Endovascular repair of abdominal aortic aneurysm does not improve early survival versus open repair in patients younger than 60 years.

OBJECTIVES: Multiple randomised trials have demonstrated lower perioperative mortality after endovascular aneurysm repair (EVAR) compared to open surgical repair for infrarenal abdominal aortic aneurysms (AAAs). However, in these trials the mortality advantage for EVAR is being lost within 2 years of repair and the patients evaluated are relatively older with no study specifically comparing EVAR and open repair for patients younger than 60 years of age. DESIGN: A retrospective analysis of prospectively collected data. MATERIALS AND METHODS: Patients younger than 60 years of age who underwent EVAR and open surgical repair for elective infrarenal AAA were identified from the 2007-09 National Surgical Quality Improvement Program (NSQIP) - a prospective database maintained at 237 centres across the United States. Univariate and multivariate analyses were performed. RESULTS: Of the 651 patients, 369 (56.7%) underwent EVAR and 282 (43.3%) underwent open repair. Thirty-day mortality for EVAR and open repair were 1.1% and 0.4%, respectively. This was not significantly different on univariate (P = 0.22) as well as multivariate (P = 0.69) analysis after controlling for other co-morbidities. On multivariate analysis, body mass index, history of stroke and bleeding disorder prior to surgery were associated with a higher 30-day mortality after AAA repair (combined open and EVAR). CONCLUSIONS: These contemporary results demonstrate that the 30-day mortality rate after open repair is similar to that after EVAR in patients younger than 60 years with infrarenal AAA.

Learning preferences, computer attitudes, and test performance with computer-aided instruction.

BACKGROUND: Learning preference refers to how individuals choose to approach learning situations. Computer-aided instruction (CAI) permits the adaptation of educational content to individual student learning strategies. METHODS: To determine if learning preference and computer attitude influence the acquisition of knowledge using CAI materials, a prototype CAI program was developed that incorporated differing learning exercises. Students (n = 180) completed Rezler's Learning Preference Inventory (LPI) and a computer attitude survey (CAS). The LPI uses three sets of paired scales to characterize learning preference and choice of learning situation. The CAS assesses student attitudes toward computers in general (CAS-G), as well as the educational use of computers (CAS-E). After finishing the program students completed a program attitude survey (CAS-P). Immediate comprehension was assessed by pretests and posttests incorporated into the program. Retention was assessed by a repeat of the posttest 4 to 6 weeks after initial program review. RESULTS: Scores (mean +/- SEM) on the pretest, posttest, and late posttest were 38.1% +/- 1.35%, 70.9% +/- 1.24%, and 62.5% +/- 1.44%, respectively. There was no correlation between students' learning preferences or computer attitude and test performance. CONCLUSIONS: The data indicate that CAI provides a means of delivering educational content that results in an increase in knowledge that is not correlated with computer attitudes or learning preferences.

Availability of content information does not improve performance on computerized case simulations.

BACKGROUND: A previous study evaluated repeated, serial administrations of computer-based simulations. The data demonstrated an increase in scores across rotations during the academic year, but no difference between scores in successive years. METHODS: The initial study only indirectly assessed the effect of information sharing on measured performance. To directly assess the effect of information transfer, 8 computer-based case simulations were administered over 2 consecutive years to 220 third-year students at the conclusion of 12 surgical clerkship rotations (6 per year). During the second year of administration information regarding content area, in the form of the case stem or introductory lead-in material, was provided to each rotation of students prior to the examination based on a sequential algorithm. RESULTS: The data demonstrate no increase in overall mean score for the examination over the 2 years. Scores were significantly different for 2 of the 8 cases, increasing in the one and decreasing in the other. CONCLUSIONS: The data demonstrate no evidence that prior knowledge of content area influences the scores of successive classes on computerized models of performance assessment.

Dissections after childbirth.

