PubMed Health⌕ Search

Biomedical subjects

J G Letourneau

Publications and source records attributed to J G Letourneau.

At least 19 recordsLinked to original sources
PubMed1998

Scrotal sonography: a valuable tool in the evaluation of complications following inguinal hernia repair.

PURPOSE: The aim of this study was to determine the utility of scrotal sonography in the evaluation of patients with scrotal pain or swelling following inguinal hernia repair. METHODS: From our database, we identified patients who were referred for sonographic evaluation because of persistent scrotal pain or swelling after inguinal hernia repair between July 1994 and February 1996. Sonograms and medical charts were reviewed retrospectively. RESULTS: Eight patients were included in this study. Doppler sonography demonstrated evidence of testicular infarction in 2 patients and absence of intratesticular diastolic flow in 1 patient. Five patients had postoperative fluid collections with sonographically normal testes. CONCLUSIONS: Scrotal sonography can diagnose testicular infarction following hernia repair and distinguish postoperative fluid collections from recurrent hernias.

Adult↗
PubMed1996

Gray-scale sonographic characterization of aminoglycoside-induced nephrotoxicosis in a canine model.

RATIONALE AND OBJECTIVES: The diagnostic usefulness of gray-scale sonography was evaluated in a canine model of aminoglycoside-induced nephrotoxicosis. METHODS: Sonography was performed before and during the onset and progression of nephrotoxicosis induced by administration of a toxic dosage of gentamicin. Subjective visualization of increased renal cortex echogenicity (IRCE) was objectified with digital image analysis methods. Results of both subjective and objective evaluation were correlated with clinicopathologic tests and renal cortex biopsy obtained concurrently. RESULTS: Subjective visualization of IRCE was associated with significant nephrotoxicosis and was superior to serum creatinine elevation in nephrotoxicity detection. Objective detection of IRCE improved nephrotoxicity detection sensitivity to that of increased urine enzymuria. CONCLUSIONS: Based on the above results, subjective visualization of IRCE in patients with aminoglycoside-induced nephrotoxicity may occur before azotemia and is suggestive of significant renal dysfunction; application of digital image analysis methods may lead to earlier sonographic recognition of nephrotoxicity.

Animals↗
PubMed1996

Sonographic evaluation of acute intrascrotal pathology.

High-resolution, real-time sonography is commonly used for the evaluation of acute scrotal pathology. Pulsed and color Doppler techniques enhance diagnostic accuracy [1, 2]. However, extensive distortion of intrascrotal anatomy can occur with advanced inflammation, infarction, or trauma, leading to decreased specificity of the sonographic examination.

Acute Disease↗
PubMed1996

Estimation of arcuate artery resistive index as a diagnostic tool for aminoglycoside-induced acute renal failure in dogs.

OBJECTIVE: To determine the potential clinical usefulness of duplex Doppler estimation of arcuate artery resistive index (a measure of intrarenal blood flow impedance) for diagnosis of aminoglycoside-induced nephrotoxicosis. ANIMALS: 30 adult, female, mixed-breed dogs, allotted to 3 groups of 10 dogs each as: toxic dosage of gentamicin, therapeutic dosage of gentamicin, and saline solution sham equivalent in volume to that of the toxic dosage of gentamicin. PROCEDURE: After baseline screening to establish normalcy (serum biochemical analysis, endogenous creatinine clearance determination, urinalysis, urine protein-to-creatinine ratio, urine culture, gray-scale sonography, and percutaneous ultrasound-guided renal biopsy), results of arcuate artery resistive index determination were compared with serum creatinine and urine specific gravity values on a Monday-Wednesday-Friday data collection schedule for 10 days. Endogenous creatinine clearance determination, ultrasound-guided renal biopsy, and urine culture were repeated at the end of data collection in all 3 groups. RESULTS: Significant differences in resistive index measurements were not observed, despite clinicopathologic and renal biopsy results compatible with severe acute tubular necrosis in dogs of the toxic dosage group. CONCLUSIONS: Duplex Doppler sonography of arcuate artery blood flow impedance, expressed as the resistive index, appears to have poor clinical usefulness as a diagnostic tool in this disorder. CLINICAL RELEVANCE: Normal arcuate artery resistive index values obtained in dogs for which aminoglycoside-induced nephrotoxicosis is suspected do not exclude the disorder. If abnormal arcuate artery resistive index values are obtained for such dogs, further evaluation for nephropathies other than aminoglycoside-induced nephrotoxicosis may be considered.

Acute Kidney Injury↗
PubMed1995

Duplex sonography after transjugular intrahepatic portosystemic shunts (TIPS): normal hemodynamic findings and efficacy in predicting shunt patency and stenosis.

