UltrasoUnd Physics & instrUmentation - Pegasus Lectures
UltrasoUnd Physics & instrUmentation - Pegasus Lectures UltrasoUnd Physics & instrUmentation - Pegasus Lectures
1. Removing Some of the Simplifications ...............................................................................................775 1.1 The Assumption: Steady State Flow ..........................................................................................776 2. The Assumption: Rigid Flow Conduits ...............................................................................................776 2.1 Elastic Arteries ...........................................................................................................................776 2.2 The Impact on Poiseuille’s Law ................................................................................................776 2.2.2 Compliance ..................................................................................................................777 2.2.3 Pressure Volume Relationship of a Compliant Vessel .................................................778 2.2.4 Pressure Volume Relationship of a Incompliant Vessel ...............................................778 2.2.5 Elastic Veins .................................................................................................................779 2.3 The Assumption: Single Flow Conduit .....................................................................................779 2.3.1 Regulation of Flow ......................................................................................................779 2.3.2 Multiple Vessels: Series and Parallel Combinations ....................................................780 2.3.2.1 Series Combinations ...................................................................................780 2.3.2.2 Parallel Combinations ................................................................................780 2.3.3 Combinations and Effective Resistance ......................................................................781 2.3.4 Extrapolating these Results to Complex Networks .....................................................783 2.4 The Assumption: Conservation of Energy and No Energy Loss to Heat ..................................784 2.4.1 General Heat Loss ......................................................................................................784 2.4.2 Impact on Bernoulli’s Equation and Calculating Pressure Gradients ..........................784 2.4.3 The Assumption: Smooth Straight Vessels ..................................................................784 2.4.4 The Assumption: Large Vessels ...................................................................................785 2.4.5 The Assumption: Newtonian Fluid (and Blood Viscosity) ..........................................788 2.4.6 The Assumption: No Turbulence (and Reynold’s Number) ........................................788 3. Pressure, Flow, and Resistance in the Cardiovascular System (The Simplified Law) ........................788 3.1 Overview ...................................................................................................................................788 3.2 Left Heart ...................................................................................................................................789 3.3 The Arterial System ...................................................................................................................790 3.3.1 Flow and Pressure in the Aorta ....................................................................................790 3.3.2 Arterial Vessel Sizes ....................................................................................................790 3.3.3 Resistance in the Arterial System ................................................................................791 3.3.4 Volumetric Demand and Vascular Bed Resistance ......................................................791 3.3.5 Effective Resistances in the Arterial System ..............................................................791 3.3.6 Flow and Pressure in the Arteries ................................................................................792 3.3.7 Flow and Pressure in the Arterioles ............................................................................792 3.3.8 Flow and Pressure in the Capillaries ............................................................................792 3.4 Venous System ..........................................................................................................................793 3.4.1 Relative Vessel Sizes....................................................................................................793 3.4.2 Resistance of the Venules.............................................................................................793 3.4.3 Resistance of the Veins and the Vena Cava .................................................................793 3.5 Right Heart ................................................................................................................................793 3.6 The Lungs ..................................................................................................................................794 3.7 Return to the Left-Sided Heart ..................................................................................................794 4. The Healthy Cardiovascular System as a Whole ................................................................................794 4.1 Velocity Versus Cross-Sectional Area .......................................................................................794 4.2 Pressure Changes Across the Arterial System ...........................................................................795 4.2.1 Overview ......................................................................................................................795 4.2.2 Increasing Pulse Pressure .............................................................................................796 4.2.3 Decrease in Pulsatility and Pressure Drop ...................................................................796 4.2.4 Pressure Drop Across the Capillaries ...........................................................................797 xxxiv Pegasus Lectures, Inc.
