Significant Tortuosity Research Articles

Effectiveness of a flexible coiled sheath for correcting an acute angle between the brachiocephalic vein and the superior vena cava for successful defibrillator implantation

Successful implantation of implantable cardioverter-defibrillators (ICDs) that is performed to avoid surgery in patients with atypical vasculature is still problematic. Acute angulations and significant tortuosity of the venous vasculature may influence both procedural success and periprocedural complications. We successfully implanted an ICD in a patient with deformed vasculature caused by tuberculosis-induced lung destruction by using a flexible coiled sheath instead of a friable peel-away sheath. This report highlights an alternative maneuver that may be an option in patients who have an acute angle between the brachiocephalic vein and the superior vena cava.

Iliofemoral anatomy among Asians: Implications for transcatheter aortic valve implantation

Background/objectivesThis study aims to examine iliofemoral anatomy and predictors of vessel size and tortuosity in Asian patients as transfemoral transcatheter aortic valve implantation (TAVI) may be limited by the smaller Asian physique. MethodsCharacteristics and vessel dimensions of 549 patients undergoing ultrasonography were reviewed. The minimal luminal diameter (MLD) along the iliofemoral vasculature of each side was identified and the larger of the two sides was used to determine suitability for transfemoral TAVI. ResultsThe mean age was 66±11years (68% males). Mean iliac MLD was 7.6±1.7mm, females smaller than males (7.2±1.7 vs 7.8±1.7, p<0.001). Mean iliac MLD decreased with age: 7.9±1.7mm, 7.4±1.9mm and 7.3±1.6mm for ages <70years, 70–79years and ≥80years respectively (p=0.038). Mean femoral MLD was 7.0±1.7mm, females smaller than males (6.3±1.5mm vs 7.3±1.8mm, p<0.001). Females were more likely than males to have iliac and femoral MLD <6mm (20% vs 12%, p=0.019 and 34% vs 21%, p=0.001). Independent predictors of smaller iliofemoral dimensions were female gender, lower body surface area, diabetes mellitus, dyslipidemia and smoking history. Significant iliac tortuosity was present in 11.8%, more frequent in males than females (15% vs 6%, p=0.005), and in those with logistic EuroSCORE ≥15 than <15 (27% vs 10%, p=0.001). ConclusionsThis study establishes the mean iliac and femoral artery diameters in a cohort of relatively young Asian patients. Age and female gender were associated with smaller vessel dimension and several independent predictors of smaller vasculature and tortuosity were identified. These results have implications for TF TAVI in Asia.

Solubility and diffusivity of cyclohexane in high density polyethylene

AbstractThe diffusivity and solubility of cyclohexane in a high density polyethylene, HDPE, were studied using a gravimetric, quartz‐spring, sorption balance. Solvent concentrations up to a weight fraction of 0.15 over a temperature range of 90 to 160°C were measured. Diffusion coefficients in the range of 10−6 to 10−7 were determined. Two types of polymer samples were used: a commercial bead form and flat sheets prepared by melting the polymer. Within the experimental error no differences were observed between the two forms indicating that there were no significant effects caused by the melting and compression. The solubility of cyclohexane in the HDPE as a function of the activity of the cyclohexane was linear. Above the melt temperature the solubility data were predicted better by the group‐contribution, lattice‐fluid equation of state (GCLF‐EoS) than by the van der Waals free‐volume (UNIFAC‐vdw‐FV) model. Below the melt temperature a correction factor for the elasticity significantly improved the predictions for both models. Although the HDPE has a crystallinity of 77.6%, the experimental data and the Vrentas‐Duda free‐volume theory indicated no significant tortuosity effects. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Use of the venture catheter to shorten the door-to-balloon time in patients with ST-Segment elevation acute myocardial infarction

Achieving a door-to-balloon time < 90 min may be challenging in patients with ST-segment elevation acute myocardial infarction with difficult to wire coronary lesions. We report use of the Venture wire control catheter to facilitate wiring in four patients with significant tortuosity proximal to a thrombotic coronary occlusion, after conventional wiring attempts failed. Early use of the Venture catheter may help shorten the door-to-balloon time in patients with challenging to wire lesions.

