Doppler Echocardiography for the Small Animal Practitioner

Preface xi About the Companion Website xiii 1 The Basics: What You Need to Know 1 Doppler Principles as They Apply to Accuracy and Quality of the Exam 1 Doppler shift 1 Types of Doppler 2 Advantages and disadvantages of each type of Doppler 4 The spectral display 4 The color display 6 Nyquist limit and aliasing 8 Accuracy of spectral flow information 12 Optimizing Doppler Displays 14 Color flow 14 Spectral Doppler 19 Laminar and Turbulent Flow 21 Normal laminar flow 21 Turbulent flow 21 Causes of spectral broadening 22 2 The Doppler Examination 23 Spectral Doppler 23 Normal spectral flows in the heart 23 Mitral valve 23 Aorta and LVOT 26 Pulmonary artery and RVOT 27 Left ventricular isovolumic relaxation time (IVRT) 31 Pulmonary venous flow 32 Left auricular flow 32 Color Flow Doppler 37 Normal color flow in the heart 37 Mitral valve 37 Aorta 38 Pulmonary artery 43 Tricuspid valve 47 3 Applications 55 Pressure Gradients (PGs) 55 PG meaning 55 Normal pressures in the heart and vessels 55 Bernoulli equation 55 Modified equation 55 How can blood flow when pressures in the ventricles and great vessels are the same?  57 Factors Affecting Flow Velocities 57 Volume 57 Narrowed pathway 57 Pressure 57 Limitations of the simplified Bernoulli equation 59 Common Applications of PG in Acquired Heart Disease 59 Using mitral regurgitation 59 Hypertrophic cardiomyopathy 62 Pulmonary hypertension 63 Diastolic Function and Doppler 66 Definitions 66 Classes of diastolic dysfunction 66 Overview of diastolic function 72 4 Doppler Features in Common Acquired Cardiac Diseases 77 Chronic Valve Disease 77 2D and M-mode features 77 Color flow evaluation 77 Spectral Doppler 80 Dilated Cardiomyopathy 82 2D and M-mode features 82 Color flow evaluation 84 Spectral Doppler 84 Hypertrophic Obstructive Cardiomyopathy 84 2D and M-mode features 84 Color flow evaluation 85 Spectral Doppler 87 Diastolic function 88 Dynamic Right Ventricular Outflow Tract Obstruction (DRVOTO) 88 2D and M-mode features 88 Color flow evaluation 90 Spectral Doppler 90 Nonspecific Cardiomyopathy 90 2D and M-mode features 90 These result in diminishing systolic function 90 Color flow evaluation 90 Spectral Doppler 91 Pulmonary Hypertension 92 2D and M-mode features 92 Color flow evaluation 93 Spectral Doppler 93 Appendix 1 Spectral Doppler Reference Ranges for the Dog and Cat 99 Appendix 2 Abbreviations 103 Recommended Reading 105 Index 107