Teruhiro Tamura

Importance of left ventricular diastolic function on maintenance of exercise capacity in patients with systolic dysfunction after anterior myocardial infarction

To investigate the role of left ventricular (LV) diastolic function in the maintenance of exercise capacity in patients with systolic dysfunction, symptom-limited cardiopulmonary exercise testing combined with radionuclide ventriculography was performed in 24 patients with an LV ejection fraction < 35% after anterior myocardial infarction. The ratio of pulmonary artery wedge pressure (PAWP) to LV end-diastolic volume (EDV), an index of global diastolic function, correlated significantly with peak oxygen consumption at peak exercise (r = -0.55; p = 0.006), whereas ejection fraction at peak exercise did not. The change in PAWP/EDV ratio from rest to peak exercise was related to the increases in stroke volume (r = -0.54; p = 0.006) and cardiac output (r = -0.51; p = 0.01) during exercise, but the change in ejection fraction was not. Resting hemodynamics did not differ between patients with preserved exercise capacity (group 1, n = 8) and those with exercise impairment (group 2, n = 16). At peak exercise, stroke volume, cardiac output, and EDV were significantly higher, and PAWP and PAWP/EDV ratio were significantly lower in group 1 than in group 2, but ejection fraction and end-systolic volume were similar in both groups. Although the incidences of hypertension, LV hypertrophy, and infarct-related coronary artery lesions did not differ between the two groups, group 2 had a significantly higher incidence of non-infarct-related coronary artery lesions than group 1 (p < 0.05). Thus in patients with LV systolic dysfunction after anterior myocardial infarction, the major cause of exercise impairment and failure to increase LV performance during exercise was diastolic dysfunction associated with the presence of non-infarct-related coronary artery lesions with the potential for exercise-induced ischemia of the noninfarcted areas.

The effect of platelet-activating-factor antagonist TCV-309 on arrhythmias and functional recovery during myocardial reperfusion

BackgroundWe investigated the effects of a platelet-activating-factor antagonist TCV-309, an antagonist of metabolites of ischemia, on arrhythmias and functional recovery during in-situ reperfusion in dogs. MethodsOpen-chest anesthetized dogs were subjected to ligation of the left anterior coronary artery. Ischemia was maintained for 20 min after which reperfusion was allowed. A cardiac surface ECG was recorded continuously with the II limb lead. Monophasic action potential, left ventricular segment shortening measured by sonomicrometer, and left ventricular pressure were recorded simultaneously under atrial pacing (group A, n =14). In a second group of dogs, TCV-309 (1 mg/kg) was administered before coronary artery occlusion (group B, n = 12). The hearts were constantly paced through the right atrium at 120beats/min throughout all experiments. Measurements were continuously obtained from before drug administration to 30 min after reperfusion. ResultsThe 90% repolarization time of monophasic action potentials in group B revealed significant recovery compared with group A until the fifth minute after reperfusion (P<0.02). Reduction of severe ventricular arrhythmias was observed during reperfusion in group B (P<0.05). The percentage segment shortening and left ventricular pressure did not differ significantly between the groups. ConclusionThe platelet-activating-factor antagonist had beneficial effects on arrhythmias but not on functional recovery during reperfusion after brief coronary artery occlusion in situ in dogs.

Acute pulmonary edema in patients with unstable angina: clinical profile and natural history

BackgroundPulmonary edema is an important manifestation of ischemic cardiac dysfunction, both in the presence and absence of myocardial infarction. However, the clinical characteristics and natural history of pulmonary edema with unstable angina have not been fully evaluated. MethodsOne hundred twenty patients admitted to our hospital within 6 hours from the onset of last chest pain were studied. Clinical features were reviewed from hospital charts and coronary angiography was performed in acute phase (33 patients) and in the late hospital phase (62 patients). The mean follow-up period was 26 months. Results: Pulmonary edema was present in 24 patients and was absent in 96 patients. The duration of chest pain was longer (P<0.01) and incidence of multivessel disease was higher (P<0.01) in patients with pulmonary edema than those without it. The total mortality rate in patients with pulmonary edema was higher that those without it (33% vs 3%; P<0.001). These data indicate that a large mass of ischemic myocardium could cause transient increase of left ventricular diastolic pressure to pulmonary edema level without infarction ever occurring. ConclusionsBecause of the high incidence of multivessel disease and the poor prognosis in patients with pulmonary edema in unstable angina, early and aggressive diagnostic efforts should be undertaken to exclude viable segments of myocardium in patients with unstable angina complicated by pulmonary edema.