4.2.5 Pressures in the Venous Side are Low .........................................................................797 4.3 The Venous System ...................................................................................................................797 4.3.1 Dichotomizing the Cardiovascular System ..................................................................797 4.3.2 Venous Pressure ...........................................................................................................797 4.3.3 Venous Capacitance and Circulatory Pressure .............................................................798 4.3.4 Hydrostatic Pressure ....................................................................................................798 4.3.5 The Calf Muscle Pump ................................................................................................799 4.3.6 Respiration Related Changes .......................................................................................800 4.3.7 Venous Resistance and Transmural Pressure ...............................................................801 4.3.8 When Things Go Wrong: Effects of Edema ..............................................................802 5. The Subcritical Diseased Cardiovascular System at Rest ...................................................................803 5.1 Asymptomatic Patients ..............................................................................................................803 5.2 Asymptomatic Patients with Exercise (Unmasking a Subcritical Stenosis)..............................805 5.3 Symptomatic Patients and Critical Stenoses .............................................................................807 6. Spectral Doppler as a Means of Assessing Hemodynamics ................................................................808 6.1 What Doppler Tells Us ..............................................................................................................808 6.2 Returning to the Hemodynamic Equations ...............................................................................809 6.3 Characteristics of the Spectrum .................................................................................................809 6.3.1 Systolic Acceleration and Pressure ..............................................................................809 6.3.1.1 Doppler Acceleration for a Healthy Large Vessel ......................................809 6.3.1.2 Doppler Risetime for a Diseased Vessel .....................................................810 6.3.2 The Spectral Window ..................................................................................................811 6.3.2.1 Presence in Healthy Vessel .........................................................................811 6.3.2.2 Absence in Diseased Vessel ........................................................................811 6.3.2.3 Absence of the Spectral Window in a Healthy Vessel ................................812 6.3.3 Systolic Acceleration and Velocity Distribution ..........................................................812 6.3.4 Flow Reversal and Phasicity ........................................................................................813 6.3.4.1 Normal Flow Reversal ................................................................................813 6.3.4.2 Abnormal Flow Reversal ............................................................................814 6.3.4.3 Arterial Signal Components .......................................................................815 6.4 Velocity Criteria .........................................................................................................................815 6.4.1 Peak Velocity ...............................................................................................................816 6.4.2 Mean Velocity ..............................................................................................................816 6.5 Doppler Indices and Ratios........................................................................................................816 6.5.1 General .........................................................................................................................816 6.5.2 Doppler Indices Defined ..............................................................................................817 6.5.3 Interpreting the Doppler indices ..................................................................................817 6.5.4 Angle independence of the Doppler indices ................................................................817 6.6 Murmurs and Bruits ...................................................................................................................818 6.6.1 Murmurs .......................................................................................................................818 6.6.2 A Doppler Bruit ...........................................................................................................818 6.6.3 Harmonic Bruit ............................................................................................................819 6.6.4 Fluttering ......................................................................................................................819 7. Flow Visualization ...............................................................................................................................820 aPPenDIX a: Vascular Principals Introduction ................................................................................................................................................825 1. Electrical Principles .............................................................................................................................825 1.1 Ohm’s Law ................................................................................................................................825 Pegasus Lectures, Inc. xxxv Table of Contents
- Page 1 and 2: Frank r. miele, msee President, Peg
- Page 3 and 4: dedication This book is dedicated t
- Page 5: thank yoU to the FolloWinG imaGe co
- Page 8 and 9: keypoints: The keypoints serve as a
- Page 10 and 11: medium Printed text CD objectives U
- Page 12 and 13: This independent learning education
- Page 14 and 15: 11. Distance Equation .............
- Page 16 and 17: 10. Exercises .....................
- Page 18 and 19: 9.2.2 Examples of Scattering in the
- Page 20 and 21: CHaPTeR 5 - Transducers Introductio
- Page 22 and 23: 2.3 Signals, Noise, and Signal-to-N
- Page 24 and 25: 19.2 Purposes for Cine Review .....
- Page 26 and 27: VolUMe 2 CHaPTeR 7 - Doppler Introd
- Page 28 and 29: 22.4 Color Display and Velocity Int
- Page 30 and 31: 8.3 Transmit Voltages for Various M
- Page 32 and 33: 1.2 Commitment to Quality .........
- Page 36 and 37: 1.2 Power .........................
- Page 38 and 39: 10.3 Pressure Volume Loop .........
