David E. Finlay

Early sonographic evaluation of the transjugular intrahepatic portosystemic shunt (TIPS)

The purpose of this study was to evaluate duplex and color Doppler findings in patients before and within 24 h after transjugular intrahepatic porto-systemic shunts (TIPS). Conventional duplex and color Doppler were used in the assessment of 19 patients who underwent TIPS as part of a prospective protocol. Patients were examined within 24 h before and after the procedure. Before TIPS, patency, flow direction, and peak flow velocity in the main portal vein and hepatic artery were studied, as well as patency and flow direction in hepatic veins, splenic vein, and inferior vena cava (IVC). Immediately after the procedure, sonographic identification of stent position, shunt patency, and flow dynamics were evaluated and patency and flow direction of hepatic veins, splenic vein, and IVC were determined. The portogram performed at the end of the procedure was compared with the 24-h sonographic studies after TIPS to determined sonographic/angiographic correlation. No intraparenchymal abnormalities or perihepatic fluid collections were detected after the procedure. The metallic stent was clearly seen in all patients. Mean peak shunt flow velocities were 139±50 cm/sec within 24 h after TIPS. Absence of flow through the shunt was correctly identified in one case and confirmed angiographically. Mean peak flow velocity in the portal vein before TIPS was 22±13.6 cm/sec and increased to 43.6±9.1 cm/sec after TIPS (p<0.05). The hepatic artery peak systolic velocity increased from 77±51 cm/sec before TIPS to 119±53 cm/sec after the procedure (p=0.029). Conventional duplex and color Doppler ultrasound proved to be a useful non-invasive diagnostic method to assess patients who have undergone TIPS. We propose its use as the primary diagnostic modality in these patients.

Effects of Central Venous Catheter Placement on Upper Extremity Duplex US Findings

PURPOSE The upper extremity veins of 17 patients who underwent operative central venous catheter placement were studied prospectively with color duplex sonography to determine which duplex changes, if any, could be due to the presence of the catheter alone and to determine if these waveform changes could mimic the dampened waveform seen peripheral to central nonvisualized or nonocclusive thrombosis or proximal stenosis. PATIENTS AND METHODS The subclavian, internal jugular, and brachiocephalic veins were examined with color duplex sonography immediately before and after catheter placement. Images obtained before and after catheterization were reviewed by two radiologists for (a) spectral broadening in both the vein of insertion and the brachiocephalic vein, (b) transmission of atrial pulsations, and (c) respiratory phasicity. RESULTS In all cases, atrial pulsatility and respiratory phasicity were present before and after catheter placement. There was no statistically significant change in the amount of spectral broadening after catheter placement. A mild increase in the peak blood flow velocity of 7 cm/sec (P = .04) in the ipsilateral brachiocephalic vein was demonstrated; however, no significant increase in velocity could be shown in the vein of insertion. CONCLUSION In this clinical setting, the hemodynamic changes within the vein from the catheter placement are minimal. Any damping of the venous waveform seen with sonography performed to rule out upper extremity deep venous thrombosis secondary to indwelling catheter--for example, loss of atrial pulsatility or respiratory phasicity--is presumably due to the presence of venous thrombosis or stenosis.