| Objective: To investigate the protection effect of warm-up phenomenon for the ischaemic heart during two consecutive exercise tests in chronic stable angina patients, and to observe the effects of chronic treatment with glibenclamide which is a KATP channel blocker on the warm-up phenomenon and the role of KATP channel in it, and to evaluate the application value of glibenclamide in these diabetic patients with coronary heart disease.Methods: Patients with the chronic stable angina who had positive exercise before and was angiographically proven that the stenosis degree was 70-90% in at least one major branch came into our study. They were divided into three groups according to the presence of diabetes and its treatment: 28 patients with the chronic stable angina only came into the NDM group, 26 patients with diabetes who were used glibenclamide for at least half of a year and had a well-controlled for the fasting blood glucose<6.1mmol/L and the HbA1c>6.5% came into the DMG group , 25 patients with diabetes but on diet who aslo had a well-contolled for the fasting blood glucose<6.1mmol/L and the HbA1c>6.5% came into the DMD group. The total number were seventy-nine. All the patients had no evidence of left ventricular hypertrophy, primary cardiomyopathy, valvular heart disease, conduction defects, history of Q wave myocardial infarction which could interfere with the interpretation of ST-segment changes, and none of them was taking digitalis. Patients were excluded if they had severe congestive heart failure, uncontrolled hypertension, poor glycaemic control(HbA1c levels greater than 6.5%)and so on. All the entry patients underwent two sequential bicycle ergometer exercises test separated by 15min on the day of the study. There needed to investigate the changes of exercise duration(ED,s), the time to 1mm ST-segment depression(T-STD,s), maximum STD (mm) and the corresponding heart-rate systolic blood pressure product (RPP or ischaemic threshold, mmHg/min×102). Then the differences of these variable indexes between the three groups were compared.Results: 1 In group NDM , all the analysed variables improved significantly during the second test(EX2)in comparison with the first test(EX1), and which showed that the ischaemic threshold was increased(184.07±32.79 vs 199.01±35.83 mmHg/min×102 , P<0.001 ), the ED and T-STDwere prolonged(548.96±98.24 vs 571.89±102.25s ,P=0.005 & 388.18±87.50 vs 429.46±87.90s,P <0.001), and the STDmax was reducted (2.10±0.38 vs 1.87±0.40mm ,P<0.001). The percentage of patients demonstrating the warm-up phenomenon above these indexes were 71%,61%,71%,75% , and the adjustment of these indexes respectively were 8.12%,4.18%,10.64%,10.48%.2 In group DMG,there was no difference in these analysed variables except T-STD between the first and second test(P>0.05).The T-STD during the second test was significantly longer than that during the first test(323.12±61.81 vs 356.70±76.27s,P < 0.001).3 In group DMD, all analysed parameters improved significantly during the second test (EX2) in comparison with the first test(EX1). For example, the ischaemic threshold was increased(182.28±38.01 vs 200.28±36.07 mmHg/min×102 ,P=0.002),as well as the T-STD was prolonged(369.52±83.60 vs 407.36±97.12s , P<0.001)and the STDmax was reducted(2.11±0.43 vs 1.94±0.38mm,P =0.005). However, the exercise duration(ED) had no the same behavior(539.24±66.98 vs 559.92±60.22s,P=0.056).4 Comparison the changes of all the indexes among groups: Comparative the changes of T-STD and ED between the two sequential exercise among the three groups, which did not show differences (P=0.774 & P=0.468 ); but showed significant differences in the changes of ischaemic threshold and STDmax( P=0.002 & P<0.001 ) ,which could have the further Comparison for each other between groups: For the changes of ischaemic threshold, group NDM and group DMD had no differences (P>0.05), but if they compared with group DMG respectively, it showed significant differences(P<0.05);For the changes of STDmax after EX2 were as same as the ischaemic threshold.Conclusion: 1 Exercise test can induce the Warm-up angina in stable angina patients. Warm-up phenomenon, as a internal protective mechanism of myocardium , can pretect the potential ischaemic myocardium from insults effectively and enhanced the tolerance to ischaemic injury. 2 Warm-up phenomenon can also occurs in chronic stable angina patients with diabete mellitus which treated with diet only and had a well-controlled of the blood glucose level. 3 The KATP channel blocker Glibenclamide could block the warm-up phenomenon and abolish this protection for heart. 4 KATP channel is related to the happening of the warm-up phenomenon.
|
PDF Full Text Request