o_1977r8vv9vk1ts2ms0kd8pksa.pdf

a Contents XIII
Heart and Great Vessels ........... 92
References .................... 93
8 Biological Safety
of Diagnostic Sonography .......... 95
Dev Maulik
Introduction ..................... 95
Acoustic Output of Diagnostic Ultrasound
Devices and Its Regulation ........... 96
Mechanisms of Bioeffects ........... 96
Thermal Effects ................... 96
Acoustic Characteristics ........... 97
Tissue Characteristics for Thermal Effect 98
Cellular Response to Heating, Acoustic
Power, and Temporal Threshold ..... 98
Experimental Evidence of Thermal
Effects ....................... 98
Acoustic Heating of Fetal Bones ..... 99
Acoustic Heating of Fetal Brain ..... 99
Clinical Significance of the Ultrasound
Thermal Effects ................. 99
Mechanical Effects ................ 101
Cavitation .................... 101
Acoustic Characteristics for Cavitation . 102
Ambient Pressure and Temperature .. 102
Tissue Characteristics for Cavitation .. 102
Biological Effects of Inertial Cavitation . 102
Clinical Significance of Acoustic
Cavitation .................... 103
Experimentally Induced Developmental
Bioeffects ....................... 104
Epidemiological Evidence of
Developmental Bioeffects ......... 104
General Outcome ............... 105
Fetal Movement ................ 105
Birth Weight ................... 105
Pediatric Malignancy ............. 106
Neurodevelopment ± General ...... 106
Neurodevelopment ± Sinistrality ..... 106
Clinical Significance .............. 107
Guidelines for Clinical Application ...... 107
References .................... 108
9 Fetal and Maternal Cardiovascular
Physiology ..................... 113
Joseph Itskovitz-Eldor, Israel Thaler
Uterine Circulation ................ 113
Functional Anatomy
of the Uteroplacental Circulation .... 113
Alterations in Uterine Blood Flow ...... 114
Regulation of Uteroplacental Circulation 115
Fetal Circulation .................. 116
Fetal Cardiac Output and Distribution . 117
Regulation of Cardiac Function ...... 117
Patterns of Venous Returns ........ 121
Umbilical-Placental Circulation ...... 123
Cardiovascular Responses to Stress ... 125
References .................... 127
10 Umbilical Doppler Velocimetry:
Normative Data and Diagnostic Efficacy 133
Dev Maulik
Doppler Interrogation of the Umbilical
Artery ......................... 133
Continuous-Wave Doppler Interrogation 133
Pulsed-Wave Doppler Interrogation ... 134
Doppler Display and Archiving ........ 134
Descriptor Indices of the Umbilical Arterial
Doppler Waveform ................ 134
Reproducibility of Umbilical Arterial
Doppler Indices ................ 135
Continuous-Wave Versus Pulsed-Wave
Doppler Indices ................ 136
Site of Doppler Interrogation ......... 136
Short-Term Temporal Variations:
Diurnal Effect .................... 137
Long-Term Temporal Variations: Gestational
Age Effect ...................... 137
Fetal Heart Rate .................. 138
Breathing ....................... 140
Behavioral States ................. 141
Blood Viscosity and Doppler Indices .... 141
Maternal Posture and Umbilical Arterial
Doppler Indices .................. 141
Maternal Exercise and Umbilical Arterial
Doppler Indices .................. 142
Summary ....................... 142
References ...................... 142
11 Fetal Descending Aorta ............ 145
Karel MarsÏ—l
Fetal Aortic Doppler Velocimetry ...... 146
Aortic Flow Estimation ........... 146
Aortic Velocity Waveform Analysis ... 147
Fetal Aortic Flow in Uncomplicated
Pregnancies ..................... 149
Intrinsic Influences on Fetal Aortic Flow
and Flow Indices .................. 151
Fetal Aortic Blood Flow During Labor ... 151
Pathophysiologic Changes of Fetal Aortic
Flow During Intrauterine Hypoxia ...... 151
Clinical Studies ................... 153
Fetal Cardiac Arrhythmias ......... 153
Fetal Anemia .................. 153
Diabetes Mellitus ............... 154
Intrauterine Growth Restriction ...... 154