Treatment of venous pulsatile tinnitus in younger women.

BACKGROUND: We present 7 cases of pulsatile tinnitus (PT) of venous origin in younger women seen over a period of 24 years and treated by Internal Jugular Bulb ligation. METHODS: All patients had a pulsatile bruit in one side of the neck that disappeared when gentle pressure over the internal jugular vein (IJV) caused it to collapse as seen in a duplex scan. Their computed tomography showed a dominant venous system with a high jugular bulb on the side of the bruit. RESULTS: The IJV was ligated under local anesthesia. Five patients in whom the ligation was done above the facial vein were cured. Two patients in whom the ligation was done below the facial vein experienced a decrease but not disappearance of the PT. CONCLUSIONS: Once other possible causes for PT have been discarded, ligation of the IJV above the facial vein cures this condition.

Experimental and clinical evidence supporting septectomy in the primary treatment of acute type B thoracic aortic dissection.

BACKGROUND: We reviewed the mechanics involved in the aneurysmal dilatation of the false lumen (FL) in type B aortic dissection and the experimental and clinical evidence supporting the proposition that the main agent for this dilatation is a differential of pressure between the false and true lumena. This difference in pressure is the consequence of a restricted outflow of the FL. Our aim was to study the relationship between the size of a septectomy that increases the outflow of the FL and its effect on the values of the differential of pressure. METHODS: A bench-top model of aortic dissection was used to determine the relationship between the area of the tears and the value of the pressure differential. A range of tear sizes was tested. RESULTS: The highest differential of pressure (6.77 mm Hg) was found with a single proximal tear. The addition of a distal tear decreases the pressure difference. The greater the sum of the areas of proximal and distal tears, the lower the pressure difference between true lumen and FL. This pressure difference approached zero, as the sum of the areas approached 250 mm(2). CONCLUSIONS: A septectomy of at least 250 mm(2), initiated from the distal tear to the proximal aorta of an area, should be part of the initial treatment of acute aortic dissection. Concomitant with it, the proximal tear should be occluded with either a bare stent or a stent graft.

Sources of error in the measurement of aortic diameter in computed tomography scans.

OBJECTIVE: This study was conducted to determine the differences in the diameter of the thoracic aorta when measured from electrocardiographic (ECG)-gated and nongated computed tomography (CT) angiography. Another aim was to define the difference in the aortic diameter when it is measured at peak systole and end diastole in ECG-gated scans. METHODS: The gated and nongated CT angiograms of 27 patients (mean age, 58 ± 16 standard deviation [SD] years) obtained on a 256-slice multidetector CT scanner were used. The transverse and anteroposterior diameters and the lumen areas were measured at 1, 4, and 8 cm below the origin of the left subclavian artery. RESULTS: There was a significant difference in the aortic measurements of diameter between gated and nongated scans found in samples taken at 1, 4, and 8 cm distal to the left subclavian artery (P < .0001). We found a considerable difference between the systolic and diastolic diameters (P < .0001). The maximum change in diameter between systole and diastole was 2.9 ± 0.9 (SD) mm (14.5%, P < .0001) at 1 cm, 5.4 mm (22.6%; median, 1.7 mm; P < .0001) at 4 cm, and 4.4 mm (16.9%; median, 1.3 mm; P < .0001) at 8 cm. There was a significant difference between the transverse and anteroposterior diameters in systole and diastole at all locations (P < .0001): The maximum change in diameter between transverse and anteroposterior diameters in systole was 5.4 ± 1.1 (SD) mm (15.7%, P < .0001) at 1 cm, 5.8 mm (19%; median, 1.4 mm; P < .0001) at 4 cm, and 5 mm (15%; median, 1.02 mm; P < .0001) at 8 cm. There was also a substantial difference between measuring the transverse diameter directly and deriving it from the lumen area (P < .0001). CONCLUSIONS: Our results showed an important difference between systolic and diastolic diameters measurements in ECG-gated scans. The standard protocol for measuring aortic diameters in gated scans of the thoracic aorta uses images at end diastole because the lack of wall motion at this time provides better resolution. This is likely to result in undersizing that, in some instances, may threaten stability and the proper seal of the stent graft. The dimensions of the aorta in a gated CT should be measured at peak systole rather than the conventional end diastole used today. Most medical centers use nongated CT or gated CT scans in end diastole to calculate sizes of endografts. In view of our findings, the latter method could result in potential complications.

