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Cardiac Biomechanics
Published in Joseph D. Bronzino, Donald R. Peterson, Biomedical Engineering Fundamentals, 2019
Andrew D. McCulloch and Roy C. P. Kerckhof
A detailed description of the morphogenesis of the muscle ber system in the developing heart is not available but there is evidence of an organized myober pattern by day 12 in the fetal mouse heart that is similar to that seen at birth (day 20) [25]. Abnormalities of cardiac muscle ber patterns have been described in some disease conditions. In hypertrophic cardiomyopathy, which is oen familial, there is substantial myober disarray, typically in the interventricular septum [10,26].
Cardiovascular System:
Published in Michel R. Labrosse, Cardiovascular Mechanics, 2018
The atria are relatively small and thin-walled, reaching peak pressures of approximately 10 mmHg. They require only a minimal contraction to “top up” the ventricular volume, since most of the blood coming into the atria will directly flow into the ventricles during diastolic filling. The ventricles are divided by a muscular interventricular septum and contract simultaneously. The right ventricle will eject blood into the pulmonary circulation and develop peak pressures of approximately 30 mmHg. On the other hand, the left ventricle will eject blood into the higher-pressure, higher-resistance systemic circulation and will develop pressures of approximately 120 mmHg. To handle such high blood pressure, the muscle wall of the left ventricle is much thicker than that of the right ventricle.
Central nervous 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
Figure 11.25a is a coronal section of the brain, taken through the line C3 of Fig. 11.25b, and showing the five standard sagittal planes, S1–S5. The following structures are numbered in Fig. 11.25a as follows: Interhemispheric fissure.Parietal lobe.Cingulate gyrus.Left lateral ventricle.Corpus callosum.Cavum septum pellucidum.Caudate nucleus.Choroid plexus, extending through the foramina of Monro.Third ventricle.Thalamus.Sylvian fissure.Medial cerebral artery.Temporal lobe.Temporal fontanelle.
Comparison of methods for delivering cardiac resynchronization therapy: electrical treatment targets and mechanisms of action
Published in Expert Review of Medical Devices, 2023
Florentina Simader, Ahran Arnold, Zachary Whinnett
Right ventricular myocardial pacing can negatively impact left ventricular (LV) function, especially in patients whose systolic function is already impaired prior to pacing. Some negative consequences of RV pacing are also evident during BVP, including dysfunction near the apex and within the interventricular septum. This has led to the exploration of LV-only pacing, (using only the lead in coronary sinus) as an alternative to BVP. The GREATER-EARTH trial was a multicenter, double-blind, crossover trial, which compared the effects of LV-only and biventricular pacing on exercise tolerance and LV remodeling in patients with an LV ejection fraction ≤ 35%, QRS ≥ 120 ms, and symptoms of heart failure. One hundred and twenty-one qualifying patients were randomized to either LV-only or BVP for two consecutive 6-month periods. No difference was observed between the two pacing approaches in exercise performance or LV function (ejection fraction improved from 24.4 ± 6.3% to 31.9 ± 10.8% and 30.9 ± 9.8% with LV and BVP, respectively, p = 0.45). Thus, LV-only pacing was non-superior to BVP but was also not observably worse and carries the benefit of only requiring a single lead.
Potential human health risks of toxic/harmful elements by consumption of Pseudevernia furfuracea
Published in International Journal of Environmental Health Research, 2022
Murat Topal, E. Işıl Arslan Topal, Erdal Öbek, Ali Aslan
The potentially toxic elements have toxicity both to humans and animals and tendency to bioaccumulate. Therefore, the environmental pollution because of these elements is a global concern. Humans are exposed to potentially toxic elements through various ways (dermal contact, inhalation, ingestion, and consuming polluted food). This situation leads to unfavorable impacts on human health (Hu et al. 2020). Long-term exposure to high nickel (Ni) concentrations can cause problems (e.g. lung cancer) (US, 2007; Ryder et al. 2020). The excessive lead (Pb) intake can cause negative effects on nervous, immune, and endocrine systems (Hu et al. 2017, 2020; Jiang et al. 2017). Pb poisoning which is one of the important health risks accounts for 0.6% of global disease burden (Nakata et al. 2021). The exposure of Pb accounted for 1.06 million deaths and 24.4 million disability adjusted life years (Boudebbouz et al. 2021). Chronic exposure to chromium (Cr) is linked to cancer and nasal septum atrophy (Ryder et al. 2020). Prolonged exposure to high concentrations of Cr, zinc (Zn), and copper (Cu) can lead to deteriorations in fertility, liver function and cholesterol (USEPA 2000; Hu et al. 2020). Cadmium (Cd) because of its long half-life (15–30 years) and multifaceted deleterious effects (e.g. skeletal, teratogenic, hepatotoxic, carcinogenic, nephrotoxic, and reproductive effects) on human health is one of the most toxic heavy metals (Boudebbouz et al. 2021).
Treatment of cardiac resynchronization therapy non-responders: current approaches and new frontiers
Published in Expert Review of Medical Devices, 2022
H. Immo Lehmann, Lana Tsao, Jagmeet P. Singh
New technologies that are available for cardiac resynchronization are mostly aiming to restore more physiologic cardiac activation through pacing of the conduction system [64]. However, a prerequisite for His-bundle pacing is that the lesion is proximal to the pacing site. Consistent benefit of His-bundle pacing for CRT eligible patients has been shown in several studies [65,66]. In His-bundle pacing, QRS narrowing can be achieved with nonselective His-capture with subsequent improvement of the LV-EF but has been often limited by the relatively difficult implantation technique, lead dislodgements, and high pacing thresholds, leading to shorter generator life. More recently, intraseptal LV pacing (left bundle branch pacing) has become an approach for resynchronization [67,68]. Using this approach, a pacing lead is advanced through the interventricular septum. In doing so, thromboembolic complications, phrenic nerve capture, and limitations of CS anatomy are avoided while offering low and relatively stable pacing thresholds [68].