The occurrence of spontaneous internal carotid or vertebral artery dissection after childbirth remains rare. To our knowledge, seven cases of arterial dissection in the postpartum period have been described in the literature as single case reports. We report four additional cases of internal carotid and vertebral artery dissection in the puerperal period, documented by angiography. Physicians should consider the possibility of arterial dissection in any young patient presenting with acute ischemic stroke, including women in the postpartum period. The availability of modern noninvasive ultrasound and imaging techniques may result in earlier diagnosis and facilitate identification of this condition.

Developments in diagnosis and classification of venous disorders: non-invasive diagnosis.

PURPOSE: This review examines the many techniques that have been used for the non-invasive diagnosis of acute and chronic venous disease and was conducted by members of the Committee on Research of the American Venous Forum. It proposes to identify those techniques with the greatest clinical potential, to suggest algorithms for the clinical application of non-invasive techniques in the identification of acute deep venous thrombosis and chronic venous insufficiency, and to identify areas of deficient knowledge and potential areas for future research initiatives. METHODS: Review of pertinent clinical and research material. RESULTS: Impedance plethysmography and ultrasonic imaging are the primary non-invasive tools used in the diagnosis of acute deep venous thrombosis. At present, ultrasonic imaging techniques are recommended on the basis of greater diagnostic accuracy in recent comparative clinical trials. Data would suggest that serial evaluation should probably be viewed as the preferred option for symptomatic patients with a negative initial examination and the presence of risk factors or physical findings suggesting a proximal deep venous obstruction/thrombosis. Chronic venous disease is the result of valvular incompetence, with or without associated venous obstruction. Duplex imaging can be used to determine the location and extent of reflux; however, there are reported procedural variations in the performance and interpretation of such studies. Recent innovations in air plethysmography may provide a means of quantifying volume changes, and permit an objective characterization of venous reflux and calf pump efficiency. CONCLUSIONS: There are still significant questions that need to be answered by well-designed research initiatives. Research applications that incorporate non-invasive diagnostic techniques may involve the diagnosis, treatment and natural history of acute deep venous obstruction/thrombosis and chronic venous insufficiency, assessment prior to and following venous reconstruction, and the basic science aspects of acute and chronic venous disease. At present, a lack of common standards is, by far, the greatest impediment to an organized research approach to venous disease.

Repeated use of computerized case simulations in a test format does not present a security risk.

BACKGROUND: Computer-based examination formats permit evaluation of patient care strategies in a realistic context. Because such examinations are complex and difficult to develop, the same case simulations must often be used on multiple occasions. METHODS: To determine if repeated, serial administration of computerized case simulations influences performance, 8 simulations were administered over 2 consecutive years to 252 third-year medical students at the conclusion of 16 surgical clerkship rotations (8 per year). One-way analyses of variance were used to compare scores across rotations during the year and to compare scores between 2 consecutive academic years. Scheffe pairwise comparisons were used to identify trends within each academic year. RESULTS: The data demonstrate an increase in scores across rotations during the year. There is, however, no difference between scores in successive years. CONCLUSIONS: The data are consistent with an increase in knowledge during the course of the year, without evidence that test information transfer influences the performance of successive classes.

Animal models for the study of lower extremity chronic venous disease: lessons learned and future needs.

The purpose of this review is to define animal models of chronic venous disease and to demonstrate how animal studies can impact our understanding and treatment of this disorder. To this end an extensive literature search was conducted highlighting potential animal models of chronic lower extremity venous disease. Scientific investigations using animals to study particular aspects of this disease are also reviewed. This review was conducted by members of the Committee on Research of the American Venous Forum to help provide direction for future venous research endeavors. Useful models of chronic venous occlusive disease involve controlled ligation of a major lower limb vein and multiple tributaries. Such a model can provide sustained venous hypertension and studies using this model have confirmed that an isodiametric graft can provide early hemodynamic relief. Models of primary, postphlebitic, and isolated chronic deep venous insufficiency are available for study. Valve repair or transplantation can positively impact the insufficiency observed in these models. Investigations into valve substitutes have generally been disappointing or are undergoing early evaluation. In conclusion, animal models for the study of some aspects of chronic venous disease do exist and have already affected our clinical approach to patients. The scientific study of basic pathophysiology, diagnostics, end-organ response, and long-term surgical treatments of this disorder in well-controlled animal experiments have not been conducted.

