Noritaka Tarumi

Residual Left Ventricular Pump Function After Acute Myocardial Infarction in NIDDM Patients

OBJECTIVE Left ventricular remodeling occurs immediately after MI, involving structural changes in noninfarcted segment. However, the residual left ventricular pump function in NIDDM patients after acute MI has not been clarified. The purpose of this study was to evaluate the difference in the process of left ventricular remodeling between NIDDM and nondiabetic patients. RESEARCH DESIGN AND METHODS Left ventricular regional EF images obtained by radionuclide angiography were investigated in 20 NIDDM and 29 nondiabetic patients the 3rd wk after acute MI. RESULTS Regional EF of the noninfarcted area and P/V had a significant hyperbolic relation with left ventricular EDV in both groups of patients. Despite no difference in the extent of myocardial necrosis and the number of coronary vessels diseased between NIDDM and nondiabetic patients, regional EF of the noninfarcted area and P/V were significantly lower when left ventricular EDV increased in NIDDM patients compared with nondiabetic patients. CONCLUSIONS Pathogenetic changes of the residual myocardium associated with NIDDM may adversely influence the process of left ventricular remodeling after MI, especially in patients with increased left ventricular EDV.

Mixed venous oxygen saturation as a guide to tissue oxygenation and prognosis in patients with acute myocardial infarction

The relation of mixed venous oxygen saturation and the cardiac index to tissue oxygenation and prognosis was investigated in 119 patients with acute myocardial infarction. There was a positive correlation between mixed venous oxygen saturation and the cardiac index in 97 survivors and 22 nonsurvivors, but a significantly lower mixed venous oxygen saturation level at the same level of cardiac index was observed in nonsurvivors compared with survivors. Results of multivariate analysis with mixed venous oxygen saturation and the cardiac index indicated that only mixed venous oxygen saturation was significantly related to survival and to hyperlactacidemia. Oxygen delivery to tissues declined significantly in nonsurvivors because of a lower cardiac index and a lower hemoglobin concentration in these patients than in survivors. However, at the same level of oxygen delivery to tissues, nonsurvivors had a significantly higher rate of oxygen consumption leading to a correspondingly greater decrease in mixed venous oxygen saturation, suggesting that a greater increase in oxygen demand was also observed in nonsurvivors than in survivors. Thus mixed venous oxygen saturation after acute myocardial infarction is a better predictor of hyperlactacidemia and survival than the cardiac index, and this may be associated with an increased oxygen demand and an impaired oxygen transport system in seriously ill patients.

Left Ventricular Diastolic Filling Properties in Diabetic Patients during Isometric Exercise

Left ventricular diastolic filling properties during isometric handgrip exercise were measured by pulsed Doppler echocardiography in 33 noninsulin-dependent diabetic patients with a normal ejection fraction and 15 control subjects. Diabetic patients were subdivided into two groups according to their resting left ventricular filling pattern (A/E): 18 patients were in group DM-1 (A/E < or = 1.1) and 15 patients were in group DM-2 (A/E > 1.1). At rest, A/E ratio and A wave were higher, and deceleration half-time was longer in group DM-2 than in normal subjects and group DM-1, but there was no significant difference between normal subjects and group DM-1. The A/E ratio increased significantly in all three groups during isometric handgrip exercise. However, the change in A/E from rest to peak exercise in group DM-1 (0.29 +/- 0.20) was significantly greater than in normal subjects (0.09 +/- 0.07). These results suggest that diabetes mellitus patients with normal resting left ventricular (LV) filling pattern (group DM-1) had LV diastolic filling abnormalities with isometric handgrip exercise. Doppler echocardiography with isometric handgrip exercise is useful in identifying underlying left ventricular diastolic dysfunction in diabetic patients.

