In patients in the acute phase of MI, low doses of scopolamine cause a sustained increase in cardiac vagal tone and improve the autonomic indices associated with mortality.

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The purpose of this randomized controlled study was to assess the haemodynamic effects, safety and tolerability in acute myocardial infarction (AMI) of one month of oral captopril, one month of oral isosorbide mononitrate and 24 h of intravenous magnesium. It was carried out in four United Kingdom and six Polish hospitals in consecutive phases: oral captopril vs oral mononitrate vs placebo were compared among 400 patients in a 'three-way' study; and then oral captopril vs placebo and oral mononitrate vs placebo were compared among 474 patients in '2 x 2' and '2 x 2 x 2' factorial studies (with 208 patients in the latter study also randomized between intravenous magnesium and open control). The factorial studies differed from the three-way study in that one group of patients was allocated both oral captopril and oral mononitrate, a higher maintenance dose of captopril was used (following the same initial dose), and once daily controlled-release mononitrate was used. In the three-way study, the mean of the lowest systolic blood pressures recorded during the first 4 h after randomization were (mmHg +/- standard error): 104 +/- 2 captopril vs 105 +/- 1 mononitrate vs 112 +/- 2 placebo (P < 0.001 for captopril or for mononitrate vs placebo), and in the factorial studies were 105 +/- 1 captopril vs 110 +/- 1 placebo (P < 0.01) and 106 +/- 1 mononitrate vs 108 +/- 1 placebo (NS). There was an excess of hypotension recorded among patients allocated active treatment (captopril > mononitrate > placebo) and there was a small, but significant, excess of cardiogenic shock with captopril compared with control in the factorial study. However, in these studies, neither captopril nor mononitrate were associated with any overall increase in the incidence of hypotension considered severe enough to lead to treatment being stopped. No other serious complications were observed, and compliance with study tablets at hospital discharge was not significantly different between the active and placebo groups. Patients allocated magnesium in the 2 x 2 x 2 factorial study had a slightly lower mean systolic blood pressure just after the initial 15 min bolus injection (126 +/- 2 magnesium vs 134 +/- 3 control; P < 0.05) but there were no significant differences during the subsequent 24 h maintenance infusion period. Apart from some facial flushing, magnesium did not appear to be associated with any complications.(ABSTRACT TRUNCATED AT 400 WORDS)

The heart rate response of 59 patients aged 17-79 years implanted with seven different types of rate responsive pacemakers was evaluated during graded exercise treadmill testing and during standardised daily activities. The heart rate response in patients with pacemakers was compared with the chronotropic response in 20 healthy controls of similar age and sex distribution who performed identical protocols. All pacemaker types adequately simulated the control heart rate response during the graded exercise treadmill test except during the early stages of exercise. However, during everyday activities, the response of ventricular rate responsive (VVIR) Most previous studies to assess sensor driven rate responsive pacemakers used treadmill testing or bicycle ergometry.'l'8 We compared heart rate changes in patients with single and dual chamber rate responsive pacemakers with the chronotropic response in a group of healthy controls during various standardised everyday activities and during graded exercise treadmill tests. Patients and methods PATIENTSFifty nine patients aged 17-79 years (mean 57-9, 35 (590o) men) had seven types of rate responsive pacemaker implanted. Ventricular rate responsive pacemakers (VVIR) were implanted in 33 patients. They were the activity sensing Siemens Sensolog I (10), minute ventilation sensing Telectronics Meta (8), activity sensing Medtronic Activitrax (8), and QT sensing Vitatron Tx II (7). None of these patients had the signs or symptoms of the pacemaker syndrome."' Dual chamber rate responsive systems were implanted in 26 patients. Six had Medico Phymos VDD systems, which require a single lead with free floating atrial bipolar sensing and unipolar ventricular sensing and pacing; 10 had DDD systems; and 10 had activity sensing DDDR systems. The table shows the indications for implantation.All patients were followed up at 6 weeks and 3 months after pacemaker implantation and were optimally programmed to the rate response mode according to the manufacturers' instructions.We studied heart rate responses in a group of 20 apparently healthy people aged 23-76 years (mean 55 0, 12 (60%) men) during standardised daily activities and treadmill testing.

Angiographic morphology was analysed in 32 patients who developed restenosis after initially successful coronary angioplasty. The mean minimal luminal diameter of the dilated coronary segments increased from 0.9 mm to 2.3 mm after dilatation, but decreased to 0.9 mm at restenosis. The reference diameter was unchanged after dilatation and at restenosis. Mean stenosis length before the initial angioplasty was 7.0 mm but at the repeat procedure had increased to 8.7 mm (mean increase 1.7 mm, 95% confidence interval 0.6 to 2.8 mm, p less than 0.01). There were no significant differences in mean trans-stenotic pressure gradient and mean eccentricity ratio between the initial and repeat angioplasty procedures. In individual patients the changes in stenosis morphology were unpredictable, but overall stenoses tended to be longer at restenosis. In some patients stenosis length increased by several millimetres but the success rate of repeat angioplasty was high and the clinical importance of the changes in stenosis morphology are uncertain.

The contribution of rate response provided by three different types of rate responsive pacemaker (Sensolog, Meta, and Vitatron TX) was assessed in 25 patients during out of hospital activity. Pacemakers were optimally programmed and full disclosure 24-hour Holter ECG recordings were obtained during everyday activities. Close visual analysis of these tracings revealed that rate response is active for less than 15% of the 24-hour study period with high rate response (paced rate above 100 beats/min) for just 5% of the day showing peak activation between 1600 and 2000 hours. Low rate response (paced rate below 100 beats/min but 5 beats above base rate) was maximal between 0800 hours and midday and comprised 10% of all heart beats during the study period. Thirty percent of study patients were nonpacemaker dependent and rate response in these subjects was significantly (P less than 0.001) less active between 0800 hours and midday than in pacemaker dependent patients though it was equivalent at all other times. Nonpacemaker dependent patients achieved natural sinus response in the morning and tended to rely on pacemaker supplied rate response in the latter part of the day.