Contemporary outcomes after distal vertebral reconstruction.

INTRODUCTION: Flow-limiting lesions or embolic phenomena can produce vertebrobasilar ischemia. This study aims to differentiate the pathophysiology of vertebral ischemia and examine contemporary outcomes after distal vertebral reconstruction. METHODS: Between February 2005 and November 2011, 41 consecutive distal vertebral artery (VA) reconstructions were performed in 34 patients, including bypass to the third portion of the VA (V3) at the C1-2 level (n = 24) or the C0-1 level (n = 7); transposition of the external carotid artery or its occipital branch onto V3 (n = 6); transposition of V3 onto the internal carotid artery (n = 3); and bypass from the ipsilateral subclavian artery to V3 (n = 1). Six patients required a concomitant carotid intervention, and nine patients required a partial resection of the C1 transverse process. Symptoms, present in 91% of patients, were attributed to a flow-limiting lesion in 16 (52%), to embolization in nine (29%), and to a mixed etiology in six (19%). RESULTS: Intraoperatively, five patients required graft revision or conversion of a transposition to a bypass, and two patients required vertebral ligation. Median blood loss was 260 mL. Median hospital length of stay was 1 day. Postoperatively, one patient (2%) required re-exploration for bleeding, a stroke occurred in one patient (2%), and cranial nerve injury occurred in three patients (7%). There were no perioperative deaths. Survival analysis showed that primary patency at 1, 2, and 5 years, respectively, was 74%, 74%, and 54%. Secondary patency was 80% at 1 year and remained so through the end of follow-up at 80 months. A statistically significant difference in patency was noted favoring arterial transposition over vertebral bypass of 100%, 100%, and 83% at 1, 2, and 5 years, respectively, vs 65%, 65%, and 39% (P = .018). Considering successful redo bypass grafting for late failure, 97% of patients demonstrated preserved patency at their last follow-up. There were two late deaths of unknown etiology and no late strokes. CONCLUSIONS: Distal VA reconstruction for flow-limiting or embolic lesions provides excellent stroke protection and symptomatic relief with acceptable perioperative risk in selected patients.

Primary extracranial vertebral artery aneurysms.

BACKGROUND: Extracranial vertebral artery aneurysms are uncommon and are usually associated with trauma or dissection. Primary cervical vertebral aneurysms are even rarer and are not well described. The presentation and natural history are unknown and operative management can be difficult. Accessing aneurysms at the skull base can be difficult and, because the frail arteries are often afflicted with connective tissue abnormalities, direct repair can be particularly challenging. We describe the presentation and surgical management of patients with primary extracranial vertebral artery aneurysms. METHODS: In this study we performed a retrospective, multi-institutional review of patients with primary aneurysms within the extracranial vertebral artery. RESULTS: Between January 2000 and January 2011, 7 patients, aged 12-56 years, were noted to have 9 primary extracranial vertebral artery aneurysms. All had underlying connective tissue or another hereditary disorder, including Ehler-Danlos syndrome (n=3), Marfan's disease (n=2), neurofibromatosis (n=1), and an unspecified connective tissue abnormality (n=1). Eight of 9 aneurysms were managed operatively, including an attempted bypass that ultimately required vertebral ligation; the contralateral aneurysm on this patient has not been treated. Open interventions included vertebral bypass with vein, external carotid autograft, and vertebral transposition to the internal carotid artery. Special techniques were used for handling the anastomoses in patients with Ehler-Danlos syndrome. Although endovascular exclusion was not performed in isolation, 2 hybrid procedures were performed. There were no instances of perioperative stroke or death. CONCLUSIONS: Primary extracranial vertebral artery aneurysms are rare and occur in patients with hereditary disorders. Operative intervention is warranted in symptomatic patients. Exclusion and reconstruction may be performed with open and hybrid techniques with low morbidity and mortality.

Synchronous carotid body and thoracic paraganglioma associated with a germline SDHC mutation.

Paraganglionic tumors are rare. A germline mutation responsible for a familial pattern of paragangliomas (PGLs) has been identified on the genes encoding for the subunits of succinate dehydrogenase (SDH). Manifestations of those with a succinate dehydrogenase subunit C (SDHC) germline mutation have been almost exclusively reported as single head and neck paragangliomas (HNPGLs). We present a 32-year-old man with a familial SDHC mutation who manifests synchronous PGLs of the carotid body and the thoracic aortopulmonary window. To our knowledge, this is the first report of such a presentation for this mutation.