Factors associated with increased extravascular lung water in cardiac tamponade and myocardial ischemia.

OBJECTIVE To evaluate and compare the factors associated with pulmonary edema in cardiac tamponade and myocardial ischemia. DESIGN Prospective, controlled laboratory study. SETTING Animal research laboratory of a university hospital. SUBJECTS Fourteen anesthetized dogs. INTERVENTION Extravascular lung water (EVLW) was measured with thermal indocyanine green dye double-indicator dilution method and hemodynamic indices were determined by the pulmonary artery flotation catheter. Seven dogs were used in the tamponade model, and seven other dogs were used in the myocardial ischemia model. Furthermore, ten dogs were dedicated to measure plasma colloid osmotic pressure (COP) and blood gas analysis during cardiac tamponade and myocardial ischemia. MEASUREMENTS AND MAIN RESULTS Mean right atrial pressure (MRAP) (7-->10 mm Hg), pulmonary capillary wedge pressure (PCWP) (10-->13 mm Hg), and EVLW (5.4-->10.1 mL/kg) increased during tamponade, but all of these indices returned to the control level after release of tamponade (MRAP, 7 mm Hg; mean PCWP, 11 mm Hg; mean EVLW, 5.2 mL/kg). Myocardial ischemia caused increases in PCWP (10-->14 mm Hg) and EVLW (5.6-->9.6 mL/kg). Although PCWP returned to the control level, EVLW remained elevated (9.2 mL/kg) after reperfusion. EVLW had good correlations with MRAP (r2 = .64, p < .05) and PCWP (r2 = .62, p < .05) during cardiac tamponade. Despite a fair correlation between EVLW and PCWP during ischemia (r2 = .73, p < .05), EVLW was not related to PCWP after reperfusion. COP decreased during myocardial ischemia and at the reperfusion period, but there was no significant change in COP in the cardiac tamponade model. CONCLUSIONS In contrast to a close relation between hydrostatic pressure and EVLW in cardiac tamponade, hydrostatic pressure was not a determinant of pulmonary edema during the reperfusion period after myocardial ischemia.

Clinical Significance of the Urinary Oxygen Tension in Patients with Ischemic Heart Disease

The clinical significance of the urinary oxygen tension (PuO2) was evaluated in 60 patients with ischemic heart disease. The PuO2 had fair relations to cardiac index and serum creatinine level (r = 0.73 and r = 0.73, respectively). Although the PuO2 had a fair relation to serum creatinine in patients with a low cardiac index, there was no relation to the cardiac index. In patients with increases in PuO2 from day 1 to day 2, the cardiac index increased, and the serum creatinine level decreased on the 2nd day, whereas a sustained decrease in cardiac index and an increase in serum creatinine were observed in patients with a decrease in PuO2 from day 1 to day 2. Thus, PuO2 can be used as an indicator of the renal function in patients with ischemic heart disease.

The factor dominating the determination of left ventricular filling varies during the first five days after acute myocardial infarction.