Left Ventricular Regional Function After Acute Anterior Myocardial Infarction in Diabetic Patients

To elucidate the pathophysiological role of diabetes mellitus in determining the left ventricular regional function of the noninfarcted area, 55 patients with acute Q wave anterior myocardial infarction (MI) were studied. The regional ejection fraction of the noninfarcted area was obtained by radionuclide angiocardiography and was used to estimate the left ventricular regional function of the noninfarcted area. Multiple regression analysis was performed to determine the important variables contributing to the regional ejection fraction based on 10 clinical variables: age, sex, QRS score, diabetes mellitus, hypertension, smoking, postinfarction angina, body mass index, serum cholesterol, and coronary atherosclerosis. A high QRS score (P < .001) and the association of diabetes mellitus (P < .05) were the important factors contributing to regional left ventricular dysfunction. The regional ejection fraction and QRS score had an inverse linear relationship in the diabetic and nondiabetic groups, and the regional ejection fraction was significantly lower in diabetic patients at every QRS score (P < .05). The association of hypertension, severity of coronary atherosclerosis, serum cholesterol level, age, and body mass index did not differ between diabetic and nondiabetic patients, which indicates that diabetes mellitus was not mediated through these atherogenic traits. Thus, diabetes mellitus is another discrete cause of regional left ventricular dysfunction of the noninfarcted area after acute MI.

Oxygen delivery, oxygen consumption and hemoglobin-oxygen affinity in acute myocardial infarction

The interrelations of oxygen delivery (DO2), oxygen consumption (VO2) and hemoglobin-oxygen affinity assessed by P50 were investigated in 43 patients with acute myocardial infarction. As DO2 declined due to low cardiac output, a significant decrease in VO2 (r = 0.75, p less than 0.001) and a significant increase in P50 (r = -0.74, p less than 0.001) were observed. In the DO2 range between 300 and 450 ml/min/m2, in which the DO2 of 32 survivors and 11 nonsurvivors overlapped, the P50 of nonsurvivors was significantly higher than that of survivors (31.5 +/- 1.6 vs 27.9 +/- 1.5 torr, p less than 0.001), but there were no significant differences in any other oxygen transport variable. As a result of differences in P50, VO2 in this range was significantly higher in nonsurvivors compared to survivors (169 +/- 17 vs 148 +/- 13 ml/min/m2, p less than 0.001). These data suggest that a normal or increased VO2 alone does not ensure survival in patients with acute myocardial infarction, and increased P50 leads to an increase in VO2. Nevertheless, the interpretation of an increased P50 in patients with acute myocardial infarction must be made with caution, even with adequate DO2 and VO2, because it may imply a precarious oxygen transport/requirement balance in peripheral tissue and, hence, a fatal outcome.

PQ Segment Depression in Acute Q Wave Inferior Wall Myocardial Infarction

BACKGROUND PQ segment deviation is almost as characteristic as the classic ST segment deviation and is detected in most patients with pericarditis. However, as infarction-associated pericarditis remains over the infarct zone, PQ segment depression is observed much less often in patients with acute myocardial infarction. METHODS AND RESULTS We designed this study to examine the clinical significance of PQ segment depression in acute Q wave inferior myocardial infarction. We examined 171 consecutive patients with acute Q wave inferior myocardial infarction by means of auscultation, ECG, and two-dimensional echocardiography. The diagnosis of pericarditis was made on the basis of pericardial rub detected by more than two observers during the first 3 days after admission. At least 0.5 mm of PQ segment depression from the TP segment lasting more than 24 hours in both limb and precordial leads was considered diagnostic of PQ segment depression. CONCLUSIONS PQ segment depression was present in 14 patients and absent in 157 patients. Eleven patients with and 55 patients without PQ segment depression had advanced asynergy (akinesis or dyskinesis) in the posterior segments, whereas 9 patients with and 20 patients without PQ segment depression had pericardial rub. When multivariate analysis was performed to determine the important variables related to the occurrence of PQ segment depression, pericardial rub was selected with advanced asynergy of the posterior segment as significant factors related to PQ segment depression. Major complications (ventricular fibrillation, sustained ventricular tachycardia, cardiogenic shock, need for pacing) were present in 63 patients; 9 with (64%) and 54 without (34%) PQ segment depression. PQ segment depression was one of the clinical signs of more extensive damage extending to the posterior segments and increased incidence of major complications.

Prevalence, resolution, and determinants of late potentials in patients with unstable angina and left ventricular wall motion abnormalities.

