The RR index test for the differentiation of atrioventricular nodal block from His--Purkinje block during incremental atrial pacing in patients with bifascicular block

AIMS: His—Purkinje block induced by incremental atrial pacingis highly predictive of an impending high degree atrioventricularblock in patients with bifascicular block. The His potentialis, however, sometimes not measurable or is lost in the ventriculardepolarization. The aim of this study was to evaluate whetherthe comparison of RR intervals before and after atrioventricularblock, induced by incremental atrial pacing, could differentiatebetween atrioventricular nodal and His—Purkinje blockin patients with bifascicular block. METHODS AND RESULTS: In 98 patients with bifascicular block, incremental atrial pacingwas performed as part of an invasive electrophysiological study.An ‘RR index’ was constructed by calculating thenumerical difference between the RR interval immediately beforeand after the atrioventricular block divided by the RR intervalimmediately before the pacing-induced block. Endocavitary recordingof the His bundle potential was used for defining the levelof atrioventricular block. The median RR index was 0·98(range 0·88–1·02) in recordings with His—Purkinjeblock and 0·49 (range 0·11–0·89)in recordings with atrioventricular nodal block (P<0·001).An RR index of 0·85 had a sensitivity of 100% and a specificityof 99% for the identification of atrioventricular block localizedto the His—Purkinje system. CONCLUSION: The use of an RR index is a helpful tool in the differentiationof His—Purkinje from atrioventricular nodal block in patientswith bifascicular block undergoing incremental atrial pacingas part of an invasive electrophysical study.     

Periods of differing mortality distribution during the first year after acute myocardial infarction

The mortality rate after acute myocardial infarction (AMI) has generally been modeled by a single exponential function. The present study was undertaken to determine, in 3 different populations, whether or not periods exist during the first year after AMI which have mortality distributions that differ from this pattern. The 3 patient populations included San Diego (346 patients, 71 deaths), Vancouver (704 patients, 146 deaths), and Copenhagen (1,140 patients, 262 deaths). Hospital admission was within 24 hours of the onset of symptoms, and patients dying within the first 24 hours after hospital admission or of noncardiac or unknown causes were not analyzed. The mortality between 2 and 21 days in the combined data base was 11.4% (range 10.9 to 11.7) and from 3 weeks to 1 year 10.5% (range 9.0 to 11.3). A high degree of similarity was noted among the shapes of the 3 survival curves. The hypothesis of an exponential mortality rate during the entire first year was rejected. Using a special statistic, changepoints at days 17,23, and 24 in the 3 populations (21 days for the combined data base) were identified and used thereafter to divide the year into 2 separate periods of mortality within which exponentiality for the mortality rate was not rejected. The point by which exactly 50% of deaths had occurred was day 19, with 75% of deaths occurring by day 100. These data further define the natural history after AMI and indicate optimal follow-up periods for short- and longer-term management strategies based on risk assessment or trials of risk reduction after AMI.     

Intestinal ischemia due to vascular elastosis caused by metastasizing carcinoid tumor of Meckel's diverticulum

A case of a carcinoid tumor arising in a Meckel's diverticulum is reported. By the time of detection, the tumor had spread to the mesentery causing ischemia of the small intestine due to the associated vascular elastosis.     

Grafted neural stem cells develop into functional pyramidal neurons and integrate into host cortical circuitry

In vitro expanded neural stemprogenitor cells can undergo region-specific differentiation after transplantation to the developing or adult brain, and display morphologies and markers characteristic of mature neurons. Here we have used patch-clamp techniques to explore whether grafted stem cells also can develop physiological properties of mature neurons and become functionally integrated within host neural circuitry. The immortalized neural progenitor cell line, RN33B, prelabeled with GFP by using a lentiviral vector, was transplanted into the cortex or hippocampus of neonatal rats. We found that the grafted GFP-positive cells differentiated into cells with morphological features of cortical or hippocampal pyramidal neurons, and that many of them had established appropriate cortico-thalamic and contralateral hippocampal connections, respectively, as revealed by retrograde tracing. Whole-cell patch-clamp recordings from grafted cells with morphological characteristics of pyramidal neurons showed that they were able to generate action potentials, and received functional excitatory and inhibitory synaptic inputs from neighboring cells. These data provide evidence that grafted neural progenitors can differentiate into morphologically mature pyramidal projection neurons, establish appropriate long-distance axonal projections, exhibit normal electrophysiological properties, and become functionally integrated into host cortical circuitry.     

Abnormal increase in urinary aquaporin-2 excretion in response to hypertonic saline in essential hypertension

Background

Secondary hyperparathyroidism (SHPT) is associated with mortality in patients with chronic kidney disease (CKD), but the economic consequences of SHPT have not been adequately studied in the European population. We assessed the relationship between SHPT parameters (intact parathyroid hormone [iPTH], calcium, and phosphate) and hospitalisations, medication use, and associated costs among CKD patients in Europe.

Methods

The analysis of this retrospective cohort study used records of randomly selected patients who underwent haemodialysis between January 1, 2005 and December 31, 2006 at participating European Fresenius Medical Care facilities in 10 countries. Patients had ?? 1 iPTH value recorded, and ?? 1 month of follow-up after a 3-month baseline period during which SHPT parameters were assessed. Time at risk was post-baseline until death, successful renal transplantation, loss to follow-up, or the end of follow-up. Outcomes included cost per patient-month, rates of hospitalisations (cardiovascular disease [CVD], fractures, and parathyroidectomy [PTX]), and use of SHPT-, diabetes-, and CVD-related medications. National costs were applied to hospitalisations and medication use. Generalised linear models compared costs across strata of iPTH, total calcium, and phosphate, adjusting for baseline covariates.

Results

There were 6369 patients included in the analysis. Mean ± SD person-time at risk was 13.1 ± 6.4 months. Patients with iPTH > 600 pg/mL had a higher hospitalisation rate than those with lower iPTH. Hospitalisation rates varied little across calcium and phosphate levels. SHPT-related medication use varied with iPTH, calcium, and phosphate. After adjusting for demographic and clinical variables, patients with baseline iPTH > 600 pg/mL had 41% (95% CI: 25%, 59%) higher monthly total healthcare costs compared with those with iPTH in the K/DOQI target range (150?C300 pg/mL). Patients with baseline phosphate and total calcium levels above target ranges (1.13?C1.78 mmol/L and 2.10?C2.37 mmol/L, respectively) had 38% (95% CI: 27%, 50%) and 8% (95% CI: 0%, 17%) higher adjusted monthly costs, respectively. Adjusted costs were 25% (95% CI: 18%, 32%) lower among patients with baseline phosphate levels below the target range. Results were consistent in sensitivity analyses.

Conclusions

These data suggest that elevated SHPT parameters increase the economic burden of CKD in Europe.