The Versatile Distal Access Catheter: The Cleveland Clinic Experience

Vascular access is fundamental to any endovascular intervention. Concentric Medical has developed the Outreach Distal Access Catheter (DAC), which affords stable access at the target vessel modulating the forces at play within the thrombectomy device complex. The DAC is a device with novel access characteristics useful in a host of other types of clinical scenarios. To review our experience with the DAC family of devices, the theory, and method of use. A retrospective review of all cases in which the DAC was used during the period 2008 to 2010 was conducted and the cases classified by indication. Catheter-related complications were recorded. The use of the DAC in a variety of settings including intracranial stenting, aneurysm coil embolization, and arteriovenous malformation embolization is described. The DAC was used in 103 procedures performed in 93 patients between August 2008 and February 2010. Indications included acute stroke, treatment of intracranial atherosclerosis, vasospasm therapy, arteriovenous malformation embolization, and aneurysm embolization. In those procedures, 113 catheters were used. No complications directly attributable to DAC use were identified. The DAC is useful for gaining access to the cerebral vasculature, especially in patients with significant tortuosity or when re-access of distal vasculature is required multiple times.

Achievement of Right Ventricular Pacing by Use of a Long Guiding Catheter in a Hemodialysis Patient Presenting Significant Tortuosity of Vasculature

Increased vascular calcification and tortuosity are rather common in end-stage renal failure patients who are on hemodialysis. It renders manipulation of catheters and performance of percutaneous transluminal interventions more difficult than expected. Such vascular alterations may be evident in large veins and pose significant difficulties in placement of pacing leads as shown in our case. To overcome such difficulties, we demonstrated in this patient case that long guiding catheters may be of particular value.

Endovascular aneurysm repair for ruptured abdominal aortic aneurysm: The Albany Vascular Group approach

Improvements in endovascular technology and techniques have allowed us to treat patients in ways we never thought possible. Today, endovascular treatment of ruptured abdominal aortic aneurysms is associated with markedly decreased morbidity and mortality compared with the open surgical approach, yet there are several fundamental obstacles in our ability to offer these endovascular techniques to most patients with ruptured aneurysms. This article will focus on the technical aspects of endovascular aneurysm repair for rupture, with particular attention to developing a standardized multidisciplinary approach that will help vascular surgeons deal with not just the technical aspects of these procedures but also address some of the challenges, including the availability of preoperative computed tomography, the choice of anesthesia, the percutaneous vs femoral cutdown approach, use of aortic occlusion balloons, need for bifurcated vs aortouniiliac stent grafts, need for adjunctive procedures, diagnosis and treatment of abdominal compartment syndrome, and conversion to open surgical repair.

Rabbit Retinal Neovascularization Induced by Latex Angiogenic-Derived Fraction: An Experimental Model

Purpose: To create a retinal neovascularization experimental model using intravitreal injection of microspheres loaded with latex-derived angiogenic fraction.Methods: Thirty-two albino New Zealand rabbits, divided in 4 groups of 8 animals, were enrolled in this study. Rabbits in groups I, II, and III received one intravitreal injection of PLGA (L-lactide-co-glycolide) microspheres with 10, 30, and 50 µg of latex-derived angiogenic fraction into their right eyes, respectively, and group IV received 0.1 ml of microspheres without the angiogenic fraction. Weekly follow-up with ophthalmoscopy and fluorescein angiography was performed; the rabbits were sacrificed in the 4th week and their eyes processed for light microscopy.Results: All eyes from group I demonstrated increased retinal vascular tortuosity, observed from 14 days after injection and maintained for 28 days, otherwise without new vessels detection. All group II eyes showed vascular changes similar to group I. Fifty percent of the eyes from group II rabbits developed retinal neovascularization 21 days after injection. All eyes from group III demonstrated significant vascular tortuosity and retinal new vessels 2 weeks after injection, progressing to fibrovascular proliferation and tractional retinal detachment. No vascular changes or retinal new vessels were observed in group IV eyes. Light microscopy confirmed the existence of new vessels previously seen on fluorescein angiography, in retinal sections adjacent to the optic disc, not observed in sections at the same area in the control group.Conclusion: Thirty- and 50-µg microspheres containing latex-derived angiogenic fraction injected into the vitreous cavity induced retinal neovascularization in rabbits.

