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V Verin

Publications and source records attributed to V Verin.

27 records · Page 2Linked to original sources
PubMed1995

Intra-arterial beta irradiation prevents neointimal hyperplasia in a hypercholesterolemic rabbit restenosis model.

BACKGROUND: Intra-arterial gamma irradiation has been shown to reduce restenosis after balloon angioplasty. The use of beta emitters should allow similar effects while inducing less undue tissue irradiation radioprotection problems. METHODS AND RESULTS: Flexible 90-yttrium (90Y) coils inside a centering balloon were used to allow homogeneous intraarterial dose delivery. One carotid and one iliac artery of 21 hypercholesterolemic rabbits were deendothelialized and then irradiated. Four dose schedules were studied: (1) control (dilated, nonirradiated); (2) 6 Gy; (3) 12 Gy; and (4) 18 Gy. Arterial specimens were histologically evaluated at 8 days and at 6 weeks. For all radiation doses at 8 days compared with controls, there was a significant decrease in bromodeoxyuridine-labeled cells (245 +/- 93 cells/cm in control, 42 +/- 27 in 6 Gy, 72 +/- 107 in 12 Gy, and 2 +/- 2 in 18 Gy groups; P < .001) and in total neointimal cells (891 +/- 415 cells/cm in control, 79 +/- 43 in 6 Gy, 192 +/- 264 in 12 Gy and 22 +/- 13 in 18 Gy groups; P < .0002). At 6 weeks, computer-derived histological percent area stenosis was reduced from 26 +/- 10% in the control group to 1 +/- 1.3% in the 18 Gy group (P < .0001), but lower doses had no significant effect. CONCLUSIONS: Administration of intra-arterial beta irradiation with a 90Y source is technically feasible and compatible with an ordinary catheterization laboratory environment. A dose of 18 Gy effectively induces long-term inhibition of neointimal hyperplasia.

Angioplasty, Balloon↗
PubMed1995

High dose rate brachytherapy for prevention of restenosis after percutaneous transluminal coronary angioplasty: preliminary dosimetric tests of a new source presentation.

PURPOSE: Balloon dilatation of coronary artery stenosis has become a standard treatment of atherosclerotic heart disease. Restenosis due to excessive intimal cell proliferation, which subsequently occurs in 20-50% of patients, represents one of the major clinical problems in contemporary cardiology, and no satisfactory method for its prevention has thus far been found. Because modest doses of radiation have proved effective in preventing certain types of abnormal cellular proliferation resulting from surgical trauma, and brachytherapy has already been used successfully after dilation of peripheral arteries, development of a radioactive source suitable for coronary artery applications would be of great interest. METHODS AND MATERIALS: Nonradioactive flexible yttrium-89 wires (diameter of 0.15 and 0.26 mm) were activated within the thermal neutron flux of an experimental reactor. Standard angioplasty balloons (2 cm long, 2.5 mm in diameter when inflated) were inserted for dosimetry into a specially manufactured tissue equivalent phantom. Four wells, drilled perpendicular to the axis of the balloon, allowed for the insertion of thermal luminescent dosimeters (TLDs; 2 mm of diameter) and spacers. The angioplasty balloon was inflated with air or with contrast media. Radioactive yttrium-90 wires were left in the central lumen of the balloon for 2 min. Doses at the surface of the balloon, and at 1, 2, and 3 mm were determined from TLD readings. RESULTS: Doses obtained at the surface of the balloon, for a 2-min exposure for the 0.26 mm wire (balloon inflated with air) and the 0.15 mm wire (air or contrast), were 56.5 Gy, 17.8 Gy, 5.4 Gy, respectively. As expected for a beta emitter, the fall-off in dose as a function of depth was rapid. External irradiation from the beta source was negligible. CONCLUSIONS: Our experiments indicate that the dose rates attainable at the surface of the angioplasty balloon using this technique allow the doses necessary for the inhibition of intimal cell proliferation to be reached within a relatively short period of time. The thin yttrium-90 wires are very easy to handle, and their mechanical and radioactive properties are well suited to the requirements of the catheterization procedure.

Angioplasty, Balloon, Coronary↗
PubMed1994

Lack of predictors of left ventricular functional improvement following coronary angioplasty.

Coronary angioplasty is frequently performed in a vessel with corresponding regional wall motion abnormalities. However, late improvement of left ventricular function remains questionable in many cases and is difficult to predict. A retrospective analysis of 115 patients with single vessel disease and corresponding abnormal regional left ventricular function at the time of coronary angioplasty was performed. All patients had control coronary angiography and a new contrast ventriculography 5.6 +/- 3.1 months later (range 0.8-11.8 months). Among those patients, 61 (53%) showed improvement of regional left ventricular function, which was not seen in the 54 (47%) others. Global ejection fraction increased significantly in the former group, whereas it remained unchanged in the later group. Before angioplasty, patients with and without improvement of systolic left ventricular function were indistinguishable in terms of history, medication, rest and stress electrocardiogram, and angiographic characteristics. During angioplasty, angina was more frequent (65% vs. 44%, p < 0.02) in patients with subsequent left ventricular functional improvement. At follow-up study, significant angiographic restenosis was more frequently encountered (68% vs. 43%, p < 0.05) in patients with no evidence of functional improvement. Thus, coronary angioplasty in a vessel responsible for left ventricular systolic dysfunction is followed in only half the cases by improvement of this parameter. No predictor of the functional outcome of the myocardium can be pointed out before the procedure is performed.

Aged↗
PubMed1993

[Closure of patent ductus arteriosus using interventional catheterization].

