Mark V. Larson
Mayo Clinic
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Featured researches published by Mark V. Larson.
Journal of Clinical Gastroenterology | 1992
Christopher J. Gostout; Thomas R. Viggiano; David A. Ahlquist; Kenneth K. Wang; Mark V. Larson; Rita K. Balm
The watermelon stomach is an uncommon but treatable cause of chronic gastrointestinal bleeding. We report our experience with the clinical and endoscopic features of 45 consecutive patients treated by endoscopic Nd:YAG laser coagulation. The prototypic patient was a woman (71%) with an average age of 73 years (range of 53-89 years) who presented with occult (89%) transfusion-dependent (62%) gastrointestinal bleeding over a median period of 2 years (range of 1 month to > 20 years). Autoimmune connective tissue disorders were present in 28 patients (62%), especially Raynauds phenomena (31%) and sclerodactyly (20%). Atrophic gastritis occurred in 19 of 19 (100%) patients, with hypergastrinemia in 25 (76%) of 33 patients tested. Antral endoscopic appearances included raised or flat stripes of ectatic vascular tissue (89%) or diffusely scattered lesions (11%). Proximal gastric involvement was present in 12 patients (27%), typically in the presence of a diaphragmatic hernia. Endoscopic laser therapy after a median of one treatment (range of 1-4) resulted in complete resolution of visible disease in four patients (13%) and resolution of > 90% in 24 patients (80%). Hemoglobin levels normalized in 87% of patients over a median follow-up period of 2 years (range of 1 month to 6 years) with no major complications. Blood transfusions were not necessary after laser therapy in 86% of 28 initially transfusion-dependent patients. The characteristic clinical, laboratory, and endoscopic features allow for a confident diagnosis that can lead to successful endoscopic treatment.
Journal of Clinical Gastroenterology | 1992
Christopher J. Gostout; Kenneth K. Wang; David A. Ahlquist; Jonathan E. Clain; Rollin W. Hughes; Mark V. Larson; Bret T. Petersen; Kenneth W. Schroeder; William J. Tremaine; Thomas R. Viggiano; Rita K. Balm
The initial experience of a specialized management team organized to provide expedient care for all acute major gastrointestinal bleeding in protocolized fashion at a large referral center is presented. Of the 417 patients, 56% developed bleeding while hospitalized. Upper gastrointestinal bleeding accounted for 82%. The five most common etiologies included gastric ulcers (83 patients), duodenal ulcers (67 patients), erosions (41 patients), varices (35 patients), and diverticulosis (29 patients). Nonsteroidal anti-inflammatory drugs were implicated in 53% of gastroduodenal ulcers. The incidence of nonbleeding visible vessels was 42% in gastric and 54% in duodenal ulcers. The rates of rebleeding were 24% (20 patients) in gastric ulcers and 28% (19 patients) in duodenal ulcers. Predictive factors for rebleeding included copious bright red blood, active arterial streaming, spurting, or a densely adherent clot. The rebleeding rate for esophagogastric varices was 57%. The mortality rate overall was 6% (27 patients), with rates varying from 3% (five patients) for gastroduodenal ulcers to 40% (14 patients) for esophagogastric varices. The morbidity rate for the entire patient population was 18% (77 patients), dominated by myocardial events (34 patients). The average length of hospitalization for gastroduodenal ulcers was 5 days, for diverticulosis 8 days, and for varices 10 days. The major efforts of a specialized Gastrointestinal Bleeding Team would be best directed at both reducing the morbidity associated with acute bleeding and reducing the overall cost of care.
Gastrointestinal Endoscopy | 1993
Thomas R. Viggiano; Jaime Zighelboim; David A. Ahlquist; Chrisiopher J. Gostout; Kenneth K. Wang; Mark V. Larson
Hematochezia from mucosal vascular lesions usually confined to the rectum represents an uncommon but problematic late complication of pelvic radiotherapy. We studied 47 patients with medically refractory hematochezia resulting from radiation-induced rectosigmoid mucosal vascular lesions. All lesions were endoscopically coagulated with Nd:YAG laser. Median duration of hematochezia before laser therapy was 11 months, despite previous medical treatment (98%) or bypass colostomy (6%). Within 3 to 6 months after laser treatment, the number of patients with daily hematochezia fell from 40 (85%) to 5 (11%; p < 0.001), and the median hemoglobin level increased from 9.7 gm/dl to 11.7 gm/dl (p < 0.001). Complications occurred in three patients (6%); no deaths occurred. The condition in six patients (12.8%) was not improved by laser treatment. Two patients (4%) ultimately required surgical treatment for bleeding control. On the basis of symptomatic, hematologic, and endoscopic responses, Nd:YAG laser photocoagulation controlled bleeding from radiation proctopathy in most patients with an acceptably low morbidity. Patients with sigmoid colon involvement responded less favorably. Endoscopic laser photocoagulation should be considered before surgical intervention for treatment of hematochezia from radiation proctopathy.
