[Physical reproduction of cardiac sutures. A new field of investigation in cardiology]. / Reproduction physique des structures cardiaques. Une nouvelle voie d'exploration en cardiologie.

A new technique of physical reproduction of cardiac anatomy has been developed from volumetric data and its practical value assessed in cardiological practice. The acquisition of the volumetric data was by 3D echocardiography. Parallel and equidistant 2D views were selected from this information. The images were printed at a scale adjusted to the true dimensions of the structures of interest and then stuck on a support, the thickness of which was identical to the distance between the views, and the slices were superimposed while respecting the initial orientation. This technique has been adapted secondarily to modern industrial processes of rapid prototyping (3D printing and powdering) allowing automatic tooling of models. Several physical models have been made: whole heart in end diastole, mitral valve stenosis and prolapse, atrial septal defect with insertion of a percutaneous prosthetic device, great vessels at the base of the heart. There are many possible cardiological applications of physical models: investigation of complex cardiac disease, pre- and per-operative simulation of surgical procedures, elaboration of prosthetic material, physiopathological studies, teaching and training, patient information.

[Evaluation of sino-atrial function using the method of extrasystole induced by constant-relative premature impulses. 1. Method and normal results]. / Evaluation de la fonction sino-auriculaire par la méthode des extrasystoles provoquées de prématurité relative constante. 1. Méthode et résultats normaux.

Atrial pacemaking under conditions of relative constancy (40 or 50% of the preceding cycle) enables us to calculate the immediate sino-atrial conduction time (retrograde and antegrade) (SACT). 17 patients were chosen for their normal sino-atrial function under spontaneous changes of the sinus cycle (SC). In each case, a significant inverse linear relationship was found between SACT and the corresponding SC. The mean correlation slope was -0.36 in 10 patients with no post-pacing depression (PPD). The slope was greater in 7 patients with a PPD (-0.89); if this depression is taken into account when the SACT is calculated, the slope decreases. In 5 patients, atropine (1 mg I.V. reduced the mean value of SC, and shortened (constant relative value) the SACT. The mechanisms for the spontaneous and induced variations in the sinus output are discussed; it may be that there are substitute pacemakers within the cells of the sino-artrial node, which are affected by variations in sympathetic or parasympathetic activity or by pacing. In clinical practice, automatism and conduction with the sinus node should be interpreted as inter-related functions, both under normal conditions and after vagal block.

[Pacemaker treatment of tachyarrhythmias by programmed rate-related interval stimulation(author's transl)]. / Schrittmachertherapie tachykarder Rhythmusstörungen durch frequenzbezogene Intervallstimulation

Programmed rate-related interval stimulation proved to be a low-risk method when applied to 74 patients with drug-resistant ventricular tachycardia or runs of ventricular extrasystoles as precursors of tachycardia. Atrial flutter was converted to atrial filbrillation and sinus rhythm by atrial interval-related multiple stimulations. Tachycardias, which could not be terminated by simple or double stimulation, were successfully suppressed by sequential ventricular R-R related multiple stimulations. Rare-related stimulation has proved to be an alternative method of treating tachy-arrhythmias unresponsive to conventional means.

[Orthorhythmic pacemaker and salvo-like cardiac stimulation. New procedure aiming at the suppression and prophylaxis of cardiac arrhythmia and the determination of electrophysiological measurement magnitudes in vivo]. / Orthorhythmischer Herzschrittmacher und salvenförmige Herzstimulation Ein neues Verfahren zur Unterdrückung und Prophylaxe tachykarder Herzhythmusstörungen und zur Bestimmung elektrophysiologischer Messgrössen in vivo

The orthorhythmic pacemaker (ORPM) represents a new apprach in cardiac stimulation. The use of conventional demand pacemakers is essentially limited to the treatment of bradycardic arrhythmias. The principle of the ORPM consists in early stimulation after premature beats, taking into account the R-R interval of the preceding spontaneous beat. In this "extrasystolic pacing" the escape interval is not fixed; rather, the premature electric stimulus will be fired after an interval, the duration of which can be selected as a fraction of the preceding cycle length. The ORPM enhances the possibilities for treatment of atrial and ventricular tachycardias due to re-entry. The idea of "bursts" of stimulation e.g. the firing of up to ten impulses within a short time, is put into practice in the actual latest ORPM model. It widens the application of the ORPM principle and allows simplified measurement of the refractory period.