Extreme Intracardiac Coiling of a Transvenous Pacemaker; A Case Report

We report an unusual complication of transvenous pacing: extreme coiling of a pacemaker catheter, which formed a redundant, twisted loop protruding into the right ventricular outflow tract. This may be a result of "tividdling" (rotation) of the pacemaker generator by the patient and/or inadequate fixation of the catheter at the venous entry site. Careful fixation of the generator to the venous entry site within the subcutaneous pocket may prevent such a complication.     

Stresses and deflections in the floor of model cavity preparations

In this study the finite element method was used in conjunction with an axisymmetric model of an idealized first molar to determine the stresses, as well as deflections in the floor of a cylindrical cavity preparation as caused by condensers of various sizes. It was found that for the 0·25 mm thickness of dentine, the 2 mm condenser and a 2 kg load, a tensile stress of approximately 70 MN/m² was obtained near the centre of the preparation. Under the same load and a 4 mm condenser a tensile stress of only 42 MN/m² was obtained. Bowen & Rodriguez (1962) and Lehman (1967) reported that the tensile strength of dentine was in the order of 51.7 MN/m² and 41.5 MN/m² respectively. Thus it was demonstrated that for certain combinations of load, condenser size, and cavity dimensions, the tensile strength of the dentine in the cavity floor could be exceeded and failure of the cavity floor could ensue.     

Riverina men's study: An exploration of rural men's attitudes to health and body image

Aim:  To determine the attitudes of rural men to matters of health and body image.
Methods:  Focus group discussions were used to examine the attitudes of a sample of Australian rural men to matters of health and body image in the context of their eating and exercise behaviours. Forty-two rural men, aged 25–64 years, took part in four focus groups, one exclusively for farmers, in south-western New South Wales (NSW).
Results:  Results from these focus groups reveal that many of the masculine myths surrounding male behaviour in relation to health and ideas on body image persist among rural men in south-western NSW. Talking about health is not considered a male past-time; visiting health professionals is still seen as a last resort; being a 'big bloke' is perceived to be advantageous and heavy drinking is still considered an Australian male domain, especially among the younger men in the groups.
Conclusion:  The present study provides a deeper understanding of rural men's attitudes to body image issues and lifestyle behaviours, which is critical to helping change health outcomes for this hard-to-reach group.     

Influence of muscle mass and work on post-exercise glucose and insulin responses in young untrained subjects

The 18 h post-exercise glucose and insulin responses of six male and six female subjects were measured following one- or two-leg cycling to determine the influence of muscle mass involvement and work. Each subject performed three exercise trials on a Cybex Met 100 cycle ergometer: (1) two-leg exercise for 30 min at 60% of the two-leg VO _{2 max}; (2) one-leg exercise for 30 min at 60% of one-leg VO _{2 max}; and (3) one-leg exercise (one-legTW) at 60% of the one-leg VO _{2 max} with the total work performed equal to that of the two-leg trial (duration ≈50 min). These trials were preceded by 2 days of inactivity and followed by an 18 h post-exercise 75 g oral glucose tolerance test (OGTT). The glucose response during the baseline OGTT demonstrated that the subjects had normal glucose tolerance with fasting serum glucose levels of 5.1 mM , and 1 and 2 h serum glucose less than 7.8 mM , respectively. The 18 h post-exercise glucose responses were significantly lower following the two-leg trial (P < 0.05), with the area under the curve values being 129.9 mM h^?1 less than the resting control level. The 18 h post-exercise insulin AUC response of the two-leg trial was significantly lower than either of the one-leg responses (14.7 pM below the one-leg and 5.0 pM below the one-leg TW) but was not associated with a change in C-peptide. The 18 h post-exercise insulin levels of the one-leg and one-legTW trials were above or near the resting control values, but were not accompanied by a significant change in C-peptide. In conclusion, the data presented here show that the amount of muscle tissue utilized during an exercise bout can influence both the glucose and insulin responses, whereas the amount of total work employed during the exercise had no effect on either of these parameters.     

The Influence of Endocardial Electrode Fixation Status on Acute and Chronic Atrial Stimulation Threshold and Atrial Endocardial Electrogram Amplitude

The endocardial atrial electrogram or "P wave amplitude" (PWA) and pacemaker atrial stimulation thresholds are important parameters determining correct pacing system function. Pacemaker lead fixation mechanism and lead age may negatively influence these parameters. Therefore, we compared acute and chronic PWA and atrial stimulation thresholds in 33 patients with permanent transvenous atrial screw-in leads, follow-up 647 days +/- 297 days; and in 31 patients with nonscrew leads, follow-up 855 days +/- 512 days (P = ns). Results: The PWA differed between the two lead types acutely (1.97 mV +/- 0.8 mV for screw-in versus 2.48 mV +/- 1.1 mV for nonscrew-in leads; P less than 0.05), but not chronically (2.21 mV +/- 0.8 mV vs 2.2 mV +/- 1.2 mV; P = ns). Acute and chronic atrial pacing thresholds did not differ between groups. We also analyzed an early interim PWA in a subgroup of patients (mean 31 days after implantation). The nonscrew fixation group interim PWA was 1.76 mV +/- 0.9 mV versus 2.7 mV +/- 1.2 mV at implant (P less than 0.001). The screw-in lead interim PWA was 2.04 mV +/- 0.9 mV versus 1.97 mV +/- 0.7 mV at implant (P = ns). Conclusions: (1) A significantly higher endocardial PWA occurs at the time of lead implantation in nonscrew versus screw-in lead groups, but the chronic PWA does not differ between the two groups. (2) A transient but marked early (mean approximately 31 days) attenuation of the PWA occurs only with nonscrew-in leads. (3) Atrial threshold stimulation energies do not differ between the two lead groups acutely or during follow-up.