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Biomedical subjects

S Nanto

Publications and source records attributed to S Nanto.

At least 19 recordsLinked to original sources

Variation during the week in the incidence of acute myocardial infarction: increased risk for Japanese women on Saturdays.

BACKGROUND: Variations in the incidence of acute myocardial infarction during the week may differ between and within communities, according to lifestyle. OBJECTIVE: To identify potential triggering factors for acute myocardial infarction by examining variations in incidence in the days of the week within the Osaka area of Japan. PATIENTS: Of 2511 consecutive patients in this region who were admitted to hospital for acute myocardial infarction between April 1998 and March 2001 and consented to take part, 2400 who had a definitely identified time of onset were enrolled. RESULTS: For this group as a whole, no significant difference in incidence was noted between days of the week. However, in subgroup analyses women were shown to have significant variation through the week, peaking on Saturday with a 39% increase in relative risk (p = 0.037); working subjects showed a peak on Monday, with a 26% increase in relative risk (p = 0.038). Stratified analyses showed that in working men there was a prominent Monday peak in the onset of infarction, with a 30% increase in relative risk (p = 0.022), while in working women, there was no significant variation through the week. CONCLUSIONS: Earlier findings of a Monday peak linked to increased physical and mental occupational stress are confirmed. There is also an increase in uncertain risk factors on Saturdays for Japanese women, possibly involving a stressful weekend burden for women. Confirmation of this finding in other communities may help identify triggers of acute myocardial infarction and be useful in prevention.

Adult↗

Abnormal myocardial free fatty acid utilization deteriorates with morphological changes in the hypertensive heart.

The left ventricle's morphological adaptation to high blood pressure is classified into 4 patterns based on mass and wall thickness. The geometric changes caused by maladaptation to pressure overload possibly relate to progression of contractile dysfunction with abnormal energy metabolism. The present study assessed whether the geometric adaptation of the left ventricle (LV) to high blood pressure relates to changes in myocardial energy metabolism, especially free fatty acid (FFA) utilization. Thirty-five patients with essential hypertension underwent echocardiography and dual isotopes myocardial scintigraphy using iodine-123 labeled 15-p-iodophenyl-3-(R,S)-methylpentadecanoic acid (BMIPP, an analogue of a FFA) and thallium-201 (Tl-201). Systolic (endocardial fractional shortening; %FS) and diastolic indices (the ratio of early to atrial filling waves; E/A) of LV function were also assessed. Quantitative myocardial BMIPP uptake was evaluated by the BMIPP/TI-201 myocardial uptake ratio (B/T). The subjects were divided into 4 groups based on LV mass and wall thickness: (1) concentric hypertrophy (CH), (2) eccentric hypertrophy (EH), (3) concentric remodeling (CR), and (4) normal geometry (N). The %FS was lower in the EH group than in the other groups. The mitral E/A ratio in the CH group was lowest. B/T was significantly decreased in the EH group compared with the N group (p < 0.05). B/T correlated with the mitral E/A ratio significantly (p < 0.05, r = 0.42), whereas there was no relationship between %FS and B/T. These results indicate that the geometric changes occurring in hypertensive hearts strongly correlate with alternations in cardiac function and with abnormal myocardial FFA metabolism, and that the latter is associated with diastolic abnormality, but not with systolic function.

Aged↗

Determination of coronary zero flow pressure by analysis of the baseline pressure-flow relationship in humans.

The present study seeks to estimate the difference between coronary zero flow pressure (Pzf) by analysis of the baseline pressure-flow relationship and the Pzf calculated during a long diastole in humans. Although Pzf is likely to provide meaningful information about the characteristics of coronary circulation, there are no available data on Pzf in humans because Pzf is overestimated when it is calculated during normal cardiac cycles. Actual Pzf was determined in 15 subjects by analyzing the coronary pressure-flow relationship during a long cardiac cycle induced by an intracoronary adenosine triphosphate (ATP) infusion, and it was compared with the Pzf calculated during a normal cardiac cycle in order to estimate the difference. Pzf calculated during a normal cardiac cycle was 47 +/- 15 mmHg, which decreased to 36 +/- 9mmHg after intracoronary administration of ATP (0.05 mg) whereas actual Pzf was 21 +/- 7 mmHg. Pzf calculated in a pressure-flow relationship during a normal cardiac cycle under vasodilation correlated well with that during a long diastole (r = 0.75, p < 0.01), although it was 15 +/- 6 mmHg greater than the actual Pzf. It was concluded that Pzf during a normal cardiac cycle could be used to anticipate Pzf.

