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Biomedical subjects

A Colombo

Publications and source records attributed to A Colombo.

At least 199 records · Page 11Linked to original sources
PubMed1998

Quantitative description of the morphology of the human palate by a mathematical equation.

OBJECTIVE: To derive a three-dimensional mathematical description of normal human hard tissue palatal size and shape. METHODS: The maxillary dental casts of 30 adolescents free from respiratory problems, who had a complete (28 teeth) permanent sound dentition with normal occlusion, were studied. The x, y, z coordinates of several standardized palatal and dental landmarks were obtained with a computerized three-dimensional digitizer. Palatal landmarks were used to derive a mathematical equation of palatal shape in the frontal and sagittal planes. Palatal width, length, frontal and sagittal heights, and sagittal slope, as well as dental arch transverse and anteroposterior dimensions, were computed. RESULTS: Neither the size nor the shape of the palate was significantly influenced by gender. Only the intercanine distance was larger (p < .025) in males than in females. CONCLUSIONS: Data collected in the present investigation could represent a first database for the quantitative description of normal human palatal morphology in subjects with a complete permanent dentition.

Adolescent↗
PubMed1998

Plaque removal prior to stent implantation in native coronary arteries: why? When? And how?

Coronary stenting has significantly reduced restenosis in focal de novo coronary lesions, but its impact in complex lesions has been less pronounced. Recent data suggest a possible role for pre-intervention plaque burden in exacerbating neo-intimal hyperplasia after stent implantation. These observations formed the basis for the hypothesis that plaque removal prior to stent implantation, using directional atherectomy in non-calcified lesions and rotational atherectomy in calcified lesions, may reduce restenosis. The currently available non-randomized experience that used this approach has shown its feasibility and favourable long-term outcome when applied in selected patients. However, the incidence of non-Q-wave myocardial infarction is increased with both rotational and directional atherectomy compared to PTCA or stent alone. The utilization of potent antiplatelet agents and/or the development of new atherectomy devices that produce lower embolization rate may decrease the incidence of these ischaemic complications. In addition, considering the increased procedural time and cost, this approach will have to be applied in selected patient subsets where debulking or stenting as a stand-alone strategy is associated with a high restenosis rate. Randomized clinical trials testing the usefulness of this approach, with both rotational and directional atherectomy, are currently in progress.

Angioplasty, Balloon, Coronary↗
PubMed1998

Bifurcational stenting.

Treatment of bifurcation lesions is a complex issue, and there is no single panacea to the variety of lesions that form this cohort. The contribution of side-branch compromise to the adverse clinical events occurring after stent implantation need not be stressed and requires an aggressive approach including balloon dilatation before and after stent deployment. Various new techniques of kissing stent placement, such as the 'T', 'V', 'Y', and the culottes technique, have been proposed in recent years to treat different anatomical situations. The angle formed by the side-branches, the severity of involvement of the ostia and the vessel size are the main factors which influence selection of the strategy. Newer generations of stents, such as the bifurcate stents, tailor-made for bifurcation lesions, are evolving, and are expected to make a positive impact on the procedural outcomes and long-term results after bifurcation stenting. The development of new strategies and stent designs has greatly improved safety and immediate outcome of bifurcational stenting, but the procedural success still needs to be matched by an equal improvement in long-term patency.

Angioplasty, Balloon, Coronary↗
PubMed1998

Persistent High Restenosis After Local Intrawall Delivery of Long-Acting Steroids Before Coronary Stent Implantation.

OBJECTIVE: This pilot study was performed to evaluate the feasibility and safety of intrawall delivery of long acting steroids before stent implantation, testing the efficacy of this treatment in reducing intimal hyperplasia in lesions at high risk for restenosis. METHODS: In 24 patients (40 lesions) local intrawall drug delivery of methylprednisolone acetate, using a new catheter device, was attempted before elective stent implantation. Treated lesions were compared to a matched control group. RESULTS: Lesions were classified AHA/ACC type C in 47% of cases, had a mean lesion length of 13.6 +/- 9.1 mm, and a mean vessel diameter of 2.85 +/- 0.44 mm. In 9 cases (25%) chronic total occlusions were treated. Methylprednisolone acetate (mean 60 +/- 23 mg) was delivered in 36 lesions (21 patients; delivery success 90%) in the remaining 4 lesions (10%) the delivery device did not cross the lesion. After drug delivery 46 stents were implanted (1.2 stent/lesion; stented segment length 30.1 +/- 18.8 mm) using high pressure for stent expansion (mean 16.4 +/- 3.1 atm). Intracoronary ultrasound guidance was used in 64% of cases. Procedural and in-hospital complications were: Two non Q wave myocardial infarctions (8%) and one (3%) subacute stent thrombosis. Angiographic follow-up was obtained in all 36 treated lesions (100%) and the angiographic restenosis rate (³ 50% diameter stenosis) was 39%. A reduction of the incidence of restenosis compared to the matched control group was not observed. CONCLUSIONS: Long acting steroids could be delivered locally with high success and low complication rates. The restenosis rate remained high in a subset of unfavorable lesions with high risk for restenosis.