In vivo assessment of rapid cerebrovascular morphological adaptation following acute blood flow increase

Pathological extremes in cerebrovascular remodeling may contribute to basilar artery (BA) dolichoectasia and fusiform aneurysm development. Factors regulating cerebrovascular remodeling are poorly understood. To better understand hemodynamic influences on cerebrovascular remodeling, we examined BA remodeling following common carotid artery (CCA) ligation in an animal model. Rabbits were subjected to sham surgery (3 animals), unilateral CCA ligation (3 animals), or bilateral CCA ligation (5 animals). Transcranial Doppler ultrasonography and rotational angiography were used to compute BA flow, diameter, wall shear stress (WSS), and a tortuosity index on Days 0, 1, 4, 7, 14, 28, 56, and 84. Basilar artery tissues were stained and analyzed at Day 84. Statistical analysis was performed using orthogonal contrast analysis, repeated measures analysis of variance, or mixed regression analysis of repeated measures. Statistical significance was defined as a probability value < 0.05. Basilar artery flow and diameter increased significantly after the procedure in both ligation groups, but only the bilateral CCA ligation group demonstrated significant differences between groups. Wall shear stress significantly increased only in animals in the bilateral CCA ligation group and returned to baseline by Day 28, with 52% of WSS correction occurring by Day 7. Only the bilateral CCA ligation group developed significant BA tortuosity, occurring within 7 days postligation. Unlike the animals in the sham and unilateral CCA ligation groups, the animals in the bilateral CCA ligation group had histological staining results showing a substantial internal elastic lamina fragmentation. Increased BA flow results in adaptive BA remodeling until WSS returns to physiological baseline levels. Morphological changes occur rapidly following flow alteration and do not require chronic insult to affect substantial and significant structural transformation. Additionally, it appears that there exists a flow-increase threshold that, when surpassed, results in significant tortuosity.

The Case for Percutaneous Endopyeloplasty

in the treatment algorithm for UPJ obstruction. Factors that define the optimal choice of surgical approach in the individual patient include ipsilateral renal function, degree of hydronephrosis, length of stricture, previous surgical intervention on the UPJ, presence of ipsilateral renal calculi, presence of a crossing vessel at the UPJ, and individual surgeon comfort level and experience. Management Relevant facts in the case scenario include a history of open pyeloplasty and presence of a 1.5-cm lower-pole calculus. Additional variables that need to be assessed before deciding the optimal management include length of stricture, anatomy of the UPJ and proximal ureter, and ipsilateral renal function. Therefore, the initial step in management would be to quantify differential renal function via a radionuclear renal scan and obtain anatomic evaluation via excretory urography. Anatomic delineation of the UPJ and proximal ureter is further defined by performing retrograde pyelography. Because the length of stricture and anatomy of the UPJ play a significant role in determining type of therapy, we typically perform the retrograde pyelography as a separate procedure in patients who have undergone pyeloplasty previously, especially if the anatomic delineation is suboptimal on excretory urography. This approach helps plan the appropriate procedure and enables us to counsel patients appropriately. This is an important issue, because many patients in whom an open pyeloplasty has failed may need a complex salvage reconstructive procedure. We assume in this debate that the segment of obstruction is short and there is no significant tortuosity of the proximal ureter. In general, endopyelotomy is a reasonable alternative for patients in whom pyeloplasty has failed, and pyeloplasty is the preferred approach for patients in whom endopyelotomy has failed. Because this patient also has a 1.5 cm calculus, the percutaneous approach would be preferred. We believe endopyeloplasty to be functionally superior to endopyelotomy, and it would therefore be our procedure of choice for this patient. This approach would effectively remove the calculus and simultaneously manage the UPJ obstruction. A crucial factor in this case is that the pyeloplasty was performed 13 years ago. We believe that the periureteral scarring is less dense if the surgical intervention was performed in the remote past as opposed to recently. It therefore would not technically prohibit performance of an endopyeloplasty.

