PubMed Health⌕ Search

Biomedical subjects

B Takase

Publications and source records attributed to B Takase.

At least 19 recordsLinked to original sources
PubMed2005

Effect of betaxolol hydrochloride on heart rate variability indices during exercise stress testing in patients with hypertension.

Betaxolol hydrochloride is a beta1-selective antagonist that produces vasodilation in patients with hypertension and ischemic heart disease. The goal of the present study was to characterize the effect of betaxolol on heart rate variability indices (HRV), a well-established prognostic marker. Symptom limited-treadmill exercise testing was performed in 17 hypertensive patients (60.9 +/- 14.8 years-old) before and immediately a 3 weeks course of betaxolol hydrochloride (5 mg daily). Frequency domain HRV (high frequency spectra, HF; 0.15-0.40 Hz: low frequency spectra, LF; 0.04-0.15 Hz) was measured during exercise treadmill testing using MemCalc software. Betaxolol hydrochloride significantly decreased the maximal systolic blood pressure and heart rate (184 +/- 29 vs. 156 +/- 26 mmHg, P < 0.01; 132 +/- 21 vs. 113 +/- 15 bpm, P < 0.01) and significantly increased HF and LF during exercise treadmill testing (HF, 32 +/- 36 vs. 56 +/- 55 men/Hz, P < 0.01; LF, 64 +/- 58 vs. 95 +/- 86 men/Hz, P < 0.01). Thus, treatment with betaxolol hydrochloride resulted in a decrease in blood pressure during exercise treadmill testing and in an increase in HRV. This suggests that this agent could have beneficial effects on long-term prognosis in patients with hypertension.

Adrenergic beta-Antagonists↗
PubMed2005

Recombinant interferon alpha treatment decreases heart rate variability indices and impairs exercise tolerance in patients with chronic hepatitis.

Complications of interferon (IFN) therapy include cardiac arrhythmias, impaired cardiac function and myocardial ischemia. Decreased heart rate variability (HRV) indices, impaired exercise tolerance and decreased left ventricular (LV) function are related to unfavorable outcome of heart disease. To investigate the effect of IFN therapy on HRV, exercise tolerance and cardiac function, 24-h ambulatory electrocardiographic monitoring (AECG), two-dimensional echocardiography, and exercise treadmill testing (ETT) was performed in 9 patients (age 56 +/- 9 years-old) with chronic hepatitis and without underlying heart disease before and after treatment with IFN (recombinant alpha 2b; 10 x 10(6) U/day for 4 weeks). HRV parameters consisted of standard deviation of RR interval (sdNN, ms), SDANN (ms), S.D. index (ms), rMSSD (ms), pNN50 (%) and frequency analysis of heart rate spectrum resulted in low (ms, 0.04-0.15 Hz), high (ms, 0.15-0.40 Hz) and total (ms, 0.01-1.00 Hz) frequency components. Ischemia was not detected by AECG or ETT, and LV function was normal after INF treatment in all patients. However, INF treatment resulted in a decrease in exercise tolerance time (449 +/- 94 s vs. 329 +/- 67 s, P < 0.05) and a decrease in several HRV parameters (S.D. index, 42 +/- 5 ms vs. 37 +/- 9 ms; rMSSD, 22 +/- 5 ms vs. 19 +/- 4 ms; pNN50, 4 +/- 3% vs. 2 +/- 1%; P < 0.05). Further, patients treated with INF tended to have a lower sdNN and total frequency spectra, although this difference did not reach the level of statistical significance. These data suggest that the arrhythmogenic effect of INF may be mediated by decreases in HRV and impairment of exercise tolerance even in patients without overt heart diseases. Further, INF therapy may be contraindicated in patients with predisposing severe cardiac disorders, including arrhythmias, ischemia and decreased LV function.

Adult↗
PubMed2005

Effect of antiarrhythmic agents on heart rate variability indices after myocardial infarction: comparative experimental study of aprindine and procainamide.

