An Interesting Observation Regarding Retrograde Vertebral Artery Flow in Patients With Dialysis Access Fistulas.

OBJECTIVES: Retrograde vertebral artery flow, the steal phenomenon, is most frequently caused by a flow-limiting stenosis of the proximal subclavian artery. The reversal of flow can be incomplete, resulting in bidirectional flow: retrograde in systole and antegrade in diastole. Less often, retrograde vertebral artery flow is the consequence of increased subclavian flow, as might occur with a well-functioning dialysis access fistula. Our objective was to evaluate bidirectional vertebral artery flow associated with dialysis access fistulas. METHODS: We retrospectively reviewed the direction of flow through the vertebral artery in systole and diastole of 335 patients with dialysis fistulas who had undergone extracranial cerebral vascular Doppler examinations. RESULTS: Fifteen patients had retrograde flow in their vertebral artery ipsilateral with the side of their fistula. There was completely reversed flow in 1 patient and bidirectional flow in the other 14. For each of these 14, the flow was antegrade in early systole and retrograde in diastole. Compression of the fistula restored the antegrade flow. CONCLUSIONS: Under conditions of reduced subclavian artery flow, bidirectional vertebral artery flow will be retrograde in early systole and antegrade in diastole. Under conditions of increased subclavian artery flow, bidirectional flow through the vertebral artery will be antegrade in early systole and retrograde in diastole.

Carotid Ultrasound Examinations: Indications Correlated With Abnormal Findings.

Our purpose was to evaluate the clinical indications for carotid duplex ultrasonography and determine for each indication how often carotid artery disease was identified.We retrospectively reviewed the consecutive reports for 3191 carotid ultrasound examinations. We tracked 14 indications to determine how often examinations were requested for each indication and correlated each indication with the finding of carotid artery disease.We found 26.5% of all examinations were abnormal; 17.5% of patients showed internal carotid artery disease; 10.9%, a moderate stenosis; 5.2%, a severe stenosis; and 1.4%, a total occlusion. For each of the 14 individual indications, with 1 exception, carotid ultrasound examination showed a 19.7% or greater chance of an abnormal result and an 11.6% or greater chance of finding a flow-limiting stenosis of an internal carotid artery.Our results validate the collaborative position of the American College of Radiology, the American Institute of Ultrasound in Medicine, the Society for Pediatric Radiology, and the Society of Radiologists in Ultrasound that, overall and for almost all indications they enumerate, carotid ultrasound examinations are a proven and useful procedure for evaluating extracranial carotid artery disease.

A program director's guide to the Medical Student Performance Evaluation (former dean's letter) with a database.

PURPOSE: The value of the Medical Student Performance Evaluation (MSPE) for a program director is in the information it contains comparing how a student performed in medical school relative to his or her classmates. The Association of American Medical Colleges has recommended that a student's class ranking be included in the summary paragraph of the MSPE and that this information be repeated in a supplementary appendix. METHODS: The authors reviewed the MSPEs from 1,479 applications for residency training positions. The aim was to determine to what extent and in what manner individual schools reveal how their students perform relative to their peers. The authors then set out to create a database containing this information. RESULTS: Working from a list of 141 US members of the Association of American Medical Colleges, complete information for 107 schools (76%) and partial information for the remaining 34 schools (24%) was gathered. Only 12 schools (9%) included complete comparative information in the summary section in accordance with the guidelines of the Association of American Medical Colleges. Other schools were in partial compliance or did not comply at all. The database the authors constructed will inform users if comparative information is available, guide users to its location in the MSPE, and explain the meaning of the language different schools use to rank or classify their students. CONCLUSIONS: The authors recognize that this database is incomplete and that the individual institutions will alter their ranking system from time to time. But this database is offered in an open format so that it can be continuously updated by users.

Doppler sonographic criteria for the diagnosis of inferior mesenteric artery stenosis.

OBJECTIVE: The purpose of this study was to define the optimal Doppler criteria for the diagnosis of inferior mesenteric artery (IMA) stenosis in patients with suspected chronic mesenteric ischemia (CMI). METHODS: A retrospective review of 205 dedicated color and pulsed Doppler sonographic studies of mesenteric arteries was performed in 205 patients. All studies were performed in patients with suspected CMI. Correlative angiography was available in 50 patients. RESULTS: The IMA was visualized in 176 of 205 Doppler sonographic examinations (86%) and in 92% of the correlative studies. The visualization rate for the detection of a patent IMA by Doppler sonography in this series was 90%. The ranges of the peak systolic velocity (PSV), end-diastolic velocity (EDV), and mesenteric-aortic velocity ratio (MAR) in the nonstenotic IMA were 70 to 200 cm/s, 0 to 33 cm/s, and 0.7 to 3.7, respectively. The ranges of the PSV, EDV, and MAR in IMA stenosis were 200 to 485 cm/s, 0 to 177 cm/s, and 0.69 to 8.1. The threshold values for severe IMA stenosis by logistic regression analysis (n = 42) were as follows: PSV, greater than 200 cm/s; EDV, greater than 25 cm/s; and MAR, greater than 2.5, with sensitivities of 90%, 40%, and 80%; specificities of 97%, 91%, and 88%; positive predictive values (PPVs) of 90%, 57%, and 67%; negative predictive values (NPVs) of 97%, 83%, and 93%; and accuracy of 95%, 79%, and 86%, respectively. CONCLUSIONS: We found that a PSV of greater than 200 cm/s was the best criterion for the diagnosis of IMA stenosis. The sensitivity, specificity, PPV, NPV, and accuracy for the PSV were 90%, 97%, 90%, 97%, and 95%, respectively.

The meaning of excellence.

RATIONALE AND OBJECTIVES: Program directors would like to interview the very best students applying to their programs. The summary paragraph of the dean's letter should provide useful information regarding a student's performance in medical school. One frequently found descriptor is excellent. However, its very frequency suggests the word may be loosely used. The purpose of this investigation is to determine the meaning of excellence. MATERIALS AND METHODS: The descriptor excellent was searched for in the summary paragraph. An effort was made to determine how many medical schools used excellent, how precisely the medical school defined this word, whether numbers were used to define the upper and lower boundaries of excellent, and what other buzzwords were used in the summary paragraphs for students not defined as excellent. RESULTS: Excellent was the most common descriptor, used by 75% of the medical schools. Defined numeric boundaries were used by 47% of schools. Tabulated results showed that within a school the range of excellence varied from as tight as 20 percentile points to so broad that 65% of the students were classified as excellent. The boundaries of excellent, among different schools, varied from as low as the third to as high as the ninety-second percentile. In half the schools, students described as excellent might be in the bottom half of their class. A total of 28% of the schools used excellent, but without any numeric definition. No school used excellent to describe its best students. CONCLUSIONS: Medical student deans often exaggerate the quality of their graduates by using the word excellent at variance with the dictionary definition of exceptionally good. Inaccurate descriptions by deans of their graduating medical students diminish the value of MSPE.