Two case presentations and surgical management of Bow Hunter's syndrome associated with bony abnormalities of the C7 vertebra.

Bow Hunter's syndrome is a condition in which patients experience vertebrobasilar symptoms on head turn. It may be a consequence of intrinsic factors such as atherosclerosis, or it may be secondary to mechanical compression. Most commonly, this occurs at the level of C2 or above. We present two rare cases of Bow Hunter's syndrome secondary to mechanical compression at the level of C7. Discussed are the anatomic conditions leading to this syndrome in these two patients, the methodology for confirming the diagnosis, and the successful management by partial resection of the transverse processes compressing the vertebral arteries.

The spectrum of arterial compression at the thoracic outlet.

OBJECTIVE: In the absence of ischemic events, arterial pathology at the thoracic outlet (TO) is rarely identified because findings of chronic arterial pathology may be masked by symptoms of neurogenic compression. This study describes the clinical presentations and significance of arterial compression at the TO. METHODS: This was a retrospective analysis of the clinical records and imaging studies of 41 patients with objective findings of arterial compression at the TO. Sixteen were diagnosed from 1990 to 2003, during which 284 patients underwent surgery for TO decompression with selective arterial imaging; 25 were diagnosed from 2003 to 2009, and 62 underwent TO surgical decompressions. RESULTS: Subclavian artery stenosis, with or without poststenotic dilatation (PSD), was found in 26 patients (63%), subclavian artery aneurysms in 12 (29%), chronic subclavian occlusion in 1(2.4%), and axillary artery compression in 2 (5%). Chronic symptoms difficult to discern from neurogenic compression were present in 27 patients (66%; 24 had subclavian stenoses or PSD, or both, 1 had subclavian occlusion, and 2 had axillary artery compression); 13 (32%) presented with acute ischemia (11 had aneurysms and 2 had PSDs), and 1 asymptomatic patient had a subclavian aneurysm. Osteoarticular anomalies were found in 27 patients (66%), including 19 cervical ribs, 4 first rib anomalies, and 4 clavicular or first rib fractures, or both. Among 27 patients with subclavian aneurysms or PSD, 21 (78%) had a bone anomaly. Arterial pathology was deemed significant in 30 patients (73%) and mild or moderate in 11 (21%). Symptoms in 23 of these patients were compatible with neurogenic compression without clinical suspicion of arterial pathology, but 13 (56%) harbored a significant arterial anomaly. CONCLUSIONS: The incidence of arterial pathology secondary to compression at the TO may be underestimated, and in the absence of obvious ischemia, significant arterial pathology may not be suspected. Two-thirds of patients with arterial compression have associated bone anomalies. Therefore, routine arterial imaging seems advisable for patients evaluated for TO syndrome in the presence of a bone anomaly at the TO or an examination that shows an arterial abnormality. In the absence of these signs, however, arterial pathology may be overlooked in patients with symptoms suggestive of neurogenic compression. Further study is needed to elucidate the incidence, natural history, and clinical relevance of arterial compression and PSD at the TO.

Hybrid repair of aortic aneurysms involving the visceral and renal vessels.

BACKGROUND: We sought to analyze our experience with hybrid treatment of aortic aneurysms involving the renal and visceral arteries. METHODS: We conducted a retrospective review of 36 consecutive patients who underwent renal/visceral bypasses followed by aortic endografting. Patient demographics, medical history, operations, complications, graft patency, and patient survival were recorded. Observational and comparative analyses were performed. RESULTS: Mean patient age was 71 years. Mean aneurysm diameter was 6.3 cm (range 4.1-9.4 cm). Crawford aneurysm types included 1 type I, 10 type II, 12 type III, 10 type IV, and 3 pararenal aneurysms. Four patients were symptomatic. One hundred twenty-three bypasses were performed (median of three per patient), including 62 renal, 32 superior mesenteric, and 29 celiac arteries. Retrograde inflow (using the iliac arteries, aorta, or a limb of an aortobifemoral graft) was obtained in 30 patients and antegrade inflow was performed in six (three from the supraceliac aorta and three celiac branch to renal bypasses). In-hospital mortality occurred in 3 patients (8.3%). Patient survival was 80% at a mean follow-up of 6 months. Major morbidity occurred in 17 patients (47%) and included need for dialysis (5), ischemic colitis (3), failure to thrive (5), temporary paraparesis (1), and need for reoperation (7). No patient sustained permanent paraplegia. Mean length of stay was 26 days (range 8-100 days). Primary renovisceral bypass graft patency rate at 8 months was 93%. During follow-up, 14 patients developed at least one endoleak, 2 patients required percutaneous intervention, and the rest remained under observation. At last follow-up, four type 2 endoleaks and one type 3 endoleak with stable or decreasing aneurysm size. CONCLUSION: Hybrid repair of aortic aneurysms involving the renal and visceral arteries is feasible with a reasonable mortality and satisfactory short-term visceral graft patency rate. However, the morbidity of the debranching procedures is high. More stringent patient selection may improve these results.

