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PubMed1992

Role of extracellular matrix in regulating fenestrations of sinusoidal endothelial cells isolated from normal rat liver.

Open fenestrations are a conspicuous feature of sinusoidal endothelial cells and allow free movement of plasma into the space of Disse. In hepatic fibrosis, the number of fenestrations decreases as interstitial collagen increases in the liver, a change that correlates with deposition of extracellular matrix in the space of Disse. In this study, the possibility of a causal relationship between altered fenestral morphology and perisinusoidal matrix has been examined by culturing rat sinusoidal endothelial cells on individual matrix proteins or on a native matrix consisting of human amniotic membrane with interstitial collagen (types I and III) on one side and basement membrane proteins (collagen types IV and V and laminin) on the other. Under culture conditions, individual components of the extracellular matrix failed to maintain fenestrations. A basement-membranelike gel matrix derived from the Engelbreth-Holm-Swarm tumor war similarly ineffective. Fenestral density and porosity (percentage of cell surface occupied by fenestrations) were significantly enhanced, however, when endothelial cells were cultured on the basement-membrane side of human amnion. These data suggest that support of endothelial fenestrations requires a complex matrix. In particular, physiologically derived basement membrane maintains fenestrations, whereas interstitial collagen matrix does not. The loss of fenestrations associated with hepatic fibrosis may be related in part to an accumulation of interstitial collagens in the space of Disse.

Amnion↗
PubMed1998

Experimental confirmation of effectiveness of fenestration in acute aortic dissection.

BACKGROUND: Aortic fenestration is used clinically to treat organ ischemia in acute descending aortic dissection. However, fenestration has not been studied experimentally. This study does so using an animal model. METHODS: Descending aortic dissection was created in six dogs, with subsequent fenestration of the infrarenal aorta. Blood flow (femoral, cephalic, and renal), blood pressure (femoral and carotid), and aortic distensibility were measured at baseline, after dissection, and after fenestration. Values were compared using paired t tests. RESULTS: Baseline femoral, cephalic, and renal arterial flows were 53+/-37, 78+/-65, and 83+/-52 mL/min, respectively. Baseline femoral and carotid pressures were 82+/-13 and 81+/-11 mm Hg, respectively. After dissection, femoral, cephalic, and renal arterial flow decreased to 20+/-21 (p < 0.05), 38+/-26, and 56+/-36 mL/min, respectively. Femoral blood pressure decreased to 28+/-17 mm Hg (p < 0.05). With fenestration, femoral, cephalic, and renal flows increased to 60+/-37 (p < 0.05), 78+/-51, and 80+/-48 mL/min, respectively. Femoral blood pressure increased to 85+/-28 mm Hg (p < 0.05). Carotid pressure remained unchanged with dissection and fenestration (77+/-17 mm Hg, 82+/-17 mm Hg, respectively). Baseline aortic distensibility (21%) decreased significantly after dissection (to 1.4%, p < 0.05) and increased after fenestration (to 12%, p < 0.05). CONCLUSIONS: Experimental aortic fenestration restored blood pressure and flow to hypoperfused organs in acute descending aortic dissection. The continued clinical application of fenestration is supported.

Acute Disease↗
PubMed2001

Fenestration of the extracranial vertebral artery: review of the literature.

STUDY DESIGN: A case report on fenestration of the extracranial vertebral artery found at forensic autopsy. OBJECTIVE: To describe an extracranial vertebral artery fenestration involving the subaxial cervical region, assessed radiographically and angiographically at forensic autopsy, in a young man. SUMMARY OF BACKGROUND DATA: Duplications or fenestrations of the extracranial course of the vertebral artery are rare and seen almost exclusively as a coincidental finding in angiographic studies. The terms "fenestration" and "duplication" are often incorrectly used synonymously. The former describes the passage of the duplicated vessel within the vertebral foramen transversarium, whereas the latter refers to the duplicated vessel coursing additionally through the spinal canal. The reported cases describing duplication are more common. Only three cases of vertebral extracranial fenestrations, involving only the upper cervical spinal segments, have been described in the literature. RESULTS: Angiography showed a fenestration of the vertebral artery localized between the intervertebral spaces of C2-C3 and C3-C4. At dissection, the vertebral artery appeared as a single vessel in the area of the fenestration. Histologically, a distinct difference in the thickness and composition of the vessel walls was found between the two vessel trunks. At autopsy, no further anomalies were observed in the vessels supplying the brain, which is contrary to the commonly held belief that fenestration is frequently associated with vascular malformations. CONCLUSION: Fenestration of the extracranial course of the vertebral artery is a developmental or congenital anomaly. A review of the literature demonstrated that this is apparently only a coincidental finding and has no pathologic significance.

