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At least 1,315 records · Page 73Linked to original sources
PubMed1998

The utility of duplex scanning in infrainguinal vein graft surveillance: results from a randomised controlled study.

OBJECTIVES: To evaluate the utility and efficacy of colour-coded duplex scanning as an adjunct to clinical surveillance of infrainguinal vein bypass surgery. DESIGN: Prospective controlled randomised trial. METHODS: The trial included 179 consecutive patients undergoing 185 primary infrainguinal vein graft reconstructions during a 3-year period. Patients alive without amputation and with open graft at 1 month were randomised to a surveillance program based on clinical examination and ankle-brachial pressure index measurement (ABI group) or additional duplex scanning (DD group). All patients were scheduled for surveillance at 1, 3, 6, 9 and 12 months after operation. RESULTS: Surveillance identified four failing grafts in the ABI group and 11 in the DD group which were revised. The number of occluded grafts was seven in ABI group and 12 in DD group. At 1-year overall cumulative assisted primary patency rates in the ABI group and in the DD group were 74% and 65% respectively (p = 0.21), corresponding secondary patency rates were 84% and 71% (p = 0.04) and limb salvage rates 88% versus 81% (p = 0.23) respectively. CONCLUSIONS: This study failed to show any beneficial effect of duplex scanning in a surveillance program, which was difficult to accomplish as a part of routine clinical work. However, the main difference in outcome appeared during the first postoperative month before the commencement of the surveillance program.

Aged↗
PubMed2001

Harnessing haemodynamic forces for the suppression of anastomotic intimal hyperplasia: the rationale for precuffed grafts.

OBJECTIVES: Standardisation of cuff geometry by manufacturing prosthetic precuffed grafts (PCG) theoretically optimises haemodynamic forces. This study was designed in order to determine whether these beneficial flow patterns are replicated in vivo in PCG. PATIENTS AND METHODS: Flow visualisation and Doppler studies performed on anatomically accurate PCG models characterised in vitro anastomotic flow patterns. Thirty-two patients (median age 68 years) in whom autologous vein was unavailable, underwent bypass using PCG. Post-operative analysis included qualitative assessment of flow within the distal anastomosis using Doppler colour flow mapping. Cardiac gating techniques and assessment of velocity distribution were performed to gain additional information. These in vivo results were validated against the bench studies. RESULTS: A cohesive vortex was identified within the distal anastomosis of in vitro models and had an integral relationship with the cardiac cycle. This flow structure was also characterised using Doppler colour flow mapping in both longitudinal and transverse planes, confirming the location of the vortex within the body and proximal part of the anastomosis. Twenty-two patients (69%) undergoing bypass with a PCG underwent successful Doppler assessment one week post-operatively, of whom 17 (77%) had a vortical flow structure identified at the distal anastomosis, similar to that characterised in vitro. Cardiac gating verified the same integral relationship of the vortex with the cardiac cycle as that described in vitro. CONCLUSION: The geometric configuration of precuffed grafts induced vortices within the distal anastomoses in 17 out of 22 patients undergoing arterial reconstruction, thereby harnessing the haemodynamic forces that may suppress anastomotic hyperplasia and improve patency rates.

Adult↗
PubMed2000

Frequency of postoperative carotid duplex surveillance and type of closure: results from a randomized trial.

