Images in cardiovascular medicine. Aortic dissection at the coronary artery sinus: magnetic resonance angiography findings.
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Biomedical subjects
Publications and source records attributed to S Skotnicki.
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We present a patient with an aneurysm that included both the aortic root and the ascending aorta. Visualization of the coronary arteries by x-ray angiography was not technically feasible. Magnetic resonance angiography (MRA) was thus performed and allowed an accurate evaluation of the involvement of the coronary arteries in the aneurysm and the patency of the proximal coronaries, as well as visualization of the aneurysm itself.
OBJECTIVE: Ultraviolet-cured acrylates and their various components and applications are reviewed in this report. METHODS: A 26-year-old woman involved in silk screening computer discs with ultraviolet-cured inks developed an acute allergic contact dermatitis on her hands and forearms. Patch testing revealed a number of strong reactions to epoxy resin and many multifunctional acrylates. RESULTS: The only one listed on the material safety data sheet to which she reacted was tripropyleneglycol diacrylate (TRPGDA). The other positive reactions likely represent cross-reactions. The positive reaction to epoxy is possibly relevant and attributable to nonhardened epoxy resin contaminant in the epoxy prepolymer. CONCLUSION: This case report shows a new application for ultraviolet-cured acrylate based inks in computer hard disc manufacturing.
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A sequencing assay was used to determine the reactivity of N-nitroso compounds that are simple methylating agents with individual nucleotides in a defined DNA sequence. The maximal difference in reactivity between guanines is about five fold. DNA in the Z, cruciform and H conformations was shown to be methylated by N-methyl-N-nitrosourea in a manner which was indistinguishable from the reactivity of B-DNA. Electronic factors rather than steric factors appear to dominate the methylation reaction. Transcriptionally active genes were shown to be methylated by N-nitroso compounds in vivo more extensively than untranscribed genes. The results suggest that local sequence, secondary conformation and transcriptional activity may all influence the carcinogenic potential of N-nitroso compounds.
Segments of 3 mm diameter fibrous polyurethane vascular prosthesis of length 3-4 cm were prepared. They were bilaterally implanted in the carotid and femoral arteries of male and female beagles. Four groups consisting of animals receiving either no medication or thrombocyte aggregation drugs were studied: Group A (8 dogs), no medication: group B (19 dogs), 500 mg acetylsalicylic acid (ASA) once daily and 25 mg dipyridamol (DIP) three times daily orally for 6 weeks after the implantation operation; group C (14 dogs), 250 mg ASA and 25 mg DIP three times daily orally for 6 weeks after the implantation operation; group D (12 dogs), 250 mg ASA and 25 mg DIP three times daily orally for 25 weeks after the implantation operation. Medication was started one week prior to the implantation operation. In group A, all prostheses were occluded at week 6. There was a significant difference in patency rates between groups B-D and C-D. No significant differences in patency rates could be found between groups B and C. The best patency rates were obtained 25 weeks after implantation in group D for both the right and left carotid and right and left femoral implantation sites. Highest patency rates were observed when ASA and DIP were given for 25 weeks.
Patency of vascular prostheses implanted in the rat aorta is usually confirmed by reoperation and inspection of the distal stump of the aorta for pulsations. Repeated reoperation on rats included in long-term investigations is not possible because of the increasing formation of scar tissue and adhesions at the site of the distal aorta. Consequently, noninvasive ultrasonic Doppler measurement was investigated to determine whether this method could provide accurate information about the patency of an implanted prosthesis. A total of 37 rats with 10-cm-long prostheses implanted in the aorta (groups C nonsupported prostheses, n = 12; and D supported prostheses, n = 25), eight normal nonoperated controls (group A), and three rats with a ligated aorta (negative controls, group B) were studied over a period of 12 weeks. The Dopplerrecordings obtained in the normal animals served as controls for the recordings of rats with an implanted prosthesis. A prosthesis was considered patent if the Dopplermeasurements obtained from the femoral artery resembled that of the normal pattern. In seven cases a prosthesis was suspected to be occluded since the Dopplermeasurements resembled those obtained after aortic ligation. Autopsy confirmed the Dopplermeasurements in all cases. No Dopplermeasurements returned to normal in the femoral artery in the aorta-ligated rats even after longer periods post-operation. It is concluded that Dopplermeasurements can accurately provide information about the patency of a vascular prosthesis implanted in the rat aorta.
The hemodynamic importance of aorto-iliac arteriosclerotic obstructive disease is hard to assess when multiple level lesions are present. Therefore, direct blood pressure measurement in the femoral artery during increased blood flow is a promising technique. Criteria for aorto-iliac disease could be defined by means of a retrospective study in which preoperative blood pressure parameters were compared with the results of arterial reconstruction. These criteria were then prospectively assessed as to their value in the diagnosis of hemodynamically significant aorto-iliac disease. As in the retrospective study, results of arterial reconstructions, and not angiography, were used as the gold standard for the blood pressure criteria. The criteria appeared to be 95 percent accurate, 95 percent specific and 95 percent sensitive in the detection of significant aorto-iliac lesions when multiple level disease is present. The positive predictive value and the negative predictive value were both 95 percent. The method is described in detail and reference is made to other studies with similar good results.
In 7 kidneys of 6 dogs one of the main stem of the renal artery was ligated. The development of the renorenal collaterals could be followed in 5, as two dogs died after the operation. In all cases intrarenal collaterals could be demonstrated, even in the postoperative dead dogs. The vessels responsible for the collateral circulation are performed interarterial anastomoses, belonging to the extra-glomerular arterial system. From the results of these and former experimental studies it can be concluded, that the renal artery of the dog when entering the renal sinus cannot be regarded as an anatomic, but at most as a functional end artery.
Blood flow through aortocoronary venous grafts and its response to a brief period of arterial occlusion--reactive hyperaemia--were studied in relation to the development of postoperative myocardial infarction. In 40 patients with intractable angina due to obstructive coronary artery disease, 72 aortocoronary venous grafts were constructed. In 18% of the grafts there was no response to the flow to temporary occlusion, due to absence of reactive hyperaemia. In the remaining grafts the flow increased from 17% to 26%. In 17-5% of the patients postoperative myocardial infarction was diagnosed. No relation could be established between this control flow through aortocoronary grafts and postoperative myocardial infarction. A significant difference was found in the magnitude of the reactive hyperaemia following occlusion of the graft between patients who developed myocardial infarction (13-0%) and those who did not (26-8%). Some of our observations suggest that the myocardium is in a state of reactive hyperaemia after coronary surgery. With certain technical precautions the flow changes caused by reactive hyperaemia can be used as an indicator of the result to be expected from bypass surgery.
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