Morphometric Analysis of Arteriolar Tortuosity in Human Cerebral White Matter of Preterm, Young, and Aged Subjects

Arteriolar tortuousities, consisting of vascular coils, loops, and spirals, appear in white matter in a subset of human cerebral vessels. Computerized morphometry was used to analyze brain sections from a broad age range of subjects to determine whether tortuosity is a phenomenon of aging or is associated with leukoaraiosis (LA) or Alzheimer disease (AD). Autopsy brains were studied from 55 subjects ranging in age from 23 weeks postconception to 102 years. Fourteen aged subjects were diagnosed with LA and 7 with AD. By using computerized morphometry, vascular curl (curvilinear length/straight length) was measured in white matter arterioles in 100-microm-thick, alkaline phosphatase-stained sections. Aging subjects, compared with young subjects, showed significant increases in both the prevalence and severity of tortuosity. Curl scores in aged subjects with LA or AD were not significantly different from aged controls without LA or AD. We conclude that 1) tortuous vessels are extremely rare in preterm babies, children, or young adults; 2) significant tortuosity, as indicated by elevated curl scores, begins in middle age; 3) tortuosity does not appear in a subset of aged individuals regardless of longevity; and 4) tortuosity does not appear in a subset of individuals with either LA or AD.

Morphometric analysis of arteriolar tortuosity in human cerebral white matter of preterm, young and aged subjects

Arteriolar tortuousities, consisting of vascular coils, loops, and spirals, appear in white matter in a subset of human cerebral vessels. Computerized morphometry was used to analyze brain sections from a broad age range of subjects to determine whether tortuosity is a phenomenon of aging or is associated with leukoaraiosis (LA) or Alzheimer disease (AD). Autopsy brains were studied from 55 subjects ranging in age from 23 weeks postconception to 102 years. Fourteen aged subjects were diagnosed with LA and 7 with AD. By using computerized morphometry, vascular curl (curvilinear length/straight length) was measured in white matter arterioles in 100-microm-thick, alkaline phosphatase-stained sections. Aging subjects, compared with young subjects, showed significant increases in both the prevalence and severity of tortuosity. Curl scores in aged subjects with LA or AD were not significantly different from aged controls without LA or AD. We conclude that 1) tortuous vessels are extremely rare in preterm babies, children, or young adults; 2) significant tortuosity, as indicated by elevated curl scores, begins in middle age; 3) tortuosity does not appear in a subset of aged individuals regardless of longevity; and 4) tortuosity does not appear in a subset of individuals with either LA or AD.

Abnormal Vessel Tortuosity as a Marker of Treatment Response of Malignant Gliomas: Preliminary Report

Despite multiple advances in medical imaging, noninvasive monitoring of therapeutic efficacy for malignant gliomas remains problematic. An underutilized observation is that malignancy induces characteristic abnormalities of vessel shape. These characteristic shape abnormalities affect both capillaries and much larger vessels in the tumor vicinity, involve larger vessels prior to sprout formation, and are generally not present in hypervascular benign tumors. Vessel shape abnormalities associated with malignancy thus may appear independently of increase in vessel density. We hypothesize that an automated, computerized analysis of vessel shape as defined from high-resolution MRA can provide valuable information about tumor activity during the treatment of malignant gliomas. This report describes vessel shape properties in 10 malignant gliomas prior to treatment, in 2 patients in remission during treatment, and in 2 patients with recurrent disease. One subject was scanned multiple times. The method involves an automated, statistical analysis of vessel shape within a region of interest for each tumor, normalized by the values obtained from the vessels within the same region of interest of 34 healthy subjects. Results indicate that untreated tumors display statistically significant vessel tortuosity abnormalities. These abnormalities involve vessels not only within the tumor margins as defined from MR but also vessels in the surrounding tissue. The abnormalities resolve during effective treatment and recur with tumor recurrence. We conclude that vessel shape analysis could provide an important means of assessing tumor activity.

