Biomedical subjects

C Ragg

Publications and source records attributed to C Ragg.

5 recordsLinked to original sources

PubMed1997

[Value of Doppler blood flow velocity measurements in peripheral percutaneous laser-assisted angioplasties].

PURPOSE: The aim of the study was to establish the prognostic value and clinical implications of blood flow velocity measurements by Doppler guide wires during peripheral laser-assisted percutaneous transluminal angioplasty (PTLA). METHODS: 39 patients presenting with symptomatic peripheral arterial obstructive disease underwent angiography and blood flow velocity assessment by Doppler guide wire (0.018") prior to and following PTLA. Both quantitative angiography (QCA) for measurement of luminal diameters and Doppler assessment of maximum peak velocities (MPV) were performed 2 cm proximal, over and 2 cm distal to stenoses. The results were compared with the following clinical endpoints: 1. Short-term clinical improvement by AHA-criteria during first follow-up examination and 2. criteria for patency suggested by Rutherford [12] within 1 year (1-22 months). RESULTS: Angiography demonstrated initial success of PTLA in all patients. Relative diameter stenosis decreased from 70 +/- 0.04% to 17 +/- 0.05%. Mean clinically category improved from 2.7 +/- 0.1 to 1.2 +/- 0.1 following intervention. Mean grade of clinical improvement was 2.8 +/- 0.1. 22/39 patients demonstrated event-free follow-up examinations. Doppler measurements of MPV post PTLA in the proximal reference segment correlated with clinical outcome. MPV > or = 90 cm/s was associated with good primary success, unlimited walking capacity and event-free follow-up. MPV > or = 70 cm/s predicted an improvement of short-term clinical outcome by 2 grades (predictive value 80%). MPV < 70 cm/s was associated with both minor primary clinical improvement (+/- 0, +1) and increased incidence of restenosis during follow-up. CONCLUSION: Following PTLA, MPV adds information to angiographic success. MPV > or = 90 cm/s in a proximal reference segment following PTLA predicts good clinical outcome, whereas MPV < 70 cm/s is associated with minor primary clinical success and increased rates of restenosis.

Adult↗

PubMed1995

Changes of fluid-dynamic parameters in peripheral stenoses with transcutaneous interventions.

UNLABELLED: Peripheral vessels provide a useful in vivo haemodynamic model allowing evaluation of local intravascular fluid dynamics. Velocity measurements using a 0.018 inch Doppler-tipped angioplasty guidewire, quantitative angiography and laboratory data were gathered from 45 patients with a total of 48 percutaneous transluminal laser assisted angioplasties (PTLA) in the superficial femoral, in the iliac, in the popliteal artery and in the peroneal artery. From these data, blood flow, whole blood viscosity, Reynold's numbers, Womersley numbers and shear stress were calculated, evaluated as to their changes post PTLA and correlated with clinical improvement at early follow-up. The clinical result was quantified as categorial improvement according to the American Heart Association guidelines. The primary angiographic results of angioplasty were satisfactory in all patients. Clinically 17/45 patients showed a marked, 6/45 a moderate, 18/45 a minimal, and 4/45 no improvement. The mean values of maximal peak velocity at stenosis decreased from 235 +/- 28 cms-1 to 84 +/- 8 cms-1 after PTLA (P < 0.01). The minimal intrastenotic cross section increased from 7.7 +/- 0.9 to 21.9 +/- 1.6 mm2 (P < 0.01). Mean trans-stenotic flow increased after intervention by about 50% (P < 0.01) and improved further by 135% after administration of adenosine triphosphosphate i.a. (P < 0.01). Reynold's numbers were elevated intrastenotically (1285 +/- 198) pre-intervention as compared to values proximal (564 +/- 81) and distal (449 +/- 66) to the stenosis and were reduced significantly (P < 0.05) at stenosis by PTLA, whereas values proximally and distally increased significantly (P < 0.01) post PTLA (proximal 829 +/- 84, intra 773 +/- 107, distal 676 +/- 98). Shear stress, reflecting mechanical interaction between flow and vessel wall, was elevated at stenosis pre-intervention to 44 +/- 8.9 Pa and reduced at post-stenoric vessel sites to 2.4 +/- 0.5 Pa. PTLA caused a decrease in stenosis to 6.3 +/- 1 Pa (P < 0.01) and an increase distally to 4.6 +/- 1 Pa (P < 0.01). Whereas in single stenoses removal of the obstruction was associated with a significant (P < 0.05) increase in trans-stenotic flow and shear stress distally, there was only auenuated increase in trans-stenotic flow in multiple lesions despite an angiographically good PTLA result. Shear stress distally remained low in those patients. Velocities and Reynold's numbers were lower in these vessels even pre PTLA. Residual flow, Reynold's number and minimal cross-section pre-intervention correlated significantly with clinical outcome. Pooling cases with no or minimal, as opposed to those with marked or moderate improvement, 81% of patients were correctly classified using the Reynold's numbers pre- and post-PTLA. CONCLUSION: Peak velocity monitoring is feasible and safe during angioplasty. Velocity provides clinically relevant physiological information in addition to angiography. Combining quantitative angiography, velocity measurements and laboratory data allow the calculation of blood flow, Reynold's numbers and shear stress, thereby providing complex fluid dynamic information. Thus the evaluation of haemo-dynamics in single and multiple obstructions before and after intervention is improved. Fluid dynamic parameters pre-and post-PTLA are significantly correlated with clinical short-term result.

