Lohff / Schaefer Cardio-Physiology Challenging Empirical Philosophy

Three Essays
1. Auflage 2022
ISBN: 978-3-7568-2362-8
Verlag: BoD - Books on Demand
Format: EPUB
Kopierschutz: 6 - ePub Watermark

E-Book, Englisch, 264 Seiten

With this volume of three essays, the authors want to create an opportunity for dialogue between different disciplines by taking a closer look at three cardio-physiological examples. In the essays presented, we will look at the exploration of different cardiological topics from the 20th century, all of which have contributed to a better understanding of certain aspects of cardiac activity. Not only do these insights provide a more complete picture of these cardiac phenomena, but it is also within this context that we can look for and into the patterns of regularities which govern this living organism. Our goal is to stimulate a dialogue on the philosophy of science in the spirit of Hans Reichenbach.

Brigitte Lohff, born in 1945, worked as a criminal psychologist in Hamburg after studying psychology. She received her doctorate in the history of science in 1977 and her habilitation in the history of medicine at Kiel University in 1986. From 1994 until her retirement in 2013, she held the chair for the history of medicine at the Hanover Medical School. She authored ca. 200 publications on the history of physiology, cardiology, and philosophy of medicine, as well as on gender medicine.

Autoren/Hrsg.

Lohff, Brigitte

Schaefer, Jochen

Leseproben

CARDIO-PHYSIOLOGY CHALLENGING EMPIRICAL PHILOSOPHY
ESSAY I The Physiological Function of the Force-Interval Relationship: A Forbidden Question? Brigitte Lohff / Jochen Schaefer
In cooperation with Johann P. Kuhtz-Buschbeck and Ekkehart Rumberger TABLE of CONTENTS Introduction 1.1. The historical background of the Force-Interval Relationship 1.2. Steps towards the exploration of the Force-Interval Relationship 1.3. Different explanatory models The clinical relevance of artificial stimulation of the heart 2.1. Are there metabolic and/or largely physiological limitations for the effectiveness of the FIR? 2.2. Do cardiac output and blood pressure change under resting conditions and physical exertion during artificial heart stimulation? 2.3. What kind of relationship exists between FIR and the Frank-Starling mechanism? 2.4. "The frequency stress test" 2.5. Influencing the force of contraction 2.6. Research into the interaction between cardiac activity and circulation 2.7. The recording of monophasic action potentials [MAP] The negative staircase-phenomenon and its clinical relevance The molecular lens: David T. Yue’s path from the macroscopic level of the FIR to the nano-level of e-c coupling Hypotheses on the scientific theoretical classification of the FIR in heart mechanics ANNEX: Publications of the Kiel-Hamburg Group 1970 – 2000 References Cover picture: Scheme of the Heart ©B. Lohff/ Fig. from: J. Schaefer: Darstellung des Aortendrucks, 1971, p. 357 (Permission to reprint by Springer Nature) 1. Introduction In 1983, Arnold M. Katz wrote a historical review of the 30-year development of research into the Regulation of Myocardial Contractility from the perspective of a "brief and personal history.” Katz paraphrased this history of research with a playful yet apt metaphorical subtitle, calling it “An Odyssey”.39 Jochen Schaefer has been working on the force-interval relationship of the heart [FIR] in clinical research since the 1960s, both theoretically and practically. As a member of a research group of cardio-physiologists, he has also experienced an odyssey in the elucidation of the function of the FIR and has personally helped to shape it. The following paper uses a historical perspective to trace the development of hypotheses, experiments, and knowledge on the role of the FIR in cardiac mechanics. The written sources of the last 60 years of research on FIR will be underpinned and supplemented, taking into account the personal perspective on this history of research. 1.1. The historical background of the Force-Interval Relationship The intensive study of the phenomenon of the force-frequency/interval relationship [Force-Interval Relationship = FIR]40 resulted from the therapeutic application possibilities of pacemaker technology, which have been emerging since the 1960s. The evolving technology of the artificial stimulation of the heart (electrostimulation, cardiac excitation) also contributed to the intensive study of FIR. The artificial, and also the natural, excitation of the heart muscle are due to electro-mechanical coupling. The basic principles and current understanding of electromechanical coupling (e-c coupling = excitation-contraction-coupling), underlying the phenomenon of the force-frequency relationship FIR, are often presented in the recently published corresponding diagrams, such as for instance by Bers.41 The well-known simultaneously records of the course of the action potential, the influx of calcium ions and the resulting contraction illustrate the interdependence and the time sequence of three different parameters: The action potential [AP measured in the unit mV], which is the trigger for the influx of calcium ion [Ca2+ measured in the unit nMol] into