Learning style influences student examination performance.

BACKGROUND: The Kolb Learning Style Inventory (LSI) measures preference for each of four learning orientations: abstract conceptualization, concrete experience, active experimentation, and reflective observation. These orientations define four learning styles: convergence, divergence, assimilation, and accommodation. METHODS: To determine if learning style correlates with objective multiple-choice and clinical measures of performance, the learning styles of third-year medical students (n = 227) were evaluated using the LSI. Performance was assessed using the United States Medical Licensing Examination step 1 (USMLE 1), the National Board of Medical Examiners (NBME) multiple-choice surgical subject examination (MCQ), and NBME computer-based case simulations (CBX). RESULTS: The data showed a significant (P < or = 0.05) relationship between learning style and performance on the USMLE 1. There was a significant (P < or = 0.05) and direct correlation between an abstract orientation and performance on the USMLE 1 (r = 0.33) and MCQ (r = 0.20). There was no relationship between learning style and clinical performance measured using the CBX. CONCLUSIONS: These data demonstrate that performance on objective measures of academic achievement is influenced by learning style, while application of that knowledge in the management of clinical situations may require additional skills beyond those measured.

Hospital-wide educational program decreases red blood cell transfusions.

BACKGROUND: Because of the numerous risks associated with the use of packed red blood cells (RBCs), it is critical that they be transfused only when appropriate. A hospital-wide educational program was developed in an attempt to improve the transfusion practices and provide a framework for blood bank audit at a Veterans Affairs teaching hospital. MATERIALS AND METHODS: The program required physicians to fill out an information sheet that listed appropriate criteria for transfusion. Charts were reviewed to determine if the transfusion met these criteria. If the transfusion was deemed inappropriate by peer review, the staff physician was notified by letter. The information sheet was used on a voluntary basis without chart review in 1989 and on a mandatory basis beginning in 1990. Transfusion rates and mortality were adjusted to patient days of hospitalization and evaluated using chi 2 analysis. RESULTS: While voluntary use did not affect transfusion rate, mandatory implementation resulted in a 26% decline (P < 0.001) between 1989 and 1990 in the number of RBC units transfused per patient days of hospitalization. A diminished use of RBCs persisted in the subsequent years. There was no increase in mortality during this time to suggest a detrimental effect from the decrease in RBC transfusion. No apparent variation in the hospital population could account for the changes. CONCLUSION: Use of a unique and simple transfusion request sheet as an educational tool resulted in improved transfusion practices at a Veteran Affairs teaching hospital.

Carotid string sign resulting from an aberrant branch of the internal carotid artery.

Branches of the extracranial internal carotid artery are very rare. A case is reported wherein an aberrant artery originated from the bulb of the internal carotid artery (ICA) approximately 2 cm from the bifurcation. The ICA was occluded distal to the branch's origin. Arteriography in this case gave the appearance of a carotid "string sign". Vascular surgeons and radiologists should be aware of this anomaly when interpreting carotid arteriograms.

Research and clinical issues in chronic venous disease.

The purpose of this study was to summarize the current issues in chronic venous disease by reviewing of the literature relating to the condition. The review was conducted by members of the Committee on Research of the American Venous Forum and includes the Committee's venous disease and current/future directions. Progress in the understanding and management of chronic venous problems has lagged behind that in arterial disease, despite the large number of patients affected. The complex pathophysiology of venous problems, lack of accepted evaluation standards and lack of prosthetic conduits are some of the factors which contribute to this. New information in these areas has laid the foundation for advances in both operations and non-operative therapy. In conclusion, many opportunities for clinical and basic research in the area of chronic venous disease are available. Application of basic science techniques, including those of molecular biology, will lead to new insights into pathophysiology of chronic venous syndrome. Developments in technology, classification and basic science suggest multiple new potentials therapeutic approaches in the next decade.

Video-assisted, retroperitoneal approach for abdominal aortic aneurysm exclusion.

