Biomedical subjects

R F Neville

Publications and source records attributed to R F Neville.

32 records · Page 2Linked to original sources

PubMed1993

Femoral arteriovenous fistula following cardiac catheterization: an anatomic explanation.

The exact etiology of femoral iatrogenic arteriovenous fistula (AVF) following cardiac catheterization is not known. The most common explanation is simultaneous placement of arterial and venous catheters for left and right heart catheterization. Using a strict protocol for groin examination before and after cardiac catheterization, seven patients were found to have a groin thrill and/or bruit as a result of AVF after catheterization in the period from July 1986 to December 1990; one patient had two fistulas, making a total of eight. During the same period, a total of 2609 cardiac catheterizations were performed using the Seldinger technique; the incidence of AVF after the procedure was thus 0.22%. Arteriography was used to confirm the presence of the fistulas and identify their exact location. All eight lesions originated below the bifurcation of the common femoral artery (CFA). Three originated at the superficial femoral artery (SFA) and five at the profunda femoris artery (PFA). In the patient with two fistulas, one originated at the SFA and one at the PFA. The veins involved were the superficial femoral (SFV) in two AVFs and the profunda femoris (PFV) or its lateral circumflex branch in six. The fact that all eight fistulas originated below the bifurcation of the CFA points to a possible anatomic explanation for the formation of iatrogenic AVF. The CFA and common femoral vein (CFV) are located side by side, which makes it difficult to puncture both with one stick. Below the bifurcation, the PFV crosses laterally behind the proximal SFA and then lies in a posterior location to the PFA.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1993

Autoradiographic mapping and characterization of insulin-like growth factor-I receptor binding in human greater saphenous vein.

PURPOSE: The proliferation of vascular smooth muscle cells is an important step in the process of intimal hyperplasia. Veins exposed to arterial pressure develop intimal hyperplastic lesions that lead to failure of vein bypasses. Insulin-like growth factor-I is a polypeptide hormone structurally related to insulin with insulin-like metabolic effects. Insulin-like growth factor-I has been found to work in concert with other growth factors, including platelet-derived growth factor, to promote the growth of vascular smooth muscle cells in culture. Insulin-like growth factor-I exerts its effects via specific receptors located on the cell surface. We studied the in situ distribution of insulin-like growth factor-I receptor binding using autoradiography and examined insulin-like growth factor-I binding characteristics in normal human greater saphenous vein. METHODS: Frozen sections 20 microns thick were prepared from the greater saphenous vein specimens. The sections were incubated in a buffer containing 125I-insulin-like growth factor-I in the presence of increasing concentrations of the unlabeled peptide. Autoradiograms were obtained by apposing the treated sections to autoradiography film. RESULTS: Analysis of the autoradiographs showed that insulin-like growth factor-I binding was consistently present in the wall of human greater saphenous vein. To characterize these binding sites binding inhibition studies were performed. High-affinity insulin-like growth factor-I receptor binding was found with dissociation constant of 1.0 +/- 0.32 nmol/L and maximum binding capacity of 0.46 +/- 0.23 pmol/mg protein. These values are consistent with a physiologic role for insulin-like growth factor-I in the tissue examined. CONCLUSIONS: The presence of high-affinity (dissociation constant = 1.0 +/- 0.32) insulin-like growth factor-I binding sites in the wall of saphenous vein suggests that insulin-like growth factor-I plays an important role in regulating the proliferation of venous wall cellular components, an essential step in the process of venous intimal hyperplasia.

Autoradiography↗

PubMed1992

The arterial wall response to intimal injury in an experimental model.