The cardiac arrhythmic suppression trial (CAST) reported that antiarrhythmic treatments in post-myocardial infarction (MI) patients resulted in poor outcome and decreased in heart rate variability indices (HRV). The goal of the present study was to determine whether aprindine and procainamide, antiarrhythmic agents that increase HRV, result in beneficial effects in post-MI rabbits. Four weeks before experiment, MI was induced in four rabbits by ligating the major branch of left coronary artery. A total of eight rabbits (four post-MI and four normal rabbits) were randomly assigned to treatment with either intravenous aprindine (1 mg/kg) or intravenous procainamide (15 mg/kg). Frequency domain HRV (low frequency spectra, LF, 0.04-0.15 Hz; high frequency spectra, HF, 0.15-0.40 Hz) were assessed by MemCalc software. Aprindine significantly increased HF and LF in both MI and normal rabbits, whereas procainamide tended to decrease HF and LF in MI and normal rabbits (in total rabbits; aprindine, LF, from 6.3 +/- 7.9 to 16.5 +/- 15.0 ms(2)/Hz, P < 0.05; HF, from 8.0 +/- 11.7 to 17.5 +/- 15.0 ms(2)/Hz, P < 0.05; procainamide, LF, from 4.9 +/- 7.4 to 4.8 +/- 8.5 ms(2)/Hz, NS; HF, from 11.1 +/- 23.0 to 5.1 +/- 10.6 ms(2)/Hz, NS). Under pharmacological denervation with propranolol (0.1 mg/kg) and atropine (0.04 mg/kg), aprindine increased LF and HF (LF, from 0.2 +/- 0.2 to 0.8 +/- 0.7 ms(2)/Hz, P < 0.05; HF, from 0.1 +/- 0.0 to 0.2 +/- 0.0 ms(2)/Hz, P < 0.05). These data suggest that aprindine can increase HRV in post-MI rabbits. Further experiments in human subjects would be of benefit.

Adrenergic beta-Antagonists↗
PubMed2005

A novel apparatus for non-contact measurement of heart rate variability: a system to prevent secondary exposure of medical personnel to toxic materials under biochemical hazard conditions, in monitoring sepsis or in predicting multiple organ dysfunction syndrome.

BACKGROUND: The impaired balance of the low-frequency/high-frequency ratio obtained from spectral components of RR intervals can be a diagnostic test for sepsis. In addition, it is known that a reduction of heart rate variability (HRV) is useful in identifying septic patients at risk of the development of multiple organ dysfunction syndrome (MODS). We have reported a non-contact method using a microwave radar to monitor the heart and respiratory rates of a healthy person placed inside an isolator or of experimental animals exposed to toxic materials. APPARATUS DESIGN AND TESTING: With the purpose of preventing secondary exposure of medical personnel to toxic materials under biochemical hazard conditions, we designed a novel apparatus for non-contact measurement of HRV using a 1215 MHz microwave radar, a high-pass filter, and a personal computer. The microwave radar monitors only the small reflected waves from the subject's chest wall, which are modulated by the cardiac and respiratory motion. The high-pass filter enhances the cardiac signal and attenuates the respiratory signal. In a human trial, RR intervals derived from the non-contact apparatus significantly correlated with those derived from ECG (r=0.98, P<0.0001). The non-contact apparatus showed a similar power spectrum of RR intervals to that of ECG. CONCLUSIONS: Our non-contact HRV measurement apparatus appears promising for future pre-hospital monitoring of septic patients or for predicting MODS patients, inside isolators or in the field for mass casualties under biochemical hazard circumstances.

Adult↗
PubMed2004

Non-contact determination of vital sign alterations in hypovolaemic states induced by massive haemorrhage: an experimental attempt to monitor the condition of injured persons behind barriers or under disaster rubble.

To assess a non-contact method to determine the physical alteration of human subjects confined behind a barrier or under disaster rubble, an experimental, non-contact monitoring system was tested on rabbits in a hypovolaemic state. New Zealand male rabbits behind a barrier were subjected to hypovolaemic shock induced by the withdrawal of arterial blood (2ml per 100g body weight). The hypovolaemic state was determined by linear discriminant analysis using non-contact-derived variables: heart rate X1 and respiratory rate X2. Sixteen rabbits were equally divided between the hypovolaemic and control groups. To obtain the heart and respiratory rates simultaneously, the fast Fourier transform (FFT) was performed on the 1215MHz microwave radar analogue output. The linear discriminant function calculated by non-contact-derived variables was negative in the eight hypovolaemic rabbits and positive in the eight controls, so that the linear discriminant function could distinguish the hypovolaemic group from the control group. The Mahalanobis D-square (an index for classification accuracy) was 5908; the classification error rate corresponding to this value was small and negligible. The hypovolaemic rabbits developed metabolic acidosis (HCO3- 18.6+/-11.1 mmol l(-1) and pH 7.15+/-0.18 in arterial blood). The systolic blood pressure of the hypovolaemic group and the control was 56+/-4 and 83+/-6 mmHg, respectively (p < 0.01). The proposed method appears promising for applications to monitor the condition of human subjects behind barriers or under disaster rubble.

