Further observations on heart-block / by G. A. Gibson and W. T. Ritchie.

Date:
1907
Catalogue details

Licence: In copyright

Credit: Further observations on heart-block / by G. A. Gibson and W. T. Ritchie. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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    occurrence of the wave 5 is readily observed. A point, to which we would particularly draw attention, as it is one which has not been hitherto demonstrated in the human heart, is the excessive length of the interval between the contraction of the fibres of the superior vena cava and the succeeding auricular contraction. This interval, the 5—a interval, is of almost constantly uniform duration throughout the tracings, being equal to o'6 of a second, though sometimes slightly shorter or longer. The excessive length of the 5—a interval can only be explained by a depression of conductivity of the fibres passing from the superior vena ,cava to the right auricle. We are confirmed in this belief by our analysis of tracings taken both before and after the administration of -fa gr. of atropine. Whereas the 5—a interval was equal to o* 6 of a second before that drug was given, 11 minutes after its administration the interval was only 0-4 of a second, half-an-hour after the atropine, the 5—a interval was 0*52 of a second, and, after one hour, that interval was again equal to o • 6 of a second. Comparing these results with those of the conductivity of the auriculo-ventricular bundle of the same case, we find that the improvement in the conductivity of the fibres between the vena cava and the auricle on the one hand, and of those of the auriculo-ventricular bundle on the other, was induced by atropine simultaneously, and that as the transient benefit, occa- sioned by that drug, passed off, the conductivity of both sets of fibres fell gradually and simultaneously to the former level. The condition of the blood-pressure in cases of heart-block has not as yet received much attention. About two years ago, certain facts bearing upon this aspect of the condition were mentioned by one of us,1 and the statement was amplified last year.2 During the careful observations which were made on the patient, whose case is fully detailed in the present paper, the blood-pressure was repeatedly observed. The highest systolic pressure recorded at any time was 190 mm. Hg., and, with this maximum systolic pressure, the mean diastolic pressure was 80 mm. Hg. At other times, with a systolic pressure of 175, the diastolic pressure was 75 mm. Hg. Here, therefore, as was stated in the contributions already 1 Edin. Med. Jown., 1905, Vol. XVIII., New Series, p. 9. 1 Brit. Med. Journ., 1906, Vol. II., p. 1113.