Adolescent↗
PubMed2004

Recurrence of thoracolumbar intervertebral disk extrusion in chondrodystrophic dogs after surgical decompression with or without prophylactic fenestration: 265 cases (1995-1999).

OBJECTIVES: To evaluate a population of chondrodystrophic dogs treated for Hansen type 1 intervertebral disk (IVD) disease by surgical decompression with or without prophylactic fenestration and determine the rate and location of surgically confirmed recurrence of intervertebral disk extrusion. ANIMALS: 265 dogs. STUDY DESIGN: Retrospective study. PROCEDURES: Medical records of dogs that underwent spinal decompression between 1995 and 1999 were reviewed. RESULTS: 3 (4.9%) dogs were euthanatized or died prior to discharge. Fenestration was performed in 252 dogs, including 37 (14.7%) at the site of decompression only, 48 (19%) at 3 to 4 disk spaces, and 167 (66%) at 5 to 7 disk spaces. There were 12 instances of recurrent disk extrusion confirmed by removal of disk at a second surgery 3.5 to 33 months after the first surgery. Recurrence was always at a new disk space, and rates did not significantly differ between dogs that underwent single or multiple fenestrations. Two recurrences were at a previously fenestrated disk space. Seven recurrences were at a site immediately adjacent to a fenestrated disk space, and 5 recurrences were at L4-5. CONCLUSIONS AND CLINICAL RELEVANCE: Prophylactic fenestration is generally successful in preventing future disk extrusions at fenestrated disk spaces. Prospective evaluation is still required to determine whether fenestration decreases the overall rate of recurrence. Prophylactic fenestration could promote disk extrusion at adjacent, nonfenestrated disk spaces. This could have a substantial clinical impact if recurrence develops at L4-5.

Animals↗
PubMed2006

Fenestration of the middle cerebral artery detected by MR angiography.

Unlike fenestration of the posterior cerebral arterial circulation, fenestration of the anterior cerebral arterial circulation has not been well described. We investigated the location and configuration of fenestration of the middle cerebral artery (MCA) detected by magnetic resonance (MR) angiography. We found 6 fenestrations of the MCA among cranial MR angiography images obtained from about 2,000 patients during the past 9 years at our institution using either of two 1.5T imagers. All images were obtained by the three-dimensional time-of-flight technique. Maximum-intensity projection images in the horizontal rotation view were displayed stereoscopically. All 6 fenestrations had small slit-like configurations, five located at the proximal M1 segment, the other, at the middle M1 segment. No associated aneurysm was found. Although MCA fenestration is extremely rare and cerebral artery fenestration usually has no clinical significance, an aneurysm can arise at the proximal end of the fenestration. Thus, recognizing MCA fenestration is important when interpreting cranial MR angiograms.

Adolescent↗
PubMed1994

The layered fabric of cerebral artery fenestrations.

BACKGROUND AND PURPOSE: Intravascular bridges, resulting from developmental anomalies of brain arteries, are now better known as arterial fenestrations. Their tendency to develop aneurysms, similar to arterial bifurcations, makes their anatomy and microstructure important for study. METHODS: Six segments of artery, each including a fenestration (five from the vertebrobasilar junction and one from the middle cerebral artery), were pressure distended, fixed, and sectioned. We made three-dimensional orientation measurements of smooth muscle and collagen, stained to enhance their birefringence, using the polarized light microscope. RESULTS: The general contour of the fenestrations is streamlined with a thickened layered subendothelium at the trailing or distal edge, structurally similar to the region of convergence of major brain arteries. Defects of the medial layer were found at both proximal and distal edges of all the fenestrations. Results included regional mean orientations of individual layers, with circular SDs. The medial layer was found to be coherently aligned perpendicular to the direction of blood flow, with a mean circular SD of 12 degrees. The adventitia was less coherent (mean circular SD, 16 degrees) with the same average orientation, and the multilayered subendothelium had layers of obliquely oriented fibers with a wide range of coherence for individual fiber groups. Layers of the side regions were analogous to those in segments of brain artery and differed significantly from the proximal and distal edges of the fenestration structure. CONCLUSIONS: The plasticity of form of the fenestrations at both the proximal and distal edges is in response to hemodynamic forces and is analogous to branching regions of brain arteries. Medial defects, a common feature in both brain arteries and fenestrations, may predispose the arterial fenestration to aneurysm formation.