Journal Article↗
PubMed1998

Clinical and Angiographic Results with the Multi-Link Stent Implanted under Intravascular Ultrasound Guidance (West-2 Study).

In view of the side effects of ticlopidine, stenting with the sole use of aspirin as post-stent treatment, has been attempted under the guidance of intravascular imaging to guarantee the optimization of the deployment. It was also hypothesized that optimal stenting under IVUS guidance would subsequently reduce the restenosis rate. With these aims the WEST-2 trial using the ACS MULTI-LINK stent was designed. This stent is composed of multiple corrugated rings connected to multiple links Ñ a design that combines radial strength, flexibility and conformability. In WEST-2, between February 1996 and August 1996, 18 centers enrolled 165 patients with stable or stabilized unstable angina and a single de novo lesion in vessel sizes ³ 2.75 mm. Optimal stenting was assessed using predefined QCA (DS% post-stent ³ 15% and stent/artery ratio ³ 1) and IVUS criteria. Patients fulfilling all criteria were treated with aspirin alone. MACE (death, MI, target lesion revascularization) as well as the restenosis rate were assessed at 6 months. In view of the results it may be concluded that the use of aspirin alone as post-stent treatment is safe when preset IVUS criteria are achieved. The target lesion revascularization rate, the restenosis percentage and the incidence of MACE encountered in this registry are among the lowest observed so far.

Journal Article↗
PubMed1998

Alcoholization of the interventricular septum (Sigwart procedure) for treatment of hypertrophic cardiomyopathy.

A patient with NYHA Class III dyspnea under medical treatment for hypertrophic cardiomyopathy underwent alcoholization of the first septal perforator. The procedure induced complete disappearance of the intraventricular gradient, with development of a Q-wave anterior myocardial infarction (peak CK rise = 1645 IU) and a complete right bundle branch block. After 5 months the patient maintains a marked improvement in functional capacity (NYHA Class I).

Cardiac Catheterization↗
PubMed1998

[A case of congenital hepatic hemangioendothelioma treated with prednisone: the echographic changes and Doppler study].

Imaging investigations and other findings observed in a term infant with a multicentric hepatic hemangioendothelioma, admitted to the Intensive Care Unit at the age of 13 days because of non specified feeding difficulties and dyspnoea, are presented. Physical examination revealed cardiac bruit and congestive heart failure with marked hepatomegaly; in addition there were multiple small skin hemangiomas. Echocardiography was negative, abdominal sonography showed multiple round lesions of mixed echogenicity in the liver, large vascular channels, a right hepatic artery and hepatic veins enlarged, a caliber of the aorta below the level of the superior mesenteric artery reduced. The infant was additionally investigated by whole-body scintigraphy with 99mTc-labeled red blood cells to determine the possibility of coexistence of other visceral hemangiomas and by MR, in which the tumor manifested as multiple well-circumscribed space-occupying nodules of high signal intensity on T2-weighted images with evidence of fast flow. The baby underwent furosemide and steroid therapy: serial two-dimensional US scans showed change in echogenicity, responding to therapy. Doppler sonography has proven to be also very useful in the monitoring therapy determining changes in flow pattern and velocity at the level of hepatic, cerebral and renal vessels: before therapy we observed a reduction of the diastolic flow until the zero line through the internal carotid artery and renal artery with an increase of the Resistance Index. It means that this important component can be compromised in the presence of a hepatic hemangioendothelioma.

Drug Therapy, Combination↗
PubMed1998

Reliability of soft tissue references for anteroposterior measurement of dental bases.