Effects of strain rate, mixing ratio, and stress-strain definition on the mechanical behavior of the polydimethylsiloxane (PDMS) material as related to its biological applications.

Tensile tests on Polydimethylsiloxane (PDMS) materials were conducted to illustrate the effects of mixing ratio, definition of the stress-strain curve, and the strain rate on the elastic modulus and stress-strain curve. PDMS specimens were prepared according to the ASTM standards for elastic materials. Our results indicate that the physiological elastic modulus depends strongly on the definition of the stress-strain curve, mixing ratio, and the strain rate. For various mixing ratios and strain rates, true stress-strain definition results in higher stress and elastic modulus compared with engineering stress-strain and true stress-engineering strain definitions. The elastic modulus increases as the mixing ratio increases up-to 9:1 ratio after which the elastic modulus begins to decrease even as the mixing ratio continues to increase. The results presented in this study will be helpful to assist the design of in vitro experiments to mimic blood flow in arteries and to understand the complex interaction between blood flow and the walls of arteries using PDMS elastomer.

Hands-free technique in the operating room: reduction in body fluid exposure and the value of a training video.

OBJECTIVES: This study sought to determine if (1) using a hands-free technique (HFT)--whereby no two surgical team members touch the same sharp item simultaneously--> or = 75% of the time reduced the rate of percutaneous injury, glove tear, and contamination (incidents); and (2) if a video-based intervention increased HFT use to > or = 75%, immediately and over time. METHODS: During three and four periods, in three intervention and three control hospitals, respectively, nurses recorded incidents, percentage of HFT use, and other information in 10,596 surgeries. The video was shown in intervention hospitals between Periods 1 and 2, and in control hospitals between Periods 3 and 4. HFT, considered used when > or = 75% passes were done hands-free, was practiced in 35% of all surgeries. We applied logistic regression to (1) estimate the rate reduction for incidents in surgeries when the HFT was used and not used, while adjusting for potential risk factors, and (2) estimate HFT use of about 75% and 100%, in intervention compared with control hospitals, in Period 2 compared with Period 1, and Period 3 compared with Period 2. RESULTS: A total of 202 incidents (49 injuries, 125 glove tears, and 28 contaminations) were reported. Adjusted for differences in surgical type, length, emergency status, blood loss, time of day, and number of personnel present for > or = 75% of the surgery, the HFT-associated reduction in rate was 35%. An increase in use of HFT of > or = 75% was significantly greater in intervention hospitals, during the first post-intervention period, and was sustained five months later. CONCLUSION: The use of HFT and the HFT video were both found to be effective.

Abdominal aortic coarctation: surgical treatment of 53 patients with a thoracoabdominal bypass, patch aortoplasty, or interposition aortoaortic graft.