Autopsy↗
PubMed1985

Fenestrated capillaries in the connective tissues of the periodontal ligament.

A quantitative ultrastructural study was undertaken to assess the number and distribution of fenestrated capillaries in the periodontal ligaments of the rat dentition. Experiments were conducted on four animals using the right mandibular incisors and first molars. For the incisor, analysis was performed in three sites along the length of the periodontal ligament. Regardless of site, there was 0.1 fenestration per micron2 of endothelium. In the basal region, the incisor periodontal ligament contained 3.5 X 10(6) fenestrations per mm3 of tissue whereas more occlusally it contained 1 X 10(6) fenestrations per mm3 of tissue. For the molar, the capillaries showed more fenestrations, 0.4 fenestration per micron2 of endothelium. There were also more per unit volume of tissue, 12 X 10(6) fenestrations per mm3. Thus, the vasculatures of the rat incisor and molar periodontal ligaments exhibit significant numbers of fenestrations which, in the case of the incisor, are not distributed uniformly along its length.

Animals↗
PubMed2003

Clipped tube fenestration after extracardiac Fontan allows for simple transcatheter coil occlusion.

BACKGROUND: Expensive devices are increasingly used to close a patent fenestration after a modified Fontan operation. We report our 5-year institutional experience of clipped tube fenestration after extracardiac Fontan operation, which allows for simple transcatheter coil occlusion. METHODS: We retrospectively reviewed 30 children, median age of 4.0 years (range, 2.4 to 8.8 years) who underwent extracardiac Fontan operation between May 1996 and May 2001, and were fenestrated using a 4- to 8-mm diameter clipped tube graft. RESULTS: Ten children had a patent fenestration occluded by transcatheter placement of 15 detachable coils (5- to 8-mm diameter). Aortic oxygen saturations increased on average by 5.5% (2% to 14%) and mean pressures in the Fontan circuit by 2.5 mm Hg (0 to 3 mm Hg). Four had immediate complete occlusion angiographically and 6 had trivial residual shunt, but complete occlusion by echocardiography at follow-up. There have been no immediate complications, late coil embolizations, thromboembolic events, or documented hemolysis within a follow-up after coil implantation of 1.7 years (0.4 to 4.5 years). Spontaneous fenestration closure was documented in 8 patients at cardiac catheterization and 9 patients by echocardiography with consistent improvement in resting transcutaneous oxygen saturation. Two children with a patent fenestration have been considered inappropriate for closure, and there was one early surgical death. There have been no complications related to the tube fenestration modification within a follow-up postoperation of 2.6 years (0.1 to 5.5 years). CONCLUSIONS: Clipped tube fenestration after extracardiac Fontan operation is a useful surgical modification that allows for simple transcatheter coil occlusion.

Cardiac Catheterization↗
PubMed2003

Staged repair of tetralogy of Fallot and diminutive pulmonary arteries with a fenestrated ventricular septal defect patch.

OBJECTIVES: Patients with tetralogy of Fallot and diminutive pulmonary arteries are at risk for suprasystemic right ventricular pressure and right ventricular failure after complete repair. We report the short-term outcome and medium-term follow-up after using a fenestrated ventricular septal defect patch as a component of staged repair in selected patients. METHODS: We reviewed 47 patients with tetralogy of Fallot and diminutive pulmonary arteries whose ventricular septal defect patch was fenestrated, either electively or as a rescue technique, at a single institution between 1984 and 2001. RESULTS: Early mortality was 10.6% and occurred only in patients who underwent rescue fenestration. Review of medium-term follow-up (median, 39 months) revealed 4 late deaths; an additional 4 patients experienced right ventricular failure despite fenestration. Most (7/8) of these late events occurred in patients who underwent planned fenestration. Excessive left-to-right shunt through the fenestration developed in only 2 patients. CONCLUSIONS: Fenestrated patch closure of the ventricular septal defect in patients with tetralogy of Fallot and diminutive pulmonary arteries resulted in 10.6% early mortality. Used preemptively in selected patients, this technique is associated with no surgical mortality and a low incidence of excessive left-to-right shunt (4%). Early survivors remain at risk for late death and right ventricular failure despite fenestration.