OBJECTIVE: Portal hemodynamics are altered by placement of a transjugular intrahepatic portosystemic shunt (TIPS). Normal duplex sonographic findings after TIPS placement and hemodynamic alterations indicating shunt failure have not yet been well described. The purposes of this study were to determine normal hemodynamic changes on duplex sonography after TIPS placement and to assess the efficacy of duplex sonography in detecting shunt dysfunction. SUBJECTS AND METHODS: Forty patients underwent TIPS placement and were entered into a study that included routine sonographic evaluation and portal venography at regular intervals. Portal venography was also performed if shunt velocities on duplex sonography changed from the baseline, which raised the question of shunt stenosis or occlusion. The pre-TIPS duplex sonographic study included determination of patency, velocity, and flow direction in the main, right, and left portal veins and in the hepatic artery. Follow-up sonography included the pre-TIPS examination in addition to velocity determinations in three segments of the shunt. Correlation was made between 82 concurrent sonographic and portal venographic studies. RESULTS: High-velocity blood flow (mean peak velocity, 135-200 cm/sec) was consistently seen within patent, well-functioning shunts. Hepatic artery peak systolic velocities increased from 79 cm/sec before TIPS placement to 131 cm/sec after TIPS placement (p < .001). Main portal vein velocities increased from 21.8 cm/sec before TIPS placement to 41.5 cm/sec after TIPS placement (p < .001). When compared with portal venography, duplex sonography was 98% sensitive and 100% specific in predicting the presence of blood flow within the stent. Sonography was highly sensitive and specific for detecting stent stenosis. Final sonographic criteria for shunt stenosis in angiographically documented cases were low-velocity shunt flow (< or = 60 cm/sec) in the entire stent, or low-velocity shunt flow with an associated focal velocity elevation. CONCLUSION: Consistent changes in portal venous and hepatic arterial hemodynamics are normally seen on duplex sonography after placement of a TIPS. Duplex sonography accurately predicts shunt patency and dysfunction when compared with portal venography. Duplex sonography is an effective, noninvasive method of evaluating shunt function and should be considered for use as the primary imaging technique in routine follow-up after TIPS placement.

Adolescent↗
PubMed1994

Endothelium-dependent vasodilation of peripheral conduit arteries in patients with heart failure.

Endothelium-dependent vasodilation of peripheral resistance vessels is abnormal in patients with heart failure, but there are little in vivo data on endothelium-dependent vasodilation of peripheral conduit vessels. This study assessed endothelium-dependent vasodilation of forearm conduit and resistance vessels in normal subjects and patients with heart failure. The effects of intraarterial endothelium-dependent and endothelium-independent vasodilators on both forearm conduit (brachial artery) and resistance vessels were assessed in 9 patients with New York Heart Association class II-III heart failure and 11 normal subjects of similar age. Brachial artery diameter was measured by two-dimensional, moderate-frequency (8 MHz) ultrasound, and forearm blood flow was measured by strain gauge plethysmography. The endothelium-dependent vasodilator, methacholine (0.3 and 1.5 micrograms/min), increased brachial artery diameter by 7.6 +/- 1.3% and 12.2 +/- 1.5% in normal subjects as compared to 6.9 +/- 2.1% and 10.4 +/- 2.4% in patients with heart failure (P = NS, normal vs heart failure). The endothelium-independent vasodilator, nitroglycerin (0.15 microgram), also produced similar increases in brachial artery diameter in the two groups (8.2 +/- 1.3% in normal subjects vs 11.1 +/- 1.4% in patients with heart failure, P = NS). In contrast, forearm blood flow responses to methacholine were significantly (P < .05) greater in normal subjects (4.1 +/- 0.5 and 9.2 +/- 1.4 mL/min/100 mL forearm volume) than in patients with heart failure (2.0 +/- 0.8 and 5.1 +/- 1.3 mL/min/100 mL forearm volume). Forearm blood flow responses to the endothelium-independent vasodilator, sodium nitroprusside, were similar between the two groups. This study suggests that endothelium-dependent and endothelium-independent vasodilation of the brachial artery is not impaired in patients with class II-III heart failure. This finding contrasts with abnormal endothelium-dependent vasodilation of forearm resistance vessels. These data suggest that there are regional differences in endothelial function in patients with heart failure.

Adult↗
PubMed1994

Duplex and color Doppler sonography of complications after percutaneous interventional vascular procedures.

