CHAPTER 25 



Pulsatile blood flow in the vascular system 



MERRILL P. SPENCER 

 ADAM B . DENISON, JR. 



Department of Physiology and Pharmacology, Bowman Gray 

 School of Medicine, Winston-Salem, North Carolina 



CHAPTER CONTENTS 



Methods of Measurement 



Properties and Principles of Flowmeters 



Cognate Phenomena 

 Elements of Vascular Hydraulics 



Resistance 



Inertance 



Compliance 



Axial Flow 



Radial Flow 



Hydraulic Impedance 



Flow Source Versus Pressure Source 



The Analogy Approach 

 Systemic Arterial Flow 



Blood Flow in the Ascending Aorta 



Pressure-Flow Relationship in the Ascending Aorta 



Ventricular Ejection Gradients 



Windkessel Model of the Arterial System 



Aortic Transformation of Flow and Pressure Pulses 



Resonant — Network Model of the Arterial System 



Transmission Line Model (Distributed System) 



Distribution of the Blood in the Aortic Arch 



Abdominal Aorta and Its Terminal Branches 



Function of the Resonant Wave 



Renal Blood Flow 



Carotid Artery Flow 



Coronary Blood Flow 

 Flow in the Systemic Veins 



Effect of the Heart's Action on Vena Caval Flow 



Effect of Normal Respiration on Vena Caval Flow 

 Pulmonary Flow 



Right Ventricular Ejection Pulse 



Pulsatile Flow in the Pulmonary Capillary Bed 

 Nonlaminar Flow and Murmurs 



Normal Murmurs 



Relationship Between the Murmur of Coarctation Stenosis 

 and Blood Flow Through the Stenotic Area 



The Murmur Envelope and Contour Rule 



General Rules Relating Murmurs to Nonlaminar Flow 

 Normal and Pathological Flow Pulses in Humans 



Flow in the Ascending Aorta 

 Descending Thoracic Aorta 

 Tricuspid Valve 



THE HIGHLY PULSATILE NATURE of the blood flow in 



both the systemic and pulmonary circuits primarily 

 arises from the intermittent action of the heart as a 

 pump. Each ventricle has a valve at its exit and 

 entrance such that the blood flow and velocity 

 oscillate from near zero, when the valves are closed, 

 to relatively great values during the time when the 

 valves are open. Great changes in the velocity arise 

 from the starting and stopping of the blood stream 

 with the opening and closure of these valves. Second- 

 ary causes of flow pulsations, particularly in the veins, 

 arise from the respiratory fluctuations and muscular 

 contractions. 



I. METHODS OF MEASUREMENT 



Methods for the detection of blood flow and pres- 

 sure oscillations within this system require a frequency 

 response flat to at least ioo cps and without phase 

 shift. Present day pressure systems achieve this ideal 

 quite well if one does not introduce long elastic 

 catheters between the pressure tap and the transducer. 

 Present day blood flowmeters, however, have not 

 achieved this degree of perfection, but recently great 

 progress has been made. In addition to the frequency 

 and phase characteristics mentioned, a blood flow- 

 meter should be capable of detecting the blood flow or 



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