Adenosine Triphosphate↗

Effects of hostility and lifestyle on coronary heart disease among middle-aged urban Japanese.

OBJECTIVE: To explore the association between multi-dimensional aspects of hostility and coronary heart disease among middle-aged urban Japanese. SUBJECTS AND METHODS: We conducted a case-control study. Cases were consecutive patients with acute coronary syndrome admitted to a hospital in Japan. Fifty-three patients (45 men and 8 women) aged 35 to 65 were enrolled. For each case, two sex and age (+/-2 years) matched controls were recruited from among participants in a health check-up program at a health promotion center located in the same area as the hospital. Two questionnaires, both with four components, were used to measure hostility and coping with anger: the one was for anger, hostility, physical aggression and verbal aggression, and the other for aggression, social inhibition, guilt, and controlled affect. RESULTS: The scores of all components from two questionnaires were higher for cases than controls, but the differences were not significant. Multivariate analysis showed that anger, fat intake, alcohol consumption and house size were significantly associated with the etiology of acute coronary syndrome. CONCLUSION: Anger, lifestyle, and socioeconomic status play important roles for the etiology of coronary heart disease in middle-aged urban Japanese.

Case-Control Studies↗

Angiographic and clinical outcome of a new self-expanding intracoronary stent (RADIUS): results from multicenter experience in Japan.

The RADIUS coronary stent featuring a multisegmented slotted tube design and self-expanding nitinol delivery system has a high radial force and flexibility, uniform expansion, and contours to the shape of the vessel. Successful stent deployment was achieved in 104 stable angina patients (106 lesions; 44% LAD, 19% circumflex, and 37% RCA). Mean minimal lumen diameter (MLD) increased from 0.77 +/- 0.46 mm to 2.88 +/- 0.61 mm and mean percent diameter stenosis (% DS) decreased from 73 +/- 14% to 6 +/- 13% immediately after the procedure. At 6-month follow-up, two patients (2%) underwent urgent target revascularization, and cerebral bleeding occurred in one patient (1%). Angiographic follow-up was performed in 94 lesions (89%) and mean MLD and mean % DS were 2.08 +/- 0.92 mm and 30% +/- 24%, respectively. Stent restenosis (>50% diameter stenosis at follow-up) was observed in 16 (17%) of all lesions. The high success rate for stent deployment, low incidence of major adverse cardiac event, and lower restenosis rate after stent implantation indicate that the RADIUS stent is useful for coronary intervention.

Adult↗

Metabolic changes in hibernating myocardium after percutaneous transluminal coronary angioplasty and the relation between recovery in left ventricular function and free fatty acid metabolism.

To elucidate the changes in oxidative metabolism in hibernating myocardium after coronary revascularization, we performed myocardial single-photon emission computed tomography with a free fatty acid analog, I-123 beta-methyliodophenylpentadecanoic acid (BMIPP), and thallium-201 before and 1 month after percutaneous transluminal coronary angioplasty (PTCA) in 11 patients with angina pectoris caused by single artery stenosis. All patients had improvement in wall motion after PTCA at the region with coronary stenosis; the wall motion abnormality score evaluated by left ventriculography decreased from 5.5+/-0.8 (mean +/- SE) to 2.1+/-0.9, p <0.01) after PTCA. The defect score of I-123 BMIPP images was significantly larger than that of thallium-201 images either before (14+/-1.3 vs 8.9+/-1.1, p <0.01) or 1 month after (7.4+/-1.5 vs 3.7+/-0.8, p <0.01) PTCA. The decrease in the defect score of both images was significant (p <0.01). Changes in the wall motion abnormality score showed a significant correlation with both the change in the defect score of thallium-201 images (r = 0.58, p < 0.01) and that of I-123 BMIPP images (r = 0.75, p <0.01). These results indicate that the metabolism of free fatty acid is impaired in hibernating myocardium, and that improvement in left ventricular function after successful PTCA is strongly associated with the recovery of oxidative metabolism.

Adult↗

Remodeling of in-stent neointima, which became thinner and transparent over 3 years: serial angiographic and angioscopic follow-up.