Acidosis↗
PubMed2003

Flow-mediated dilation in brachial artery in the second half of pregnancy and prediction of pre-eclampsia.

Endothelial injury and increased vascular reactivity are involved in the pathogenesis of pre-eclampsia (pregnancy-induced hypertension). To investigate whether flow-mediated dilation (endothelium-dependent dilation) and the reactive hyperemic response can predict pre-eclampsia, we prospectively measured flow-mediated dilation and the Doppler flow velocity pattern (V, cm/s) in the brachial artery using high-resolution ultrasound in 43 pregnant women (32+/-5 years old) in the second half of their pregnancy, and compared the findings with traditional risk factors. Regarding the Doppler flow velocity pattern, the pulsatility index (PI)=(systolic V-diastolic V)/mean V and resistance index (RI)=(systolic V-diastolic V)/systolic V were calculated. For the flow-mediated dilation, the per cent diameter changes were determined based on those from baseline to hyperemic conditions. Nine women suffered from pre-eclampsia and 34 women remained normotensive. Only flow-mediated dilation was found to be significantly lower in the subsequently developed pre-eclampsia patients (1.6+/-1.0% in subsequently developed pre-eclampsia patients vs 11.0+/-4.5% in normotensive patients, P<0.05). Neither the other traditional factors nor the Doppler flow velocity pattern were significantly different between the subsequently developed pre-eclampsia and normotensive patients. If a normal cutoff value of 3.0% obtained from age-matched 14 nonpregnant women (32+/-7 years old) in our laboratory was used, the positive predictive value of flow-mediated dilation (<3.0%) for subsequent pre-eclampsia is 90% and the negative predictive value is 100%. In conclusion, flow-mediated dilation in brachial artery can be a simple and noninvasive modality to predict pre-eclampsia.

Adult↗
PubMed2001

Impaired endothelium-dependent vasodilation in the brachial artery in variant angina pectoris and the effect of intravenous administration of vitamin C.

UNLABELLED: Endothelial dysfunction in the coronary artery contributes to the pathogenesis of variant angina, and endothelial dysfunction in variant angina may be associated with increased oxidant stress in the systemic arteries. We investigated whether endothelial dysfunction exists in the peripheral artery in patients with variant angina, and also examined the effect of vitamin C, an antioxidant, on endothelium-dependent vasodilation. Using high-resolution ultrasound, both the flow-mediated vasodilation (FMD, endothelium-dependent vasodilation) and sublingual nitroglycerin-induced vasodilation (NTG-D, endothelium-independent vasodilation) in the brachial artery were measured in 28 patients with variant angina and 24 control subjects who had normal coronary arteries. FMD was significantly impaired in patients with variant angina compared with control subjects (1.8 +/- 2.2% vs 6.4 +/- 4.9%, p <0.001). FMD and NTG-D before and after intravenous administration of either vitamin C or placebo were measured in 17 patients with variant angina. FMD significantly improved after the administration of vitamin C (from 2.2 +/- 2.4% to 4.5 +/- 1.6%, p <0.01), but not after administration of the placebo (from 2.0 +/- 2.6% to 1.7 +/- 1.9%). The improved FMD due to vitamin C in patients with variant angina, however, was not significantly different from that in the control subjects. NTG-D was not significantly different between patients with variant angina and control subjects (14.0 +/- 7.8% vs 13.6 +/- 5.0%) and it was also not affected by vitamin C. IN CONCLUSION: (1) FMD in the brachial artery is impaired in patients with variant angina, and (2) the acute administration of the antioxidant, vitamin C, was observed to reverse this endothelial dysfunction. These findings support the theory that the systemic inactivation of nitric oxide due to oxidative stress might exist in patients with variant angina.

Angina Pectoris, Variant↗
PubMed2001

Coronary remodeling of proximal and distal stenotic atherosclerotic plaques within the same artery by intravascular ultrasound study.

