American journal of physiology . iastole and in this manner the beats maycontinue for several minutes. The views advanced to explainthis phenomenon I shall not attempt to discuss here. I wishmerely to record certain facts which seem to indicate thatsudden abnormal changes in blood pressure tend to produce this 1 Lingle: This journal, 1905, xiv, p. 49. 248 D. J. Edwards condition. It is worthy of notice that Sewall and Donaldson,^under the designation of dicrotism of heart action, havedescribed a phenomenon that is apparently the same as I haveobserved, and they state that this character appear
American journal of physiology . iastole and in this manner the beats maycontinue for several minutes. The views advanced to explainthis phenomenon I shall not attempt to discuss here. I wishmerely to record certain facts which seem to indicate thatsudden abnormal changes in blood pressure tend to produce this 1 Lingle: This journal, 1905, xiv, p. 49. 248 D. J. Edwards condition. It is worthy of notice that Sewall and Donaldson,^under the designation of dicrotism of heart action, havedescribed a phenomenon that is apparently the same as I haveobserved, and they state that this character appears uponsudden lowering of the arterial pressure by a very small A of Fig. 6 shows the effect upon the heart actionof a sudden increase in blood pressure. At the point indicatedby the asterisk, in the left hand part of the tracing, the pul-monary artery and left aorta were clamped off, whereuponblood pressure immediately rose with the resultant arhythmiccharacter. It should be added that in this individual the trac-. FiGURE 5. Blood pressure variations that suggest the Traube-Hering waves ofmammals. Time line indicating seconds is also abscissa. ing shown in the entire preceding part of the experiment wasperfectly regular. In the right hand part of the tracing theclamp was removed from the artery and as the blood pressurereturned to normal the arhythmic heart action the use of adrenahn solution the same phenomenon wasevident: When the effect of the extract was at its maximumthe arhythmic character appeared, and, as the constrictor actionwore off and the blood pressure returned to normal, the heartregained its usual rhythm. In tracing B of Fig. 6 we have a similar effect upon the actionof the heart, but in this case it was produced by a lowering ofthe blood pressure. The right half of the tracing shows thenormal rhythm in the early part of the experiment. Later onin the experiment there had been some loss of blood and prob-ably also some loss of vascu
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