Although transient myocardial ischemia such as exercise-induced ischemia has not been reported to be associated with the occurrence of late potentials, the association of late potentials with more profound ischemic damage, which is represented by reversible but prolonged left ventricular wall motion abnormalities, has not been demonstrated. We prospectively evaluated 37 unstable angina patients who had reversible but prolonged wall motion abnormalities after resolution of chest pain and electrocardiogram (ECG) changes. Signal-averaged ECG (SAECG) and echocardiogram were recorded during the acute phase and before hospital discharge. Late potentials were present in 6 (16 percent) patients on the initial SAECG recording and resolved in all 6 patients on the second recording before hospital discharge. Normalization of inferior left ventricular wall motion abnormality and multivessel disease were observed more frequently in patients with late potentials on the initial recording than in patients without (p < 0.05 and p < 0.05, respectively). In conclusion, late potentials were observed in patients who had reversible but prolonged wall motion abnormalities; these late potentials were resolved with improvement of left ventricular wall motion abnormalities. These results suggest that myocardial ischemia with prolonged wall motion abnormalities is a possible mechanism of the occurrence of late potentials.

Difference between women and men in left ventricular pump function during predischarge exercise test after acute myocardial infarction

To evaluate the difference in left ventricular (LV) pump function during predischarge exercise testing between postmenopausal women and age-matched men with myocardial infarction, global and regional ejection fraction, LV end-diastolic volume, and the ratio of systolic blood pressure to LV end-systolic volume were investigated using radionuclide angiography in 25 postmenopausal women and 37 age-matched men. There were no significant differences in the resting radionuclide angiographic indexes between women and men. Global and regional ejection fraction of noninfarcted area, and the ratio of systolic blood pressure to LV end-systolic volume decreased at peak exercise in women, but these indexes increased in men. Although there was no significant difference in the amount of change in LV end-diastolic volume during exercise between the 2 groups, the amount of increase in LV end-systolic volume was significantly larger in women than in men. The ratio of systolic blood pressure to LV end-systolic volume had a curvilinear relation with LV end-diastolic volume at rest and peak exercise, but the ratio of systolic blood pressure to LV end-systolic volume was larger at any LV end-diastolic volume in men than in women during exercise. Thus, lower global ejection fraction and the ratio of systolic blood pressure to LV end-systolic volume during exercise in postmenopausal women compared with age-matched men indicate that gender may have played an important role in the LV remodeling process.

Heart rate variability and left ventricular dilatation early after myocardial infarction.

To assess clinically whether alterations of autonomic tone precede left ventricular dilatation, heart rate variability and early left ventricular dilatation after a first myocardial infarction were assessed. Low-frequency power (LF), high-frequency power (HF), and total power (TP) were obtained by ambulatory electrocardiogram on day 1 in 53 patients with a first acute myocardial infarction. Left ventricular end-diastolic volume determined by echocardiography was obtained on day 1 and day 14. Stepwise linear regression analysis was used to assess the associations of early left ventricular dilatation with heart rate variability adjusted for clinical variables. Higher LF and TP were significantly associated with early left ventricular dilatation after adjustment for age, sex, site of myocardial infarction, acute revasucularization, peak creatine kinase level, history of hypertension, and use of angiotensin-converting enzyme inhibitors and beta-blockers. Higher LF and TP preceded early left ventricular dilatation after myocardial infarction.

Clinical significance of pericardial effusion in Q-wave inferior wall acute myocardial infarction.

To assess the clinical significance of pericardial effusion in Q-wave inferior wall acute myocardial infarction, 185 consecutive patients were examined by means of electrocardiogram, echocardiogram and hemodynamic monitoring. A pericardial effusion was present in 44 patients and was absent in 141 patients. Electrocardiographic right ventricular infarction (> or = 1 mm of ST-segment elevation and Q wave in V4R) was detected in 54 patients, with 20 patients having pericardial effusion. Patients with pericardial effusion had significantly more left ventricular segments with advanced asynergy, lower cardiac output, higher pulmonary artery wedge pressure and higher incidence of right ventricular infarction than those without pericardial effusion. There were 17 in-hospital deaths. Although there was no significant difference in the mortality rate between patients with and without right ventricular infarction, a significantly higher hospital mortality rate was observed in patients with pericardial effusion compared to those without it (23 vs 5%). Pericardial effusion was selected with age and pulmonary artery wedge pressure as important variables associated with hospital mortality by the discriminant analysis. Patients who developed pericardial effusion, regardless of right ventricular infarction, had more extensive myocardial damage, and hence, pericardial effusion was one of the predictors of increased hospital mortality.