- Page 40 and 41: To learn the basics of ultrasound (
- Page 42 and 43: 42 Note: Children generally learn t
- Page 44: Additionally, all fractions can be
1. Removing Some of the Simplifications ...............................................................................................775<br />
1.1 The Assumption: Steady State Flow ..........................................................................................776<br />
2. The Assumption: Rigid Flow Conduits ...............................................................................................776<br />
2.1 Elastic Arteries ...........................................................................................................................776<br />
2.2 The Impact on Poiseuille’s Law ................................................................................................776<br />
2.2.2 Compliance ..................................................................................................................777<br />
2.2.3 Pressure Volume Relationship of a Compliant Vessel .................................................778<br />
2.2.4 Pressure Volume Relationship of a Incompliant Vessel ...............................................778<br />
2.2.5 Elastic Veins .................................................................................................................779<br />
2.3 The Assumption: Single Flow Conduit .....................................................................................779<br />
2.3.1 Regulation of Flow ......................................................................................................779<br />
2.3.2 Multiple Vessels: Series and Parallel Combinations ....................................................780<br />
2.3.2.1 Series Combinations ...................................................................................780<br />
2.3.2.2 Parallel Combinations ................................................................................780<br />
2.3.3 Combinations and Effective Resistance ......................................................................781<br />
2.3.4 Extrapolating these Results to Complex Networks .....................................................783<br />
2.4 The Assumption: Conservation of Energy and No Energy Loss to Heat ..................................784<br />
2.4.1 General Heat Loss ......................................................................................................784<br />
2.4.2 Impact on Bernoulli’s Equation and Calculating Pressure Gradients ..........................784<br />
2.4.3 The Assumption: Smooth Straight Vessels ..................................................................784<br />
2.4.4 The Assumption: Large Vessels ...................................................................................785<br />
2.4.5 The Assumption: Newtonian Fluid (and Blood Viscosity) ..........................................788<br />
2.4.6 The Assumption: No Turbulence (and Reynold’s Number) ........................................788<br />
3. Pressure, Flow, and Resistance in the Cardiovascular System (The Simplified Law) ........................788<br />
3.1 Overview ...................................................................................................................................788<br />
3.2 Left Heart ...................................................................................................................................789<br />
3.3 The Arterial System ...................................................................................................................790<br />
3.3.1 Flow and Pressure in the Aorta ....................................................................................790<br />
3.3.2 Arterial Vessel Sizes ....................................................................................................790<br />
3.3.3 Resistance in the Arterial System ................................................................................791<br />
3.3.4 Volumetric Demand and Vascular Bed Resistance ......................................................791<br />
3.3.5 Effective Resistances in the Arterial System ..............................................................791<br />
3.3.6 Flow and Pressure in the Arteries ................................................................................792<br />
3.3.7 Flow and Pressure in the Arterioles ............................................................................792<br />
3.3.8 Flow and Pressure in the Capillaries ............................................................................792<br />
3.4 Venous System ..........................................................................................................................793<br />
3.4.1 Relative Vessel Sizes....................................................................................................793<br />
3.4.2 Resistance of the Venules.............................................................................................793<br />
3.4.3 Resistance of the Veins and the Vena Cava .................................................................793<br />
3.5 Right Heart ................................................................................................................................793<br />
3.6 The Lungs ..................................................................................................................................794<br />
3.7 Return to the Left-Sided Heart ..................................................................................................794<br />
4. The Healthy Cardiovascular System as a Whole ................................................................................794<br />
4.1 Velocity Versus Cross-Sectional Area .......................................................................................794<br />
4.2 Pressure Changes Across the Arterial System ...........................................................................795<br />
4.2.1 Overview ......................................................................................................................795<br />
4.2.2 Increasing Pulse Pressure .............................................................................................796<br />
4.2.3 Decrease in Pulsatility and Pressure Drop ...................................................................796<br />
4.2.4 Pressure Drop Across the Capillaries ...........................................................................797<br />
xxxiv<br />
<strong>Pegasus</strong> <strong>Lectures</strong>, Inc.
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