BACKGROUND: Recently, it has been reported that the luminal diameter shows phasic changes after stenting: the progression of luminal narrowing followed by its regression. To elucidate the mechanisms involved in the phasic changes in luminal diameter after stenting, we examined the changes in neointimal thickness and the appearance of neointima by a series of angiographic and angioscopic observations for 3 years after stent implantation. METHODS AND RESULTS: In 12 patients who received a Wiktor coronary stent, serial angiographic and angioscopic examinations were performed immediately, 2 to 4 weeks, 3 months, 6 months, and 3 years after the stenting without repetition of angioplasty. Neointimal thickness was determined by angiography as the difference between stent and luminal diameters. The angioscopic appearance of neointima over the stent was classified as transparent or nontransparent according to the visibility of the majority of the stent. Neointimal thickness increased significantly at 3 months (0.75+/-0.32 mm) without further changes at 6 months (0.74+/-0.32 mm). Thereafter, however, it decreased significantly over 3 years (0.51+/-0.26 mm). The angioscopic appearance was classified as transparent in 8 patients (100) immediately after stenting, 6 patients (100%) at 2 to 4 weeks, 2 patients (17%) at 3 months, 2 patients (20%) at 6 months, and 7 patients (58%) at 3 years. CONCLUSIONS: The neointima became thick and nontransparent until 6 months and then became thin and transparent by 3 years. We conclude that neointimal remodeling exists after stenting and plays a major role in the alteration of coronary luminal diameter after stenting.

Adult↗

Mechanism of impaired left ventricular wall motion in the diabetic heart without coronary artery disease.

OBJECTIVE: To elucidate whether impairment of the myocardial free fatty acid (FFA) metabolism and small vessel abnormalities in the myocardium are etiologic or contributory factors of myocardial dysfunction in patients with NIDDM without any significant coronary artery disease. RESEARCH DESIGN AND METHODS: We performed myocardial imaging with 123I-labeled beta-methyl-p-iodophenyl pentadecanoic acid (BMIPP), a branched analog of FFA, and dipyridamole-infusion 201thallium scintigraphy (Dip) in nine patients who demonstrated left ventricular wall motion abnormalities without any significant coronary artery disease and in fifteen control cases. As an index of myocardial FFA metabolism, the heart-to-mediastinum count ratio (H/M) of BMIPP was calculated from the mean count in the regions of interest at the heart and the upper mediastinum. RESULTS: Nine patients with reduced wall motion documented by left ventriculography (LVG), (hypokinetic group) demonstrated significantly lower BMIPP uptake (2.1 +/- 0.2, mean +/- SD) than fifteen patients with normal wall motion (normokinetic group) (2.3 +/- 0.2, P < 0.05). Regional ventricular wall motion observed by LVG, regional BMIPP uptake, and regional redistribution phenomenon (RD) were evaluated for five regions of the left ventricle: anterior, septal, apical, lateral, and inferoposterior regions. Wall motion was abnormal in 24 out of 120 regions. Regional BMIPP uptake was reduced in 47 regions. RD in Dip was observed in 23 regions. In regional analysis, the existence of defect in the BMIPP image showed significant correlation with wall motion abnormality (P < 0.01), but there was no significant relationship between the RD in Dip and regional wall motion abnormality (P = 0.16). Myocardial biopsy specimens obtained from the right ventricle of 20 patients showed no pathologic changes, with the exception of two patients. CONCLUSIONS: Our findings suggest that impairment of myocardial FFA metabolism rather than small vessel abnormalities in the myocardium is responsible for modest left ventricular dysfunction in patients with diabetes.

Adult↗

Intracoronary administration of adenosine triphosphate increases myocardial adenosine levels and coronary blood flow in man.

