Theoretical analysis of effect of tip atomic species on apparent barrier height on Al(100) surface.

We have analyzed the effect of the tip atomic species on the tip-sample separation and the bias-voltage dependence of apparent barrier height (ABH) on an Al(100) surface using the boundary-matching scattering-state density functional method, which can be used to calculate electron states under applied bias voltages self-consistently within the density functional theory. We found that, from the dependence of the tip-sample separation, the difference between measurements with the two tip atomic species is larger in the ABH than in the maximum barrier height evaluated from the calculated potential profile. Furthermore, we found that the bias-polarity dependence of the ABH measured with the Na tip shows behavior opposite to that shown by the ABH measured with the Al tip. These results can be understood from the difference in the degree of lateral confinement of tunneling electrons in the tunneling barrier region between the two atomic species.

[Coronary collateral function evaluated by coronary hemodynamics and myocardial lactate metabolism during rapid atrial pacing].

To elucidate coronary collateral function in the ischemic myocardium, we studied coronary hemodynamics and myocardial lactate metabolism of the collateral-dependent myocardium before and during rapid atrial pacing. Subjects consisted of 38 patients who were categorized into 3 groups according to their coronary and coronary collateral arteriographic findings: 14 patients with normal coronary arteriograms (Group A), 15 with significant stenosis in the left anterior descending coronary artery (LAD) without collaterals (Group B), and 9 with LAD stenosis and collaterals (Group C). Estimates of cross-sectional area (CSA) obtained from the orthogonal coronary arteriograms, and the great cardiac vein flow (GCVF) and myocardial lactate extraction ratio (MLER) before and during rapid atrial pacing were used as parameters to evaluate coronary stenosis. The results were as follows: 1. The cross-sectional areas in Groups B and C were 86% and 91% of that in Group A, respectively. 2. In Group B, there was a good linear relationship between cross-sectional area and % delta GCVF, as shown in % delta GCVF = 2.90 + 36.22 x CSA (r = 0.61, p < 0.05). This relationship was modified in Group C, increasing % delta GCVF against CSA. 3. Myocardial lactate extraction ratio in Groups B and C decreased significantly after rapid atrial pacing, while, it remained unchanged in Group A. This ratio after rapid atrial pacing did not differ significantly between the 2 groups. 4. In 3 of 4 patients with total LAD occlusions, GCVF and anterior coronary resistance before and during rapid atrial pacing were similar to those of Group A.(ABSTRACT TRUNCATED AT 250 WORDS)

[Continuous measurement of coronary sinus oxygen saturation in patients with effort angina and vasospastic angina].

Coronary sinus oxygen saturation (CSO2-Sat) was measured continuously using a fiberoptic catheter system during interventional catheterization, i.e., pacing stress test and ergonovine provocation test to determine whether such measurement can detect myocardial ischemia. Subjects consisted of 24 patients who underwent routine cardiac catheterization; 14 patients with effort angina, 3 with old myocardial infarction and 3 with valvular heart disease were assigned to pacing stress test, and 4 with vasospastic angina were assigned to ergonovine provocation test. The results were as follows: 1. Among 14 patients with effort angina, ischemic electrocardiographic changes occurred in 10 patients during pacing stress test. Of these 10 patients, CSO2-Sat decreased in 8 with ischemic electrocardiographic changes. All patients with decrease in CSO2-Sat had significant left coronary artery stenosis. CSO2-Sat continued to decrease throughout intervention and never came back to the baseline. Decrease in CSO2-Sat was more than 5% in most of the cases. 2. In all patients with vasospastic angina, coronary vasospasm was induced by the ergonovine provocation test. CSO2-Sat declined (> 5%) gradually, preceding anginal pain and ischemic ST segment changes. The present study suggests that continuous monitoring of coronary sinus oxygen saturation may be useful in detecting myocardial ischemia at its early stage, except for patients with right coronary artery disease.

[Continuous monitoring of coronary sinus oxygen saturation during pacing loading in patients with syndrome X].

