Transcutaneous oxygen pressure measurements in type I diabetic patients for early detection of functional diabetic microangiopathy

Seventy-six type I diabetic patients free of peripheral artery disease and 82 age-matched healthy volunteers were studied by means of transcutaneous oxygen pressure measurements. Two transcutaneous probes were attached to the skin at the subclavian region and at the supramalleolar region. Basal transcutaneous oxygen pressure values and values during breathing of 5 and 10 1 O2 min-1, the rate of rise of oxygen pressure and the time required from the beginning of the oxygen pressure increase to the achievement of its maximum were recorded, and a regional perfusion index was calculated. Nearly all the measured transcutaneous oxygen parameters showed significant differences between diabetic and control subjects. The differences were most pronounced with the transcutaneous oxygen pressure values during oxygen breathing. Even patients with a diabetes duration of less than 1 year and free of any detectable microangiopathic complication, differed significantly from control subjects. These findings may indicate a microcirculatory disturbance in diabetic patients, which might be considered as the manifestation of a functional diabetic microangiopathy preceding any morphological alterations of the vasculature in diabetes mellitus.     

In-vivo Release of a GnRH Agonist from a Slow-release Poly(lactide-glycolide) Copolymer Preparation: Comparison in Rat,Rabbit and Guinea-Pig

Abstract— Different batches of 50:50 poly((±)-lactide-glycolide) copolymer (PLG) were used as biodegradable carriers for D-Phe⁶-gonadotropin-releasing hormone (GnRHa) in the form of injectable long-acting implants loaded with 10% GnRHa and tracer amounts of [¹²⁵I]GnRHa. After their injection subcutaneously into rats, rabbits, and guinea-pigs, the release kinetics of the peptide were determined by counting the radioactivity remaining in the implants (i) after recovery from the rats after death or (ii) directly on the skin above the injection site of rabbits and guinea-pigs in-vivo. No significant differences in the release pattern of the peptide amongst the three species whether the release process was controlled by diffusion or by degradation of the polymeric matrix were found. It is concluded that the results of in-vivo release tests using laboratory animals are valid for man and that enzymes are not involved in the degradation of the polymeric matrix. The results may be of general importance for the use of long-term release PLG formulations of highly active drugs, especially peptides and proteins.     

The Cook Inc. Gianturco-Roubin Flex-Stent

The Cook Inc. Gianturco-Roubin Flex-Stcnt was approved by the Food and Drug Administration in May 1993 for the treatment of acute and threatened closure following balloon angioplasty or treatment with another percutaneous device. However, the stent is frequently used for additional, nonapproved indications, including the treatment of restenosis lesions, lesions that demonstrate early recoil, high risk lesions, and the treatment of primary (de novo) lesions in an attempt to improve the clinical outcome in these different settings. The aim of this article is to review the available data regarding the use of the Flex-Stent for these approved and nonapproved indications. (J Interven Cardiol 1996;9:145–152)     

Beat-to-Beat Repolarization Lability Identifies Patients at Risk for Sudden Cardiac Death

QT Interval Variability and Sudden Death. Introduction : Recent studies have implicated repolarization lability in the genesis of malignant ventricular arrhythmias. However, few data exist on assessment of temporal QT interval variability and its relation to arrhythmogenesis. We tested the ability of the QT variability index (QTVI), a measure of beat-to-beat QT interval fluctuations measured on a single ECG lead, to identify patients presenting with malignant ventricular arrhythmias and predict their subsequent occurrences.
Methods and Results : We measured the QTVI in 95 patients presenting for electrophysiologic study (EPS). The ability of the QTVI to identify patients with sudden cardiac death (SCD) or sustained monomorphic ventricular tachycardia (MVT) on presentation and during follow-up of 23.7 ± 14.3 months was compared with spatial QT dispersion, T wave alternans ratio during atrial pacing, MVT inducibility at EPS, signal-averaged ECG, heart rate variability, and ejection fraction. The QTVI was higher in patients with heart disease than in controls (-0.7 ± 0.7 vs −1.1 ± 0.5, P < 0.05), and higher in patients presenting with SCD than in other patients with heart disease (0.0 ± 0.6 vs −0.8 ± 0.5, P < 0.05). The QTVI was the only clinical variable that identified patients who presented with SCD ( P = 0.004, odds ratio = 12.5) on stepwise, logistic multiple regression. Fourteen patients had arrhythmic events during follow-up. In a Kaplan-Meier analysis of arrhythmic events, QTVI ≥ 0.1 was a discriminator for higher risk of arrhythmic events ( P < 0.05).
Conclusions : (1) This noninvasive measure of temporal repolarization lability identified patients with SCD and predicted arrhythmia-free survival. (2) Further studies are needed to determine the mechanisms that mediate beat-to-beat QT interval variability.     

Influence of external cardiac pacing on cerebral oxygenation measured by near‐infrared spectroscopy in children after cardiac surgery

Background: The brain of children in the early period after repair of congenital heart defects with cardiopulmonary bypass (CPB) may be more vulnerable to hemodynamic changes because of impaired cerebral autoregulation. During postoperative testing of the external temporary safety pacer, we performed desynchronizing ventricular pacing (VVI) while monitoring cerebral oxygenation using near‐infrared spectroscopy (NIRS). Methods: We prospectively investigated 11 children (6 girls, 5 boys). Mean age was 6.1 months (±3.8 months) and mean weight: 5.3 kg (±1.5 kg). We performed measurements at four study steps: baseline I, VVI pacing, baseline II and atrial pacing (AOO) to exclude effects of higher heart rate. We continuously measured the effects on hemodynamic and respiratory parameters as well as on cerebral tissue oxygenation index (TOI). Hemoglobin difference (HbD) was calculated as a parameter for cerebral blood flow (CBF). Results: Ventricular pacing leads to a significant decrease in arterial blood pressure and central venous saturation accompanied by an immediate and significant decrease in TOI (63.3% ± 7.6% to 61.5% ± 8.4% [P < 0.05]) and HbD (0.51 ± 1.8 μmol·l⁻¹ to −2.9 ± 4.7 μmol·l⁻¹ [P < 0.05]). Conclusion: Cardiac desynchronization after CPB seems to reduce CBF and cerebral oxygenation in children.