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A Survey of Medical Imaging Systems
Published in Robert B. Northrop, Non-Invasive Instrumentation and Measurement in Medical Diagnosis, 2017
The moving objects are generally RBCs; there are ∼5 × 106 RBCs in a cubic mm of blood. Each RBC is a flattened disk of ∼7.5 μm diameter and ∼1.9 μm thick on the edge and ∼1 μm thick in the center. Thus, RBC dimensions are ≪λ of the ultrasound, which means they are way too small to present ultrasound images. Also, in blood vessels with laminar flow, the blood velocity has a parabolic profile, maximum at the center and zero at the vessel walls. In the great arteries and in the chambers of the heart, flow can be turbulent over parts of the cardiac cycle. Thus, the reflected Doppler signals from blood are a superposition of many, many small, scattered signals from moving RBCs with different cross sections and velocities. In general, the intensity of the Doppler-shifted backscatter from moving RBCs is ∼40 dB less than that from surrounding tissues (Routh 1996).
Mechanotransduction in Heart Formation
Published in Juhyun Lee, Sharon Gerecht, Hanjoong Jo, Tzung Hsiai, Modern Mechanobiology, 2021
In addition to gene and chromosomal mutations, exposure to teratogens during gestation has also been associated with cardiac malformations. For example, prenatal exposure to ethanol and retinoic acid has been associated with TOF and DORV [23], while exposure to theophylline, a drug used to treat respiratory diseases, is associated with DORV, transposition of the great arteries and hypoplastic left ventricle [27]. Meanwhile, maternal nutrition can affect heart formation [28], as can maternal diabetes [29, 30], with maternal diabetes predominantly leading to DORV and truncus arteriosus [31].
Pediatric Imaging in General Radiography
Published in Christopher M. Hayre, William A. S. Cox, General Radiography, 2020
Allen Corrall, Joanna Fairhurst
This is when the hole that allows lung bypass while the fetus is in the womb is still present one month after the date the baby was actually due (Tasker, McClure, & Acer, 2013). Some heart conditions such as the transposition of the great arteries require this to remain open and steroids are given to ensure this until the defect is corrected. If the defect does not close spontaneously and causes heath issues it can be closed surgically or percutaneously.
Usefulness of insertable cardiac monitors for risk stratification: current indications and clinical evidence
Published in Expert Review of Medical Devices, 2023
Amira Assaf, Dominic AMJ Theuns, Michelle Michels, Jolien Roos-Hesselink, Tamas Szili-Torok, Sing-Chien Yap
SCD is an important mode of death in patients with congenital heart disease (CHD), especially in patients with repaired tetralogy of Fallot (TOF), transposition of the great arteries (TGA) with a systemic RV, cyanotic heart disease, Ebstein anomaly and Fontan circulation [100]. The incidence of SCD In more contemporary cohorts is declining due to advances in surgical techniques and perioperative management [101–103]. For example, the incidence of SCD have markedly declined for TGA patients after the introduction of the arterial switch operation [101]. SCD/VA risk models have been developed for adults with CHD (ACHD) [8], but also for specific CHD lesions, especially for patients with repaired TOF and TGA with a systemic right ventricle [7,104]. In the 2022 ESC VA/SCD guidelines a primary prevention ICD is recommended (class I) in ACHD patients with biventricular physiology, NYHA II–III heart failure and LVEF ≤35% despite 3 months of optimal medical therapy [18]. A primary prevention ICD should be considered (class IIa) in patients with suspected arrhythmogenic syncope and either moderate ventricular dysfunction or inducible VA [18]. A primary prevention ICD may be considered (class IIb) in patients with advanced single ventricle or systemic RV dysfunction with additional risk factors (i.e. NSVT, NYHA II/III, severe AV valve regurgitation, QRS ≥140 ms in TGA) [18]. Both the 2022 ESC VA/SCD and 2018 AHA/ACC ACHD guidelines give a class IIa indication for a primary prevention ICD in TOF patients with multiple risk factors for SCD [105,106]. These risk factors include LV dysfunction, NSVT, QRS duration ≥180 ms, extensive RV scarring on CMR, severe QRS fragmentation, or inducible VA.