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Non-traumatic neurological conditions in medico-legal work
Published in Helen Whitwell, Christopher Milroy, Daniel du Plessis, Forensic Neuropathology, 2021
Air emboli may be introduced into the vascular system during spinal surgery, particularly when the sitting position is used for cervical spinal surgery (McCarthy et al. 1990). This is of the greatest concern if there is a right-to-left cardiac shunt (such as a patent foramen ovale), and, if untreated, this may result in a cardiorespiratory arrest (Pham Dang et al. 2002). Air emboli can also be associated with the insertion of central venous catheters.
Cardiovascular system
Published in A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha, Clark’s Procedures in Diagnostic Imaging: A System-Based Approach, 2020
A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha
In addition to the MR signal magnitude that is used to display anatomical information, MRI raw signal data contains information about the phase of the signal. The phase of the MR signal is influenced by the motion of excited hydrogen nuclei along the magnetic field gradients that are applied during the image acquisition process. It is possible, using specially designed flow-sensitive MRI sequences combined with the reconstruction of images that represent the phase of the signal, to measure the velocity of blood flow. This can provide further functional information about the both the velocity and volume of flow of blood through the cardiac valves or in the great vessels. For example, patients with congenital heart disease, the flow rate and volume in the pulmonary artery can be compared to that in the aorta to measure the magnitude of a cardiac shunt. Quantitative flow velocity measurement is performed either with gradient echo pulse sequence over several minutes with multiple signal averages and free breathing or during a breath-hold using a fast gradient echo technique. The velocity range to be measured is chosen by adjusting the flow sensitivity of the gradient echo sequence, using the velocity encoding parameter (VENC) [38].
Medical management of the cardiac patient undergoing coronary angiography
Published in John Edward Boland, David W. M. Muller, Interventional Cardiology and Cardiac Catheterisation, 2019
Sara Hungerford, Peter Ruchin, Gerard Carroll
Cardiac catheterisation also plays an important diagnostic role in determining the aetiology of left ventricular dysfunction (i.e. secondary to either coronary artery disease or cardiomyopathy); the exclusion of coronary artery disease and invasively quantifying pressure-volume relationships in the presence of valvular heart disease; quantification of, and pharmacological challenge in, the setting of pulmonary hypertension, and; the diagnosis and quantification of an intra-cardiac shunt. Patients with primary arrhythmias, such as ventricular tachycardia, atrial fibrillation and even existing left bundle branch block may also benefit from early definition of their coronary anatomy.
Commentary: Physical activity after patent foramen ovale (PFO)-associated stroke: a personal narrative and call to action
Published in Topics in Stroke Rehabilitation, 2023
Jeff K. Vallance, I. Hale, G Hansen
At the prompting of colleagues, my family physician and I pursued further diagnostic examinations throughout the next month. MRI imaging 12 days after the event revealed a hypointense area in the left posterior frontal lobe consistent with infarction. There were no signs of atrial fibrillation on 24-hour Holter monitor. Echocardiogram with agitated saline revealed an immediate appearance of a moderate amount of bubbles in the left atrium and left ventricle indicating the presence of a cardiac shunt. Transcranial doppler indicated a high-grade right-to-left shunt with curtain effect (i.e. when microbubbles are so great in number that they are indistinguishable). Transesophageal echocardiogram (TEE) with agitated saline contrast showed >30 contrast bubbles at rest and a large 8 mm PFO with 20 mm tunnel and adjacent 2 mm atrial septal defect (ASD).
Cerebral fat embolism syndrome in a patient with homozygous sickle cell disease in the setting of multisystem inflammatory syndrome in children
Published in Baylor University Medical Center Proceedings, 2023
Kirstin Sepulveda, Tesneem Issa, Gueorgui Dubrocq
The pathophysiological changes associated with sickle cell disease (such as anemia and pulmonary hypertension) coupled with brief spikes in right-heart pressure caused by the precipitating event are believed to create conditions favorable for a temporary right-to-left cardiac shunt; this transient pathway potentially allows emboli to pass directly from the heart to the brain through otherwise innocuous cardiac malformations.7 While our patient’s initial imaging did not show any circulatory abnormalities, an agitated saline transthoracic contrast echocardiograph performed on hospital day 6 revealed a very small left-to-right shunt elicited only by Valsalva maneuver, consistent with patent foramen ovale. This case illustrates the need for change in the management of suspected MIS-C in patients with sickle cell disease, as extensive interventions and close monitoring may be required.
Updates in the management of congenital heart disease in adult patients
Published in Expert Review of Cardiovascular Therapy, 2022
Danielle Massarella, Rafael Alonso-Gonzalez
Population data estimate a lifetime prevalence of cardiac shunt lesions of 9.19 per 1000 children and 1.60 per 1000 adults. Most commonly, these are simple lesions such as atrial and ventricular septal defects and patent ductus arteriosus [114]. Natural history studies have taught us that the development of pulmonary arterial hypertension results inevitably from a longstanding or unrepaired hemodynamically significant shunt, and its prevention remains one of the foremost goals of the treatment of this class of congenital cardiac anomalies. Luckily, successive surgical eras have seen a decrease in the incidence of unrepaired lesions diagnosed in adulthood, particularly in developed countries. Nevertheless, the high morbidity and mortality associated with Eisenmenger syndrome persists today [115]. Depending on age at repair, long-term benefits to closure must be weighed carefully against procedural risks as well as those related to underlying pulmonary vascular disease. In the current era, procedural morbidity and mortality related to surgical or transcatheter approaches is exceedingly low [10].