Percutaneous closure of patent ductus arteriosus can be performed with the Rashkind technique. This procedure has been performed in 16 patients in Geneva since 1989. The age of the patients varied from 2 to 44 years (4 boys, 7 girls, and 5 women). Pulmonary hypertension was present in only 1 child. A 12 mm Rashkind umbrella was used in 11 patients with ductus of < or = 4 mm inner diameter, while a 17 mm umbrella was used in 5 cases for larger ducts. Ductus closure was carried out through a transvenous femoral approach in 15 cases, while in 1 patient a transarterial approach was employed because of impossibility of passing the ductus from the pulmonary artery. There was neither mortality nor morbidity in this series. The aortography performed just after device placement showed total ductus occlusion in 8 patients and partial closure in 8 others. The follow-up by color Doppler showed disappearance of the residual shunt in 4 of these 8 patients. Prophylaxis of bacterial endocarditis is therefore no longer necessary in 13 patients with complete ductus closure. Our experience with this technique confirms its efficacy and the possibility it offers of avoiding thoracotomy in the vast majority of patients with a patent ductus arteriosus. Further miniaturization of the device and delivery system should make it applicable in the neonatal period.

Adolescent↗
PubMedDate not supplied

A morphological-mechanical explanation of edge restenosis in lesions treated with vascular brachytherapy.

PURPOSE: Edge restenosis in stenotic lesions treated by implantation of a conventional stent followed (or preceded) by a catheter-based brachytherapy is often attributed to "geographic miss" (GM). We propose a complementary (or, possibly, alternative) explanation based on the concept that a clear postprocedural mismatch between the in-stent lumen and the normal (undilated) lumens of the proximal and/or distal vessel segments results in an excessive, damageable increase of axial wall stress in these segments. METHODS: The possible poststenting situations at both margins of a stent are examined, and based on the presence or absence of an increase in axial wall stress, predictions are made about the lesion evolution. The concept is then also examined in the light of published observations. RESULTS: None of the analyzed observations appeared to be incompatible with the proposed morphological-mechanical explanation. CONCLUSION: From a mechanical point of view, optimal matching of the proximal and distal stent diameters to the corresponding normal diameters of the adjacent arterial segment is likely to reduce the rate of edge restenosis.

Brachytherapy↗
PubMedDate not supplied

Yttrium-90 delivered via a centering catheter and afterloader, given both before and after stent implantation, inhibits neointima formation in porcine coronary arteries.

BACKGROUND: Intracoronary radiation (IR) studies have shown reduction of neointima formation (NF). Extrapolation of animal studies with beta-radiation to clinical trials have shown variable results, which may be related to dosimetry, centering issues, and/or shielding of beta-rays by the stent metal. We examined the effect of yttrium-90 (90Y), a pure beta-emitter delivered via an automatic afterloader to a centering catheter, on the inhibition of NF in balloon-injured (BI) porcine coronary arteries as well as in arteries receiving 90Y either prior to or following stent implantation (SI). METHODS: Twenty-three swine (44 coronary arteries) were studied. In the first study, IR (18 Gy at 1.2 mm from the balloon surface) was administered in 17 arteries following BI, while eight control arteries were subjected to BI only. In the second study, 10 swine (19 coronary arteries) underwent SI. IR (18 Gy) was administered in six arteries before and in eight arteries after SI, while five control arteries received SI only. The animals were sacrificed 2 weeks after BI and 4 weeks after SI. Their coronaries were perfusion fixed and stained, and vessel parameters (intimal area [IA] and medial fracture length [FL]) were analyzed by computer-aided histomorphometry. RESULTS: Arteries subjected to IR following BI had less NF compared to controls (IA/FL = 0.14 +/- 0.2 mm vs. 0.49 +/- 0.2 mm; P = 0.003). IA was reduced significantly in the arteries receiving radiation before and after SI compared to controls (0.92 +/- 0.98 and 0.00 +/- 0/00 vs. 2.72 +/- 1.2 mm2; P = 0.014), despite similar SI in all groups. CONCLUSIONS: IR with 90Y delivered via a centering catheter is safe and effective with complete and homogenous inhibition of NF in the context of BI or SI in the porcine coronary model.

Animals↗
PubMedDate not supplied

Early experience with coronary stenting.

From April 1988 to December 1991, we implanted 75 coronary stents (29 self-expanding and 46 balloon expandable) in 62 patients. All had New York Heart Association class II to IV angina, and 11 (18%) had prior coronary artery bypass grafting (CABG). Thirty nine patients (63%) had 1 vessel disease, and 23 (37%) had multivessel disease. The mean left ventricular ejection fraction was 63 +/- 11%. The indications for coronary stenting were acute post percutaneous transluminal coronary angioplasty (PTCA) occlusion in 45 (73%) (bail out stenting) and restenosis in 17 (24%) (elective stenting). There were 52 single stent (84%), 7 double stent (11%), and 3 triple stent procedures (5%). The mean stent diameter was 3.8 +/- 0.5 mm, and the mean stent length 21 +/- 7 mm. The attempted vessels were the left main coronary artery in 2(3%), left anterior descending coronary artery in 27 (44%), left circumflex coronary artery in 8 (13%), right coronary artery in 17 (27%), and a saphenous vein graft in 8 (13%). Technical success was achieved in 74 stent implantations (98%). Technical failure occurred in 1 case with a self expanding stent because of inability to reach the lesion. In hospital complications (mean hospital stay 10 +/- 10, range 2-60 days) included temporary stent occlusion in 2 patients (3%) treated by balloon dilatation and thrombolysis with intravenous urokinase, permanent stent occlusion in 5 patients (8%), Q-wave infarction in 5 patients (8%), CABG in 4 patients (11%), and death in 3 patients (5%). At least 1 major complication (Q wave infarction, CABG, or death) occurred in 8 patients (13%).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