| BackgroundCervical rotatory manipulation could treat cervical spondylosis (especially for radiculopathy), it is widely used in clinical practice for its significant effect. The cervical disease is more common in the elderly who are often suffered atherosclerosis (AS) in this age. In recent years, cardiovascular and cerebrovascular events are increasing after cervical manipulation. It has caused for concern because of the serious complications, such as dizziness, arterial dissection, ischemic stroke, paralysis, shock and even death.Cervical rotatory manipulation is bound to extend the carotid artery during operation. In the case of the occurrence of carotid atherosclerosis, artery elasticity has declined. At this point, when the operations of cervical rotatory manipulation over the physiological area, whether tensile properties of patients’ carotid artery will be impacted? Some animal researches have shown that the maximum load, the maximum displacement, the maximum stress and the maximum strain of atherosclerotic carotid artery is significantly lower than normal. Compare to normal artery, atherosclerotic carotid artery has different tensile properties that it can not be substantial extension as normal artery. So it is necessary to study the effect of cervical rotatory manipulation on tensile properties of atherosclerotic carotid artery, and provides the scientific basis for the safe application of cervical rotatory manipulation.In addition, it is the important factor which lead to cardiovascular and cerebrovascular events that atherosclerotic plaque rupture and fall of after cervical rotatory manipulation. When the carotid atherosclerosis, whether hemodynamic of carotid artery and the stability of atherosclerotic plaque will be impacted by cervical rotatory manipulation? And then Cause associated complications? Previous studies abroad are more concentrated in the direction of the complex plaque. However, The formation of atherosclerotic plaque is a slow pathological process. Though there is no obvious clinical symptoms during the formation of early atherosclerotic plaque, it is the complex lesions predecessor who cause clinical symptoms. It is particularly important to study early atherosclerosis. So the research is aimed to study the effects of cervical rotatory manipulation on endothelium ultrastructure of early atherosclerosis carotid artery, and provides the scientific basis for the safe application of cervical rotatory manipulation on treatment of patients with early carotid atherosclerosis.ObjectiveWith the acute cardiovascular and cerebrovascular events increasing after cervical rotatory manipulation, in order to study the effects of cervical rotatory manipulation on tensile properties and endothelium ultrastructure of early atherosclerosis carotid artery, investigate whether this approach can hurt the vascular tissue which has occurred in atherosclerosis or not, whether the atherosclerotic plaque will be ruptured or not, so as to provide the references for the security of such manipulation.MethodTwenty male New Zealand rabbits (weight 2.0～2.5kg,4-month-old) were randomly divided into control group (n=10) and experimental group 0=10), after adaptive feeding 15 days they all were fed with high-cholesterol diet (2% cholesterol +10% lard+88% basal diet) for 18 weeks, normal diet were supplement in the meantime. A rabbit was killed in each group in the first 4 weeks,8 weeks,12 weeks. Full length of the carotid artery were taken, longitudinal incision, then were fixed in a 4% formaldehyde solution, progressively dehydrated, transparent, embedded in paraffin, serial sections, HE staining, pathological changes observation.After 12 weeks of high-cholesterol diet, the rabbits in experimental group were applied with cervical rotatory manipulation (rotating on each side once a day during a total of 4 weeks). The rabbits were taken squatting position during operation, take 3 to 5 minutes to appease them until their neck muscles relax. Made its neck anteflexion 10～15°, took no fixed cervical rotatory manipulation:rabbit’s occiput was held by operator’s thumb and index finger of one hand, operator’s palm against its neck, another palm boosting its bottom jaw, upward and rotated(amplitude of 90～120°) rabbit’s neck with two hands. However, no manipulation was applied in rabbits from control group.Then the rabbits were executed for getting the bilateral carotid arteries 20mm after cervical rotatory manipulation. The arteries were measured the thickness and diameter of blood vessels with no stress in vitro, so that the cross-sectional area of the sample were determined. The original thickness and diameter of the samples were input into the computer within the control of the machine. In this study, the samples were official tested after the start-up process which repeatedly loading and unloading 20 times. Mechanical tests were tested on biological tissue material mechanical testing machine. When experimented, the samples of two sides were clipped on the soft tissue test clip, using 10 N sensors, measurement error of 10-3, load speed of 10 mm/min. until the samples were stretched to breaking. After the destruction of the samples, the computer was automatically output the tensile data, such as maximum load, the maximum displacement, the average tension, the elastic modulus, and elongation at break and obtain the stress-strain curve. Before endothelium ultrastructure of early atherosclerotic carotid artery were observed by scanning electron microscope, five pairs of carotid arteries were taken in each group, which were fixed with 2.5% glutaraldehyde and 1% osmium nitride, then washed by 0.1mol/L phosphate buffer, then dehydration, drying, gold-plated.SPSS 13.0 was used for statistical analysis of the data obtained. Two groups of data are presented as mean± standard deviation, using two independent sample t test P<0.05 is as statistically significant difference.ResultsFirstly, atherosclerotic pathology of rabbit carotid artery after 4 weeks of high-cholesterol diet:endothelium was integrity and smooth, with medial smooth muscle traveling