Journal of Clinical Gastroenterology | 1994
Jaime Zighelboim; Mark V. Larson
Primary colonic lymphomas are rare, but we identified 15 cases at our institution between 1973 and 1992. They comprised 5.8% of all cases of gastrointestinal lymphoma (15 of 259) and 0.16% of all cases of colon cancer (15 of 9,193) during the last 20 years. The most common presenting symptoms were abdominal pain and weight loss (40% each). In seven patients (47%), a palpable abdominal mass was noted on the initial physical examination. The most frequent site of involvement was the cecum (73%). Histologically, six (40%) were classified as high-grade and nine (60%) as intermediate-grade non-Hodgkins lymphoma. The tumors usually presented at an advanced stage: in 13 of 15 patients (87%), the lymphoma had spread to the adjacent mesentery, the regional lymph nodes, or both when first diagnosed. The 5-year survival rate was 27% for all patients and 33% (4 of 12) for patients treated with combination chemotherapy. Two patients relapsed after 8 years of complete remission. Primary colonic lymphomas have an aggressive behavior and only a marginal response to surgery and combination chemotherapy.
Annals of Vascular Surgery | 1990
John W. Hallett; Meredith E. James; David A. Ahlquist; Mark V. Larson; Molly K. McAfee; Kenneth J. Cherry
This paper reviews the operative management over the past 27 years of 102 patients with chronic mesenteric ischemia, and summarizes recent clinical trends and ongoing research in this area. The most important trends in the diagnosis and management of chronic intestinal ischemia include: (1) increasing use of duplex ultrasound scanning in the initial evaluation of patients with possible intestinal angina; (2) rapidly evolving noninvasive clinical tests to assess mucosal perfusion (reflectance spectrophotometry, laser Doppler flow analysis, and tonometry); and (3) preferential use of antegrade mesenteric grafts or transaortic endarterectomy for mesenteric atherosclerotic occlusive disease. Surgical revascularization continues to provide excellent early relief of symptoms (93%) and a low late recurrence rate (10%). New noninvasive diagnostic tests for chronic intestinal ischemia and excellent results of surgical revascularization support a continued aggressive approach to the early recognition and treatment of patients with chronic intestinal angina. With the aging population, we anticipate that the number of patients with chronic intestinal ischemia will increase.
Gastrointestinal Endoscopy | 2013
Elizabeth Rajan; Prasad G. Iyer; Amy S. Oxentenko; Darrell S. Pardi; Jeffrey A. Alexander; Todd H. Baron; David H. Bruining; Stephanie L. Hansel; Mark V. Larson; Joseph A. Murray; John DeBritto; Ross A. Dierkhising; Christopher J. Gostout
BACKGROUND Minimum training for capsule endoscopy (CE) is based on societal guidelines and expert opinion. Objective measures of competence are lacking. OBJECTIVES Our objectives were to (1) establish structured CE training curriculum during a gastroenterology fellowship, (2) develop a formalized assessment tool to evaluate CE competency, (3) prospectively analyze trainee CE competency, (4) define metrics for trainee CE competence by using comparative data from CE staff, and (5) determine the correlation between CE competence and previous endoscopy experience. DESIGN Single-center, prospective analysis over 6 years. SETTING Tertiary academic center. SUBJECTS Gastroenterology fellows and CE staff. INTERVENTIONS Structured CE training was implemented with supervised CE interpretation. Capsule Competency Test (CapCT) was developed and data were collected on the number of CEs, upper endoscopies, colonoscopies, and push enteroscopies performed. MAIN OUTCOME MEASUREMENTS Trainee competence defined as CapCT score 90% or higher of the mean staff score. RESULTS A total of 39 fellows completed CE training and CapCT. Fellows were grouped according to number of completed CE interpretations: 10 or fewer (n = 13), 11 to 20 (n = 19), and 21 to 35 (n = 7). Eight CE staff completed CapCT with a mean score of 91%. Mean scores for trainees with fewer than 10, 11 to 20, and 21 to 35 CE interpretations were 79%, 79%, and 85%, respectively. A significant difference was seen between staff and fellow scores with 10 or fewer and 11 to 20 interpretations (P < .001). No correlation was found between trainee scores and previous endoscopy experience. LIMITATIONS Single center. CONCLUSION Using a structured CE training curriculum, we defined competency in CE interpretation by using the CapCT. Based on these findings, trainees should complete more than 20 CE studies before assessing competence, regardless of previous endoscopy experience.