Background:Left ventricular diastolic dysfunction may occur after the onset of acute myocardial infarction. Left ventricular diastolic filling dynamics are related to many factors. To evaluate the influence of left ventricular filling pressure on Doppler-derived left ventricular diastolic flow profiles in patients with acute myocardial infarction, we studied serial changes in filling during the first 5 days after the onset of uncomplicated acute myocardial infarction.Methods: The study population consisted of 14 patients with acute myocardial infarction and 15 normal subjects. Doppler echocardiographic studies (left ventricular transmitral inflow and outflow velocity patterns) were performed on admission, and on the third and fifth days after infarction. Hemodynamic parameters were measured simultaneously using Doppler echocardiography. Results:The E wave was lower, the A wave and A: E ratio were higher, deceleration half time and isometric relaxation time were prolonged, and peak left ventricular ejection flow velocity was lower in myocardial infarction patients than in normal subjects. The E wave and pulmonary capillary wedge pressure were positively correlated on the first and the third day (r = 0.77, P< 0.001, and r = 0.67, P< 0.01, respectively), but not on the fifth day. The E wave and isometric relaxation time were negatively correlated on the fifth day (r=-0.72, P<0.01), but not on the first and third day. Conclusion:Left ventricular filling pressure (preload) was an important mechanism for maintaining left ventricular filling during the first 3 days, but the relaxation of the ventricle began to play a dominant role on the fifth day.

The effects of infusion of trieicosapentaenoyl-glycerol emulsion on extravascular lung water during myocardial ischemia and reperfusion in dogs

To test the effects of eicosapentaenoic acid (EPA) infusion on pulmonary edema induced by coronary ligation and reperfusion, extravascular lung water (EVLW) was measured in situ by the thermal-dye double indicator dilution method in dogs. In the control group of five dogs, 30 mL of a 10% soybean oil emulsion was infused through a leg vein. One hour after infusion, the left anterior descending coronary artery below the first diagonal branch was ligated for 15 min and then reperfused for 30 min. In the EPA group, six dogs were similarly treated with an emulsion of a 10% trieicosapentaenoyl-glycerol (90% pure). EVLW, pulmonary capillary wedge pressure, mean pulmonary artery pressure, mean blood pressure, and cardiac index were measured before and 15 min after coronary ligation, and 15 min and 30 min after coronary reperfusion. There were no significant differences in the hemodynamic indices between the two groups. EVLW significantly increased up to two times of baseline during coronary ligation in the control group (P< 0.05) and more during reperfusion (P<0.01), whereas EVLW did not increase in the EPA group. In conclusion, EPA inhibited EVLW accumulation and may be useful for ameliorating one of the ischemia-reperfusion-induced complications, pulmonary edema.

Effect of atrial and ventricular activation interval on hemodynamics during atrioventricular and ventriculoatrial pacing : determination from pressure-volume loops in dogs

To determine the effect of relative timing of atrial and ventricular activation on hemodynamic indices, we evaluated pressure-volume loops during pacing at 160 beats/min with various atrioventricular intervals in dogs. End-systolic pressure, end-diastolic volume, and stroke volume were reduced during pacing at atrioventricular intervals of 0 ms, compared with 80 ms. These changes were more significant during pacing at atrioventricular intervals of -50 and -100 ms than at 0 ms. During tachycardia, the abnormal timing of atrial contraction leads to unfavorable hemodynamic change and the degree of the changes are determined by the ventriculoatrial activation interval.

Ventriculoarterial Coupling during Low-Level Exercise Testing after Myocardial Infarction

To evaluate the change of ventriculoarterial coupling during low-level exercise in patients after myocardial infarction, the ratio of systolic blood pressure to left ventricular end-systolic volume (P/V ratio) and the ratio of systolic blood pressure to stroke volume (effective arterial elastance) were investigated using radionuclide angiography in 73 consecutive patients with a negative predischarge exercise test. The patients were divided into three groups according to their resting left ventricular ejection fraction: group A (n = 12) > or = 60%; group B (n = 32) 41-59%; group C (n = 29) < or = 40%. The ejection fraction increased significantly during exercise in all three groups. There was no significant difference in the change of the P/V ratio during exercise between groups A and B, but it was significantly smaller in group C. The effective arterial elastance increased during exercise in group A, did not change in group B, and decreased in group C. Thus, the augmentation of myocardial contractility was an important factor related to the increase in ejection fraction during exercise in patients with normal or slightly reduced cardiac function, whereas the decrease in effective arterial elastance was important in patients with poor cardiac function.