Characteristics of Human Myocardial Bridges in Health and in Coronary Atherosclerosis

This paper studies the characteristics of the myocardial bridges and the anterior interventricular artery in people aged 22–75 years using a histological method. Histological sections were made from three segments of the artery: proximal to the bridge, intramural and distal to the bridge. We found no differences in thickness of myocardial bridges, cross-sectional area of the perivascular space, as well as ratio of the cross-sectional areas of the perivascular space and intramural segment between the groups of hearts with coronary atherosclerosis (n = 7) and without it (n = 7). In subjects with coronary atherosclerosis, the cross-sectional area of the artery wall in the segment proximal to the bridge was larger than that in the group without atherosclerosis due to increased intima thickness. However, no changes in the lumen of the artery were observed. For citation: Dmitrieva E.G. Characteristics of Human Myocardial Bridges in Health and in Coronary Atherosclerosis. Journal of Medical and Biological Research, 2021, vol. 9, no. 4, pp. 454–458. DOI: 10.37482/2687-1491-Z083

Influence of shape-memory stent grafts on local aortic compliance

The effect of repair techniques on the biomechanics of the aorta is poorly understood, resulting in significant levels of postoperative complications for patients worldwide. This study presents a computational analysis of the influence of Nitinol-based devices on the biomechanical performance of a healthy patient-specific human aorta. Simulations reveal that Nitinol stent-grafts stretch the artery wall so that collagen is stretched to a straightened high-stiffness configuration. The high-compliance regime (HCR) associated with low diastolic lumen pressure is eliminated, and the artery operates in a low-compliance regime (LCR) throughout the entire cardiac cycle. The slope of the lumen pressure–area curve for the LCR post-implantation is almost identical to that of the native vessel during systole. This negligible change from the native LCR slope occurs because the stent-graft increases its diameter from the crimped configuration during deployment so that it reaches a low-stiffness unloading plateau. The effective radial stiffness of the implant along this unloading plateau is negligible compared to the stiffness of the artery wall. Provided the Nitinol device unloads sufficiently during deployment to the unloading plateau, the degree of oversizing has a negligible effect on the pressure–area response of the vessel, as each device exerts approximately the same radial force, the slope of which is negligible compared to the LCR slope of the native artery. We show that 10% oversizing based on the observed diastolic diameter in the mid descending thoracic aorta results in a complete loss of contact between the device and the wall during systole, which could lead to an endoleak and stent migration. 20% oversizing reaches the Dacron enforced area limit (DEAL) during the pulse pressure and results in an effective zero-compliance in the later portion of systole.

Case Studies in Physiology: Using premature ventricular contractions to understand the regulation of carotid artery longitudinal wall motion

Benign arrhythmias can be a useful tool to probe new hypotheses in physiology. We tested the control of longitudinal motion of the common carotid artery wall using observations from spontaneous premature ventricular contractions in a healthy male. Forwards wall motion remained unchanged despite large deviations in local blood velocity and backwards wall motion mirrored changes in pulse pressure, blood velocity, and cardiac motion, thereby revising our original hypothesis of the control of longitudinal wall motion.

A blood-mimicking fluid with cholesterol as scatter particles for wall-less carotid artery phantom applications

Aim of the study: At present, there are few scatter particles used in preparing blood-mimicking fluids, such as nylon, sephadex, polystyrene microsphere, and poly(4-methystyrene). In this study, we present cholesterol as a new scatter particle for blood-mimicking fluid preparation. Materials and methods: The procedure for the preparation of the proposed blood-mimicking fluid involved the use of propylene glycol, D(+)-Glucose and distilled water to form a ternary mixture fluid, with cholesterol used as scatter particles. Polyethylene glycol was first used as part of the mixture fluid but the acoustic and physical properties were not suitable, leading to its replacement with D(+)-Glucose, which is soluble in water and has a higher density. A common carotid artery wall-less phantom was also produced to assess the flow properties. Results: The prepared blood-mimicking fluid with new scatter particles has a density of 1.067 g/cm3, viscosity of 4.1 mPa.s, speed of sound 1600 m/s, and attenuation of 0.192 dB/cm at 5 MHz frequency. Peak systolic velocity, end diastolic velocity and mean velocity measurements were gotten to be 40.2 ± 2.4 cm/s, 9.9 ± 1.4 cm/s, and 24.0 ± 1.8 cm/s, respectively. Conclusion: Based on the results obtained, the blood-mimicking fluid was found suitable for ultrasound applications in carotid artery wall-less phantoms because of its good acoustic and physical properties.

