The effects of losartan on signal-averaged P wave in patients with atrial fibrillation.

BACKGROUND: Losartan has recently been reported to suppress atrial structural remodeling. However, few reports exist on signal-averaged electrocardiography (ECG) for preventing atrial electrical remodeling. We examined the effect of losartan on atrial electricity by using signal-averaged ECG of P waves. METHODS: The subjects comprised 40 patients with essential hypertension complicated with symptomatic paroxysmal atrial fibrillation. The patients received pilsicainide for the complication; they were defibrillated and divided into two subgroups for antihypertensive therapy: calcium antagonist-administrated (CB) and losartan-administrated (LOS) groups. We recorded the signal-averaged electrocardiography of P waves and calculated (1) filtered P wave duration (PD), (2) the voltage integral for the entire P wave (integral-p), and (3) the root mean square voltages of the terminal 40, 30, and 20 ms (RMS-40, RMS-30, and RMS-20). Procollagen C propeptide type I (PIP) and A- and B-type natriuretic peptide (ANP and BNP, respectively) levels in the groups were measured before and after antihypertensive agent administration. RESULTS: RMS-20 increased significantly and PD decreased significantly in the LOS group 24 weeks after antihypertensive drug administration; however, they remained unchanged in the CB group. Integral-p decreased significantly in both groups, and the decrease rate was significantly higher in the LOS group. Serum BNP levels decreased significantly only in the LOS group. CONCLUSIONS: Losartan inhibits atrial remodeling by inhibiting left atrial fibrosis as indicated by the procollagen C propeptide type I, ANP, and BNP levels. Signal-averaged ECG demonstrated that losartan suppresses atrial fibrillation recurrence by improving atrial conduction disturbance.

Risk factors associated with soft coronary artery plaques in Japanese, as determined by 16 slice multidetector-row computed tomography.

PURPOSE: The acute coronary syndrome is often caused by the rupture of plaques and thrombus formation even without significant stenosis, and patients with soft plaques, but without significant stenosis evidenced by coronary angiography (CAG), often develop an acute coronary syndrome. To address this discrepancy, a qualitative diagnosis of coronary plaques using a 16 slice multidetector-row CT was conducted. METHODS AND RESULTS: Volume rendering and cross-sectional MPR images were obtained. Based on the CT values, plaques on the coronary artery wall were classified as lipid-rich soft plaques (CT value<50 HU) and non-soft plaques (>50 HU).A significant correlation was observed between the percent stenosis determined in cross-sectional MPR images and those determined by CAG (r=+0.92, p<0.01). Diffuse plaques with CT values of less than 50 HU often caused stenosis at level of 75% or less, which were not indicated by percutaneous transluminal coronary angioplasty. CONCLUSIONS: Although diffuse soft plaques with CT values less than 50 HU are not an indication of intervention, a risk of an acute coronary syndrome exists, due to rupture. These soft plaques must be stabilized by treatment even when they do not cause significant stenosis, and MDCT is considered to be useful for their evaluation.

Relationships between thermic effect of food, insulin resistance and autonomic nervous activity.

BACKGROUND: The thermic effect of food (TEF) is higher in lean than in obese human subjects. OBJECTIVE: Relationships between TEF and insulin resistance during meals, from the point of view of autonomic nervous activity, were evaluated. METHODS: Autonomic nervous activity was evaluated in 20 young adults using the spectral analysis of heart rate variability from one hour before to two hours after a meal. Heart rate data were analyzed based on low frequency components (LF power, 0.04-0.15 Hz), high frequency components (HF power, 0.15-0.40 Hz), and LF/HF ratios. Energy expenditure and the TEF were measured 30 min after a meal. Homeostasis model of insulin resistance index (HOMA-IR) was also measured. RESULTS: The LF/HF ratio was significantly increased 30 min after a meal (p<0.05). No correlation between LF power and HF power with TEF was found, but the LF/HF ratio was significantly and positively correlated with TEF (r=+0.56, p<0.05). Moreover, a significant negative correlation was found between the HOMA-IR and TEF (r=-0.601, p<0.05). CONCLUSIONS: The findings suggest that a reduction in insulin sensitivity induces a poor response of sympathetic nervous activity in the postprandial phase and a reduction in postprandial energy expenditure.

Effects of thrombus suction therapy on myocardial blood flow disorders in males with acute inferior myocardial infarction.