The aims of the present investigation were to devise a new anteroposterior measurement of maxillomandibular discrepancies that would consider both hard and soft tissue contributions, and to verify the correlation of this measurement to a well-established linear assessment of anteroposterior discrepancy. On the pretreatment lateral cephalographs of 300 orthodontic patients (162 males, 138 females) aged between 6 and 50 years, the Wits appraisal and a new "soft tissue" Wits appraisal (linear distance between the projections of soft tissue A and B points on the bisecting occlusal plane) were measured. In the analyzed sample, the former was more variable than the latter. The two measurements were significantly correlated to each other without sex- or age-characteristic patterns. From the correlation, reference values for the new measurement were estimated and found to be between -1.9 mm and 5.4 mm for individuals with a normal occlusion. The new measurement could allow a more careful evaluation of the soft tissue drape together with the underlying hard tissue structure.

Adolescent↗
PubMed1998

Predictors of major in-hospital ischemic complications and length of hospital stay after coronary stenting.

Although recent data show that coronary stenting reduces procedural complications and late restenosis, major concern has been expressed about the greater hospital cost associated with the use of this device as compared to conventional coronary angioplasty. Since length of hospital stay after surgical procedures is a major determinant of resource use, the identification of variables associated with an excessively long hospital stay after intracoronary stent placement may have important practical consequences. The purpose of this study was to assess factors responsible for the occurrence of in-hospital complications and prolonged hospital stay after coronary stenting in 939 consecutive patients enrolled in the Registro Impianto Stent Endocoronarico (RISE Study Group). Consecutive patients undergoing coronary stent implantation at 16 medical centers in Italy were prospectively enrolled in the Registry. Clinical data, qualitative and quantitative angiographic findings were obtained from data collected in case report forms at each investigator site. Major ischemic complications were considered death, Q-wave myocardial infarction, emergency bypass surgery and emergency repeat angioplasty. The study group consisted of 939 patients (781 men, 158 women with a mean age of 59 years) in whom 1392 stents were implanted in 1006 lesions and expanded at a maximal inflation pressure of 14.7 +/- 3 atmospheres. The great majority of patients (92%) received only antiplatelet drugs after coronary stenting. During hospitalization, there were 45 major ischemic complications in 39 patients (4.2%): 13 events were related to acute or subacute thrombosis (1.4%). On multivariate logistic regression analysis, the following factors were predictive of in-hospital complications: increasing age (OR 2.19, 95% CI 1.18-4.07), unplanned stenting (OR 3.46, 95% CI 1.65-7.23) and maximal inflation pressure (OR 0.83, 95% CI 0.75-0.93). Mean hospital stay after stent implantation was 4.1 +/- 4.4 days and was related, by multivariate regression analysis, to female sex (p = 0.0001), prior bypass surgery (p = 0.03), non-elective stenting (p = 0.0001), use of anticoagulation (p = 0.0001) and development of major ischemic complications (p = 0.0001). This Registry shows that in an unselected population of patients undergoing coronary stenting, major ischemic complications occur at a relatively low rate (4.2%) and thrombotic events can be kept at 1.4%, despite the omission of anticoagulation in the great majority of patients. Length of hospital stay was affected by the occurrence of major ischemic complications, unplanned stenting, use of anticoagulation, female sex and prior bypass surgery. Accumulating experience, further reduction in complications and complete omission of anticoagulation may decrease length of hospital stay, thus reducing the use of resources after coronary stenting.

Adult↗
PubMed1997

Contemporary percutaneous treatment of unprotected left main coronary stenoses: initial results from a multicenter registry analysis 1994-1996.