the cell. The influx of Ca2+ triggers the cellular processes that lead to muscle contraction. The course of the contraction is recorded schematically via the percentage change in the length of the heart muscle cell. The dependence of the force development of a heart muscle on the (preceding) stimulus interval (i.e., the frequency) during electrostimulation – later known as the staircase phenomenon – was first described in 1871 by Carl Ludwig's American student Henry Pickering Bowditch (1840–1911)42 at the Leipzig Physiological Laboratory.43 The following experimental observation was thus described - as summarized by Schütz in 1958: "He [Bowditch] observed that the first amplitude of contractions after a longer resting period was lower than the amplitudes of the contractions registered before the period of rest. The contractions following the first beat gradually increased in amplitude again. This staircase phenomenon occurs especially after prolonged cardiac arrest."44 Bowditch had already suspected a far-reaching significance of the staircase phenomenon for the understanding of heart mechanics: "The interval between a contraction of the heart and the pre-ceding beat is of such importance for the strength of the contraction that a study of these effects a prime necessity."45 Bowditch's observation was never followed up on though in either Ludwig's laboratory or any other research group. Only 30 years later, in 1902, Robert Session Woodworth (1869-1956) developed his staircase concept based on Bowditch's work.46 He verified this phenomenon experimentally and provided an initial physiological explanation for this effect: "The length of the optimum interval is governed by the interplay of two opposing factors, […] No long series of rapid beats is necessary to produce an increase in height. A single contraction following another at a short interval is sufficient to increase the height of the following contractions. The shorter also the interval between two contractions, the greater is their strengthening effect on the following contractions. [...] The two opposing factors are then the stimulating effect of a rapid succession of contractions, and the recuperative effect of a long pause. On the one hand, the following of one contraction close upon another acts to accelerate the production of available energy immediately afterwards; but on the other hand, the production of available energy is a gradual process, and a long pause enables more to accumulate than does a short pause. A short interval preceding a contraction tends to make that contraction weak and the following contractions strong."47 In the following six decades of the 20th century, roughly 200 publications that dealt with the force-interval relationship appeared, however, they mainly considered changes due to chemical and physical influences.48 The significance of this phenomenon was interpreted by Schütz in 1958 as follows: "Thus, the staircase phenomenon reveals the relationship between two basic biological states: rest and activity. In other words, the staircase creates a condition favorable to activity, which deteriorates during inactivity, and vice versa, inactivity and rest create a favorable intracellular milieu for themselves and stabilise themselves by making it more difficult for the activity to develop again."49 The characteristic features of the course of the "staircase phenomenon" (“Treppe-Phänomen”) in the isolated heart muscle was already presented in a diagram by Woodworth in 1902.50 1.2. Steps towards the exploration of the Force-Interval Relationship From the mid-1960s onwards, new - also clinically relevant - possibilities for artificial heart stimulation developed utilizing pacemaker technology. In this context, several research groups were formed internationally - including in Kiel and Hamburg - to study the theoretical and clinical aspects of artificial heart stimulation (electro-stimulation). At that time, physiologists in general had different approaches for investigating physiological problems, which were also used in FIR research. The respective experiments in the research context of the stair phenomenon led to partly contradictory results. In 1963, the research situation could be characterized as follows: "Nevertheless, much confusion remains regarding the processes underlying the interval-strength relationship and their interaction. Apparent conflicts have arisen because of attempts to generalize from observations made on a single species or on muscle from a single region of the heart. Seemingly contradictory results have been obtained under experimental conditions that differed with respect to temperature, ionic environment, oxygen supply, and other factors."51 Further confusion in the investigation on “the staircase effect” resulted from the terminology used to describe this phenomenon: "The terminology has become increasingly confusing: basic processes have been referred to by terms that describe only one of their manifestations and in some cases several manifestations of the same process have been described as independent entities. Some of the terms that have been used suggest knowledge of the changes in the myocardium which are responsible for the...