The aim of this intravascular ultrasound study was to compare the type and the degree of vessel remodeling in proximal and distal de novo lesions within the same coronary artery in patients with stable angina pectoris. Seventy-six de novo coronary artery lesions in 38 coronary arteries of 38 patients were imaged by intravascular ultrasound. The vessel area (VA) within the external elastic lamina and the lumen area (LA) were measured, and the wall area (VA-LA) was calculated at the lesion site, and the proximal and distal reference sites. The VA ratio was defined as (lesion VA/average of the proximal and distal reference VAs) to represent the degree of vessel remodeling. The proximal coronary segments showed compensatory enlargement more often (68% vs 29%, p < 0.01) than the distal segments, and the VA ratio at the lesion site was significantly larger (1.1 +/- 0.3 vs 1.0 +/- 0.2, p <0 .01) in proximal segments than in distal segments. The type of coronary remodeling was discordant in 61% and concordant in only 39% of coronary arteries between the proximal and distal segments. The type of coronary remodeling of proximal and distal coronary lesions was inhomogeneous, even within the same vessel. Proximal coronary segments showed more prominent compensatory enlargement than distal segments, which have a similar degree of luminal narrowings.

Adult↗
PubMed2001

Angioplasty decreases prolonged QT dispersion in patients with angina pectoris but not in patients with prior myocardial infarction.

BACKGROUND AND HYPOTHESIS: Prolonged QT dispersion (QTd) is shortened by successful percutaneous transluminal coronary angioplasty (PTCA) in patients with ischemic heart disease. Particularly, QTd plays an important role in the prognostication in patients with prior myocardial infarction (MI). However, whether the effect of PTCA on QTd differs in patients with and without prior MI is not clear, and this study sought to clarify this question. METHODS: In 41 consecutive patients with ischemic heart disease, we measured QTd from a routine 12-lead electrocardiogram taken at 72 h before and after successful PTCA. Patients were divided into two groups based on the presence or absence of prior MI: Group 1 consisted of 24 patients with angina (61 +/- 11 years old) without prior MI and Group 2 was comprised of 17 patients (69 +/- 10 years old) with prior MI. QTd was calculated as the difference between the maximum and minimum QT and QT corrected for heart rate (QTc), using Bazett's formula for calculating QTcd. All measurements were obtained manually and blindly. RESULTS: In Group 1, 15 of 24 patients (63%) demonstrated multivessel disease and 16 of 24 (67%) patients had high QTd > 60 ms. Percutaneous transluminal coronary angioplasty decreased QTd and QTcd in Group 1 (QTd, from 83 +/- 35 to 57 +/- 19 ms, p < 0.05 ; QTcd, from 89 +/- 37 to 63 +/- 33 ms, p < 0.05), whereas no changes were observed in Group 2 (QTd, from 73 +/- 25 to 69 +/- 22 ms, NS; QTcd, from 80 +/- 30 to 79 +/- 28 ms, NS). QTd is more sensitive to decrease by successful PTCA in patients with angina than in patients with prior MI. CONCLUSIONS: The effect of successful PTCA on inhomogeneity of ventricular repolarization reflected by QTd in patients with prior MI is different from that in patients without prior MI.

Aged↗
PubMed2001

Endothelial dysfunction and decreased exercise tolerance in interferon-alpha therapy in chronic hepatitis C: relation between exercise hyperemia and endothelial function.

BACKGROUND: We previously reported that reversible endothelial dysfunction is caused by interferon-alpha therapy (IFN) in patients with chronic hepatitis C. In experimental studies, limb blood flow during exercise is reported to be dependent on endothelium-derived nitric oxide. HYPOTHESIS: The purpose of this study was to confirm the effect of IFN on endothelial function and to investigate whether exercise hyperemia is dependent on endothelial function in humans. METHODS: We performed symptom-limited exercise treadmill testing and measured flow-mediated vasodilation (FMD, endothelium-dependent vasodilation) and sublingual glyceryl-trinitrate-induced dilation (GTN-D, 0.3 mg, endothelium-independent vasodilation) in the brachial artery by using high-resolution ultrasound in 10 patients with chronic active hepatitis C (age 53 +/- 11 years, 2 men, 8 women) before and immediately after administration of recombinant interferon 2b (10 million U/day) for 4 weeks. RESULTS: There were no significant abnormal findings in any patients in routine studies of 24-h ambulatory electrocardiogram monitoring, two-dimensional echocardiography, and exercise treadmill testing both before and after treatment. Leg fatigue and exhaustion were the reasons for termination of exercise treadmill testing in each patient. Pressure rate product was calculated at rest and peak exercise. Interferon-alpha therapy significantly (p<0.05) decreased FMD (6.8 +/- 3.1 vs. 1.9 +/- 2.6%), exercise treadmill testing tolerance time (437 +/- 89 vs. 395 +/- 62 s) and peak pressure rate product (283 +/- 41 vs. 241 +/- 47 mmHg x beats/min x 10(-2)), but not GTN-D (13.4 +/- 5.4 vs. 17.0 +/- 5.5%). The change of FMD due to IFN significantly and highly correlated with exercise treadmill testing tolerance time (r = 0.86, p<0.001), but not with change of peak pressure rate product, suggesting that FMD is more closely related to the condition of the peripheral circulation than is cardiac performance. CONCLUSION: These results suggest that IFN in patients with chronic hepatitis C impairs endothelial function and exercise tolerance, and that endothelial function might be at least partly involved in exercise hyperemia in humans.