Abnormalities, Multiple↗
PubMed1998

Late fenestration closure in the hypoplastic left heart syndrome: comparison of hemodynamic changes.

BACKGROUND AND OBJECTIVES: Although survival of patients with the hypoplastic left heart syndrome treated by staged surgical palliation has improved, hemodynamic data after fenestrated Fontan operation and after fenestration closure have not been reported in this patient population. We sought to describe the hemodynamic status of these patients at cardiac catheterization performed for the purpose of fenestration closure and to compare these data with data from contemporary patients with other forms of univentricular heart. METHODS AND RESULTS: Hemodynamic responses to fenestration closure during cardiac catheterization were reviewed in 40 consecutive patients, including 20 with the hypoplastic left heart syndrome and 20 with other forms of univentricular heart defects. Hemodynamics before fenestration closure (arterial saturation and pressure, Fontan baffle saturation and pressure, pulmonary capillary wedge pressure, systemic arteriovenous oxygen content difference, and right-to-left shunt fraction) were nearly identical between the two groups. Significant (p < 0.05) changes after fenestration closure included increases in arterial saturation (9%), mean arterial pressure (3 mm Hg), and baffle pressure (1 mm Hg) and arteriovenous oxygen content difference (18 ml/L), with near elimination of right-to-left shunting. Cardiac output decreased by 21% and systemic oxygen transport by 13%, with no differences between the two patient groups. Mean baffle pressures were <17 mm Hg in 32 patients (80%). CONCLUSIONS: Hemodynamics after fenestrated Fontan operation and responses to fenestration closure in patients with the hypoplastic left heart syndrome were remarkably similar to that in patients with other univentricular heart defects.

Adolescent↗
PubMed1985

Endothelial fenestral diaphragms: a quick-freeze, deep-etch study.

The route by which water, solutes, and macromolecules traverse the endothelial cell has long been a subject of study for both physiologists and cell biologists. Recent physiologic studies describe a slit-shaped pore (5.1-5.7-nm wide) as the communicating channel, although no channel of such dimensions has been visible in electron microscopic preparations. That this channel should be found within the fenestral diaphragm has long been suggested. In this report, by the aid of a new technique in tissue processing, we are able to demonstrate a possible morphologic correlate within the fenestral diaphragm of fenestrated capillaries. Quick-freezing and deep-etching of whole tissue blocks allows the sublimation of water from the endothelial pores, thus leaving the channels through the diaphragms empty and readily replicated with a platinum-carbon shadow. The structure of the diaphragm was revealed thus to be composed of radial fibrils of 7 nm in diameter, interweaving in a central mesh, and creating by their geometric distribution, wedge-shaped channels around the periphery of the pore. The average channel had a maximum arc length of 5.46 nm. Fenestrated endothelia from various tissues, including endocrine and exocrine pancreas, adrenal cortex, and kidney peritubular capillaries, displayed the same diaphragmatic structure, whereas continuous capillaries in muscle had no such diaphragm. Photographic augmentation of electron micrographs of etched replicas displayed marked enhancement at n = 8, confirming an octagonal symmetry of the fenestral diaphragm. Finally, cationic ferritin, clearly visible as a marker after etching, heavily bound to the flowerlike structure within the fenestral pore. We conclude that the fenestral diaphragm contains the structure responsible for fenestrated capillary permeability and that the communicating channel has the shape of a wedge.

Animals↗
PubMed1983

Effect of fenestration soft contact lenses on corneal oxygen availability.