Preoperative selective intercostal angiography in patients undergoing thoracoabdominal aneurysm repair

ObjectiveThis study was designed to test the hypothesis that detection of the location of the major artery supplying the spinal cord, that is, the artery of Adamkiewicz or the great radicular artery (GRA), with angiography would help prevent paraplegia. Knowing which intercostal artery provides this important branch would enable prompt, focused revascularization. MethodThe surgical outcome in 131 patients with Crawford extent 1 and 2 degenerative aneurysms and 69 patients with descending thoracic aortic dissection was correlated with findings on selective intercostal arteriograms. Angiographic maneuvers were done with care, and the procedures were aborted if there was loose or “shaggy” mural thrombus, significant tortuosity, or difficulty entering each dissection channel. No attempts were made to find major contributions proximal to T6. Subarachnoid drains were placed in all patients, and all but five patients underwent distal aortic perfusion with controlled cooling to 32°F. Five patients underwent cold circulatory arrest, enabling replacement of the distal aortic arch. We defined paraplegia simply as the inability to walk at hospital discharge, paraparesis as impaired ambulation, and both as having spinal cord dysfunction (SCD). ResultsA GRA was found in 65 (43%)of the 151 patients studied. Of the 65 patients with the GRA identified, SCD developed in 3 (4.6%) patients. Thirteen of 135 (9.6%) patients in whom the GRA was not identified, either because they were not studied or were studied and the GRA was not found, developed SCD (P = .35) However, when the GRA was identified, SCD occurred only in the group with aortic dissection. None of the 45 patients with degenerative aneurysms with the GRA identified had SCD, compared with 9 of 55 (16%) patients studied but without a GRA found (P = .01). ConclusionThe approach with selective intercostal angiography did not improve overall results. One third of our patients were not studied, and they fared as well as patients who were studied and the GRA was localized (not studied, 4 of 49, 8% with SCD; GRA localized, 3 of 65, 5% with SCD; P = .8). However, when the GRA was found, SCD occurred only in patients with aortic dissection. The studies confirmed the concept that the existence of mural thrombus in degenerative aneurysms results in the occlusion of many intercostal arteries, leaving those remaining patent to supply rich vascular watersheds through acquired collateral channels. As a result, in the group of patients with degenerative aneurysms, the identification of the critical intercostal artery allows focused reimplantation with uniform success. This is not the case in patients with aortic dissection. In those patients, most intercostal vessels remain patent, such that the insertion of one pair is insufficient to supply the paravertebral plexus and the spinal cord. Finally, failure to identify the GRA angiographically with our methods does not provide assurance that the GRA does not exist. Therefore negative findings did not provide license to ligate all intercostal arteries.

Evaluación con ultrasonografía intravascular de stents implantados sin predilatación (stents directos). Comparación de resultados según el tipo de lesión

Direct stenting is a safe and feasible technique in selected lesions yielding excellent angiographic results. However, there are no studies providing intravascular ultrasonographic examination after direct stenting. The aim of this study was to evaluate direct stent expansion with ultrasonography and to know whether there are differences in the results based on lesion types. Patients with amenable lesions for direct stenting were enrolled; including patients with no occlusion, no calcification, no significant tortuosity or angulation, a length 15 mm and a reference lumen diameter 2.5 mm. Intravascular ultrasonography was performed after stent implantation. The ultrasonographic criteria for optimal expansion were: complete apposition and a minimal intrastent lumen area > 80% of the average reference luminal area and 90% of the distal reference lumen area. We included 40 patients (50 lesions). The final angiographic result was good in all the patients but in one case an additional stent was used due to dissection. The ultrasonographic examination did not show significant differences between type A and B lesions. Optimal expansion was achieved in 14/21 (66%) of type A lesions and 17/29 (58%) of type B lesions (p = 0.5). The balloon/artery ratio was the only factor significantly related to ultrasonographic results. When this ratio was 1.1-1.2 (25 cases), 76% of the stents were optimally expanded and when the ratio was < 1. 1 (25 cases) only in a 48% an optimal result was achieved (p < 0.05). Direct stenting in selected lesions provides ultrasonographic results comparable to those expected with conventional stenting and these results could be even improved if a balloon artery ratio 1.1-1.2 is used. Taking into consideration the selection criteria the differences observed between lesion types A and B are not significant.