Adult↗
PubMed2001

Different mechanisms of isoproterenol-induced and nitroglycerin-induced syncope during head-up tilt in patients with unexplained syncope: important role of epinephrine in nitroglycerin-induced syncope.

INTRODUCTION: A reduction in left ventricular volume and an increase in epinephrine levels have been reported in tilt-induced neurally mediated syncope. To compare the mechanisms of isoproterenol-induced and nitroglycerin-induced syncope during head-up tilt and to investigate the role of catecholamines, the temporal changes in plasma levels of norepinephrine and epinephrine and in left ventricular volume were measured. METHODS AND RESULTS: The first study population consisted of 90 patients with syncope of unknown etiology and 12 control subjects. The second study population consisted of 43 patients with unexplained syncope. In the first study, head-up tilt (80 degree angle) was conducted for 40 minutes, and norepinephrine and epinephrine levels were measured. In the second study, all patients were randomly allocated to either isoproterenol test (20 patients) or nitroglycerin test (23 patients) for 20-minute head-up tilt. Isoproterenol infusion was given at a rate of 1 to 3 microg/min. Intravenous infusion of nitroglycerin was started at 250 microg/hour with increasing dosages up to 1,500 microg/hour. Norepinephrine and epinephrine were measured in peripheral venous blood. Left ventricular volumes were measured by echocardiography with patients in the supine position and during head-up tilt every 1 minute. End-diastolic volume and end-systolic volume were calculated. In the first study, 61 patients demonstrated a positive response and 29 patients demonstrated a negative response. Plasma norepinephrine changes during head-up tilt were not significantly different, whereas epinephrine levels were significantly higher in the positive patients than in the negative and control subjects (148 +/- 118 pg/mL vs 66 +/- 31 pg/mL and 55 +/- 27 pg/mL). Thirteen of the 20 patients given isoproterenol and 15 of the 23 patients given nitroglycerin showed a positive head-up tilt (65.0% vs 65.2%; P = NS). During isoproterenol and nitroglycerin infusion head-up tilt, epinephrine in the positive group determined by the nitroglycerin test was significantly higher than that in the other three groups (103 +/- 38 pg/mL vs 60 +/- 33 pg/mL, 31 +/- 21 pg/mL, and 50 +/- 52 pg/mL). In contrast, end-systolic volume was significantly smaller in the positive group than in the other three groups based on findings of the isoproterenol test. CONCLUSION: The findings suggest that nitroglycerin triggers head-up tilt-induced syncope by increasing epinephrine levels, whereas isoproterenol induces syncope by decreasing left ventricular volume.

Adolescent↗
PubMed2001

New thermo-couple copper constantan catheter for measuring regional coronary blood flow and evaluating metabolism.

A new thermodilution catheter with a thermo-couple copper constantan and latex balloon in the tip has recently been developed. This device has two orifices. The left anterior descending (LAD) and/or left circumflex (LCX) flows were measured using a Doppler flow wire. The correlation between the LAD and GCV flow as well as between the LCX and CS-GCV flow were studied in closed chest animals. The flow distributions were evaluated by colored microspheres that were infused into the LAD and LCX. The regional lactate extraction ratio was measured by GCV and/or CS blood sampling performed either with or without balloon inflation before and during pacing in either LAD or LCX occluded animals. The correlations between the LAD and GCV flow, as well as between the LCX and CS-GCV flow were significant (r=0.96, r=0.93, n=30, p<0.001). The flow distribution by color microspheres in the GCV was 75+/-10% for the LAD, whereas in CS it was 70+/-12% for the LCX. By pacing, the lactate extraction ratio of the drained blood from the ischemic myocardium was +10+/-3% in the GCV blood, whereas it was -10+/-4% (p<0.01) in the CS blood. Thus, this new thermodilution catheter with a balloon was found to be useful for measuring regional coronary hemodynamics and also for evaluating the regional myocardial metabolism.