Repair of occult arterial injuries is advocated to prevent thrombosis, arteriovenous fistula, and pseudoaneurysm formation. However, recent clinical series describe the healing of arterial intimal injuries and recommend nonoperative therapy. To investigate the arterial wall response to intimal injury, we created intimal flaps in 46 canine femoral arteries. The intimal flaps were imaged by arteriography, angioscopy, and intravascular ultrasound acutely, and at one and three weeks and five months post-injury. Lumen area was measured using caliper techniques (arteriography) and computerized video planimetry (angioscopy, intravascular ultrasound). Intimal and medial thickness were measured by intravascular ultrasound prior to harvest for histologic evaluation by light microscopy. Analysis of 32 patent arteries was performed after exclusion of 14 thrombosed arteries. Residual lumen area (mm2) correlated closely among the imaging modalities at one week (8.7 +/- 1.1, 7.3 +/- 2.0, 6.9 +/- 1.8), three weeks (4.2 +/- 0.9, 2.9 +/- 1.0, 2.7 +/- 0.8), and five months (5.3 +/- 0.9, 5.0 +/- 0.5, 5.0 +/- 0.9). Maximal intimal and medial thickness occurred three weeks post-injury, coincident with the maximal reduction in lumen area. Although intimal injuries can cause acute and delayed arterial thromboses, observation may be appropriate in selected cases. The evaluation of those patients chosen for nonoperative therapy should extend beyond three weeks, as this is the time of maximal arterial wall response with a continued potential for adverse clinical events.

Analysis of Variance↗

PubMed1992

In vitro and in vivo intravascular ultrasound imaging.

This paper presents our experience with intravascular ultrasound imaging of animal and human arteries in vitro and in vivo using a high-frequency (20 M Hz) ultrasound transducer. In vitro, 32 human coronary artery segments were imaged with intravascular ultrasound and compared with corresponding histological sections. Ultrasound and histology measurements correlated significantly (P less than 0.0001) for coronary artery cross-sectional area (r = 0.94), lumen cross-sectional area (r = 0.85) and wall thickness (r = 0.92). In vivo, 19 sheep and eight human common femoral arteries were imaged and the angiographic lumen diameter of 14 animal and six human arteries was compared to the diameter of the corresponding ultrasound images. Significant correlations were found for lumen diameter in animals and humans (P less than 0.001, r = 0.91 and P less than 0.0001, r = 0.96, respectively). These studies demonstrate that this technique can provide high resolution images of arterial vessels and may have unique advantages in diagnosing atherosclerotic vascular disease and in catheter based therapies.

Adult↗

PubMed1991

In vivo human atherosclerotic plaque recognition by laser-excited fluorescence spectroscopy.

Arterial wall perforation and chronic restenosis represent important factors limiting the clinical application of laser angioplasty. Discrimination of normal and atherosclerotic vessels by laser-excited fluorescence spectroscopy may offer a means of targeting plaque ablation, thereby reducing the frequency of restenosis and transmural perforation. In this study, with use of a 325 nm low power helium-cadmium laser, in vivo endogenous surface fluorescence was excited through a flexible 200 microns optical fiber within a 0.018 in. (0.046 cm) guide wire in contact with the intima of 268 vascular interrogation sites from 48 patients either during open heart surgery or during percutaneous catheterization procedures. Fluorescence spectra could be recorded in all patients in bloodless and blood-filled arteries. Endogenous surface fluorescence was analyzed measuring peak intensity, peak position and shape index of the spectra. Compared with normal wall, noncalcified and calcified coronary atheroma showed a 42% (p less than 0.001) and a 58% (p less than 0.001) decrease of peak intensity, and higher shape index (p less than 0.001 and p less than 0.01, respectively). In addition, peak position was shifted to longer wavelengths for noncalcified coronary atheroma (p less than 0.001). Compared with normal aorta sites, aortic plaques demonstrated a 46% decrease of peak intensity, longer peak position wavelengths (p less than 0.05) and a higher shape index (p less than 0.001). Using an atheroma detection algorithm, prospective analysis of aorta and coronary spectra showed a specificity of 100% for identifying normal sites and a sensitivity of 73% for recognizing atherosclerotic sites.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1991

A prospective evaluation of arterial intimal injuries in an experimental model.

