Differential Findings of Color M-mode Doppler Echocardiography according to the In-hospital Congestive Heart Failure Following Actue Myocardial Infarction

BACKGROUND: Abnormalities of the left ventricular diastolic function can be classified by pulsed Doppler echocardiography, but sometimes it may be difficult to differentiate normal diastolic function from pseudonormalization. Heart failure caused by increased left ventricular filling pressure is rather associated with pseudonormalization or restrictive pattern than normal pattem or relaxation abnormality. We investigated the usefulness of color M-mode Doppler echocardiographic indexes in differentiating normal relaxation from pseudonormalization after acute myocardial infarction. METHOD: Echocardiographic examination including color M-mode Doppler was performed in 44 patients with acute myocardial infarction between 10 and 14 days after attack. 34 patients without in-hospital congestive heart failure(CHF) were assigned as group I, and 10 patients with in-hospital CHF as group II. Flow propagation slope(FPS), time difference(TD) between the occurrence of peak flow velocity in the apical region and at the mitral tip, and normalized time difference(nTD) by mitral and apical distance were measured with color M-mode Doppler echocardiography. RESULTS: FPS was lower in group II(group I, 42.0+/-20.6cm/sec vs group II, 27.8+/-8.0cm/ sec , p=0.065). Both groups had similar TD and nTD. FPS was compared in patients with E/ A ratio of mitral inflow greater than 1(22 patients of group I and 7 patients of group II). Patients with E/A) 1 in group II had significantly lower FPS(group I, 52.1+/-17.5cm/sec vs group II, 31.0+/-7.4cm/sec ; p(0.01). CONCLUSION: FPS was significantly decreased after acute myocardial infarction in patients with in-hospital CHF compared with patients without in-hospital CHF, even when E/A ratio of mitral inflow was greater than 1. Therefore, FPS was an useful index in differentiating normal relaxation from pseudonormalization.

On-line Assessment of Left Atrial Area and Function by Automated Border Detection Echocardiography

BACKGROUND: Automated border detection (ABD) echocardiography is a convenient and objective tool in the estimation of left atrial (LA) area and function when compared to the off-line, two-dimensional echocardiographic method that requires manual tracing of the endocardial border. In addition, the applicability of the ABD system to instantaneously derive LA area and function may provide a noninvasive method to assess the diastolic interaction between the left ventricle and the left atrium. METHOD: 53 patients with a normal sinus rhythm and an apical four chamber view of LA area (in which at least 75% of the endocardium was clearly visible) were selected for this study. The on-line echocardiographic assessment of LA areas and function with automated boundary detection was performed and compared with the off-line estimation. From the instantaneous cavity area displayed by the ABD system, the extents of left atrial area decrease resulting from rapid ventricular filling (D) and atrial contraction (AC) were measured. The D/AC ratio was compared with the transmitral Doppler flow velocity E/A ratio. RESULTS: 1) The end-systolic area (ESA) and the end-diastolic area (EDA) of the left atrium, diastolic atrial emptying index (AEMI) and the systolic atrial expansion index (AEXI) with the ABD system were not different from those with the off-line, manually trace method. 2) ESA, EDA, AEMI and AEXI determined by the ABD system and the off-line method showed strong correlations (r=0.87, 0.79, 0.52 and 0.49 respectively). 3) D/AC ratio with the ABD system correlated significantly with the transmitral Doppler velocity E/A ratio (r=0.70). CONCLUSION: The ABD system may be used in the assessment of LA area and LA function and the diastolic interaction between the left atrium and the left ventricle.

Dispersion of QT Interval and Other Repolarization Indexes in Acute Myocardial Infarction

BACKGROUND: It is known that QT dispersion represents asynchronous repolarization of ventricle which is related to ventricular fibrillation. The incidence of ventricular arrhythmia is increased after acute myocardial infarction. So this study compared QT dispersion and other repolarization indexes for detection of asynchronous repolarization in acute myocardial infarction. We also investigated which portion of repolarization is the key portion of the asynchrony. METHODS: In 37 acute myocardial infarction patients and 38 angina patients dispersion of QT, JT, JTpeak and QTpeak were measured. We also measured maximum adjacent dispersion of same parameters in precordial leads. In 20 survived patients and 17 dead patients after acute myocardial infarction were also compared. We also investigated correlation of PVC's on Holter monitoring with these repolarization parameters. RESULTS: 1) All ventricular repolarization indexes(QT, QTc, JT, JTpeak, QT peak and TpeakTend dispersion) were significantly increased in acute myocardial infarction group than compared with those of angina group(p<0.05). 2) Maximal precordial dispersion(QT, QTc, JT, JTpeak and QTpeak) were also significantly increased in acute myocardial infarction group than angina group(p<0.05). 3) Dead patient group after myocardial infarction showed significantly increased QTc and TpeskTend dispersion compared with those of survived patient group(p<0.05). 4) Multivariate linear correlation showed that TpeakTend dispersion and JT dispersion was correlated with QT dispersion. CONCLUSIONS: There were asynchronous myocardial repolarization changes in acute myocardial infarction. Our study demonstrated that T wave change was major determinant of dispersion of myocardial repolarization.

Insulin Resistance and Coronary Artery Disease

BACKGROUND: Insulin resistance has been identified as one of the risk factor of atherosclerosis. Hypertension, obesity, glucose intolerance and dyslipidemia could induce atherosclerosis through mechanism of insulin resistance. And there are some reports that hyperinsulinemia itself could induce coronary artery disease(CAD). Then we planed to investigate relationship between CAD and insulin resistance. And smoking is also known as one major risk factor of CAD. So we also investigated the relationship between smoking and insulin resistance in the CAD patients. METHODS: Among 36 subjects in whom coronary angiography was done, we grouped 25 subjects who had stenotic coronary artery as a CAD group and 11 subjects without stenosis as control group. We compared insulin and glucose response to oral glucose load(75g), serum lipid concentrations, blood pressure, and degree of obesity between two groups. We also divided CAD group into smoking and nonsmoking subgroups, compared the above parameters. RESULTS: 1) There were no significant difference in body mass index, blood pressure, creatinine, cholesterol, HDL-cholesterol, between the CAD group and the control group. There were significantly higher incidence of smokers in CAD group. 2) Insulin concentration at 120 minutes after glucose load were significantly higher in the CAD group than the control group. 3) In the CAD group, fasting plasma insulin concentration insulin area, peak plasma insulin concentration and insulin concentration at 60,90,120 minutes after glucose load were significantly higher in non-smoking group. CONCLUSION: Enhanced insulin reponse such as higher insulin concentration 60 minutes after glucose load in the CAD group suggests that insulin resistance is a risk factor of CAD. And insulin response was more pronounced in the non-smoker subgroup than smoker subgroup in the CAD patients. Thus role of insulin resistance in provoking coronary artery disease is more important in the non-smoker.