Auricular fibrillation and its relationship to clinical irregularity of the heart / by Thomas Lewis.

  • Lewis, Thomas, Sir, 1881-1945.
Date:
[1910?]
Catalogue details

Licence: In copyright

Credit: Auricular fibrillation and its relationship to clinical irregularity of the heart / by Thomas Lewis. Source: Wellcome Collection.

    34/80 (page 336)
    known that auricular fibrillation may be of many grades, the movement of muscle levers is fine or coarse in the same exjjeriment or from animal to animal. It is only rarely that an actual correspondence can be found between the individual muscle movements and the electric variations, and this is to be expected, for the whole auricle is active, and only a small portion of the muscular movement is recorded. Nevertheless, correspondence may be found in some degree. When the muscular movement is small, and the vibration of the lever rapid, the oscillations tend to be of small excursion and, as seen under vagal stimulation, may reach a rate of 900 or more per minute.* With the coarse fibrillary movements on the other hand, the electrical variations are of greater amplitude and are slower. Fig. 20 shows simul- taneous curves from ventricle and auricle, and an electrocardiogram. In the left hand portion of the figure the auricle is fibrillating, the ventricular beats are irregular, the movement in the auricle is of the coarse variety. In this instance the auricular muscle, though fibrillating, ap2:)ears throughout to be on the borderland of a return to co-ordinate contraction. Thus in the last half of the fibrillary period the separate vibrations, as seen in the muscle curve, are almost though not absolutely regular at a rate of 450 per minute. The movement in the first half of the fibrillary period is more disorderly and a little more rapid. The figure is a reduction of a greatly magnified photograph of the original curve. During the whole of the fibrillary period it is possible to establish a definite relationship between the individual movements expressed by the auricular curve and the oscillations which ajjpear upon the electric curve. During the last half of the fibrillary period (R' to R’^) an oscillation falls with each of the peaks R and with each of the variations T. As a result the height of these weaves is enhanced, and a picture bearing a superficial resemblance to 2 : 1 heart-block is produced. The rate of the auricular movement, the absence of absolute regularity and the great reduction of the auricular muscular movement when compared to the normal demonstrate, however, that this portion of the curve cannot be interpreted m this way. In the earlier portion of the curve (beats 2-7) the auricular mco-ordination is more clearly visible, but here also a complete analysis of the electrocardiogram is possible by exact fixation of the instants at which the individual auricular and ventricular movements fall. The curve as a whole IS a complex picture composed of an accurate super-imposition of R and T ‘rf° pi’t ‘ ventricular systoles, and of auricular variations, fik n f ■ seem that the oscillation appearing in auricular fibres*'and that* “''‘‘Re® occurring in the individual otaT’result of 'ovement of the myoeardiograph lever is the ndilidua fibres Tf™; ’“ “-'d relaxations of the contractfon 1^,' th fi’^-'es are in llc^a e when ! “*i T u- such a state would be ant.c.pated when the auricle is tending to return to a normal or co-ordinate Speaking of tlio coarser oscillations only.