Adenosine triphosphate (ATP) is reported to be released mainly from presynaptic vesicles and cardiomyocytes. The released ATP, which can be degraded to adenosine, may cause coronary vasodilation. However, there is no clear evidence that ATP is degraded to adenosine and causes coronary vasodilation in humans. The present study was undertaken to test whether intracoronary administration of ATP increases myocardial adenosine levels and coronary blood flow. In 11 patients, 3 doses of ATP (0.1, 0.2, and 0.4 mg) were injected into the left anterior descending coronary artery. The velocity of coronary blood flow was measured by Doppler flow probe, and the adenosine concentration in the coronary sinus blood was measured. We also continuously infused ATP (0.2 mg/min) for 1 min in another 10 patients. Coronary blood flow increased dose dependently soon after injection of ATP. Coronary arteriovenous differences in adenosine concentration increased [from 21 +/- 15 to 178 +/- 15 pmol/ml (p < 0.05) 10 sec after the injection of ATP (0.4 mg)] and there were marked reductions in both aortic blood pressure and heart rate. The adenosine levels returned to baseline 20 sec after the injection of ATP, and aortic blood pressure and heart rate also recovered, although coronary blood flow remained increased. Furthermore, continuous infusion of ATP for 1 min increased coronary blood flow velocity and coronary arteriovenous differences in adenosine concentration from 25 +/- 14 to 71 +/- 13 pmol/ml (p < 0.05) in 10 patients. These results indicate that intracoronary administration of ATP immediately increases coronary blood flow and the adenosine concentration of coronary venous blood, which returns to the baseline level thereafter. The differences in the time courses of increases in coronary venous adenosine levels and coronary blood flow after ATP injections suggest that vasodilatory mechanisms other than adenosine, eg, nitric oxide and prostaglandins, may also be involved in the ATP-induced coronary vasodilation. ATP may be used as a cardioprotective agent as well as adenosine.

Adenosine↗

Elevation of the plasma histamine concentration in the coronary circulation in patients with variant angina.

In the present study plasma histamine was found to be elevated in the great cardiac vein in 8 of 11 patients with variant angina but in none of 8 control patients. Although further investigation is required to determine the exact cause-and-effect relation between histamine release and provocation of spontaneous variant anginal attacks, the present study presents clinical evidence that histamine may well be related to episodes of variant angina as suggested in animal studies.

Adult↗

Is the presence of hyperlipidemia associated with impairment of endothelium-dependent neointimal relaxation after percutaneous transluminal coronary angioplasty?

To determine whether hyperlipidemia affects the endothelium-dependent vasomotor response along the dilated vessel after percutaneous transluminal coronary angioplasty (PTCA), we evaluated 32 patients with one-vessel disease, 3-6 months after successful PTCA without restenosis. Fourteen patients had mild stenotic lesions not subjected to PTCA (non-PTCA sites) in addition to the PTCA sites. Vessel diameter changes at 32 PTCA and 36 non-PTCA sites were assessed by quantitative angiography, before and after intracoronary injection of acetylcholine (20 micrograms to the right and 50 micrograms to the left coronary artery) and of nitroglycerin (0.1-0.3 mg). The acetylcholine response ranged from 46% (dilation) to -100% (constriction). All coronary arteries were dilated in response to nitroglycerin, which suggested preservation of the function of vascular smooth muscle, and the presence of an abnormality in endothelial function in those patients with a constrictor response to acetylcholine. There was a negative correlation between the acetylcholine response and the serum total cholesterol level at PTCA sites (r = -0.37; P = 0.038) and at non-PTCA sites (r = -0.46; P = 0.005). These findings indicate that hyperlipidemia is associated with a loss of endothelium-dependent vasodilation, not only at non-PTCA but also at PTCA sites, at which restoration of endothelial function might have occurred. They also suggest that hyperlipidemia may be related to the functional state of the regenerated endothelium at sites where PTCA had been previously performed.

Acetylcholine↗

Zero flow pressure in human coronary circulation.

UNLABELLED: Coronary pressure flow (P/F) relationship has been investigated mainly from the viewpoint of coronary resistance. However, recent experimental evidence suggests that the zero flow pressure intercept (Pzf) provides important characteristics of coronary circulation. Although Pzf is likely to provide meaningful information about characteristics of coronary circulation, no data are available about Pzf in humans. The authors attempted to determine Pzf in humans by analyzing P/F relationship during long cardiac pause. This relationship, provoked by intracoronary adenosine triphosphate (ATP) infusion, was analyzed in 9 patients (8 men, 1 woman) with coronary heart disease (ages: fifty-six +/- six years). After the diagnostic cardiac catheterization, ATP, 0.6 mg/3 mL, was administrated by bolus intracoronary injection during measurements of coronary blood flow velocity. Coronary blood flow velocity in the left anterior descending artery was measured with a 0.018-inch Doppler angioplasty guide wire (FloWire, Cariometrics, Inc., Mountain View, Calif.). The dynamic P/F relationship was obtained by correlation of the instantaneous aortic pressure and flow velocity with each other at constant intervals. The least square linear regression analysis was applied to the P/F data to yield the extrapolated Pzf axis. Immediately after intracoronary injection of ATP, long pause (5320 +/- 1498 msec) appeared and coronary blood flow velocity decreased to 11 +/- 8 cm/sec. Pzf calculated with P/F relationship was 14 +/- 7 mmHg. CONCLUSIONS: Thus, the results clearly demonstrate that Pzf is higher than right atrial and left ventricular end-diastolic pressure in humans, indicating the complexity of the determinants of the Pzf.