BACKGROUND/PURPOSE: In several nonrandomized studies investigators have reported on the value of postoperative carotid duplex surveillance (PCDS) with mixed results; however the type of closure was not analyzed in these studies. In this study we analyze the frequency and timing of postoperative carotid duplex ultrasound scanning according to the type of closure from a randomized carotid endarterectomy (CEA) trial comparing primary closure (PC) versus patching. PATIENT POPULATION AND METHODS: We randomized 399 CEAs into 135 PCs, 134 polytetrafluoroethylene (PTFE) patch closures, and 130 vein patch closures (VPCs) with a mean follow-up of 47 months. PCDS was done at 1, 6, and 12 months and every year thereafter (a mean of 4.0 studies per artery). Kaplan-Meier analysis was used to estimate the rate of > or = 80% restenosis over time and the time frame of progression from < 50%, to 50%-79% and > or = 80% stenosis. RESULTS: Restenoses of > or =80% developed in 24 (21%) arteries with PC and nine (4%) with patching. Kaplan-Meier estimate of freedom of > or = 80% restenosis at 1, 2, 3, 4, and 5 years was 92%, 83%, 80%, 76%, and 68% for PC, respectively, and 100%, 99%, 98%, 98%, and 91% for patching, respectively, (P <.01). Of 56 arteries with 20% to 50% restenosis, two of 28 patch closures and 10 of 28 PCs progressed to 50% to < 80% restenosis (P =.02); none of the patch closures and six of 28 PCs progressed to > or =80% (P =.03). In PCs, the median time to progression from <50% to 50%-79%, < 50% to > or =80%, and 50%-79% to > or = 80% was 42, 46, and 7 months, respectively. Of the 24 arteries with > or =80% restenosis in PC, 10 were symptomatic. Thus, assuming th symptomatic restenosis would have undergone duplex scan examinations regardless, there were 14 asymptomatic arteries (12%) that could have been detected only with PCDS (estimated cost, $139, 200), and those patients would have been candidates for redo CEA. Of the 9 arteries (3 PTFE closures and 6 VPCs) with > or =80% restenosis with patch closures, 6 asymptomatic (4 VPCs and 2 PTFE closures) arteries (3%) could have been detected with PCDS. In patients with normal duplex scan findings at the first 6 months, only four (2%) of 222 patched arteries (two asymptomatic) developed > or = 80% restenosis versus five (38%) of 13 in patients with abnormal duplex scan examination findings (P<.001). CONCLUSIONS: PCDS is beneficial in patients with PC, but is less beneficial in patients with patch closure. PCDS examinations at 6 months and at 1- to 2-year intervals for several years after PC are adequate. For patients with patching, a 6-month postoperative duplex scan examination with normal results is adequate.

Blood Vessel Prosthesis Implantation↗
PubMed1996

Marginal fit of electroformed ceramometal crowns.

PURPOSE: A method of fabricating ceramometal crowns using gold copings produced by an electroforming process has been described, which purportedly results in restorations exhibiting an excellent marginal fit. This study compares the fit of electroformed ceramometal crowns with ceramometal crowns fabricated using conventional lost wax casting techniques. MATERIALS AND METHODS: Electroformed and conventional ceramometal crowns were fabricated for prepared extracted teeth. Specimens were cemented, embedded in acrylic resin, sectioned, polished, photographed, and measured to compare marginal fit. RESULTS: Marginal fit of electroformed ceramometal crowns was superior to the fit of ceramometal crowns fabricated using conventional casting techniques. The difference was statistically significant at a P = .05 level. CONCLUSIONS: Crowns utilizing copings fabricated by electroforming methods appear to have a fit superior to conventional ceramometal crowns fabricated using copings made by lost wax casting. The ease in laboratory electroforming techniques and the esthetic advantages of a gold-colored coping can be capitalized on without concerns of a poorer fit.

Crowns↗
PubMed1996

Is colour Doppler ultrasound a sensitive screening method in diagnosing deep vein thrombosis after hip surgery?

Patients under going orthopedic surgery are at high risk of developing deep vein thrombosis. One hundred and thirty-eight consecutive patients undergoing total hip replacement or hip fracture surgery were included in this study. They were surveilled with colour Doppler ultrasound (CDU) and bilateral ascending contrast phlebography. The prevalence of proximal and distal DVT in this study was 5.8% and 20.3% respectively. CDU has a satisfactory sensitivity in patients with symptomatic deep vein thrombosis, especially in the proximal region. These results could not be confirmed in the present study of asymptomatic patients. The sensitivity was 62.5% (95% confidence interval: C.I. 24-91%) and the specificity 99.6% (C.I. 98-100%) for proximal DVT; 53.6% (C.I. 34-73%) and 98% (C.I. 96-99%) respectively for distal thrombi. the overall sensitivity was 58.1% (C.I. 39-75%) and the specificity 98% (C.I. 96-99%). The positive predictive value was 83.3% (C.I. 36-99%) and 75% (C.I. 51-91%) for proximal and distal DVT respectively. The negative predictive value was 98.9% (C.I. 98-100%) and 94.9% (C.I. 92-98%) for proximal and distal DVT respectively. The results of this study showed that even with a highly specialised and experienced investigator the sensitivity of CDU was too low to make it suitable for screening purposes in a high risk surgical population.

Anticoagulants↗
PubMed1997

Duplex assessment of run-off before femorocrural reconstruction.

