Reperfusion of Infarct Related Artery Achieved by Direct Percutaneous Transluminal Coronary Angioplasty Counteracts Left Ventricular Remodeling after Acute Myocardial Infarction More Than Thrombolysis

The purpose of this study was to compare the effect of direct percutaneous transluminal coronary angioplasty (PTCA) and intravenous recombinant tissue plasminogen activator (rt-PA) on left ventricular remodeling in patients with acute myocardial infarction (AMI). To address this issue, patients with AMI randomly assigned to direct PTCA or intravenous rt-PA as part of a large multicenter study (Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries [GUSTO] IIb Angioplasty Substudy) were evaluated with two-dimensional echocardiography at predischarge. An echocardiographic infarct size index and the end-diastolic and end-systolic left ventricular volumes were computed. Patients with an infarct size index equal to or higher than the mean value were considered to have a large infarction. Of 26 enrolled patients, 13 were assigned to PTCA (9 successfully reperfused: i.e., TIMI-3 flow after PTCA) and 13 to rt-PA (10 successfully reperfused: i.e., ST resolution after rt-PA). In patients considered successfully reperfused, end-systolic volumes tended to be lower in PTCA patients than in rt-PA patients (43 ± 17 cc vs 59 ± 21 cc, P = 0.09), although there were no differences in infarct size index (7.3 ± 2.8 vs 7.0 ± 2.8) and ejection fraction (52%± 10% vs 46%± 12%). End-systolic volume depended on infarct size index in the overall patient population (r = 0.60, P = 0.007) and in rt-PA patients (r = 0.80, P =0.005), while no correlation was found in PTCA patients. Considering patients with large AMIs, end-systolic volumes were higher in the four patients treated with rt-PA than in the four patients treated with direct PTCA (P < 0.01). Considering all the 26 enrolled patients, these differences were also present, but they did not reach statistical significance. In conclusion, our results suggest that, in patients with large AMIs, adequate reperfusion obtained by direct PTCA has a more marked effect in counteracting ventricular remodeling than that obtained by systemic rt-PA. This beneficial effect of direct PTCA, independent of any reduction in regional wall-motion abnormalities, should be taken into account when comparing the clinical value of direct PTCA with that of systemic thrornbolysis in the treatment of AMI.     

Effects of Different Electromagnetic Fields on Circadian Rhythms of Some Haematochemical Parameters in Rats

Objective To investigate the effects of different electromagnetic fields on some haematochemical parameters of circadian rhythms in Sprague-Dawley rats. Methods The study was carried out in 18 male and 18 female rats in good health conditions exposed to 50 Hz magnetic sinusoid fields at the intensity of 1000 μT, 100 μT, and 0 μT （control group） respectively, and in 18 male and 18 female rats in good health conditions exposed to 1.8 GHz electromagnetic fields at the intensity of 50 V/m, 25 V/m and 0 V/m （control group）, respectively. Following haematochemical parameters for glucose, triglycerides, and total cholesterol were measured. Results Different effects of electromagnetic fields on circadian rhythms of both male and female rats were observed. Different changes occurred in some haematochemical parameters for glucose, triglycerides, and total cholesterol （P〈0.05）. Conclusion Exposure to different electromagnetic fields is responsible for the variations of some haematochemical parameters in rats.