Functional Heart Mechanisms

Abstract

Studies on frogs, turtles, rabbits, cats, dogs, and man over more than 20 years and participated in by numerous associates, including Doctors Kruse, Waddel, Koenig, Criep, Hover, McLain, and Lauler have led to numerous conclusions:

I. Contraction normally begins in the superior vena cava and spreads to auricles and ventricles. The evidence and proof include: a. Direct observation. b. Simultaneous recording of contraction of veins, auricles, and ventricles alone and combined with galvanometric recording of electrical variation. (Fig. 1.) c. Sequence of recovery from vagus inhibition. (Fig. 2.) d. Transmission of premature venous contractions to auricles and ventricles. (Fig. 2.) e. Photographic (cinema) recording.

In man, the evidence is mainly derived from polygraphic and gal-vanometric records, the hitherto occasionally observed, but unexplained U-wave corresponding to the venous electrical variation observed in lower animals. It may be observed in most subjects by increasing galvanometer sensitivity as by slacking the fibre, and placing one electrode in the supra-sternal notch, right supra-clavicular fossa or in the mouth. Standard figures showing time relations of heart activities recorded simultaneously by different means as by polygraph and galvanometer are confirmatory.

II. Heart abnormalities and experimental irregularities as arhythmias, alternation, etc., are usually due to changes in fundamental properties of tissues or their time relations. Other cause, as failure of conduction or spread of excitation— “block” in the current sense —at most, is rare. Due regard to the composite character of gross manifestations, i. c., the algebraic summation of unit or segmental response, is of utmost value in heart studies as in all other tissue studies.

III. Differences in different species studied are mainly, if not wholly, quantitative.

IV. Venous and auricular galvanometer records, when taken as entities, show form and characteristics very similar to ventricular ones, provided the galvanometer is adjusted for adequate sensitiveness.