BACKGROUND: This study was a prospective evaluation of colour duplex imaging for the assessment of distal run-off before femorocrural reconstruction. METHODS: Patients with critical ischaemia who required a distal bypass underwent preoperative run-off assessments using dependent Doppler, arteriography and duplex imaging by a vascular surgeon, radiologist and technologist respectively; each was blinded to the findings of the others. Preoperative data were compared with intraoperative clinical findings and completion flow studies/ arteriograms. RESULTS: Forty-three consecutive patients (33 men, ten women; mean age 78 (range 53-95) years; 12 diabetic) undergoing 44 femorocrural reconstructions for critical ischaemia were assessed. The 30-day primary cumulative graft patency for the series was 86 per cent. Dependent Doppler correctly predicted a suitable run-off vessel in 21 limbs but was indeterminate in four and unrecordable in 19. Arteriography correctly predicted a suitable run-off vessel in 32 cases, but was indeterminate in six and failed to demonstrate run-off in three patients. Arteriography suggested an inferior vessel in three cases. Duplex correctly predicted a suitable run-off vessel for all 44 grafts. CONCLUSION: Duplex imaging is superior to arteriography for preoperative assessment of distal run-off for femorocrural reconstruction.

Aged↗
PubMed2003

Color-flow duplex ultrasound scan versus computed tomographic scan in the surveillance of endovascular aneurysm repair.

OBJECTIVE: The purpose of this study is to compare both computed tomographic scan (CT) and color flow duplex ultrasound scanning (CDU) as surveillance modalities for clinically significant endoleaks and to evaluate concordance in abdominal aortic aneurysm (AAA) diameter measurements in patients after endovascular aneurysm repair (EVAR) in a busy hospital vascular laboratory. METHODS: We conducted a retrospective review of all patients who underwent endovascular repair of abdominal aortic aneurysms between February 1996 and November 2002 and had same-day CT and CDU studies. Ninety-seven patients enrolled in phase II clinical studies of Ancure devices had long-term follow-up with both modalities. The other patients underwent simultaneous studies, usually only at the 1-month postoperative visit. Peripheral vascular studies were performed by two certified vascular technicians; all CT scans were reviewed by one vascular surgeon. CT was used as the standard against which the sensitivity, specificity, negative predictive value, and positive predictive value of CDU in endoleak detection was determined. Statistics were performed by using the paired t test; a P value <.05 was considered significant. Kappa statistic was used to assess the correlation between CDU and CT in identifying endoleaks. The correlation between CT and CDU in AAA size measurements as well as in serial size measurements was also determined. RESULTS: Four hundred ninety-five same-day CT and CDU examinations were reviewed in 281 patients. Patients had an average follow-up of 34.6 months (range, 1 to 72 months). Thirty-five leaks were identified among the patients studied (12.4% overall). In comparison with CT, diagnosis of endoleak with ultrasound scanning was associated with a sensitivity of 42.9%, specificity of 96.0%, positive predictive value of 53.9%, and negative predictive value of 93.9%. The correlation between the two modalities was modest (kappa statistic 0.427). The minor axis transverse diameter as measured by ultrasound and CT scans (4.81 +/- 1.1 cm on CT and 4.55 +/- 1.1 cm on ultrasound) correlated closely (r =.93, P <.001.) Seventy percent of paired studies differed by < or =5 mm. Changes in aneurysm size throughout follow-up were -.29 +/-.71 cm on CT scan -.34 +/-.57 cm on duplex ultrasound scan. The correlation coefficient was.65 (P <.001). There was no significant difference in the change as measured by either modality on the paired t test. CONCLUSIONS: Although CDU demonstrates a high degree of correlation with CT scan in determining aneurysm size change over time, it has a low sensitivity and positive predictive value in endoleak detection. In the hospital vascular laboratory at a large tertiary care center, CDU cannot effectively replace CT scan in surveillance after EVAR.

Aged↗
PubMed1999

[Immediate results of surgical treatment of proximal aortic dissection].

From 1984 to 1997, 112 patients have been operated at the Department of Cardiac Surgery of the Azienda Ospedaliera of Parma for acute dissection of ascending aorta. They were 73 males and 39 females of mean age 59.2 years (range 19-79); in the majority they presented a history of essential hypertension and atherosclerotic disease: the first diagnostic suspicion has been confirmed either by angio-CT scan or by CT scan plus aorthography and, from 1994, with transesophageal color doppler echocardiography that is becoming a valuable and precise tool wich can be used in emergency room. Bentall type composite repair or modified Bentall technique has been possible in 37 patients, while in the remaning 75, surgical aortic repair has been achieved by interposition of a dacron vascular prosthesis. Cardiac procedures that were performed in addition were coronary bypass grafthing, resuspension of the aortic valve, AVR. Total arch replacement with reimplantation of brachiocephalic vessels were performed in 6 patients and partial in 10, when intimal tear extended into the arc. Thirthythree in hospital deaths (29.4%) occurred (15 in S.O. and 18 in UCI). Follow up of the hospital survivors was conducted at a mean postoperative interval of 55 months (range 2 to 149 months with 6 late death related to aortic dissection). Our experience shows an increased incidence hypertension and aortic atherosclerosis, compared with marfan's syndrome as a source of acute aortic dissection in the late years, transesophageal echocardiography is a excellent tool for aortic dissection but it may miss dissection localized in other aortic portion, the need of an individualized and conservative surgical approach tailored to the pathology encountered.

