Clinical Evaluation of VDD Pacing with a Unipolar Single-Pass Lead

Twenty patients with advanced AV block and normal sinus node function underwent pacemaker implantation, randomly receiving a CPI 910 ULTRA II model VDD pacemaker. The first 13 patients received the implantation of a single lead with a screw-in positive ventricular fixation tip and a unipolar ring floating atrial electrode spaced 13 cm from the tip. A subsequent group of seven patients received a conventional porous tinned-tip lead with a pair of unipolar ring floafing electrodes. The second solution was adopted because the best atrial signal was not always in the high or mid-high atrium portion, but sometimes in the middle or mid-low position. With the modified double-electrode lead, the floating atrial electrode that detects the best signal can be selected, cutting out the pin of the one not used. The comparisons between minimal atrial slew rate and maximal ventricular slew rate, as well as those between minimal P wave amplitude and maximal R wave amplitude, show a highly significant range difference, as large as P < 0.01. Surface electrocardiograms, stress tests, and 24-hour Holter monitoring showed the correct functioning of the system with an average sensing failure from 0.05 to 1%. In conclusion, VDD stimulation is feasible with a single unipolar lead and a floating atrial electrode in conjunction with a pacemaker generator (CPI 910 ULTRA II) originally designed for permanent twin-lead implantation.     

Arterial Shunt with Pump Infusion Line for the Treatment of Chronic Thoracic Aortic Aneurysms: The "Modified Shunt of Gott"

Dissection of the aneurysm is the most dangerous step during graft replacement of the descending thoracic aorta. Sudden hemorrhage may follow wall rupture or disruption of major collaterals before the aorta can be clamped. A simple modification of the classic Gott is illustrated, which makes the shunt work also as a partial bypass if needed, with rapid reinfusion of blood losses. Nineteen of 25 patients requiring resection of descending aortic aneurysms from 1982 to 1990 were treated with this method with no mortality.     

Risk factors for catheter‐related thrombosis (CRT) in cancer patients: a patient‐level data (IPD) meta‐analysis of clinical trials and prospective studies

Background: Knowledge of independent, baseline risk factors for catheter‐related thrombosis (CRT) may help select adult cancer patients who are at high risk to receive thromboprophylaxis. Objectives: We conducted a meta‐analysis of individual patient‐level data to identify these baseline risk factors. Patients/Methods: MEDLINE, EMBASE, CINAHL, CENTRAL, DARE and the Grey literature databases were searched in all languages from 1995 to 2008. Prospective studies and randomized controlled trials (RCTs) were eligible. Studies were included if original patient‐level data were provided by the investigators and if CRT was objectively confirmed with valid imaging. Multivariate logistic regression analysis of 17 prespecified baseline characteristics was conducted. Adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were estimated. Results: A total sample of 5636 subjects from five RCTs and seven prospective studies was included in the analysis. Among these subjects, 425 CRT events were observed. In multivariate logistic regression, the use of implanted ports as compared with peripherally implanted central venous catheters (PICCs), decreased CRT risk (OR, 0.43; 95% CI, 0.23–0.80), whereas past history of deep vein thrombosis (DVT) (OR, 2.03; 95% CI, 1.05–3.92), subclavian venipuncture insertion technique (OR, 2.16; 95% CI, 1.07–4.34) and improper catheter tip location (OR, 1.92; 95% CI, 1.22–3.02), increased CRT risk. Conclusions: CRT risk is increased with use of PICCs, previous history of DVT, subclavian venipuncture insertion technique and improper positioning of the catheter tip. These factors may be useful for risk stratifying patients to select those for thromboprophylaxis. Prospective studies are needed to validate these findings.     

Side-reactions in peptide synthesis

The impurities which formed in the large-scale synthesis of THF-γ2, an immunomodulatory peptide of formula H-Leu-Glu-Asp-Gly-Pro-Lys-Phe-Leu-OH, were identified by a combination of analytical methods, and their structure confirmed by synthesis. Most impurities originated from side-reactions involving the aspartyl residue (cyclization, β-aspartyl formation and cleavage). Based on this knowledge, modifications were introduced into the work up and the purification procedure which resulted in a very pure final product (>99% by RP-HPLC).