A Case of Stent Embolizations into the Left Renal and Right Common Iliac Artery during Primary PTCA

Coronary stent embolization is a rare event but may result in clinically relevant cardiac ischemia or peripheral embolization during the procedure. We report a case of systemic embolizations of two coil stents during the primary PTCA in acute myocardial infarction, who were treated successfully with a double wire helix technique and a gooseneck snare. Although in our experience this rare complication did not produce any clinical com- plications, care should be taken to prevent this possibility, especially in patients with significant vessel tortuosity, calcification, total occlusion, or mild stenosis proximal to the target lesion. (Korean Circulation J 1999;29( ( ( (11 :

Iris Vascular Changes in Newborns of Diabetic Mothers

Routine ophthalmic examinations of 600 full-term neonates, including 54 born to mothers with insulin-dependent diabetes mellitus and 12 whose mothers had developed gestational diabetes, revealed significant tortuosity and dilatation of the iris vessels in over half of the infants born to diabetic mothers. Ninety percent of the newborns in the diabetic group presented hypoplasia of the iris stroma and pupil dynamics were altered in 85%. The vessel changes resolved spontaneously within 2 weeks after birth. These changes, which have also been observed in cocaine-intoxicated newborns, should raise the suspicion of adverse vascular effects in the fetus caused by maternal diabetes.

Femoral artery catheterization and vessel tortuosity.

In the era of selective and superselective arteriography, vessel tortuosity, even in the presence of good pulses, can impede catheterization of the aorta and its branches. We assessed 101 patients who had femoral arteriography to determine whether there was a significant difference in tortuosity between the right and left sides and to define the degree to which significant tortuosity was bilateral. Fourteen and 21 patients had tortuosity greater than 1 standard deviation above the mean of the population on the right and left sides, respectively. This difference was not statistically significant. Twenty-three of the 29 patients with tortuosity greater than 1 standard deviation above the mean had this finding unilaterally. There is no advantage to preferentially beginning catheterization on a particular side. Furthermore, since 80% of significant tortuosity is unilateral, the contralateral femoral artery should be approached with only minimal delay when tortuosity that impedes catheterization is encountered.

Surgical Treatment of the Massively Dilated Ureter in Children. Part I. Management by Cutaneous Ureterostomy

One of the major therapeutic challenges facing the pediatric urologist is the massively dilated ureter. When conservative measures, such as relief of obstruction or treatment of infection, have failed or are likely to fail, surgical treatment must be directed at the massive dilatation itself. These circumstances were encountered in 366 massively dilated ureters in 244 children during a 10-year period. Loop and/or terminal cutaneous ureterostomy was used to manage 125 of these ureters in 74 children. Indications for temporary non-intubated proximal urinary diversion included uncontrolled infection, sepsis, azotemia, significant ureteral redundancy and tortuosity, and questionable over-all renal function. Advantages of loop ureterostomy included more proximal drainage and less stomal problems but terminal ureterostomy required a significantly lesser number of surgical procedures in reconstructing the urinary tract. Temporary splinting of the ureter in dry ureteral reimplantations has diminished markedly the incidence of ureterovesical complications. No instances of permanent vesical contracture were noted after long periods of defunctionalization. After initial reconstruction of 47 cutaneous ureterostomies good results by all parameters were obtained in 68 per cent. Additional surgical procedures in selected initial failures have resulted in a final success rate of 85 per cent.

Doppler sonography diagnosis of cerebrovascular disease.

Sonographic patterns for the Doppler ophthalmic test (DOT) were determined by reviewing the type of graphic record obtained from 25 patients who had undergone angiography. Three principal patterns were identified, depending upon whether there was augmentation (Type 1), diminution (Type 2) or no change (Type 3) in the character of the supraorbital Doppler signal upon temporal artery compression. Type 1 records were seen in 28 of 33 instances where the carotid arteries remained patent. Type 2 records occurred in 10 of 14 instances where there was significant carotid stenoses or tortuosity and in two instances in a patient with a subclavian steal syndrome. A "false-positive" test was recorded in one instance in a patient with vascular headaches. There were three Type 3 records.