Adult↗
PubMedDate not supplied

Isolation and culture of the three vascular cell types from a small vein biopsy sample.

The availability of small-diameter blood vessels remains a significant problem in vascular reconstruction. In small-diameter blood vessels, synthetic grafts resulted in low patency; the addition of endothelial cells (EC) has clearly improved this parameter, thereby proving the important contribution of the cellular component to the functionality of any construct. Because the optimal source of cells should be autologous, the adaptation of existing methods for the isolation of all the vascular cell types present in a single and small biopsy sample, thus reducing patient's morbidity, is a first step toward future clinical applications of any newly developed tissue-engineered blood vessel. This study describes such a cell-harvesting procedure from vein biopsy samples of canine and human origin. For this purpose, we combined preexisting mechanical methods for the isolation of the three vascular cell types: EC by scraping of the endothelium using a scalpel blade, vascular smooth muscle cells (VSMC), and perivascular fibroblasts according to the explant method. Once in culture, cells rapidly grew with the high level of enrichment. The morphological, phenotypical, and functional expected criteria were maintained: EC formed cobblestone colonies, expressed the von Willebrand factor, and incorporated acetylated low-density lipoprotein (LDL); VSMC were elongated and contracted when challenged by vasoactive agents; perivascular fibroblasts formed a mechanically resistant structure. Thus, we demonstrated that an appropriate combination of preexisting harvesting methods is suitable to isolate simultaneously the vascular cell types present in a single biopsy sample. Their functional characteristics indicated that they were suitable for the cellularization of synthetic prosthesis or the reconstruction of functional multicellular autologous organs by tissue engineering.

Animals↗
PubMedDate not supplied

Material choice for restorative dentistry: inlays, onlays, crowns, and bridges.

New materials--specifically the new CAD/CAM zirconia-based systems--are available now for restorative dentistry. When esthetics are not a factor, gold remains the standard, particularly for intracoronal restorations and full posterior coverage. Tooth-colored crowns made with zirconia are new and offer great promise for the future, although more long-term in vivo studies are necessary.

Crowns↗
PubMedDate not supplied

Surveillance of in situ infrainguinal bypass grafts: conventional vs. color flow duplex ultrasonography.

Surveillance of in situ saphenous vein bypass grafts with duplex scanning detects graft abnormalities which may lead to graft thrombosis. Correction of these defects, while grafts are still patent, potentially improves overall graft patency. In this study we compared color flow and conventional duplex to determine whether color flow provided additional information not obtainable by conventional duplex examination. The primary patency rate (patency maintained without intervention) for all 51 cases was 76% (39/51). The secondary patency rate (patency maintained by identification and correction of graft defects before failure) was 88% (45/51). Duplex scanning reduced the graft failure rate by 50%. Color flow and conventional duplex examination provided the same information regarding incipient graft failure. In 20 patients monitored with both techniques, the same number of proximal (100%) and distal (90%) anastomoses were imaged. The same number of graft defects (three vein graft stenoses, one proximal femoral artery stenosis) were identified. Velocity data obtained using the two techniques (peak systolic velocity in an area of stenosis and the duplex velocity ratio) were not always the same, making calculation of percent stenosis from this data inaccurate. Color flow duplex is useful in monitoring graft patency, but provides no additional information over that provided by conventional scanning.

Blood Flow Velocity↗
PubMed2006

[Bilateral cervical arterial dissection as a sign of proximal aortic dissection: a rare cause of recidivating TIA].

Proximal aortic dissection is a life-threatening disease. In addition to other complications, involvement of the brain-supplying arteries can lead to acute cerebral ischemia. In the presented case, only the patient's clinical course and duplex sonography, which showed bilateral cervical arterial dissections, led to the diagnosis of aortic dissection. This case emphasizes that early ultrasound examination is crucial in patients with suspected cerebral ischemia.

Aortic Dissection↗
PubMed2000

Changes of the infrarenal aortic segment after conventional abdominal aortic aneurysm repair.