BACKGROUND: Coronary artery bypass surgery (CABG) has been considered the therapy of choice for patients with unprotected left main (ULMT) coronary stenoses. Selected single-center reports suggest that the results of percutaneous intervention may now approach those of CABG. METHODS AND RESULTS: To assess the results of percutaneous ULMT treatment from a wide variety of experienced interventional centers, we requested data on consecutive patients treated after January 1, 1994, from 25 centers. One hundred seven patients were identified who were treated either electively (n=91) or for acute myocardial infarction (n=16). Of patients treated electively, 25% were considered inoperable, and 27% were considered high risk for bypass surgery. Primary treatment included stents (50%), directional atherectomy (24%), and balloon angioplasty (20%). Follow-up was 98.8% complete at 15+/-8 months. Results varied considerably, depending on presentation and treatment. For patients with acute myocardial infarction, technical success was achieved in 75%, and survival to hospital discharge was 31%. For elective patients, technical success was achieved in 98.9%, and in-hospital survival was strongly correlated with left ventricular ejection fraction (P=.003). Longer-term event (death, infarction, or bypass surgery) -free survival was correlated with ejection fraction (P<.001) and was inversely related to presentation with progressive or rest angina (P<.001). Surgical candidates with ejection fractions > or = 40% had an in-hospital survival of 98% and a 9-month event-free survival of 86+/-5%, whereas patients with ejection fractions < 40% had 67% and 22+/-12% in-hospital and 9-month event-free survivals, respectively. Nine hospital survivors (10.6%) experienced cardiac death within 6 months of hospital discharge. CONCLUSIONS: While results for selected patients appear promising, until early post-hospital discharge cardiac death can be better understood and minimized, percutaneous revascularization of ULMT stenosis should not be considered an alternative to bypass surgery for most patients. When percutaneous revascularization of ULMT is required, directional atherectomy and stenting appear to be the preferred techniques, and follow-up angiography 6 to 8 weeks after treatment is probably advisable.

Aged↗
PubMed1997

Long-term angiographic and clinical outcome of patients undergoing multivessel coronary stenting.

BACKGROUND: Randomized clinical trials have shown that multivessel coronary angioplasty is feasible and provides similar long-term survival as bypass surgery in selected patients. However, the higher need for repeat intervention, in particular, coronary artery bypass graft surgery, remains a problem. The objective of this study was to test the hypothesis that multivessel stenting is safe and effective in reducing the need for repeat interventions, in particular, the need for bypass surgery. METHODS AND RESULTS: Between March 1993 and June 1995, 100 consecutive patients (243 lesions) had multivessel coronary stenting. High-pressure stent optimization was used in all patients. Procedural success was achieved in 97% of lesions; 2 patients (2%) required emergency bypass surgery. Angiographic follow-up was obtained in 89% of patients at 5.2+/-2.5 months. Angiographic restenosis occurred in 22% of the lesions, but 37% of patients had > or = 1 lesion with restenosis. Clinical follow-up was obtained in all patients at 21 +/- 10 months: target lesion revascularization was needed in 30 patients (30%), repeat angioplasty in 28 patients (28%) and coronary bypass surgery in 2 patients (2%); the overall survival rate was 96% (2% noncardiac death). CONCLUSIONS: Multivessel coronary stenting can be performed with high success rate and low need for emergency bypass surgery. Compared with historical results with multivessel percutaneous transluminal coronary angioplasty, patients who undergo multivessel stenting need less repeat interventions, in particular, less coronary bypass surgery and have similar long-term survival.

Aged↗
PubMed1997

Comparison of immediate and intermediate-term results of intravascular ultrasound versus angiography-guided Palmaz-Schatz stent implantation in matched lesions.

BACKGROUND: Intravascular ultrasound (IVUS) provides more precise information than angiography about vascular dimensions. This information is used by some centers to optimize intracoronary stent implantation. There are no direct comparisons of the effects on restenosis of optimal IVUS-guided versus angiography-directed high-pressure stenting. METHODS AND RESULTS: Lesions of patients who had a 6-month angiographic follow-up study were eligible for matching. From 445 consecutive lesions treated by Palmaz-Schatz (P-S) stenting guided by IVUS (IVUS group) in Milan, 173 lesions were individually matched with 173 of 476 consecutive lesions treated by P-S stenting directed by angiography (Angio group) in Hamburg. Lesions were selected by a computerized program according to baseline clinical, angiographic, and procedural variables. Immediate and 6-month angiographic results were retrospectively compared, distinguishing an "early phase" from a "late phase." This distinction was based on the more aggressive dilation strategy with larger balloons and more demanding IVUS criteria for optimal stent expansion used in Milan in the early phase. In both phases, a larger minimum lumen diameter (MLD) immediately after stenting and after 6 months was achieved in the IVUS group than in the Angio group. In the early phase, the dichotomous restenosis rate was lower in the IVUS group than in the Angio group (9.2% versus 22.3%; P=.04). In the late phase, there was no difference in restenosis between the groups (22.7% versus 23.7%; P=1.0). CONCLUSIONS: In matched lesions treated with high-pressure stenting, IVUS guidance achieved a larger MLD than angiographic guidance. However, in the IVUS group, the restenosis rate was lower only in the early phase, when balloons larger than currently used were selected to maximize the stent lumen area.

Adult↗