Aortic Blunt Trauma Analysis during a Frontal Impact

The aorta is the largest artery of the human body, and it is considered in the continuous medium mechanics as a hyperelastic material for its biological properties. The thoracic aorta is directly affected in vehicular collision events by compression generated between the ribcage and the three-point seatbelt tension producing injuries in the artery wall. A three-dimensional model of the thoracic aorta was constructed from digital tomographic images considering the ascending aorta, the aortic arch, and the descending aorta. The model obtained presents acceptable characteristics such as a length of 222.8 mm and an ascending aortic diameter of 22.7 mm, 22.7 mm in the aortic arch, and 16.09 mm in the descending aorta. A 150 ms time numerical simulation was developed through the finite element method (MEF), and the model was analyzed simulating a compression load on the artery at its front location. Boundary conditions were considered by selecting specific nodes in the model, such as the points where the artery is held in the thorax with other elements. In addition, displacement nodes were considered to establish a natural behavior of the artery. The outcomes show significant displacements in the artery wall. The most affected areas are the aortic arch and descending aorta, whose displacements reach 14 mm from their original position. Based on the abbreviated injury scale (AIS), the degree of injury to the aorta in this collision event is estimated, an AIS 2 with a moderate severity index and required medical attention.

Toxoplasmosis and Its Potential Role to Change the Levels of C - reactive protein and Vitamin D3 in Atherosclerosis Patients

Atherosclerosis is a condition of the hardening of a blood vessel via the development of plaques around the artery wall which causes the artery to narrow, leading to severe complications. Toxoplasmosis is an opportunistic parasitic infection that causes pathological complications in immunocompromised patients, which lead to increase the burden on the immune system in these patients. This study aims to assess the incidence rate of toxoplasmosis in atherosclerosis patients and its potential to change C - reactive protein (C-RP) and vitamin D3 levels. Serum samples (150) were tested for the positivity of anti-Toxoplasma IgG and IgM antibodies by means of Enzyme-linked immunosorbent assay (ELISA). In addition, C-RP was assessed in all serum samples by means of Latex Fixation Test, while VtD3 was estimated by MiniVidas device. The results revealed that the seroprevalence of toxoplasmosis in atherosclerotic patients was comparatively higher as compared to that in the control group, with significant differences in C-RP and VtD3 levels. These results suggest that the decreased levels of VD3 lead to increase the incidence of T. gondii infection in atherosclerosis patients.

IS SLIM BETTER THAN PAUNCHY?

Aorto-Pulmonary Mismatch (APM) in Transposition of the Great Arteries (TGA) may be accountable for dilatation of neoaortic root and regurgitation of neoaortic valve as late complications of ASO. The manuscript from Arcieri et al. highlights an important aspect about ASO technique: should we approach APM during ASO and what would be the best strategy to do so? Techniques to approach APM at the time of ASO have been published sporadically and are very rarely employed by surgeons. Reconstruction of the neoaorta is generally achieved by trimming of the suture line between pulmonary root (neoaortic root) and ascending aorta resulting in an abnormal dilated and bulky neoaortic root already at the time of ASO. Reduction of the pulmonary root dimension by ressection of a fragment of the pulmonary artery wall possibly results in a more homogenous neoaorta with consequent better hemodynamics. We believe that approaching APM during ASO will have a compelling positive impact in the late survival of the patients with complex TGA.