To determine whether patients with syndrome X suffer from myocardial ischemia, coronary sinus oxygen saturation was continuously measured during pacing loading in 31 patients. Subjects were categorized by groups as syndrome X (11 patients), effort angina (14), and old myocardial infarction and valvular heart disease (6). Pacing loading induced evidence of ischemia in all syndrome X patients and in eight of the 11 patients with effort angina, while there was no such evidence in those with old myocardial infarction and valvular heart disease. Coronary sinus oxygen saturation in syndrome X decreased significantly from 44.2 +/- 5.8% to 33.5 +/- 4.4% (p less than 0.01), and it decreased from 47.0 +/- 4.9% to 31.2 +/- 4.0% (p less than 0.01) in effort angina with induced ischemic evidence, indicating that a significant reduction in coronary sinus oxygen saturation reflects the presence of myocardial ischemia. In the group with old myocardial infarction and valvular heart disease, coronary sinus oxygen saturation remained nearly unchanged during pacing. The pattern of depression of coronary sinus oxygen saturation during pacing was steeper in effort angina than in syndrome X. Therefore, we conclude that, although syndrome-X may not be a homogeneous group of patients, most of them may develop myocardial ischemia due to reduced vasodilator reserves of the small coronary artery.

[A case of myocardial infarction due to the left main trunk lesion, in which percutaneous coronary recanalization and emergency coronary-aorto bypass graft, and subsequent percutaneous coronary angioplasty were effective not only from a viewpoint of survival but from comeback to social life].

A case of acute myocardial infarction due to the lesion in the left main coronary artery was reported. A 50-year male was referred to our department for suspected acute myocardial infarction. Physical examination on admission revealed slight cyanosis with cold sweating due to severe chest pain. Pulse was irregular and heart rate was 78 beats/min. Blood pressure was 100/80 mmHg. A series of electrocardiograms (ECG) and laboratory data provided the diagnosis of wide-ranged anterolateral infarction in the left ventricle. Emergency coronary angiograms taken without delay showed a subtotal occlusion (99% stenosis) of the left main coronary trunk (LMT) before the initiation of intracoronary thrombolysis (PTCR). Following the intracoronary infusion of urokinase of 1,200,000 units, symptoms and ECG changes transiently improved but worsened later, and LMT stenotic lesion and delayed filling of myocardium were similar with before PTCR. Emergency coronary-aorto bypass graft (CABG) was undertaken without a significant delay to both the left anterior descending artery (LAD) and left circumflex coronary artery (LCX). With these treatments, the patient could survive despite the wide area of infarction due to LMT lesion. Coronary angiograms performed 37 days after the CABG showed that the graft to LAD was completely occluded and the LCX graft was patent with partial stenosis. Treadmill test at this time induced an anginal episode with ischemic ECG changes on moderate exercise, indicating the presence of significant area of ischemic myocardium. For salvage of the ischemic myocardium, percutaneous transluminal coronary angioplasty (PTCA) was successfully performed for the LMT stenosis, resulting in no episode of angina nor ischemic ECG changes during exercise loading.(ABSTRACT TRUNCATED AT 250 WORDS)

[Coronary hemodynamics in a patient developing chest pain in the middle age in congenital coronary-pulmonary fistula].

Recently reports of congenital coronary-pulmonary fistula have been increasing with the wide-spread use of coronary angiography. However, the cause of the angina sometimes seen as a chief complaint in coronary fistula has not been well demonstrated although it has been suggested that coronary steal phenomenon accounts for it. This report documented coronary hemodynamics in a patient who came to develop anterior chest pain in the middle age owing to congenital coronary-pulmonary fistula, measuring coronary flow before and after the fistula-closure operation. A 35-year-old woman suffered from a sudden onset of severe anterior chest pain in April, 1986. She was referred to our hospital on suspicion of ruptured aneurysm of Valsalva. Auscultation disclosed continuous murmur at 3 LSB, but no evidence of ruptured aneurysm of Valsalva was detected by echocardiography nor aortography. Coronary angiography showed both left and right coronary fistula into the stem of pulmonary artery and otherwise normal angiogram. Great cardiac vein flow (GCVF) measured with regional thermodilution method was 25 ml/min at rest (70 bpm) and 30 ml/min during rapid atrial pacing (150 bpm) before the operation, and 30 ml/min (78 bpm) and 58 ml/min (150 bpm) after the operation, respectively. Before the surgery, anterior coronary resistance (CRant) was higher than that in normal subjects at rest and remained almost steady during atrial pacing. After the surgery, CRant was still higher at rest but remarkably reduced during pacing of 150 bpm. These findings suggest that the gradual increase in peripheral coronary resistance for a long time may lead to the inducement of coronary steal in the middle-later age in patients with coronary fistula.