Effect of Coronary Angioplasty on QT Dispersion

BACKGROUND AND OBJECTIVES: The change in QT dispersion (QTd) immediately after balloon angioplasty reflects the immediate impact of ischemia. We intended to analyze the immediate impact of ischemia on myocardial repolarization. MATERIALS AND METHODS: Forty-six patients who underwent percutaneous coronary intervention were enrolled. The standard 12-lead electrocardiogram (ECG) was recorded just before, during, and 1 minute, 5 minutes and 10 minutes after ballooning. QTd was determined by the difference between the maximum and minimum QT interval (QTi). We then calculated the corrected QTi (QTc) using Bazett's formula. QTd and QTi were compared according to the site of the ballooned vessel, number of ballooned vessels and history of acute myocardial infarction. RESULTS: QTd just before, during, and 1 minute, 5 minutes and 10 minutes after ballooning were 35.21+/-10.36 msec, 54.56+/-16.89 msec, 50.91+/-14.20 msec, 45.52+/-9.6 msec and 38.56+/-10.89 msec, respectively. QTd increased markedly during ballooning, but after myocardial ischemia was relieved, decreased rapidly. Ten minutes after ballooning, QTd was reduced to a similar level as that of baseline. There were no significant differences between the AMI and non-myocardial infarction groups, single-vessel and multi-vessel groups, and the location of the stenosed artery. There was no significant difference in QTi according to different stenosed vessel. CONCLUSION: QT (QTc) dispersion increased rapidly with myocardial ischemia and reduced rapidly after the myocardial ischemia was resolved. Therefore, increased QTd can be used as an early clue of myocardial ischemia.

The Relationship of Left Atrial Volume and Left Ventricular Diastolic Dysfunction

BACKGROUND AND OBJECTIVES: Mitral flow Doppler has been used to evaluate left ventricle (LV) diastolic function by mitral E/A flow ratio, isovolumic relaxation time (IVRT) and deceleration time (DT) of E wave. Such variables can be affected by various factors. The increase in left atrium (LA) afterload and preload is accompanied by increased LA size. So, we investigated the relationship of LA volume and LV diastolic dysfunction. MATERIALS AND METHOD: From January 2000 to July 2000, 39 patients were included in this study. They were classified into normal (M:F=5:6, mean age 54.0+/-11.4 years), impaired relaxation (M:F=5:4, mean age 70.0+/-5.5 years), pseudonormal (M:F=5:3, mean age 68.3+/-13.2 years) and restrictive physiology (M:F=10:1, mean age 65.5+/-12.7 years) according to mitral inflow variables. The LA volume of each groups was measured by Simpson method, M-mode method and arealength method. RESULTS: 1) The LA volumes measured by Simpson method, M-mode method and area-length method were correlated (p<0.001, r=0.925 in Simpson compared with arealength method). 2) The LA volume by Simpson method were found 54.4+/-16.4 cm3 in normal, 57.3+/-9.2 cm3 in impaired relaxation, 81.4+/-28.8 cm3 in pseudonormal and 119.8+/-64.5 cm3 in restrictive physiology. 3) The LA volume were significantly increased in pseudonormal group compared with normal (p<0.05). CONCLUSION: The LA volume is a useful and easy diagnostic stool for evaluating of LV diastolic function.