Abdominal aortic aneurysm (AAA) repair is a common procedure associated with significant morbidity and mortality. Although attempts have been made to reduce operative risk in patients with significant comorbid disease by combining aneurysm exclusion with axillofemoral bypass, the morbidity is not greatly reduced when the standard operative approach is required for exclusion. The authors describe a technique for staple exclusion of AAA using a minimally invasive, video-assisted retroperitoneal approach.

Management of synchronous renal cell carcinoma and aortic disease.

BACKGROUND: We have noted a significant incidence of renal cell carcinoma (RCC) detected during evaluation for aneurysmal and aortoiliac occlusive disease. The approach to synchronous malignancy and aortic disease (staged versus concurrent resection) is controversial, as is the management of incidental RCC (partial versus radical nephrectomy). PATIENTS AND METHODS: We reviewed our experience with incidental RCC in patients undergoing aortic reconstruction between 1991 and 1994. Ninety-seven patients underwent aortic reconstruction for aneurysmal (72), occlusive (20), or embolic disease (5) during the time frame under review. All were men. Of the 80 preoperative computerized tomographic (CT) scans obtained, 7 (9%) demonstrated renal lesions suspicious for RCC. All lesions were explored and excised by partial or radical nephrectomy before heparinization and completion of the planned aortic procedure. RESULTS: The overall mortality rate was 3%. None of the deaths occurred in patients undergoing combined procedures. Four partial and three radical nephrectomies were performed. Of the 7 renal lesions, 2 were complex cysts and 5 were RCC. Both patients with complex cysts were treated with wedge resection. One patient required surgical drainage of a wound abscess after partial nephrectomy. No significant differences were found between preoperative (1.4 +/- 0.1 mg/dL) and postoperative (1.8 +/- 0.2 mg/dL) creatinine levels following combined procedures. On follow-up CT scans done at 6-month intervals (mean follow-up 24 months), no evidence exists of recurrence, metastasis, or graft infection. CONCLUSIONS: This patient population demonstrated an unexpectedly high prevalence of incidental RCC (5 or 80 CTs, 6%). No increase in mortality was found when RCC and aortic disease were treated at the same operation. While partial nephrectomy was associated with one wound infection in this series, it is an effective treatment for small incidental RCC and may avoid unnecessary nephrectomy in patients with benign disease. Base on the high incidence of RCC in this population, we recommend exploration of all suspicious lesions. Nephrectomy can be performed safely in the same setting as aortic reconstruction. Because underlying renal dysfunction is not uncommon in patients with aneurysmal and aortoiliac occlusive disease, nephron-sparing surgery should be considered.

Localization of aortic disease is associated with intrinsic differences in aortic structure.

PURPOSE: While localization of atherosclerosis and aneurysms to the infrarenal aorta has been attributed, in part, to hemodynamic factors, anatomic differences between the proximal and the distal aorta may also be important. Our purpose was to determine the changes in content and organization of major structural proteins (elastin and collagen) throughout the normal human aorta. METHODS: Biochemical analysis for desmosine-isodesmosine (elastin) and hydroxyproline (collagen) content was done by HPLC on complete 1-cm transverse rings removed from the ascending and descending thoracic aorta and abdominal supraceliac, suprarenal, and midinfrarenal aorta. Elastin and collagen content was normalized to lumenal surface area and compared by ANOVA: Light microscopy and optical micrometry were used to determine changes in intimal, medial, and adventitial thickness and number of elastin lamellae at each level. RESULTS: Both collagen/cm2 and elastin/cm2 decrease from the proximal to distal aorta. Collagen content did not differ among the three abdominal segments, but there was a 58% decrease in elastin between the suprarenal and the infrarenal aorta. The proportion of elastin and collagen does not differ throughout the aorta except in the infrarenal aorta where there is decreased elastin relative to collagen. CONCLUSION: Collagen and elastin in the distal aorta bear an increased load as compared to the proximal aorta. The infrarenal aorta differs biochemically and histologically from the remainder of the aorta. A decrease in infrarenal elastin without a corresponding decrease in collagen may effect the compliance and integrity of the distal aorta. These anatomic differences may be important in predisposing the infrarenal aorta to atherosclerosis and aneurysm formation.