Duplex and color Doppler sonography have proved to be excellent noninvasive modalities for evaluating complications of percutaneous interventional vascular procedures. Complications including hematoma, pseudoaneurysm, arteriovenous fistula, thrombosis, stenosis, and vessel occlusion are routinely diagnosed with Doppler sonography. Hematomas exhibit variable echogenicity and internal complexity but never demonstrate internal blood flow. A pseudoaneurysm is a contained extravasation of blood that, unlike a hematoma, maintains a patent vascular connection with the injured vessel. Puncture-related arteriovenous fistulas are false vascular channels between an adjacent artery and vein that demonstrate low-resistance arterial signal, high-velocity venous outflow, and variable flow patterns within themselves. Narrowing in a stent demonstrates high-velocity turbulent flow with conventional Doppler and color aliasing with color Doppler techniques. Thrombus can be seen directly as a mural-based or luminal defect; however, it is often alterations in color flow dynamics, waveform characteristics, and flow velocities that permit conclusive diagnosis. Early experience in evaluation of stent stenosis in patients with transjugular intrahepatic portosystemic shunts suggests that low-velocity shunt flow indicates stenosis, likely related to the presence of low-resistance collateral pathways. Familiarity with both the interventional procedures and their possible complications facilitates prompt diagnosis and treatment.

Aneurysm↗
PubMed1994

Surveillance of infrainguinal vein grafts with duplex sonography.

This review considers the relative roles of traditional noninvasive vascular tests and conventional duplex and color flow Doppler sonography in the surveillance of infrainguinal autologous vein grafts. The purpose of surveillance is to identify significant anatomic or flow abnormalities that predispose to thrombosis, but can be repaired before graft thrombosis occurs. Although a few authors believe that serial measurements of the ankle-brachial index and other noninvasive vascular tests can serve as the primary method of surveillance for infrainguinal grafts, most authors do not concur. After the first postoperative month, stenosis caused by intimal hyperplasia is the most common cause of graft failure, usually occurring within 18 months after placement. Duplex sonography is both highly sensitive and specific for detection of such stenoses. Specific duplex sonographic criteria have been established for grading of stenoses and for the diagnosis and classification of arteriovenous fistulas. A large body of evidence suggests that graft thrombosis can occur without prior warning symptoms and that long-term graft patency improves if the asymptomatic lesions detected with duplex sonography are repaired before symptoms develop.

Arteriovenous Shunt, Surgical↗
PubMed1994

Color Doppler sonography of transjugular intrahepatic portosystemic shunts (TIPS).

Transjugular intrahepatic portosystemic shunts (TIPS) have largely replaced surgically created shunts in the treatment of life-threatening sequelae of portal venous hypertension [1-5]. Conventional duplex and color Doppler sonography are proving to be useful tools in the assessment of the stents and their associated hemodynamic changes [2-5]. A thorough Doppler survey before and immediately after TIPS placement provides a baseline for evaluation of shunt function and procedure-related complications. Routine follow-up studies at regular intervals after the procedure provide noninvasive assessment of shunt patency and late complications. This pictorial essay illustrates the anatomic and hemodynamic abnormalities present with portal hypertension before TIPS and discusses the expected duplex and color Doppler findings after TIPS. The sonographic characteristics of immediate and delayed complications, as well as potential diagnostic pitfalls, are discussed.

Follow-Up Studies↗
PubMed1993

Hemodynamic, respiratory, and metabolic effects of laparoscopic cholecystectomy.

In 10 patients undergoing laparoscopic cholecystectomy, creation of pneumoperitoneum caused immediate venous hypertension and stasis in the lower extremities as measured by percutaneous catheter and duplex scanning. These changes disappeared after deflation. As measured by spirometry, significant reductions in forced vital capacity of 23% and forced expiratory volume in 1 second of 22% were present 24 hours after surgery, and plasma interleukin-6 levels rose to 18 pg/mL. The visual analogue scale of resting pain increased to a median value of 2.5 postoperatively. When compared with other studies of open cholecystectomy, our results showed fewer restrictions of ventilation, lower cytokine levels, and lower pain scores. The minimal soft tissue trauma and early ambulation after laparoscopic cholecystectomy may decrease the risk of thrombosis despite an acute episode of venous stasis.

Blood Flow Velocity↗
PubMed1993

Duplex and color Doppler sonography of hemodialysis arteriovenous fistulas and grafts.

Surgically constructed Brescia-Cimino arteriovenous fistulas and synthetic loop grafts are common means of vascular access for hemodialysis. Although angiography has been the traditional method of imaging these vascular systems, duplex and color Doppler sonography offer a noninvasive method of evaluating dysfunctional hemodialysis access. In normally functioning fistulas, waveforms of flow in the supply arteries and throughout the graft are monophasic, with peak systolic velocities of 100-400 cm/sec and end-diastolic velocities of 60-200 cm/sec. The draining veins have arterial pulsations with peak velocities of 30-100 cm/sec. Arterial and venous stenoses, graft thrombosis (occlusive and nonocclusive), infection, aneurysm and pseudoaneurysm formation, and arterial steal are relatively common abnormalities that can threaten or destroy graft function and can be diagnosed sonographically. Although abnormal hemodynamics in access fistulas are usually detected during hemodialysis, sonographic evaluation at the time of initial dysfunction may reveal an underlying correctable abnormality, and specific therapy may be instituted before the condition progresses. In addition, use of sonography may obviate an invasive angiographic examination if no significant hemodynamic problem is present.