Catheterization↗
PubMed2001

The repeatability of left ventricular volume assessment by a new ambulatory radionuclide monitoring system during head-up tilt.

The precise measurement of changes in left ventricular volume is important to elucidate the mechanisms of neurally mediated syncope. This study was conducted to determine whether or not a brand-new ambulatory radionuclide monitoring system (C-VEST system) can be clinically used to easily and precisely measure left ventricular volume and function in tilt testing. To assess the repeatability of the C-VEST system, 12 healthy volunteers (mean age 24+/-4 years old) underwent 20 minute head-up tilt testing and we measured the temporal changes in left ventricular volume and ejection fraction twice a day (first and second studies). To investigate the changes in the C-VEST measurements and the detector position in the first and second studies, tilt testing was performed with an 80-degree passive tilt, which is the same as the standard procedure used in diagnosing neurally mediated syncope. The coefficient of repeatability for both the C-VEST and detector position was well within the clinical range (coefficient of repeatability in left ventricular volume ranged from 1.7 to 2.8; coefficient of repeatability in the detector position ranged from 2.3 to 3.1). Precise evaluation of the left ventricular volume can be achieved by an ambulatory radionuclide monitoring system in tilt testing.

Adult↗
PubMed2001

Significance of circulatory epinephrine levels in exercise-induced neurally mediated syncope.

BACKGROUND AND HYPOTHESIS: Previous research has failed to document temporal changes in epinephrine levels in patients with neurally mediated syncope associated with exercise. The purpose of this study was to investigate the role of circulatory catecholamines in exercise-induced neurally mediated syncope, specifically focusing on epinephrine levels. METHODS: The present study deals with temporal changes of circulatory catecholamine levels during head-up tilt tests (40 min, 80 degree tilt) in 62 patients with syncope of unknown origin, 7 of whom had syncope associated with exercise (exercise-induced group, 19+/-3 years). Data were compared with 10 control subjects (control group, 45+/-23 years). Of the 55 patients with syncope not associated with exercise, 32 tested positive for the head-up tilt tests (positive group, 31+/-16 years) and 23 patients tested negative (negative group, 46+/-19 years). Blood samples for circulatory catecholamine assay were obtained from the antecubital vein in the baseline supine position 2 min after the tilt started, every 10 min during tilt, and at the time of the onset of symptoms or the end of tilt. Levels of norepinephrine and epinephrine were determined using the high-pressure liquid chromatography (HPLC) method (pg/ml). RESULTS: Plasma norepinephrine levels among the four groups were similar at the supine position and during tilt testing. In contrast, patients in the exercise-induced group had significantly higher maximum epinephrine levels during head-up tilt testing than the other three groups (288+/-191 vs. 148+/-117, 66+/-31, and 54+/-27 pg/ml, respectively, p < 0.05). Patients in the positive group had higher maximum epinephrine levels than those in the negative group (p <0.05). Also, patients in the exercise-induced group and those in the positive group had a significantly shorter tilt-testing time than patients in the negative and control groups. CONCLUSIONS: A marked increase of epinephrine was observed during head-up tilt testing in patients with neurally mediated syncope associated with exercise. The present findings further accelerate the identification of the role of epinephrine in the mechanisms behind neurally mediated syncope associated with exercise.

Adolescent↗
PubMed2001

Disaster and cardiac disease.

Evidence obtained over the past decade has revealed that cardiac events and sudden cardiac deaths do not occur randomly but are caused by daily activities and emotional stress. Important triggers may be stress on autonomic nervous tone and sympathetic activities. Such sympathetic activities are changed in a circadian manner with fluctuations in blood rheology and catecholamine secretion. The threshold of electrical instability, left ventricular dysfunction and coronary stenosis may become reduced through the acceleration of sympathetic tone due to emotional stress, thus causing malignant arrhythmia and plaque rupture. Recognition of this multifactorial pathophysiology provides a basis for understanding preventive strategies.

Cardiovascular Diseases↗