sick sinus syndrome.

The most "natural" rate adaptive pacemaker is VDD for patients with AV block. Nothing equivalent exists for patients with sick sinus syndrome (SSS). Even if they are paced in the AAI mode, the AV synchrony is often lost under exercise if nodal rhythms develop which cause the atria to contract against closed valves by retrograde conduction. We tried to develop a concept of rate adaptive pacing which is applicable in SSS patients by guaranteeing AV synchrony. It is known that AV delay shortens with increasing rate under exercise in normal subjects. Three AAI paced patients were evaluated to find out whether a similar correlation is valid between exercise and AV delay with constant rate. A nonconventional ECG was registered during the whole procedure by using an analog tape recorder. The pacing rate was changed with and without exercise on a bicycle to determine its influence on AV delay and by calculating the AV delay averaged over the last 8 beats. In all three patients a reproducible correlation existed between exercise and shortening of the AV delay. This effect was already detectable after 10 s. Increasing the pacing rate above "physiological" rates caused prolongation of the AV delay (over-stimulation phenomenon). We, therefore, concluded that measuring the AV delay in atrial paced patients with SSS by means of a ventricular electrode can be used as a fast parameter for rate adaptive pacing with AV synchrony. The "over-stimulation" phenomenon can additionally be utilized for controlling "physiological" rates depending on individual needs.