Arteriovenous Shunt, Surgical↗
PubMed1993

Sonography of the upper extremity and jugular veins.

Color Doppler sonography is a useful technique for rapid, noninvasive evaluation of venous disease in the upper extremity. It has been used successfully to evaluate thrombosis related to indwelling central catheters. In addition, Doppler sonography shows promise for monitoring thrombolytic therapy after "effort thrombosis" and detecting intermittent venous compression related to thoracic outlet syndrome.

Arm↗
PubMed1993

Evidence of venous stasis after abdominal insufflation for laparoscopic cholecystectomy.

Intraoperative venous stasis may increase the risk for perioperative deep vein thrombosis and pulmonary embolism. To determine if abdominal insufflation during laparoscopic cholecystectomy causes venous stasis, eight patients undergoing this procedure had their left common femoral veins examined by a duplex scanner before and after abdominal insufflation; the veins then were examined again before and after deflation. The right femoral veins were catheterized to measure femoral venous pressures. Abdominal insufflation to 14 millimeters of mercury pressure increased femoral venous pressures (10.2 +/- 4.1 millimeters of mercury to 18.2 +/- 5.1 millimeters of mercury; p < 0.001) and slowed peak blood velocities (24.9 +/- 8.5 centimeters per second to 18.5 +/- 4.5 centimeters per second; p < 0.05) without changing the cross-sectional areas (1.1 +/- 0.4 centimeter squared to 1.2 +/- 1.5 centimeter squared; p = NS) of the common femoral veins. Insufflation also reduced or eliminated pulsatility in the common femoral veins in 75 percent of the patients, indicating that insufflation was causing partial proximal venous obstruction. After 80 +/- 21 minutes of surgery, these changes remained significant. Deflation of the abdomen restored normal venous pulsatility in all patients, reduced femoral venous pressures (18.5 +/- 5.2 millimeters of mercury to 12.2 +/- 9.8 millimeters of mercury; p < 0.001), increased the peak blood velocities (14.2 +/- 6.8 centimeters per second to 28.1 +/- 16 centimeters per second; p < 0.05) and decreased the cross-sectional areas (1.4 +/- 0.6 centimeters squared to 0.9 +/- 0.4 centimeters squared; p < 0.05) of the common femoral veins, indicating venous decompression had occurred. The results suggest abdominal insufflation causes venous stasis during laparoscopic cholecystectomies. Measures shown to reduce intraoperative venous stasis, such as pneumatic compressive stockings, may benefit patients undergoing these procedures.

Adult↗
PubMed1992

Portal vein reflectors: duplex sonographic appearance.

Duplex sonography has established utility in the noninvasive evaluation of the portal venous system. Recently, the duplex sonographic features of suspected portal venous air have been described. We report on an experimental study in dogs undertaken to establish if the same sonographic features could be reproduced in a laboratory setting and to determine if small fragments of clot emboli could produce similar gray-scale and Doppler findings. Injections of microbubbles of air and clot fragments into the portal venous system were monitored using duplex ultrasound. The gray-scale and Doppler features of flow in the main portal vein were indistinguishable in both microbubble and clot injections. Superimposition of high-amplitude spikes on the normal portal venous waveform was seen in 19 of 24 (79%) microbubble and 13 of 23 (56%) clot fragment injections. We conclude that the appearance of rapidly moving, bright intraluminal echoes coupled with spike-like aberrations of the portal venous waveform can be associated with portal venous air bubbles or small blood clot emboli.

Animals↗
PubMed1992

Assessment of vascular complications of renal, hepatic, and pancreatic transplantation.

The assessment of the vasculature of the transplant recipient is complex; current emphasis is on utilization of noninvasive techniques, particularly conventional and color duplex sonography. These examinations reduce the need for diagnostic angiography, and their findings provide crucial information with regard to vascular complications seen after transplantation, such as arterial or venous stenosis or occlusion, arteriovenous fistulas, and pseudoaneurysms. However, the complexity of the clinical settings of these vascular complications often makes other noninvasive examinations, as well as angiography, necessary. Some complications are common to all three types of transplantations, but some, such as graft thrombosis in pancreatic transplantation, predominate in one particular type of transplant. Use of imaging is also important in identifying candidates for liver transplantation. In addition, access for therapeutic radiologic intervention can be provided with diagnostic angiographic procedures.

Humans↗