Doppler ultrasonography of peripheral vascular disease: the potential for ultrasound contrast agents.

Noninvasive diagnosis of peripheral vascular disease started with the introduction of Doppler technology. The development of high frequency ultrasound and color Doppler imaging allows continuous assessment of vascular disorders along the arterial tree. However, the technique remains operator dependent. It also suffers from anatomic limitations, such as bowel gas and ultrasound attenuation due to depth or wall calcification. Ultrasound contrast agents increase the Doppler signal intensity and should therefore reduce the rate of technical failures. They are useful for detecting the flux in cases of attenuated ultrasound beam and reduced blood flow. Their administration using continuous infusion protocols increases the duration of the effect. New imaging modalities such as harmonic imaging and pulse inversion imaging reduce Doppler artifacts and allow real time detection of the microbubbles flowing in the blood stream. Future directions include ultrasound-guided therapy of occlusion using encapsulated drugs targeted to the thrombus.

Color Doppler US of renovascular disease in native kidneys.

One hundred eighty-seven native kidneys in 96 patients were examined with color Doppler ultrasound (US) to (a) determine the color Doppler US characteristics of renovascular disorders and (b) assess the value of color Doppler US in detection of such disorders. Correlative angiography or computed tomography was performed in 94 patients. The following renovascular disorders were found: renal artery (RA) stenosis (40 cases), RA thrombosis (13 cases), RA aneurysm (four cases), renal vein thrombosis (three cases), arteriovenous fistula (three cases), peripheral infarction (one case of bilateral infarcts), and distal occlusive disease (three cases). One case of aortal coarctation was also found. Color Doppler US failed to demonstrate the proximal main RA in 25% of cases (among 193 RAs total including supernumerary RAs). The sensitivity and specificity of color Doppler US for the detection of RA stenosis or thrombosis were 89% and 99%, respectively. Color Doppler US thus appears to be effective in the diagnosis of renovascular disease in native kidneys.

[Femoral arteriovenous fistulas after vascular puncture for hemodialysis]. / Fistules artério-veineuses fémorales après ponction vasculaire pour hémodialyse.

From 1978 to 1991 we observed 10 patients who developed femoral arteriovenous fistula after venous puncture for hemodialysis. The fistula most often appeared after several punctures, but 3 developed after a single puncture. Diagnosis was made on the basis of local observation and auscultation of the vessel (bruit + thrill n = 10, hematoma n = 4, pulsatile mass n = 1). Two patients had arteriography and 2 had echo-doppler. Arteriography was not required for diagnosis (since clinical signs were sufficient), or for treatment, since echo-doppler and surgery indicated the location of the fistula. Five patients underwent surgery. In all cases, continuity of the main vessels of the lower member was maintained or reestablished during surgery. Surgery is mandatory for high flow rate. Such fistulas cannot be used and can cause cardiac failure in patient with another fistula for hemodialysis. Surgery should not be undertaken too early because of the possibility of spontaneous clotting (particularity if echo-doppler shows low flow rate), and to allow organization of the lesions and easier dissection. Auscultation of the vessel should be a routine procedure after any femoral vein puncture in order that this complication not be overlooked.

[Renal Doppler ultrasonography in the diagnosis of acute obstructions of the upper urinary tract]. / Apport du Doppler rénal dans le diagnostic des obstructions aiguës du haut appareil urinaire.

A comparative study of the resistivity indices (RI) obtained in both kidneys has been carried out in 30 controls and 60 patients with suspected unilateral acute obstruction of the upper urinary tract. Doppler findings (difference in the mean RI of both kidneys, delta RI) in the pathologic population have been systematically correlated to the data yielded by intravenous pyelography (IVP). In the control population delta RI was always < or = 0.03 (mean delta RI = 0.01, SD = 0.01). Considering that an increase in delta RI > or = 0.05 (> mean RI + 3 SD) is significant, 93% sensitivity and 100% specificity are obtained for the diagnosis of unilateral acute obstruction. Comparison of the resistivity indices of both kidneys is more specific and more sensitive than the assessment of the index on the obstructed side only; it improves the performance of ultrasonography in the initial diagnosis of acute urinary tract obstruction.