Magnesium administration may improve heart rate variability in patients with heart failure.

BACKGROUND AND AIM: Intracellular magnesium (icMg) depletion may coexist with normomagnesemia. Mg deficiency (serum and/or intracellular) and decreased heart rate variability (HRV) are common in heart failure (HF). Since both are predictors of poor prognosis, it was of interest to evaluate the effect of Mg supplementation on HRV in patients with HF. METHODS AND RESULTS: We investigated the effect of Mg administration on HRV in normomagnesemic patients with systolic HF. HRV, serum Mg and icMg were determined before and after 5-week 300 mg/day Mg citrate treatment in 16 patients (group 1). The control group included 16 Mg-non-treated HF patients (group 2). HRV was determined by a non-linear dynamics analysis, derived from the chaos theory, which calculates HRV-correlation dimension (HRV-CD). After 5 weeks, serum Mg (mmol/l) increased more significantly in group 1 (from 0.78+/-0.04 to 0.89+/-0.06, p<0.001), than in group 2 (from 0.79+/-0.07 to 0.84+/-0.06, p=0.042). IcMg and HRV-CD increased significantly only in group 1 (from 59+/-7 to 66+/-9 mmol/g cell protein, p=0.025, and from 3.47+/-0.42 to 3.94+/-0.36, p<0.001, respectively). In group 2, the differences in the respective parameters were 63+/-12 to 66+/-9 mmol/g cell protein (p=0.7) and 3.59+/-0.42 to 3.55+/-0.4 (p=0.8). CONCLUSION: Mg administration to normomagnesemic patients with systolic HF increases serum Mg, icMg and HRV-CD. Increasing of HRV by Mg supplementation may prove beneficial to HF patients.

Enhancement of bone apposition to stainless steel cortical screws by surface modification using heat treatment: an experimental study.

OBJECTIVE: The purpose of the present study was to test whether the surface of stainless steel cortical screws modified by an oxidation process (heat treatment) resulted in enhancement of bone apposition as a consequence of better bone apposition to the metal surface. DESIGN: Control and heat-treated commercial cortical screws (stainless steel 316L) were inserted alternately into the tibiae of eight goats with a fixed insertion torque. Fluorochrome bone label was given during the six-week experimental period, after which the goats were killed and the extraction torque force measured. The screws and the adjacent bone were processed for histology. MAIN OUTCOME MEASURE: It was hypothesized that the heat-treated transcortical metal screws would have a greater extraction torque than untreated control screws. RESULTS: The extraction torque of the heat-treated screws was 0.59 +/- 0.06 newton-meters, which was significantly (p < 0.0001) higher (1.7-fold) than that of the control screws (0.35 +/- 0.02 newton-meters). Histomorphometric measurements demonstrated a 65 percent, significant (p < 0.05), increase in the area of fluorescence (indication of new bone deposition) adjacent to the heat-treated implant versus the control screws. CONCLUSIONS: Heat treatment of the cortical screws prior to insertion significantly increases fixation strength to the host bone in a large animal model. The clinical applicability will be to achieve bone apposition similar to that seen with titanium implants but with a stiff low-cost material.