The management of arterial intimal defects remains controversial because of uncertainty concerning their natural history. We developed an experimental canine model to prospectively evaluate posterior wall intimal flaps in the superficial femoral artery. Arterial intimal flaps were constructed in 20 anesthetized dogs (40 arteries) and evaluated by arteriography, and angioscopy, and intravascular ultrasound. Postoperative patency rates at 1 (n = 20) and 3 weeks (n = 20) were compared with a control group of ten animals (n = 20, arteriotomy without intimal flap). Acute thromboses occurred in five experimental arteries with thromboses of eight additional experimental arteries at followup. Control patency was 100%, while experimental group patencies were 75% (p less than 0.05) at 1 week and 60% (p less than 0.009) at 3 weeks. All thrombosed arteries had intimal flaps with greater than 75% luminal stenosis. We conclude that intimal injuries cause arterial thromboses acutely and during subsequent followup. Intimal flaps with stenosis greater than 75% as determined arteriographically are at greatest risk for thrombosis. Angioscopy and intravascular ultrasound characterize arterial intimal defects and may delineate injuries requiring surgical or endovascular repair.

Angiography↗

PubMed1991

Intravascular ultrasound imaging: in vivo peripheral and coronary artery studies.

Recent in vitro studies have demonstrated that intravascular ultrasound can obtain high-resolution cross-sectional images of arterial vessels. To further expand the use of this technique for in vivo visualization of peripheral and coronary vessels, we imaged 24 femoral and 13 carotid arteries from 19 sheep. Using a manual rotation technique, high-resolution images were obtained in 95% of the vessel sites with a rigid probe and in 82% of the vessel sites with a flexible catheter. In 14 of these arteries, good correlation was found between the lumen diameter measured by ultrasound and by angiography (P less than .001, r = .91). In addition, 6 left circumflex coronary arteries were imaged from 6 additional sheep by motor-driven rotation of the ultrasound probe at 1,800 rotations per minute, obtaining clear delineation of coronary lumen morphology and lumen-intima interface. Strong correlation was found also between intravascular ultrasound and cineangiography for coronary artery diameter measurement (P less than .001, r = .96). These studies demonstrate that this technique can provide high-resolution images of arterial vessels in vivo and may have unique advantages in diagnosis of atherosclerotic vascular disease and in the guidance of new catheter-based therapeutic modalities.

Animals↗

PubMed1991

Intravascular ultrasonography: validation studies and preliminary intraoperative observations.

Intravascular ultrasonography is emerging as an important imaging modality to assess the presence, distribution, and extent of atherosclerotic vascular disease. To determine the accuracy and clinical utility of intravascular ultrasonography, a flexible catheter-based system was used to generate two-dimensional, cross-sectional vascular images. In 23 arteries of 11 sheep 206 in vivo images demonstrated an echo-free lumen surrounded by three distinct concentric acoustic transitions corresponding to intima, media, and adventitia. Ultrasound measurements of lumen diameter and area correlated significantly with those of corresponding arteriographic measurements obtained by use of digital calipers (r = 0.91, r = 0.86). To evaluate clinical feasibility, intraoperative images (n = 160) were obtained in 10 patients undergoing vascular bypass or hemodialysis access procedures. The images depicted luminal configuration and arterial wall morphologic characteristics. Measurements of lumen diameter and lumen area correlated closely with corresponding intraoperative arteriography (r = 0.81, r = 0.79). The ultrasound images demonstrated arterial stenoses, intimal hyperplasia, intraluminal thrombus, polytetrafluoroethylene graft material, and anastomotic sites. We conclude that flexible catheter-based ultrasonography produces images that accurately demonstrate arterial wall architecture, lumen diameter, and area. Intraoperative application can produce images that provide unique information thus expanding the clinical potential of ultrasonography as a guidance system for vascular procedures.

Animals↗

PubMed1991

Endovascular management of arterial intimal defects: an experimental comparison by arteriography, angioscopy, and intravascular ultrasonography.

