Objectives This study aimed at investigating the cellular mechanism of isoproterenol （ISO） on delayed afterdepolarizations （DADs） and triggered activity （TA） of the noninfarcted myocardium in the myocardial infa...Objectives This study aimed at investigating the cellular mechanism of isoproterenol （ISO） on delayed afterdepolarizations （DADs） and triggered activity （TA） of the noninfarcted myocardium in the myocardial infarcted rabbit model.Methods Rabbits with the left anterior descending coronary artery occlusion were prepared and recovered for 8 wk （healed myocardial infarction, HMI）. Myocytes were isolated from regions of the noninfarcted left ventricular free wall. ISO was added to cellular surface by perfusion way. Action potentials and ion currents were recorded with whole-cell patch clamp. Results The results showed that treatment with ISO induced more DADs and TA events in HMI myocytes. Iti and IC,_L of myocytes treated with ISO were increased significantly compared with HMI cells, which contributed to DADs-related triggered arrhythmia. Conclusions The results suggested that more arrhythmia events of DADs and TA developed in myocytes with ISO treatment. The underlying mechanism was associated with the augment of I6 and calcium influxing展开更多
Objective: To explore whether successful valvuloplasty increases mitral valve reserve capacity in patients with mitral stenosis. Methods: Thirty-eight patients with pure rheumatic mitral stenosis underwent isoproteren...Objective: To explore whether successful valvuloplasty increases mitral valve reserve capacity in patients with mitral stenosis. Methods: Thirty-eight patients with pure rheumatic mitral stenosis underwent isoproterenol stress echocardiography before and after successful percutaneous balloon valvuloplasty. The mitral valve area (by direct planimetry of two-dimensional echocardiography), mean transmitral pressure gradient (by continuous-wave Doppler echocardiography), and cardiac output (by M-mode echocardiography) were measured at rest and under isoproterenol infusion to achieve heart rate of different stages. Results:Between the measurements before and after valvuloplasty, significant differences were observed in the mitral valve area (0. 91±0. 28 vs 1. 87±0. 23 cm2, P<0. 01), mean transmitral pressure gradient (12. 5±6. 3 vs 3. 9±1. 9 mmHg, P<0. 01) and cardiac output (3. 93±1. 44 vs 4. 73±1. 01 L/min, P<0. 05) at rest. Before valvuloplasty, the mean transmitral pressure gradient increased significantly (P<0. 01) as heart rate increased, but there were no significant differences in the measurements of mitral valve area and cardiac output (both P>0. 05). In contrast, there was a significant increase after valvuloplasty in the mean transmitral pressure gradient (P<0. 01), but both mitral valve area and cardiac output further increased (both P< 0. 01) as heart rate increased. Moreover, valvuloplasty decreased the mean transmitral pressure gradient at peak heart rate from 23. 0±4. 5 to 7. 75±2. 30 mmHg (F<0. 01) under submaximal stress. Conclusion: Successful percutaneous balloon valvuloplasty soon causes a significant increase of mitral valve reserve capacity in patients with mitral stenosis, which is conspicuously manifested under condition of hemodynamic stress. Stress echocardiography provides a safe, feasible and non-invasive means of assessing the reserve capacity.展开更多
基金This work was supported by the National Natural Science Foundation of China （No： 30770901）.
文摘Objectives This study aimed at investigating the cellular mechanism of isoproterenol （ISO） on delayed afterdepolarizations （DADs） and triggered activity （TA） of the noninfarcted myocardium in the myocardial infarcted rabbit model.Methods Rabbits with the left anterior descending coronary artery occlusion were prepared and recovered for 8 wk （healed myocardial infarction, HMI）. Myocytes were isolated from regions of the noninfarcted left ventricular free wall. ISO was added to cellular surface by perfusion way. Action potentials and ion currents were recorded with whole-cell patch clamp. Results The results showed that treatment with ISO induced more DADs and TA events in HMI myocytes. Iti and IC,_L of myocytes treated with ISO were increased significantly compared with HMI cells, which contributed to DADs-related triggered arrhythmia. Conclusions The results suggested that more arrhythmia events of DADs and TA developed in myocytes with ISO treatment. The underlying mechanism was associated with the augment of I6 and calcium influxing
文摘Objective: To explore whether successful valvuloplasty increases mitral valve reserve capacity in patients with mitral stenosis. Methods: Thirty-eight patients with pure rheumatic mitral stenosis underwent isoproterenol stress echocardiography before and after successful percutaneous balloon valvuloplasty. The mitral valve area (by direct planimetry of two-dimensional echocardiography), mean transmitral pressure gradient (by continuous-wave Doppler echocardiography), and cardiac output (by M-mode echocardiography) were measured at rest and under isoproterenol infusion to achieve heart rate of different stages. Results:Between the measurements before and after valvuloplasty, significant differences were observed in the mitral valve area (0. 91±0. 28 vs 1. 87±0. 23 cm2, P<0. 01), mean transmitral pressure gradient (12. 5±6. 3 vs 3. 9±1. 9 mmHg, P<0. 01) and cardiac output (3. 93±1. 44 vs 4. 73±1. 01 L/min, P<0. 05) at rest. Before valvuloplasty, the mean transmitral pressure gradient increased significantly (P<0. 01) as heart rate increased, but there were no significant differences in the measurements of mitral valve area and cardiac output (both P>0. 05). In contrast, there was a significant increase after valvuloplasty in the mean transmitral pressure gradient (P<0. 01), but both mitral valve area and cardiac output further increased (both P< 0. 01) as heart rate increased. Moreover, valvuloplasty decreased the mean transmitral pressure gradient at peak heart rate from 23. 0±4. 5 to 7. 75±2. 30 mmHg (F<0. 01) under submaximal stress. Conclusion: Successful percutaneous balloon valvuloplasty soon causes a significant increase of mitral valve reserve capacity in patients with mitral stenosis, which is conspicuously manifested under condition of hemodynamic stress. Stress echocardiography provides a safe, feasible and non-invasive means of assessing the reserve capacity.
