Latis™ Catheter: New Technology for Thrombectomy of Vascular access Grafts

Purpose

The most common complication of vascular access surgery is thrombosis. This study compared the gold standard Fogarty Thrombectomy Catheter, to the new latis Catheter with an advanced monofilament matrix.

Methods

30 patients with thrombosed access grafts were randomly assigned to undergo thrombectomy with the Fogarty or latis catheter. An angioscope measured remaining graft thrombi.

Results

Twenty-nine of 30 subjects were successfully thrombectomized. No statistical differences in age, gender, race, or extension graft requirements were found. Catheter use in the latis group was: 1 in 14 procedures, and 2 in 1 procedure; Fogarty group: 1 in 10 procedures, 2 in 3 procedures, and 3 in 2 procedures. The average number of catheter passes was: latis 3.06 (1–6 passes) and Fogarty 4.13 (1–9 passes). A trend in favor of the latis catheter was demonstrated; however, statistical significance was not reached (p = 0.067). The overall 6-month primary patency rates were latis (40%) and Fogarty (30%). The estimated patency at the 50th percentile for latis is 120 days and Fogarty 108 days. Statistical significance was not reached with a p-value of the Log-Rank statistic of 0.68 and a p-value of the Wilcoxon statistic of 0.78.

Conclusions

The latis and Fogarty catheters are very similar. However, the latis balloon is more rugged with fewer catheters used and reduced number of passes. A difference in primary patency could not be demonstrated. The angioscope identified significant residual thrombus despite no returning thrombus from the catheter. Consequently, our protocol is modified to include the angioscope.

Verapamil vs quinine in recumbent nocturnal leg cramps in the elderly

In an open-labeled trial with eight elderly patients (aged 62 to 87 years) suffering from nocturnal leg cramps refractory to treatment with quinine sulfate, we ruled out other active disease processes and substituted verapamil hydrochloride therapy (120 mg at bedtime). Response to treatment was assessed by biweekly observations by the primary care physician and nightly by the research registered nurse for the entire duration of the trial, lasting eight weeks. Observations made and clinical conditions reported were indicative of improvement and disappearance of cramping when therapy was changed from quinine to verapamil. This noteworthy improvement in patients with recumbent nocturnal leg cramps is an important finding and merits further investigation.

Pharmacokinetics of ranitidine in patients with renal failure

The pharmacokinetics of ranitidine were studied in ten patients with renal failure (creatinine clearance, 6-54 mL/min) after intravenous (IV) (50 mg) and oral doses (150 mg). After oral administration, peak plasma concentrations of 378-808 ng/mL were obtained in two to six hours. Plasma concentrations declined very slowly and concentrations greater than 100 ng/mL were obtained for 16 to 20 hours after the dose. The elimination half-life following oral administration was 8.5 +/- 2.8 hours (standard deviation [SD]), and the bioavailability of ranitidine was 43.3% +/- 10.5%. After IV administration, the elimination half-life, plasma clearance, renal clearance, and volume of distribution were 7.0 +/- 1.0 hours, 170 +/- 38 mL/min, 36.0 +/- 25.0 mL/min, and 1.3 +/- 0.4 L/kg, respectively. About 20% of the IV dose and 9% of the oral dose were recovered unchanged in urine. There was a significant correlation between the renal clearance of ranitidine and creatinine clearance (r = .74, P less than .05) after IV administration. The elimination half-life in patients with renal insufficiency is about three times greater than that reported in the literature for healthy subjects. Similarly, the plasma clearance in these patients is about 20% of that reported in healthy subjects. The results indicate that ranitidine elimination is appreciably reduced in renal failure and that an adjustment of dose in patients with renal failure is warranted. A dose of 75 mg bid may be adequate in maintaining the therapeutic plasma concentrations that are required for adequate H2-blocking activity.

Pharmacokinetics of ranitidine after intravenous administration in hemodialysis patients

The pharmacokinetics of ranitidine and its removal by hemodialysis were determined in 9 patients with chronic renal failure requiring hemodialysis. Ranitidine (50 mg) was administered as an intravenous bolus at the beginning of the dialysis procedure, which lasted for 4 h. The elimination half-life, plasma clearance and volume of distribution (VD area) of ranitidine in these patients were 9.0 +/- 2.6 h (mean +/- SD), 305 +/- 152 ml/min and 3.5 +/- 1.9 liters/kg, respectively. About 8% of the administered dose was removed during a single dialysis procedure. The elimination of ranitidine is appreciably reduced in these patients. These results suggest that the dose of ranitidine should be adjusted in patients with severe renal failure who are undergoing hemodialysis, and a suitable schedule for dosing such patients is suggested.