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131.
The incidence and morphology of shudders in carotid arterial pulse tracings were examined in 73 patients with aortic valve disease documented by cardiac catheterization. Two forms of carotid shudder were recorded: coarse and fine. Shudders were present in 67 per cent of patients with aortic stenosis, 48 per cent of patients with aortic insufficiency, and 57 per cent of patients with mixed aortic stenosis and insufficiency. No significant difference existed among these three groups of patients with respect to the over-all incidence of carotid shudders or with respect to the incidence of coarse or fine shudders. In patients with aortic insufficiency, stroke volume index (Fick) and phonocardiographic systolic ejection murmur amplitude were significantly greater (p less than 0.01, p less than 0.001, respectively) in those with coarse carotid shudders compared with those manifesting fine or absent shudders. Loud, flow-related, systolic ejection murmurs of aortic insufficiency are capable of producing radial vibrations in the aortic wall which are recorded as carotid shudders. The finding of a carotid shudder in a patient with aortic valve disease does not enable the physician to distinguish between stenosis, insufficiency, or mixed stenosis and insufficiency. 相似文献
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AB Butterfield CW Miller WV Lumb FD McLeod AW Nelson MB Histand 《Canadian Metallurgical Quarterly》1977,26(2):215-224
The effect of chronically elevated blood flow on the development of atherosclerosis in miniature swine was studied. Fistulas connecting the right external iliac artery and vein were surgically created in four swine, while three were not fistulated. Pulsed Doppler velocity detection cuffs placed around the abdominal aorta and both iliac arteries of all pigs permitted chronic measurements of blood velocity, blood velocity distributions, and blood flow. All swine were fed an atherogenic diet consisting of 20% beef tallow, 3% cholesterol, and 5% cholic acid for 6 months. This diet elevated the serum cholesterol to values exceeding 500 mg/100 ml. Creation of the arteriovenous fistula (AVF) markedly elevated blood velocity and flow in the abdominal aorta and in the shunted iliac artery. In the shunted animals the aortic blood flow was 42.1 +/- 2.0 ml/sec compared with 17.3 +/- 1.4 ml/sec in the unshunted swine. The velocity distribution pattern across the vessel was also indicative of an elevated wall shear stress. After 6 months, the animals were killed and the arterial vessels examined macroscopically and microscopically for the presence of atherosclerotic lesions. In the shunted pigs, 17 +/- 15% of the lumenal surface was occupied by sudanophilic lesions, whereas 80 +/- 8% of the surface was covered by lesions in the unshunted (control) pigs. From these studies, it is apparent that mechanical factors related to blood flow rates can influence the development of atherosclerotic lesions in swine. 相似文献
135.
PURPOSE: Combining computational blood flow modeling with three-dimensional medical imaging provides a new approach for studying links between hemodynamic factors and arterial disease. Although this provides patient-specific hemodynamic information, it is subject to several potential errors. This study quantifies some of these errors and identifies optimal reconstruction methodologies. METHODS: A carotid artery bifurcation phantom of known geometry was imaged using a commercial magnetic resonance (MR) imager. Three-dimensional models were reconstructed from the images using several reconstruction techniques, and steady and unsteady blood flow simulations were performed. The carotid bifurcation from a healthy, human volunteer was then imaged in vivo, and geometric models were reconstructed. RESULTS: Reconstructed models of the phantom showed good agreement with the gold standard geometry, with a mean error of approximately 15% between the computed wall shear stress fields. Reconstructed models of the in vivo carotid bifurcation were unacceptably noisy, unless lumenal profile smoothing and approximating surface splines were used. CONCLUSIONS: All reconstruction methods gave acceptable results for the phantom model, but in vivo models appear to require smoothing. If proper attention is paid to smoothing and geometric fidelity issues, models reconstructed from MR images appear to be suitable for use in computational studies of in vivo hemodynamics. 相似文献