A comparison of adenosine and verapamil for the treatment of supraventricular tachycardia in the prehospital setting.

STUDY OBJECTIVE: To compare the efficacy and base hospital physician use of adenosine with that of verapamil in the prehospital treatment of supraventricular tachycardia (SVT). DESIGN: A 12-month prospective chart review of adenosine administration and a 12-month retrospective chart review of verapamil administration. SETTING: A single-tier advanced life support emergency medical service system. PARTICIPANTS: Prehospital adult patients presenting with narrow-complex SVT. INTERVENTIONS: Field paramedics identified SVT. They then administered verapamil or adenosine under on-line physician medical control. Paramedics administered up to two i.v. doses of verapamil, 2.5 mg and 5 mg, or up to two i.v. doses of adenosine, 6 mg and 12 mg. They recorded ECG readings; blood pressure; pulse; respirations; and symptoms before, during, and after drug administration. RESULTS: During the verapamil period, paramedics identified 102 cases of SVT and administered verapamil to 17 patients. Review by a cardiologist revealed 6 of the 17 patients to have been in atrial fibrillation, atrial tachycardia, or sinus tachycardia. Of the remaining 11 patients, 7 (64%) converted from SVT to sinus rhythm. During the adenosine period, paramedics identified 89 cases of SVT, and they administered adenosine to 64 patients. Eight patients had no review because prehospital rhythm strips were lost. Of the remaining 56 patients, 24 were later determined to have been in atrial fibrillation, atrial tachycardia, sinus tachycardia, atrial flutter, or ventricular tachycardia. Of the remaining 32 patients who were in SVT, adenosine converted 25 (78%) to sinus rhythm. An important incidental finding was the misinterpretation of tachydysrhythmias in 30 of 73 patients by paramedics and base hospital physicians. CONCLUSION: Our study showed no difference in conversion rates between verapamil and adenosine. Base hospital physicians were more likely to order adenosine than verapamil. Paramedics and base hospital physicians often misinterpret tachydysrhythmias.

Pseudoaneurysm of the external carotid artery following radical neck dissection and irradiation: a case report and review of the literature.

A 54-year-old man developed a pseudoaneurysm of the left external carotid artery 8 years after concluding treatment for squamous cell carcinoma of the tongue. Treatment included radiation therapy, radical neck dissection and a myocutaneous pectoralis major flap. Percutaneous transcatheter embolization resulted in thrombosis of the pseudoaneurysm. A review of the literature yielded only six other reported cases of pseudoaneurysm of the external carotid artery proper.

Abdominal aortic aneurysms are associated with altered matrix proteins of the nonaneurysmal aortic segments.

PURPOSE: Abdominal aortic aneurysms (AAA) are associated with diffuse arteriomegaly and peripheral aneurysms, suggesting a generalized process. Elastin and collagen are the key structural proteins of the aorta, and their relative content is markedly altered in tissue from AAA. Our purpose was to investigate elastin and collagen content in the proximal, nonaneurysmal segments of aortas with infrarenal AAA. METHODS: After extraction of lipid, calcium, and soluble proteins, hydroxyproline (collagen) and desmosine-isodesmosine (elastin) contents were determined by high-performance liquid chromatography in the ascending and descending thoracic, supraceliac, and suprarenal aorta. By repeated measures of analysis of covariance, collagen was found to be increased throughout the aorta in AAA as compared with normal aorta or aorta with atherosclerotic occlusive disease. This difference remained significant when adjustments were made for group differences in age and degree of atherosclerosis. This increase in collagen content results in a dilutional decrease in elastin concentration. These data demonstrate that the same matrix protein alterations found in AAA tissue occur throughout the aorta, differing only in magnitude in the aneurysmal and nonaneurysmal segments. These data suggest that aneurysm formation may related to alterations in the regulation of elastin and collagen.