Adult↗

PubMed1994

CT angiography of the pelvic arteries.

UNLABELLED: A comparison was performed between CT angiography and digital subtraction angiography (DSA) on 55 patients with atherosclerotic obstructions of the pelvic arteries. Two post-processing algorithms were employed, maximum intensity projection (MIP) and 3D technique. RESULTS: (a) MIP: conformity with DSA: 20/23 occlusions and 24/36 stenoses; underestimation: three occlusions, seven stenoses; overestimation: five stenoses. (b) 3D display: conformity with DSA: 19/23 occlusions and 16/36 stenoses; underestimation: four occlusions, 17 stenoses; overestimation: three stenoses. The MIP technique proved to be the only method to display the localisation of vascular calcifications with their exact topographical relationship to the stenoses and occlusions. MIP also proved to be valuable in controlling the position of intravascular stents. Complementary to DSA, the MIP method therefore seems to be a clinically valuable technique for calcified and non-calcified stenoses, and for displaying intravascular stents. Its use in interventional procedures could therefore become increasingly important.

Adult↗

PubMed1994

[CT angiography and arterial DSA in the evaluation of occlusive processes in pelvic arteries. Initial results].

UNLABELLED: 32 patients with iliac artery stenosis and occlusion were studied by means of CT angiography. The results were compared with the results of intraarterial digital subtraction angiography (DSA). Postprocessing was performed with Maximum Intensity Projection (MIP) and 3-D-display. RESULTS: 1. MIP: 27/37 stenoses/occlusions were correctly assessed, underestimation of 5 stenoses/occlusions (4 stenoses, one occlusion), overestimation of 5 stenoses. 2. 3-D-Display: 22/37 stenoses/occlusions were correctly assessed, underestimation of 9/37 (8 stenoses, one occlusion), two false negative results (one stenosis, one occlusion), overestimation of 4/37 stenoses. The MIP technique proved to be the only method to display the localisation of vascular calcifications with their exact topographical relationship to the stenoses and occlusions. MIP also proved to be valuable in controlling the position of intravascular stents. Complementary to DSA, the MIP method therefore seems to be a clinically valuable technique for calcified and noncalcified stenoses.

Adult↗

PubMed1976

Chromosomal studies of human prostatic tumors in vitro.

Chromosomal studies were performed on primary cultures from human prostatic adenomas and carcinomas. All cells from both tumor types showed diploid chromosomal counts with a normal human karyotype. Chromosomal analysis was also performed on cells of the permanent epithelial line EB 33 derived from a human prostatic carcinoma in this laboratory. In contrast to the primary cultures, hypotriploid chromosome numbers were found during continuous culture for more than 1 year. The range of chromosome numbers increased with time in culture and was reduced to the original model number of 64 by only one animal passage ("nude" mice). Feulgen fluorometry on different passages of the permanent cell line EB 33 showed tetraploidy. This discrepancy to the hypotriploid chromosome number can be explained by different Feulgen hydrolytic properties of the different cell types.

Animals↗