To determine the feasibility of the endovascular management of intimal defects while comparing the accuracy of arteriography with angioscopy and intravascular ultrasonography, we developed an in vivo model of arterial intimal flaps. In 10 superficial femoral arteries of five anesthetized mongrel dogs, intimal flaps were constructed and then imaged by arteriography, angioscopy, and intravascular ultrasound. A flexible microbiopsy forceps was used to remove each intimal flap under angioscopic guidance. Arteriographic lumen diameters were measured and cross-sectional areas calculated. Corresponding measurements by angioscopy and intravascular ultrasound with reduction in luminal area at the flap were obtained by use of computerized planimetry. Uniplanar arteriography identified 60% (6/10) of the intimal flaps, whereas angioscopy and intravascular ultrasound demonstrated 100%. Lumen diameter (in millimeters) measured by arteriography (3.4 +/- 0.6) correlated significantly with measurements by angioscopy (3.5 +/- 0.5, r = 0.77) and intravascular ultrasound (3.5 +/- 0.6, r = 0.96). Similarly, lumen area (square millimeters) by arteriography (9.2 +/- 2.9) correlated with measurements by angioscopy (8.9 +/- 2.2, r = 0.82) and intravascular ultrasound (8.6 +/- 2.7, r = 0.91). Reduction in lumen area by the flap by angioscopy (37 +/- 7%) and intravascular ultrasound (33 +/- 8%) also correlated significantly (r = 0.72). The intimal flaps were removed successfully in all 10 arteries as confirmed by arteriography, angioscopy, and intravascular ultrasound. We conclude that the endovascular management of intimal defects is possible. Additionally, angioscopy and intravascular ultrasound accurately evaluate lumen diameter and area while providing direct assessment of intimal defects.

Animals↗

PubMed1990

Popliteal artery agenesis: a new anatomic variant.

Agenesis of the popliteal artery has not been described as a vascular anomaly in the lower extremity. This case report describes congenital absence of the popliteal artery discovered during operative exploration after a traumatic injury to the lower extremity. The preoperative arteriogram suggested acute occlusion of the popliteal artery. Intraoperative exploration and arteriography were consistent with agenesis of the popliteal arterial segment, and postmortem examination confirmed these arteriographic and intraoperative observations. Embryologically, failure of the middle portion of the sciatic artery to persist would account for this anomaly. A review of series reporting congenital anomalies of the lower extremity vasculature failed to discover previous mention of this particular abnormality. Agenesis of the popliteal artery should be included among those vascular anomalies that may affect management of lower extremity vascular disease.

Adult↗

PubMed1990

Coronary artery imaging with intravascular high-frequency ultrasound.

Safe and effective clinical application of new interventional therapies may require more precise imaging of atherosclerotic coronary arteries. To determine the reliability of catheter-based intravascular ultrasound as an imaging modality, a miniaturized prototype ultrasound system (1-mm transducer; center frequency, 25 MHz) was used to acquire two-dimensional, cross-sectional images in 21 human coronary arteries from 13 patients studied at necropsy who had moderate-to-severe atherosclerosis. Fifty-four atherosclerotic sites imagined by ultrasound were compared with formalin-fixed and fresh histological sections of the coronary arteries with a digital video planimetry system. Ultrasound and histological measurements correlated significantly (all p less than 0.0001) for coronary artery cross-sectional area (r = 0.94), residual lumen cross-sectional area (r = 0.85), percent cross-sectional area (r = 0.84), and linear wall thickness (plaque and media) measured at 0 degrees, 90 degrees, 180 degrees, and 270 degrees (r = 0.92). Moreover, ultrasound accurately predicted histological plaque composition in 96% of cases. Anatomic features of the coronary arteries that were easily discernible were the lumen-plaque and media-adventitia interfaces, very bright echoes casting acoustic shadows in calcified plaques, bright and homogeneous echoes in fibrous plaques, and relatively echo-lucent images in lipid-filled lesions. These data indicate that intravascular ultrasound provides accurate image characterization of the artery lumen and wall geometry as well as the presence, distribution, and histological type of atherosclerotic plaque. Thus, ultrasound imaging appears to have great potential application for enhanced diagnosis of coronary atherosclerosis and may serve to guide new catheter-based techniques in the treatment of coronary artery disease.

