Normalized Idioventricular QT Interval Variability in Patients with Q- and Non-Q Wave Myocardial Infarction

BACKGROUND AND OBJECTIVES: The aim of the study was to evaluate the difference of temporal lability in myocardial repolarization between acute non-Q (NQMI) and Q-wave myocardial infarction (QMI), and to discern whether the locations of myocardial infarction influence such temporal lability. SUBJECTS AND METHODS: Twelve patients with NQMI and 28 with QMI, including 16 anterior (AMI) and 12 inferior MI (IMI) patients were enrolled. Twenty four-hour ambulatory ECG recordings of each patient were analyzed, and the digitized data was partitioned into 30-min sections. The QT intervals were measured using a template matching strategy. We then calculated the low (LF:0.03 - 0.15 Hz) and high frequency (HF:0.15 - 0.4 Hz) power of the QT interval variability using an algorithm capable of removing the influence of the RR-interval on QT interval variability (Normalized Idioventricular QT variability Index:IV-QT). RESULTS: For patients with QMI, the low frequency IV QT (LF IV-QT) was higher than that of NQMI (1.941+/-0.101 and 1.556+/-0.114 respectively, p<0.05). No difference was seen in the high frequency IV QT (HF IV-QT) of the two groups. For QMI patients, both the LF IV-QT and HF IV-QT were higher in day time (6AM-6PM) than in night time (6PM-6AM). Comparing the differences of these indices by the location of QMI, both the LF IV-QT and HF IV-QT of AMI were higher than those of IMI patients (2.231+/-0.135 vs 1.355+/-0.131 and 2.341+/-0.161 vs 1.346+/-0.145 respectively, p<0.0005). Both indices of each group also demonstrated a circadian change. CONCLUSION: In cases of QMI, the temporal lability in myocardial repolarization is larger than that seen in NQMI. Moreover, it was worse in AMI than IMI. Finally, such temporal repolarization lability tends to have a circadian pattern in QMI.

Optimally Timed Rate-adaptive Atrioventricular Delay in AV Sequential Pacing

BACKGROUND: Although the net atrioventricular compliance can be obtained by invasive catheterization (Ccath) in mitral stenosis (MS), feasibility of noninvasive echocardiographic calculation of the compliance (Cecho) and its hemodynamic significance were not tested. METHODS: Using valve area by 2D planimetry (A2D) and deceleration slope (dv/dt) of transmitral velocity decay in continuous wave Doppler echocardiographic tracing, Cecho was defined as -A2D/(gamma dv/dt), which was compared with Ccath obtained directly during the catheterization in 30 MS patients with sinus rhythm. Exercise Doppler echocardiography with symptom-limited treadmill was performed in 66 patients with moderate to tight MS: mean mitral gradient (MG) and peak pressure gradient of tricuspid regurgitation (PGTR) at baseline and immediately after exercise were obtained using continuous wave Doppler echocardiographic tracing. Hemodynamic variables including Cecho, MG, PGTR and mitral valve area were analyzed to determine the association with patients' exercise tolerance. RESULTS: Cecho in 30 patients with tight MS (valve area 0.9+/-0.2 cm 2) was 4+/-1 ml/mmHg (2-7 mmHg), which showed a significant correlation with Ccath (r=0.48, p=0.01). Exercise time in 66 patients with moderate to tight MS showed significant negative correlation with resting MG, resting and postexercise PGTR, and positive correlation with Cecho: exercise time in those patients did not show any significant correlation with resting valve area. In multivariate analysis, Cecho and postexercise PGTR were independent factors determining exercise time in MS. CONCLUSIONS: The net atrioventricular compliance in MS can be calculated by noninvasive echocardiography, and it is an important hemodynamic factor determining exercise tolerance in MS.

Changes in t-PA and PAI-1 levels after exercise in patients with diabetes mellitus: A sex and age-matched control study / 대한내과학회지

OBJECTIVES: Plasma fibrinolytic activity is determined by the balance between plasmonogen activators and their inhibitors. The aim of this study was to compare the fibrinolytic activity before and after exercise of the type 2 diabetic patients with control group. METHODS: We measured plasma tissue-plasminogen activator (t-PA) and plasminogen activator inhibitor-1 (PAI-1) antigen before and after standardized treadmill exercise in 21 type 2 diabetic patients (14 men, 11 women, ages 46.2+/-5.6 years) and 21 sex and age- matched control group (10 men, 11 women, ages 48.6+/-5.4 years). RESULTS: 1) Post exercise t-PA antigen increased in both diabetic group (from 7.36+/-3.89 to 10.62+/-4.81 ng/ml, p0.05) and control group (from 30.04+/-10.40 ng/ml to 31.06+/-10.88 ng/ml, p>0.05). 3) In diabetic group, significant correlations between base line PAI-1 antigen levels and serum triglyceride levels were observed. And post exercise PAI-1 antigen levels were correlated with systolic blood pressure. CONCLUSION: The results show that plasma t-PA antigen level is increased after vigorous exercise in patients with type 2 diabetes mellitus and plasma PAI-1 antigen level is not changed. The increment of plasma t-PA level is not different with healthy subjects.