CHAPTER 23 



Functional anatomy of cardiac pumping 1 



GERHARD A. BRECHER 

 PIERRE M. GALLETTI 



Department of Physiology, Emory University 

 School of Medicine, Atlanta, Georgia 



CHAPTER CONTENTS 



Macroscopic Structures 



Composition of Cardiac Tissues 



Architecture of the Ventricular Myocardium 



Architecture of the Atrial Myocardium 

 Pressure and Flow Effects During the Cardiac Cycle 

 Correlation of Other Cardiac Events With the Cardiac Cycle 



Atrial Pressures 



Electrocardiogram 



Vibrocardiogram (Apex Cardiogram I 

 Function of the Heart Valves 



Veno-Atrial Junction 



Atrioventricular Valves 



Arterial Valves 

 Ventricular and Atrial Volumes in Various Activities 



Ventricular Volume 



Atrial Volume 

 Atrial Filling 

 Ventricular Filling 



Differences Between Right and Left Cardiac Cavities 

 The Pericardium 

 Closing Remarks 



ALTHOUGH THE PURELY MECHANICAL NATURE of 



cardiac pumping is taken for granted by modern 

 scientists, this view has not always been accepted in 

 the past. Only during the last hundred years were the 

 forces of muscle contraction finally stripped of the 

 'vis vitalis' and ascribed exclusively to energy trans- 

 formation according to the laws of physics and 

 chemistry. In this historical process, the heart which 

 had been formerly thought of as the seat of emotions, 

 was deprived of all metaphysical connotations and 

 became an organ of purely mechanical function just 



1 The results of some recent experiments of the authors and 

 their colleagues are quoted in this paper. This work was sup- 

 ported in part by USPHS grant H-3796, and grants from the 

 Life Insurance Medical Research Fund and the Georgia 

 Heart Association. 



as the skeletal muscle. It is of interest to trace briefly 

 the emergence of this concept (160, 161). 



During the age of the pyramids (3000-2500 B.C.) 

 an unknown Egyptian clearly recognized the heart 

 as the center of a system of distributing vessels and 

 associated the pulse with the cardiac beat. The Greek 

 philosopher Alcmaeon of Croton (about 500 B.C.) 

 distinguished the veins from the arteries and asserted 

 that the seat of sensation was not in the heart but in 

 the brain. The function of the heart as a pump was 

 apparently expressed for the first time by Plato (427- 

 347 B.C.) when he stated: it "pumps particles as from 

 a fountain into the channels of the veins, and makes 

 the stream of the veins flow through the body as 

 through a conduit." Hippocrates (493-423 B.C.) 

 had described the cardiac valves, the ventricles and 

 the great vessels, but he did not refer to the pumping 

 action, which he might have taken for granted. For 

 Aristotle (384-322 B.C.) the heart was the seat of 

 "innate heat" and also of the soul. This notion was 

 probably based on the observation that death results 

 from dissection of the beating heart. However, from 

 his studies on the embryonic chick heart Aristotle 

 may have had knowledge of the pumping function. 

 Erasistratus (310-250 B.C.), who described the 

 aortic valves, pulmonary valves, and chordae 

 tendineae, and Galen of Pergamon (131-201 A.D.) 

 both stated that the heart is a pressure-suction pump. 

 Their view was founded mainly on the assumption 

 that during diastole blood was sucked into the 

 ventricles by active enlargement of the cardiac walls 

 [discussed by Ebstein (40), Bohme (14)]. They also 

 believed that blood is expelled backward into the 

 caval veins during ventricular systole. The first 

 definite statement concerning the continued forward 

 flow of blood from the right ventricle through the 

 lungs into the left heart was made by Ibn an-Nafis 

 (1210-1299 A.D.). The first scientist of the Renais- 



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