OBJECTIVE: Abdominal aortic coarctation is uncommon and often complicated with coexisting splanchnic and renal artery occlusive disease. This study was undertaken to define the clinical and anatomic characteristics of this entity, as well as the technical issues and outcomes of its operative treatment. METHODS: Fifty-three patients, 34 males and 19 females, underwent surgical treatment of abdominal aortic coarctations from 1963-2008 at the University of Michigan. Patient ages in years ranged from 2-4 (n = 4), 5-8 (n = 17), 9-14 (n = 16), 15-20 (n = 11) and 25-49 (n = 5). The mean age was 11.9 years. Developmental disease (n = 48), inflammatory aortitis (n = 4), and iatrogenic trauma (n = 1) were suspected etiologies. Aortic coarctations were suprarenal (n = 37), intrarenal (n = 12), or infrarenal (n = 4). Patients often had coexisting occlusive disease of the splanchnic (n = 33) and renal (n = 46) arteries. RESULTS: Major clinical manifestations included: aortic and renal artery-related secondary hypertension (n = 50), symptomatic lower extremity ischemia (n = 3), and intestinal angina (n = 3). Primary aortic reconstructive procedures included: thoracoabdominal bypass (n = 26), patch aortoplasty (n = 24), or an aortoaortic interposition graft (n = 3). Primary splanchnic (n = 19) or renal (n = 47) arterial reconstructions were performed as simultaneous (n = 45) or staged (n = 13) procedures in relation to the aortic surgery. Benefits existed regarding improved control of hypertension (n = 46), as well as elimination of extremity ischemia (n = 3) and mesenteric angina (n = 3). Secondary renal or splanchnic arterial reoperations (n = 8) were performed without mortality 5 days to 12 years postoperative for failed primary procedures. Secondary aortic procedures, 5 to 14 years postoperative, were performed for patch aortoplasties that became stenotic (n = 2) or aneurysmal (n = 1), and when thoracoabdominal bypasses developed an anastomotic narrowing (n = 1) or proved inadequate in size with patient growth (n = 1). No perioperative mortality accompanied either the primary or secondary aortic reconstructive procedures. CONCLUSION: Abdominal aortic coarctation represents a complex vascular disease. Individualized treatment changed little over the period of study, remaining dependent on the pattern of anatomic lesions, patient age, and anticipated growth potential. This experience documented salutary outcomes exceeding 90% following carefully performed operative therapy.

Whole genome expression profiling reveals a significant role for immune function in human abdominal aortic aneurysms.

BACKGROUND: Abdominal aortic aneurysms are a common disorder with an incompletely understood etiology. We used Illumina and Affymetrix microarray platforms to generate global gene expression profiles for both aneurysmal (AAA) and non-aneurysmal abdominal aorta, and identified genes that were significantly differentially expressed between cases and controls. RESULTS: Affymetrix and Illumina arrays included 18,057 genes in common; 11,542 (64%) of these genes were considered to be expressed in either aneurysmal or normal abdominal aorta. There were 3,274 differentially expressed genes with a false discovery rate (FDR)

Refinements in mathematical models to predict aneurysm growth and rupture.

The growth of aneurysms and eventually their likelihood of rupture depend on the determination of the stress and strain within the aneurysm wall and the exact reproduction of its geometry. A numerical model is developed to analyze pulsatile flow in abdominal aortic aneurysm (AAA) models using real physiological resting and exercise waveforms. Both laminar and turbulent flows are considered. Interesting features of the flow field resulting from using realistic physiological waveforms are obtained for various parameters using finite element methods. Such parameters include Reynolds number, size of the aneurysm (D/d), and flexibility of the aneurysm wall. The effect of non-Newtonian behavior of blood on hemodynamic stresses is compared with Newtonian behavior, and the non-Newtonian effects are demonstrated to be significant in realistic flow situations. Our results show that maximum turbulent fluid shear stress occurs at the distal end of the AAA model. Furthermore, turbulence is found to have a significant effect on the pressure distribution along AAA wall for both physiological waveforms. Related experimental work in which a bench top aneurysm model is developed is also discussed. The experimental model provides a platform to validate the numerical model. This work is part of our ongoing development of a patient-specific tool to guide clinician decision making and to elucidate the contribution of blood flow-induced stresses to aneurysm growth and eventual rupture. These studies indicate that accurately modeling the physiologic features of real aneurysms and blood is paramount to achieving our goal.

Global expression profiles in human normal and aneurysmal abdominal aorta based on two distinct whole genome microarray platforms.

Abdominal aortic aneurysms (AAA) are the thirteenth cause of death in the United States. The etiology of the disease is yet largely unknown, although several environmental risk factors (e.g., smoking) have been identified and the search for finding genetic risk factors has been initiated. The purpose of our study was to gain insight into the pathobiology of AAA by determining which genes are expressed in the abdominal aorta under either the diseased or normal states, thereby generating the whole-genome-wide expression profiles for these conditions.