Adult↗

PubMed1990

Race as a risk factor in the severity of infragenicular occlusive disease: study of an urban hospital patient population.

We retrospectively studied the arteriograms of 135 men admitted for evaluation of lower extremity ischemia to examine whether race influences the severity of infragenicular occlusive disease. The scoring system prepared by the Ad Hoc Committee on Reporting Standards for the Society for Vascular Surgery and the International Society for Cardiovascular Surgery was used to grade the severity of stenosis in each of the upper, middle, and lower thirds of the anterior and posterior tibial and peroneal arteries (collectively called "infragenicular" arteries). The patients were divided into two groups: 83 blacks (140 arteriogram limbs) and 52 whites (87 arteriogram limbs). Disease severity scores between the groups were compared, and the existence of five known risk factors for atherosclerosis were considered for poststratification adjustment. Results showed that higher disease scores, indicating more severe disease, were found in the black population in every segment of the infragenicular arteries. The mean (+/- SE) score for all the infragenicular segments in blacks was significantly higher than that in the whites (2.08 +/- 0.05 vs 1.57 +/- 0.06, p less than 0.001). The black and white groups were comparable in terms of age (65.2 vs 64.6 years), prevalence of diabetes (20% vs 25%), smoking history (93% vs 90%), and hypercholesterolemia (51% vs 63%). Hypertension was more prevalent among the black patients (51% vs 27%, p less than 0.001). When only the non-hypertensive patients in both groups were considered, however; the mean severity score was still significantly higher in blacks (2.10 +/- 0.06 vs 1.42 +/- 0.06, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Black or African American↗

PubMed1989

An in vivo feasibility study of intravascular ultrasound imaging.

Increasingly complex vascular reconstructions and emerging endovascular therapeutic modalities have stimulated the need for improved vascular imaging. To determine the feasibility of in vivo intravascular ultrasound, a miniature probe 1 mm in diameter with a 25 MHz center frequency was used to obtain two-dimensional, 360-degree cross-sectional images. In sheep, 14 superficial femoral arteries were imaged at different sites, and a portion of each vessel was resected for immediate in vitro imaging and histologic examination. In vivo images clearly showed the intima, media, and adventitia of the vessel wall as well as the lumen-intima and media-adventitia interfaces. There was a significant correlation in measured lumen area between resected artery ultrasound images and histologic sections. We conclude that intravascular ultrasound can produce high-resolution dynamic images that demonstrate vessel wall architecture and allow precise calculation of lumen area.

Animals↗

PubMed1989

Seeding of intravascular stents with genetically engineered endothelial cells.

The use of intravascular stents may be limited by both local thrombosis and restenosis due to intimal proliferation. In an effort to provide solutions to these problems, we seeded stents with genetically engineered endothelial cells in vitro. Using retroviral-mediated gene transfer, we inserted the gene for either bacterial beta-galactosidase or human tissue-type plasminogen activator (t-PA) into cultured sheep endothelial cells. The endothelial cells were seeded onto stainless steel stents and grown until the stents were covered. Expression of intracellular beta-galactosidase and high level secretion of t-PA were demonstrated both before and after the transduced cells were seeded onto the stents. Eight stents were expanded by in vitro balloon inflation, with observation of the seeded endothelial layer both prior to and after expansion. Most of the endothelial cells remained on the stents after balloon inflation. We conclude that intravascular stents can be coated with a layer of genetically engineered endothelial cells that can be either specifically labeled or made to secrete high levels of a therapeutic protein. Much of the layer of genetically engineered cells remains after the expansion of the stent in vitro. In vivo implantation of stents coated with genetically engineered endothelial cells may allow 1) introduction of genetically engineered endothelial cells directly into the vascular wall and 2) improvement of stent function through localized delivery of anticoagulant, thrombolytic, or antiproliferative molecules.

Animals↗