Several studies have reported that the use of a distal protection device decreases the incidence of slow-flow and/or no-reflow in patients with myocardial infarctions. In the present study, we investigated the influence of a RESCUE/Thrombuster system and a PercuSurge GuardWire catheter on coronary microcirculation disorders in patients with acute myocardial infarction using the natriuretic polypeptide (ANP), the brain natriuretic peptide (BNP), and (99m)Tc-tetrofosmin myocardial scintigraphy (TF). The group consisted of a 77 patients with initial inferior myocardial infarction who had undergone emergency coronary angioplasty. The patients were randomly divided into: Group D (n=28), in which a direct stent alone was inserted, Group R/T (n=25), in which a stent was inserted after RESCUE system or a Thrombuster system was performed, and Group P (n=24), in which a stent was inserted after thrombus suction using a PercuSurge GuardWire catheter. Patients with coronary slow-flow/no-reflow were 3, 2 and 0 cases in Group D, Group R / T and Group P, respectively. In the present study, patients with good-reflow were enrolled in order to investigate the coronary microcirculation disorder in patients with visually similar coronary blood flow obtained in coronary angiography after percutaneous coronary reperfusion therapy. TF myocardial scintigraphy was performed 10+/-3 days after admission. Bull's eye images were divided into 8 sections, and each section was evaluated in 4 grades. The grade of each segment was regarded as the defect score. The results were compared with the database prepared based on bull's eye maps from 50 healthy adults in our hospital, and count areas of -2 x SD (standard deviation) or less were calculated as the extent score (%), reflecting the area in which myocardial blood flow was decreased. The extent and severity scores in Groups P and R/T were significantly lower than those in Group D. Coronary angiography at the chronic stage (6 months after surgery) showed the patency of the responsible vascular lesion in all patients. However, the ANP, BNP, cardiac index, and pulmonary capillary wedge pressure (PCWP) were significantly improved in Groups R/T and P, compared to Group D (p<0.01). These results suggest that the use of a RESCUE/Thrombuster system and a PercuSurge GuardWire catheter system in patients with acute inferior wall infarction improves coronary microcirculation disorders and acute- to chronic-phase cardiac function.

The relationship between autonomic nervous activity and physical activity in children.

BACKGROUND: There have been few studies that have reported on heart rate variability and the development of autonomic nervous function in children. This study investigated the relationship between heart rate variabilities at night and physical activity in children. METHODS: The study subjects were 29 children, including 17 boys and 12 girls. The daily activity product and heart rate variabilities during sleep at night (00.00-05.00 hours) were measured and several aspects of these parameters were analyzed. In one child (an 8-year-old girl), heart rate variability and the physical activity product were measured for 12 days. RESULTS: There was a negative correlation between the mean R-R interval and the duration (min) of heavy exercise per day (r = -0.39, P < 0.05). In the 8-year-old girl, from whom data was obtained for 12 days, the duration of heavy exercise per day was negatively correlated with the mean R-R interval (r = -0.63, P < 0.05), the number of changes in successive R-R intervals greater than 50 msec (RR50) (r = -0.74, P < 0.01), and the high frequency (HF) component (r = -0.66, P < 0.05). Furthermore, the daily number of steps was negatively correlated with the mean R-R interval (r = -0.66, P < 0.05), RR50 (r = -0.71, P < 0.05) and the HF component (r = -0.66, P < 0.05). There was a negative correlation between the amounts of energy consumption and the mean R-R interval (r = -0.69, P < 0.05). There was a negative correlation between the amounts of energy consumption and RR50 (r = -0.76, P < 0.01). Moreover, there was also a negative correlation between the amount of energy consumption and the HF component (r = -0.71, P < 0.05). CONCLUSION: These findings suggested that physical activities increase heart rate during sleep, but reduce parasympathetic nervous activity at night. Because both the HF component and RR50 reduce with growth, the exercise-related inhibition of parasympathetic nervous activity may be a developmental stimulus to reach a balanced autonomic nervous pattern in adults.

Long-term follow-up in japanese public office workers of the influence of blood pressure on ECG changes.

BACKGROUND: The relationship between annual changes in blood pressure (BP) and the electrocardiogram (ECG) was studied to clarity what factors give early detection of complications and predict the outcome of therapy. METHODS AND RESULTS: The influence of BP on the ECG was assessed in 830 Japanese office workers. Those with hypertension (HT) more frequently developed left atrial and ventricular overload compared with normotensive subjects. In addition, those with borderline HT (systolic pressure 140-160 mmHg and/or diastolic pressure 90-95 mmHg) and even those with lower blood pressure (systolic pressure 130-140 mmHg and/or diastolic pressure 85-90 mmHg) developed left atrial and ventricular overload more frequently than normotensive subjects. CONCLUSIONS: Based on these results, BP should be closely followed up when routine systolic and diastolic pressure levels exceed 130 mmHg and 85 mmHg, respectively, in persons in their 40 s to 50 s and the goal of antihypertensive therapy should be lower than reported previously.