Auricular fibrillation and its relationship to clinical irregularity of the heart / by Thomas Lewis.
- Thomas Lewis
- Date:
- [1910?]
Licence: In copyright
Credit: Auricular fibrillation and its relationship to clinical irregularity of the heart / by Thomas Lewis. Source: Wellcome Collection.
64/80 page 366
![of impulse formation is relatively liigli so far as the ventricle is concerned. The main delay is in the bundle itself.* The close analogy between the two sets of curves allows of similar con- clusions in the clinical instance. The difference in the P-H intervals of normal and abnormal beats in the patient is greater than in the experiment. But the auricle of man is larger than that of the tlog. 3die normal intervml in the [)atient is nearly twice that found in the animal. Rc'turning again to the clinical case, in Pig. 28 it will be seen that there is irregularity during the paroxysm itself, and that this irregularity is due to the i)rcsence of premature beats intei'rupting an otherwise regular rhythm. One of the interrupting beats has been caught electrocardio- graphically and is shown in Pig. 30, The extra beat is of the type recognised as due to an extrasystole of the left ventricle. Now’ the pause w'hich follows the premature beat is fully compensatory, and this in itself is valuable confirmatory evidence' of the auricular origin of the ectopic rhythm which it disturl)s. The su])raventricular origin of the paroxysmal beat is also shown l)y the shape of the ventricular electric com])lex. Another point of interest in the clinical curves is well seen in the first escaped beat of Pig. 26. Here neither normal nor inverted \ariation is present. Such heart cycles have been of common occurrence in this ])atient at the termination of |)aroxysnis, and many such beats interru])t the normal rhythm. A comj)lete ])ai'allel is found in beat 15 of Pig. 2i). One may infer from an examination of the intervals, if not from a priori arguments based on the isoelectric interval directly ])i’eceding the peak K’\ that this is an example of a transition form between beats 14 and 16. 'Phat is to say, that w'c are dealing with a beat which starts at a higlu'r level than beat 14, and at a lower level than beat- 16. In brief, it has its origin at a ■|)oint lying between tin* normal ])ace-makert and the lowest or junctional level of the auricular tissue. 'The same conclusion applies to clinical beats of a similar nature seen in Pig. 26. Of the esca])('d beats in Pig. 26, the first and second probably belong to this catc'gory, w hile the third is of the same nature as the beats of the paroxysm. * J hat auricle is net (giving the pace to (lie \cntriclc is certain, for the folK)\viiig reasons:—.An increased coiuluctivity would not he expected tluring the clinical paroxysm, for the rate is increased. Neither would a gradually decreasing comhictixity ho anticipated in the escapoil heats following the librillation, for the rate is lowered and blocking of some of tho fibrillary impulses was previously present. f tor the [)ur[)f)ses of tho argument thei’e is no need to place the normal pace-maker of tho heart in the neighbourhood of the superior vena cava, but as a matter of fact the evidence as a whole ])oints in this direction. In a single ex|)erimont, using direct leads from varit)us parts of a dog s auricle, it was found that the neighbourhooil t)f the su])erior vena cava becomes oloctionegati\0 or acti\'o before either aj)])cnilix, inferior ^■ena ca\ a or a [)oint of musculature at the groove directly below the sui)erior vena ca\a on tho front of the heart. In several experi- ments it was found that the auricular electric complex of extrasj’stolos iiulucod in different parts of the auricle shows notable variations. 'I’lio auricular complex of extrasystoles originating near the superior vena cava resembles tho normal eomidox most closely. This evidence points very ilelinitely to tho lausenco of the paco-makor in the neighbourhood of tho superior cava.](https://iiif.wellcomecollection.org/image/b29000610_0064.jp2/full/800%2C/0/default.jpg)