Recent clinical and experimental evidence suggests that a better physiological response to hydrogel lens wear can be obtained with fenestrations. To determine whether those observations could be attributed to increased corneal oxygenation, the equivalent oxygen percentage (EOP) was measured at the cornea of eight subjects wearing hydrogel contact lenses which had multiple fenestrations of 0.8 and 1.8 mm. It was possible to increase the mean EOP by 1.7 +/- 1.3% O2 (p less than 0.002) beneath a standard thickness lens using four 1.8-mm fenestrations. However, such lenses were uncomfortable to wear. Fenestrations that provided comfortable wear (0.8-mm diameter) did not significantly increase the EOP beneath standard thickness lenses (-0.1 +/- 1.0% O2, p greater than 0.1 for four fenestrations, and +0.2 +/- 1.2% O2, p greater than 0.1 for eight fenestrations) or ultrathin lenses (-0.1 +/- 1.3% O2 p greater than 0.1 for four fenestrations). It is concluded that fenestrations do not provide a clinically efficient means of increasing the oxygen tension beneath hydrogel contact lenses.

Adult↗
PubMed1985

Carbonic anhydrase in epithelia and fenestrated juxtaepithelial capillaries of Macaca fascicularis.

Thirty-nine epithelia of the monkey Macaca fascicularis and their underlying connective tissue were stained for carbonic anhydrase (CA) and studied by light microscopy. The capillaries immediately adjacent to the epithelium, 'juxtaepithelial', were also studied by electron microscopy with special attention to presence or absence of fenestrations. Only juxtaepithelial capillaries stained. These were fenestrated under many epithelia and all fenestrated juxtaepithelial capillaries stained. Often staining and fenestration were limited to the part of their circumference facing the epithelium. There was a strong association P less than 0.002 between CA-staining and fenestration of the capillaries, a moderately strong association P less than 0.02 between CA-staining of the membrane of the epithelium and the adjacent capillaries, and no association between staining of the epithelial cytoplasm on the one hand and the epithelial membrane or the capillaries on the other. Fenestrated capillaries containing CA despite unstained epithelia were found in the thyroid, parathyroid, adrenal cortex, islets and anterior pituitary, and also, but not consistently, in the prostatic and the seminal glands. Unfenestrated capillaries containing CA were found in the stomach, colon and lung, and in the Graffian follicle and Fallopian tube. The hypothesis is advanced that capillary CA besides conventional functions plays a part in conserving the state of fenestration of the endothelium and that CA-inhibitors could exert part of their therapeutic and side actions by reducing fenestrations.

Animals↗
PubMed1996

Pressures required to move gas through the native airway in the presence of a fenestrated vs a nonfenestrated tracheostomy tube.

SUBJECT: It is occasionally desirable for patients with a tracheostomy tube to breathe through their native airway. We hypothesized that capped tracheostomy tubes with cuffs deflated would create substantial additional resistance to airflow without fenestration but would provide minimal resistance to airflow when the tube had a fenestration. METHODS: Two tracheal models were tested simulating a large (26 mm) and an average (18 mm) trachea. Tests were carried out with fenestrated and nonfenestrated tracheostomy tubes of sizes ranging from No. 4 to No. 10. Negative pressure inspiration was simulated using suction. RESULTS: With a large trachea or small tubes, the suction required to generate flows of 40 L/min or greater remained less than 5 cm H2O with or without a fenestration. However, with an average-sized trachea and no fenestration, the pressure required to generate flows of 40 L/min or greater exceeded 5 cm H2O and with No. 8 or No. 10 tubes exceeded 20 cm H2O. A fenestration routinely reduced the required pressure to less than 5 cm H2O. CONCLUSION: The effort required to move gas across the native airway in the absence of a fenestration may be substantial. If a patient is to breathe through a native airway, a fenestrated tube should be used unless the tracheostomy tube is a No. 4.

Equipment Design↗
PubMed2001

Prevalence of dehiscences and fenestrations in modern American skulls.

