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Biomedical subjects

M Lafortune

Publications and source records attributed to M Lafortune.

At least 19 recordsLinked to original sources
PubMed1992

Renal arterial stenosis: slowed systole in the downstream circulation--experimental study in dogs.

To test the effect of stenosis of the renal artery on the downstream intrarenal blood flow, a snare was placed around the renal artery in 10 dogs and compressed to create stenosis while Doppler curves were obtained from interlobar arteries. Pulsed Doppler examination of the segmental and interlobar arteries was performed by means of placement of a 7.5-MHz mechanical sector transducer directly on the surface of the kidney. The following calculations were made: degree of stenosis (evaluated with aortography), acceleration index (AI) (the acceleration of systole), and resistive index. The Doppler measurements were compared with findings on angiograms. The AI for normal arteries ranged from 2.2 to 4.3, and for arteries with 75% or greater stenosis, from 1.0 to 1.3. Systolic peaks disappeared as near occlusion was achieved. These changes were reversible within seconds of release of the arterial snare. Such change is identical to change in the pulsus tardus and parvus waveforms seen in both acute and chronic severe stenosis of the renal artery in humans.

Animals↗
PubMed1992

Stenosis of the renal artery: assessment of slowed systole in the downstream circulation with Doppler sonography.

Slowing and dampening of systole in the arterial network distal to stenosis is a well-known Doppler sign of severe arterial stenosis. To determine whether this sign is present in boys and girls with such stenosis, intrarenal Doppler curves (acceleration index [AI] and resistive index [RI]) were compared with findings on renal arteriograms in 20 boys and girls; the AI was also measured in 10 boys and girls without renal disease. Statistical analysis of AI and RI measurements was performed. Eleven of 32 renal arteries were normal. The normal AI was 4.0-7.0; in arteries with greater than 75% stenosis, the AI was 0.7-1.7. In five arteries studied after angioplasty, the AI had changed from 0.7-1.5 to 4.0-5.6 at the first posttreatment examination (performed 28 hours to 1 week after angioplasty), and it remained normal during the 3-year follow-up period. In kidneys with stenotic arteries, the RIs were lower (0.43-0.54) than in healthy subjects (0.56-0.63). Regression and correlation coefficients of AI and RI measurements were statistically significant, and discrimination between normal arteries and those with greater than 75% stenosis was excellent.

Child↗
PubMed1992

Patent paraumbilical vein: anatomic and hemodynamic variants and their clinical importance.

Fifty-five of 353 patients with suspected portal hypertension studied with Doppler sonography had a patent paraumbilical vein. Of these 55 patients, 39 had the classic intrahepatic venous circulation found in Cruveilhier-Baumgarten syndrome: hepatopetal flow in all segmental portal veins and hepatofugal flow leaving the liver in a paraumbilical vein in the falciform ligament to join veins of the anterior abdominal wall. Sixteen patients had variants of the classic pattern: Flow in one or more segmental portal veins of the left lobe or the entire liver was hepatofugal. In addition, new venous channels connecting the left portal vein with the extrahepatic paraumbilical vein were found. Assessment of liver function with the Pugh score showed severe impairment in the majority of patients with a patent paraumbilical vein. Patients with the classic intrahepatic circulation had smaller esophageal varices than those with hemodynamic or anatomic variants. The presence of a patent paraumbilical vein did not prevent formation of esophageal varices in the patients studied.

Adolescent↗
PubMed1992

Development of the fetal brain in the second trimester: an anatomic and ultrasonographic demonstration.

The authors provide an anatomic and ultrasonographic description of the fetal brain from the 16th to the 27th week of development. During the second trimester the primitive brain is smooth and homogeneous and has few sulci and relatively large lateral ventricles. The cerebral hemispheres consist largely of cells migrating from the periventricular germinal matrix to the primitive cortex. The "featureless" hemispheres yield homogeneous ultrasonographic images very different from the more complex and familiar cerebral anatomy of fetuses and premature babies in the third trimester.

Brain↗
PubMed1991

Air in the portal vein: sonographic and Doppler manifestations.

Three patients with portal venous gas (one with radiographic and computed tomographic findings) had similar sonographic and Doppler patterns in the portal vein (PV). These patterns consisted of hyperechogenic foci moving within the lumen of the PV, producing sharp bidirectional spikes superimposed on the usual Doppler tracing of the PV. An injection of 0.25-0.50 cm3 of air, oxygen, nitrogen, and carbon dioxide into the jejunal vein of nine dogs yielded identical portal venous sonographic and Doppler patterns. In addition, the liver parenchyma of the dogs became hyperechogenic after the injection of gas. Gas in the PV is accompanied by the following signs: echogenic, moving foci within the lumen of the PV; sharp spikes on Doppler spectral display; and hyperechogenic foci within the liver parenchyma.

Adult↗
PubMed1991

Segmental anatomy of the liver: a sonographic approach to the Couinaud nomenclature.

The authors developed a simplified description of the segmental anatomy of the liver on the basis of the Couinaud nomenclature. This approach was demonstrated with normal in vivo sonographic images and livers dissected in corresponding planes. The branches of the portal vein, which lead to the center of individual segments, are used as key landmarks in the determination of segmental location. The hepatic veins, ligaments, fissures, and gallbladder are used as external boundaries of the segments.