Journal of Gastroenterology and Hepatology | 2006
Gavin C. Harewood; Garrett Lawlor; Mark V. Larson
Introduction: Current guidelines endorse colon cancer screening every 5–10 years in patients over 50 years of age. However, there is no consensus regarding what age is appropriate to stop screening. The aim of this study was to characterize neoplasia occurrence/recurrence in a large cohort of patients ≥70 years of age undergoing colonoscopy.
Mayo Clinic Proceedings | 2002
Vege Santhi Swaroop; Mark V. Larson
Screening for colorectal cancer has become the standard of care and is currently recommended by most major health organizations, including the American Cancer Society. Randomized controlled trials using fecal occult blood testing as the screening strategy have shown a reduction in mortality due to colorectal cancer. However, colorectal cancer differs from other cancers in that a variety of screening tests have been approved and recommended by experts. The advantages and disadvantages of different screening tests have been the subject of intense debate. Colonoscopy has theoretical advantages over other screening tests, including direct visualization of the entire colon and, more importantly, removal of precancerous adenomatous lesions. This review discusses the advantages and disadvantages of colonoscopy as a screening test for colorectal cancer with regard to efficacy, cost-effectiveness, and patient compliance.
Journal of Vascular Surgery | 1991
Russell G. Bourchier; Peter Gloviczki; Mark V. Larson; Qing-hua Wu; John W. Hallett; David A. Ahlquist; Peter C. Pairolero
Mechanisms of intravascular fluid depletion after temporary occlusion of the supraceliac aorta were investigated in a canine model. During ischemia and reperfusion, hemodynamic parameters, superior mesenteric artery flow, intestinal mucosal perfusion, and mucosal permeability were monitored. After 12 hours of reperfusion, the volumes of intravenous electrolyte fluid required to maintain hemodynamic stability and fluid lost into the gastrointestinal tract and peritoneal cavity were measured. The distribution of total body water was analyzed by use of radionuclide dilution techniques. Group A animals underwent laparotomy only, group B had the supraceliac aorta occluded for 45 minutes, group C had superoxide dismutase administered after 45 minutes of aortic occlusion, and group D animals were exposed to mild hypothermia during a similar ischemia and reperfusion period. No significant difference was found in mean superior mesenteric artery flow or mucosal perfusion during ischemia among groups B, C, and D. During reperfusion superior mesenteric artery flow returned to values similar to control in all groups. Aortic occlusion increased mucosal permeability most significantly in group B (p less than 0.01). Mean intravenous fluid requirements (ml/mg) were the following: group A, 80 +/- 5; group B, 201 +/- 9 (p less than 0.01); group C, 116 +/- 7 (p less than 0.05); group D, 245 +/- 24 (p less than 0.05). Mean gastrointestinal fluid loss was highest in the hypothermic group and smallest if superoxide dismutase was given. Mean intracellular fluid volume was increased in groups B and D compared with group A (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)
Surgical Endoscopy and Other Interventional Techniques | 2008
Gregory D. Kennedy; David E. Larson; Bruce G. Wolff; Desmond Winter; Bret T. Petersen; Mark V. Larson
BackgroundThe utility of routine ileoscopy as a component of screening colonoscopy is unclear. Many endoscopists believe that routine intubation of the terminal ileum is a requirement for a full-screening colonoscopy. The authors have hypothesized that routine ileal intubation during screening colonoscopy is of little diagnostic value.MethodsA retrospective analysis was performed using a prospectively maintained colonoscopy database of patients identified as undergoing a screening colonoscopy. All had undergone intubation of the terminal ileum at a tertiary referral center. Those who had undergone screening colonoscopy at the Mayo Clinic (Rochester, MN) were entered prospectively into a database. The study identified 6,408 patients who met the criteria of having terminal ileal intubation at the time of screening colonoscopy. The main outcome measured was abnormality of the terminal ileum at ileal intubation.ResultsIleoscopy showed grossly abnormal findings for only 1% of the patients, and pathologic abnormalities were identified for only 0.3% of all the patients.ConclusionsThe findings support the conclusion that intubation of the terminal ileum should not be a required part of screening colonoscopy.