BACKGROUND: The purpose of this study was to examine the prevalence, distribution, and features of alveolar dehiscences and fenestrations in modern American skulls and correlate their presence with occlusal attrition, root prominence, and alveolar bone thickness. METHODS: A representative sample of 146 dentate modern American skulls from a collection at the National Museum of Natural History were examined. RESULTS: The skulls were from subjects ranging in age from 17 to 87 years old (mean 49.1 years). The mean number of teeth per skull was 22.7 and the mean number of either dehiscence or fenestration defects per skull was 3.0. Of the 3,315 individual teeth examined, 4.1% (135) had dehiscences and 9.0% (298) had fenestrations. A dehiscence was present in 40.4% of the skulls, and a fenestration was present in 61.6% of skulls. Mandibular canines were most often affected by dehiscences (12.9%), while maxillary first molars were most often affected by fenestrations (37.0%). Sixty-seven percent of dehiscences were found in the mandible, and 58% of fenestrations were found in the maxilla. CONCLUSIONS: The presence of dehiscences and fenestrations were positively correlated with thin alveolar bone and negatively correlated with occlusal attrition. African-American males and Caucasian females were significantly more likely to have dehiscences, while African-American females were significantly more likely to have fenestrations.

Adolescent↗
PubMed1991

[Bilateral fenestrations of the vertebrobasilar artery with trigeminal neuralgia. Case report].

Fenestration of cerebral vessels is congenital and usually of no clinical significance. A 58-year-old female presented with left trigeminal neuralgia associated with double fenestrations of the vertebrobasilar artery. Vertebral angiography showed bilateral fenestrations in the intracranial segment. The left fenestrated artery originated at the distal portion of the vertebral artery and terminated at the middle portion of the basilar artery, compressing the left Vth cranial nerve root. The neuralgia improved after microvascular decompression. Fenestration of cerebral vessels is usually single. Five of eight reported cases with double fenestrations had bilateral extracranial fenestrations at the atlantoaxial portion of the vertebral artery. Bilateral fenestrations of the vertebrobasilar artery with trigeminal neuralgia have not been previously reported.

Basilar Artery↗
PubMedDate not supplied

Basilar artery fenestrations detected by MR angiography.

Basilar artery (BA) fenestrations are the most frequently observed fenestrations of the cerebral arteries. Our goal was to examine the magnetic resonance (MR) angiographic incidence, location, and characteristic configuration of BA fenestration. Between April 1996 and March 2000, 600 cranial MR angiographies were performed at our institution. The majority of the patients examined had or were suspected to have cerebrovascular disease. We retrospectively reviewed these 600 MR angiograms. A 1.5 Tesla scanner was used in all studies, and maximum intensity projection (MIP) images obtained using the three-dimensional time-of-flight (3D-TOF) technique were displayed stereoscopically. Ten BA fenestrations (1.7%) were detected on MR angiograms. In 87 cases from the early period, the vertebrobasilar (VB) junction was unfortunately not included in the imaging slices. Eight of the 10 fenestrations were located at the proximal BA: six of them were small with a slit-like shape, and two were relatively large with a convex-lens-like shape. A small fenestration was located at the distal BA, and the remaining one was a total duplication of the BA. We stress that knowledge and recognition of BA fenestration are useful and important in the interpretation of cranial MR angiography. Since saccular aneurysms are reported to arise frequently at BA fenestration, the VB junction should be included in the imaging slices of routine cranial MR angiography.

Basilar Artery↗
PubMed2006

[Use of covered stents to occlude extracardiac Fontan fenestration].

INTRODUCTION: A fenestration is usually surgically created to improve the post-operative course of patients undergoing total cavopulmonary connection. It, however, has a potentially deleterious effect on the long-term period. Closure of these fenestrations is usually performed by interventional catheterization. No device has been specially designed and closure of extracardiac fenestration, in particular, can be challenging. We report our experience in occlusion of such fenestrations using covered stents (Numed Inc). METHODS: From July 2005 to October 2005, we attempted to occlude extracardiac Fontan fenestration using CP covered stents in 4 consecutive patients. RESULTS: All patients had a successful occlusion of the fenestration. The procedure was performed from femoral or jugular vein respectively in three and one patient. Mean central venous pressure did not increase significantly (from 11.25 to 12.75 mmHg) whereas mean oxygen saturation increased significantly from 92% to 99% (p=0.0047). Abolition of shunt was obtained immediately after insertion of the covered stent in all patients. No early complications were observed. All patients were ambulatory the day after the procedure. CONCLUSION: The insertion of a covered stent inside the extracardiac Fontan conduit allowed the exclusion of the fenestration in all patients without the need of crossing the fenestration and with no early mortality or morbidity. Long-term follow-up are needed before considering the use of such device as the device of choice in that application.

Adolescent↗