Adolescent↗
PubMed1991

[Transcranial Doppler ultrasound].

Over the last decade, transcranial Doppler examination of the cerebral vessels has been made possible by the development of a high-intensity, low-frequency (2 MHz) pulse probe. The middle, the anterior and the posterior cerebral arteries, the cavernous portion of the carotid artery and the basilar artery can thus be easily studied transtemporally or transorbitally or from below the foramen magnum. The transcranial Doppler examination is already used clinically to study arteriosclerosis and in the diagnosis and follow-up of vasospasm and arteriovenous malformations. This review describes the examination procedure and summarizes and illustrates its major indications.

Basilar Artery↗
PubMed1990

Ureterovesical jets in infants and children: duplex and color Doppler US studies.

Ureteric jets were studied with conventional duplex Doppler (79 patients) and with color Doppler flow imaging (22 patients). Correlation with voiding cystourethrography (VCUG), performed ont he same day, was obtained in all patients. Thirty-six patients with normal VCUG results and normal renal and bladder ultrasound (US) studies served as the control group for 39 patients with vesicoureteric reflux (VUR) and 26 patients with urinary tract disorders other than reflux. The site of the ureteric orifice and duration, direction, and turbulence of the jets were recorded. Duration varied from 0.4 sec to 7.5 sec and depended largely on fluid intake. Duration varied in an individual patient by up to 2 sec from one jet to another. The direction of the normal jet was anteromedial and upward. Jets from refluxing ureters can appear normal. Severe renal parenchymal scarring reduced frequency and amplitude of the jets. Doppler analysis of the ureteric jet does not allow diagnosis or exclusion of VUR. Color Doppler was more sensitive in demonstrating ureteric jets than was gray-scale, real-time US and facilitated the study, but it was equally unable to help predict reflux.

Adolescent↗
PubMed1990

Fetal lobation. An anatomo-ultrasonographic correlation.

Remnants of the fusion of fetal renunculi have been mistaken for renal scars or tumors. We compared anatomic cuts of 24 cadaveric kidneys with fetal lobation (ages ranged from 16 weeks gestation to 49 years) to identical ultrasonographic sections performed in a water bath and to sonograms of healthy persons of similar ages as the cadavers. Fetal lobation was characterized as follows: there were fine, linear demarcations indenting the renal surface, separating normal lobes, consisting of a central pyramid and surrounding cortex. Separate renunculi seen in early fetal life progressively fuse throughout gestation, leaving interlobar grooves. During the third trimester, the renal surface becomes smoother and the interlobar grooves become invisible. One prominent indentation of the renal surface, the interrenuncular junction, incorporates perirenal fat and invaginates the anterior surface of the upper third of the kidney to the hilum and is the most easily visible remnant of fetal lobation. The sharply defined linear remnants of interlobar grooves should not be mistaken for scars, which are wider, less well defined and always associated with loss of renal cortex.

Adolescent↗
PubMed1989

[Doppler ultrasound and portal hypertension: quantitative analysis].

Usually, the clinical evaluation of diffuse hepatic changes only needs the answers to three important questions: is there a flow, in which direction and are the porto-caval shunts efficient? When an answer is found to these questions, the quantitative measurement of the portal flow can give complementary precisions to achieve a better physiopathological understanding of portal hypertension or blood malignancies and for the follow-up evaluation.

Adult↗
PubMed1989

[Doppler ultrasound in portal hypertension: qualitative analysis].

Duplex Doppler US is a procedure that enables confirmation--and in many instances--detection of portal hypertension by visualizing the presence of collateral blood vessels and determining the direction of the portal flow. In addition, absence of Doppler signal into the veins allows assessment of venous thrombosis both in the portal and hepatic veins.

Budd-Chiari Syndrome↗
PubMed1988

The radiological report: what is useful for the referring physician?

To assess what constitutes a useful radiological report for referring physicians, we sent a questionnaire to 200 doctors (general practitioners, internists, and surgeons). Questions testing style, length of the report, and several points of content, including mention of clinical correlation, negative findings, and sequence of further investigations, were included. The principal qualities useful to the clinician were clarity, brevity, and clinical correlation. Advice on planning of future investigations was especially valued by general practitioners.

Communication↗
PubMed1987

Non-surgical treatment of a congenital splenic cyst.

A congenital splenic cysts in a 5.5 year old girl was aspirated under ultrasonographic guidance and injected with 150 mg Tetracycline (intended for IV use). Septation and gradual resorption of the cyst occurred during the following weeks, leaving small residual cysts which have remained stable for the last 12 months. Splenectomy and its possible complications were avoided.

Child, Preschool↗
PubMed1987

Surgical portosystemic shunts in children: assessment with duplex Doppler US. Work in progress.

The patency of 12 surgical portosystemic shunts in 11 children with portal hypertension was assessed with duplex Doppler ultrasonography. Results were compared with surgical, angiographic, and clinical findings. Seven of nine patent shunts were directly seen, and flow in them was assessed. One proximal splenorenal and one mesentericocaval shunt were not directly seen because of intestinal meteorism. The obstructed shunts were not seen, and no flow could be detected at their site. The presence and direction of flow in the splanchnic venous system were determined in all children, obviating the need for further angiographic studies.

Adolescent↗