OBJECTIVES: to delineate the natural history of the residual infrarenal aortic segment after conventional abdominal aortic aneurysm (AAA) repair. DESIGN: open prospective study. PATIENTS AND METHODS: between 1990 and 1997, 100 patients, who underwent conventional infrarenal AAA repair at our department, were followed annually by means of colour duplex ultrasonography. Data from 76 patients who had at least 3 scans were analysed. RESULTS: mean duration of follow-up was 4.7 years (range: 3-8 years). The residual infrarenal aorta dilated a mean of 0.57 mm annually. No patient required reoperation. There was no significant correlation between dilatation and any of the recorded risk factors except for the initial neck diameter (p=0.03). CONCLUSIONS: conventional AAA surgery is durable so that surveillance, during the first 5 postoperative years, is not justified in terms of cost-effectiveness. The impact of such a dilatation on endovascular AAA repair requires further investigation.

Aged↗
PubMed2002

Spectral and profile analysis of Doppler recording following below-knee arterial distal bypasses.

BACKGROUND: Arterial below knee distal bypasses are associated with a high risk of thrombosis as compared to proximal bypasses. We assumed that before the bypass occludes, in the early postsurgical period, measurable velocity changes, and/or the presence of high intensity transient signals (HITS) would occur. METHODS SETTINGS: institutional reference center, hospitalized patients. SUBJECTS: satisfactory Doppler recording was obtained in 51 among 61 consecutive patients (32 males, 19 females, height: 165+/-7 cm, weight: 68+/-12 kg) suffering lower extremity arterial disease, that underwent saphenous (n=33), prosthetic (n=4) or sequential (n=14) below knee bypasses. We performed a spectral and profile analysis of a single postsurgical 2 hour Doppler recording at the ankle level and analyzed Doppler derived indices and clinical risk factors in the evaluation of the risk of bypass occlusion within 7 days following surgery. RESULTS: Primary patency at day 7 was observed in 41 of the 51 operated patients. The presence of HITS was found in approximately 30% of the patients and provided no information on the risk of thrombosis. No clinical variable was significantly associated with an increased risk of thrombosis. Whatever the duration of recording, the presence of a diastolic forward flow and wide systolic velocity changes were poor indicators of bypass thrombosis risk. On 512 beat recordings, a mean systolic velocity below 1630 Hz and a standard deviation of the resistance index >0.095 were associated with a 6.74 [1.6-28.4] (p<0.01) and 14.5 [3.6-58.9] (p<0.001) times increases in the risk of bypass occlusion respectively, compared with subjects that do not fulfill each criteria. CONCLUSIONS: Periods of transient asymptomatic no-flow-reflow events may be observed before the bypass irreversibly occludes. Prolonged Doppler recording should be preferred to short term analyses, to allow for the detection of these transient events and may provide potential indices for future research.

Algorithms↗
PubMed1997

Colour duplex scanning and pulse-generated run-off for assessment of popliteal and cruropedal arteries before peripheral bypass surgery.

BACKGROUND: This prospective pilot study compared the diagnostic accuracy of duplex scanning and pulse-generated run-off (PGR) with intra-arterial digital subtraction angiography (IADSA) for assessment of popliteal, crural and pedal arteries, and explored the reliability of investigation with the combination of duplex scanning and PGR in patients who needed femorodistal reconstruction. METHODS: In 23 limbs, 345 arterial segments were graded independently with duplex scanning and IADSA as normal, stenosed or occluded and compared using weighted kappa analysis. PGR was rated as good, poor or no run-off and compared with pedal arch patency on IADSA. Based on information derived from duplex scanning and PGR a vascular surgeon proposed treatment and the distal anastomosis site for bypass, which was compared with definitive treatment as determined by IADSA. RESULTS: Overall agreement between duplex scanning and IADSA for popliteal and crural arteries was moderate (kappa 0.47, 95 per cent confidence interval (c.i.) 0.39-0.55) with best agreement within the popliteal and proximal tibial arteries. Agreement within pedal arteries was fair (kappa 0.35, 95 per cent c.i. 0.17-0.53). PGR detected good run-off in five of 21 pedal arteries shown to be occluded on IADSA. In 16 of 23 patients treatment based on duplex scanning and PGR was identical to that based on IADSA. Eight of eleven femoropopliteal bypasses were predicted accurately. CONCLUSION: Operative strategy could have been based on investigation by duplex scanning and PGR in a substantial number of patients scheduled for femoropopliteal bypass surgery. Agreement between duplex scanning and IADSA within very distal arterial segments was fair.

Adult↗
PubMedDate not supplied

Photochromic visualization for investigation of artificial heart valves.

This report contains results of investigation into hydrodynamics of artificial heart valves by means of photochromic flow visualization (PFV). The PFV method is based on activation of colored tracers in originally colorless photochromic solutions by pulse laser radiation during 10(-6)-10(-9) sec.

Blood Flow Velocity↗