Adenosine Triphosphate↗

A case of hypertensive-diabetic cardiomyopathy demonstrating left ventricular wall motion abnormality.

We report a case of hypertensive-diabetic cardiomyopathy demonstrating left ventricular regional wall motion abnormality, with a normal coronary artery documented on coronary arteriography. Dipyridamole-infusion 201Tl scintigraphy demonstrated transient perfusion defects in the infero-posterior wall of the left ventricle, where reduced wall motion was demonstrated on contrast left ventriculography. Myocardial SPECT (single photon emission tomography) imaging with [123I] beta-methyliodophenylpentadecanoic acid (BMIPP) and 201Tl demonstrated reduced [123I]BMIPP uptake compared with 201Tl uptake in the infero-posterior wall of left ventricle. These results suggest that the impairment of myocardial free fatty acid metabolism is an etiologic or contributory factor for regional wall motion abnormality, together with small-vessel coronary artery disease, in this patient.

Cardiomyopathies↗

Elastic recoil and intimal thickening after coronary stenting.

In this study, the long-term elastic recoil of the stents and the intimal thickening over the stents were evaluated separately. Twenty-nine patients who received a Wiktor coronary stent were angiographically followed-up at 2 weeks, 3 months, and 6 months. The elastic recoil of the stent was evaluated by the changes in minimum stent diameter. The intimal thickness was evaluated by the difference between minimum stent diameter and minimum lumen diameter. Minimum stent diameter showed no significant change up to 6 months. The significant increase (P < 0.05) of the intimal thickness was detected only between 2 weeks and 3 months. In conclusion, the Wiktor stent prevented the elastic recoil up to 6 months, and was covered by the neointima which increased its thickness mainly between 2 weeks and 3 months after stenting. It was suggested that stent restenosis was not caused by the elastic recoil, but by the intimal thickening.

Aged↗

A technique for changing a PTCA balloon catheter over a regular-length guidewire.

In 100 patients who underwent coronary angioplasty with more than one balloon catheter for a lesion, these over-the-wire balloon catheters were changed by using a regular-length guidewire. In order to change to another balloon, the inflation device was connected to the central guide wire lumen of the catheter after pulling back the catheter until the proximal end of the regular length guide wire disappeared. By pulling back the balloon catheter from the guiding catheter by applying a pressure with the inflation device, the balloon was taken out of the guiding catheter leaving the wire in the coronary artery. One hundred forty-nine of 163 attempted procedures were completed successfully. Our technique helped in performing a fast, safe, and reliable changing procedure compared to the procedure with an extended guidewire.

Adult↗

Long-term clinical effect of nilvadipine in patients with chronic heart failure: a double-blind placebo-controlled study.

The long-term effect of calcium channel blockers on chronic heart failure is disappointing, probably because of reflex sympathetic activation through arterial vasodilation. However, nilvadipine may be beneficial for treatment of chronic heart failure since this drug has minimal effects on sympathetic activation. In this study, the effects of 12-week administration of nilvadipine or placebo on symptoms of heart failure and cardiac function were investigated in 23 patients with mild-to-moderate chronic heart failure in a double-blind trial. The patients were randomly assigned to either a nilvadipine group (16 mg daily) or a placebo group. Intergroup comparisons did not show significant differences in any parameters. Serious adverse effects were not observed during the study. Thus, this study failed to show any beneficial effect of nilvadipine in the long-term treatment of patients with chronic heart failure. We conclude that the long-term administration of nilvadipine (16 mg daily) is neither effective nor harmful in the treatment of patients with chronic heart failure.

Calcium Channel Blockers↗