clear but not hyperplasia. Atherosclerotic pathology of rabbit carotid artery after 8 weeks of high-cholesterol diet:endothelium damaged and hyperplasia which protruded into the lumen, and foam cells became formation. Atherosclerotic pathology of rabbit carotid artery after 12 weeks of high-cholesterol diet:visible foam cell accumulated and visible red thrombus became formation in lumen clearly, showing that it was in line with early atherosclerotic lesions.Secondly, The maximum load, the maximum displacement, the average load, the elastic modulus and elongation at break in experimental group were (1.36±0.35) N, (6.84±2.08) mm, (0.44±0.30) N, (4.30±2.66) MPa and (83.08±51.32)%, respectively, while the corresponding data in control group were (2.92±0.65) N, (9.23±2.62) mm, (1.17±0.63) N, (3.71±0.60) MPa and (154.19±34.32)%. The maximum load, the average load and elongation at break in experimental group were obviously smaller than those in control group (P<0.05), while no statistical differences in the maximum displacements and elastic modulus between two groups were found (P>0.05).Thirdly, stress-strain curve in control group rose evenly and gently, proving artery wall compliance was still good. Despite the pressure rose, the elastic modulus didn’t rise continuously as the pressure did, because of the good elasticity of artery wall. However, slope and speed of the rise of stress-strain curve in experimental group was significantly different from the control group. In this case, slope increased gradually, curve moved to the left side and became steep, elastic segment was significantly shorter, plateau was smaller, indicating that it was less elastic than that in control group.Endothelium ultrastructure of carotid artery in experimental group showed the following four conditions by scanning electron microscope:(A) Endothelium was abnormal in morphology and arrangement, with chunky cell swelling, volume reduction, and shrinkage of endothelium. (B) Endothelium was partial destruction and fell off, shaping hole, forming shallow and irregular defects, but there were no large and deep ulcers. (C) There were varying amounts of red blood cells, platelets and mononuclear cell adhesion to the rough endothelium. (D) Endothelium damaged, a lot of fibrous tissue proliferated on the surface. Endothelium ultrastructure of carotid artery in experimental group showed the similar results, so there was no significant difference between two groups.ConclusionFirstly, atherosclerotic pathology of rabbit carotid artery after 12 weeks of high-cholesterol diet:visible foam cell accumulated and visible red thrombus became formation in lumen clearly, showing that it was in line with early atherosclerotic lesions. Without amorphous necrotic disintegration product, cholesterol crystals, calcium deposits and elastic fiber breakage, it was not a mature atherosclerosis in animal models. Endothelium ultrastructure of carotid artery also showed the early atherosclerotic lesions by scanning electron microscope. Endothelium was abnormal in morphology and arrangement, with chunky cell swelling, volume reduction, and shrinkage of endothelium. There were varying amounts of red blood cells, platelets and mononuclear cell adhesion to the rough endothelium. Endothelium damaged, a lot of fibrous tissue proliferated on the surface. Endothelium was partial destruction and fell off, shaping hole, forming shallow and irregular defects, but there were no large and deep ulcers.There were also no typical plaques from smooth muscle-derived foam cells. Mature rabbit model of atherosclerosis had not been built by 12 weeks of high-cholesterol diet.Secondly, tensile strength of atherosclerosis carotid artery decreased and tensile properties changed after cervical rotatory manipulation. Atherosclerosis carotid artery was stretched, made certain deformation occurs, and fracture furthermore. The maximum load, the average load and elongation at break in experimental group were obviously smaller than those in control group (P<0.05), while no statistical differences in the maximum displacements and elastic modulus between two groups were found (P>0.05). It may associate with that the animal model was not yet mature. Because the higher the degree of atherosclerosis, the lower elasticity of blood vessel. Therefore, tensile properties of atherosclerosis carotid artery declined after cervical rotatory manipulation. At the time of atherosclerosis patients with cervical rotation manipulation, in order to avoid harming the carotid artery, the operator should pay attention to the intensity and magnitude of the operation. In addition, precise control of the intensity and magnitude of cervical rotation manipulation also need to be further explored.Thirdly, it is the important factor which lead to cardiovascular and cerebrovascular events that atherosclerotic plaque rupture and fall of after cervical rotatory manipulation. Atherosclerotic plaque or thrombus would shed in atherosclerosis patients who had operated by cervical rotation manipulation which was over intensity and magnitude. Shedding microthrombus followed into the cerebral circulation, and most of them (73% -85%) followed into the internal carotid artery system. After cerebrovascular blocked by microthrombus, it caused local brain tissue ischemia and hypoxia, brain tissue softening, necrosis, the last cause of stroke. This study shows that, the experimental group and the control group were both had been established as early atherosclerotic rabbit model. But without amorphous necrotic disintegration product, cholesterol crystals, calcium deposits and elastic fiber breakage, it was not a mature atherosclerosis in animal models. Endothelium ultrastructure of carotid artery in experimental group showed the similar results in control group, so there was no significant difference between two groups. There is no obvious effects of cervical rotatory manipulation on endothelium ultrastructure of early atherosclerotic carotid artery in rabbits, and this manipulation can be safely used in patients with early atherosclerotic. |
PDF Full Text Request