Biomedical subjects

Mikiko Nakagawa

Publications and source records attributed to Mikiko Nakagawa.

At least 19 recordsLinked to original sources

PubMed2007

Smoking is associated with urinary albumin excretion: an evaluation of premenopausal patients with type 2 diabetes mellitus.

Cigarette smoking and an increase in urinary albumin excretion are associated with high mortality in patients with type 2 diabetes mellitus. We tested the hypothesis that the presence of a smoking habit correlates with increased urinary albumin excretion in premenopausal Japanese women with type 2 diabetes mellitus. The study consisted of 20 premenopausal Japanese patients with type 2 diabetes mellitus in the current-smokers group (age, 45 +/- 4 years, mean +/- SD). The control group consisted of 35 age-matched never-smoker patients (age, 45 +/- 5 years). Serum triglyceride levels were higher and high-density lipoprotein cholesterol levels were lower in the current-smokers group than in the never-smokers group (P < .05 and P < .01, respectively). Furthermore, fasting plasma insulin concentrations and the homeostasis model assessment index were higher in the current-smokers group than in the never-smokers group (P < .005 and P < .001, respectively). Urinary albumin excretion also was higher in the current-smokers group than in the never-smokers group (P < .0001). Multivariate logistic analysis revealed that urinary albumin excretion is independently associated with current smoking in Japanese premenopausal with type 2 diabetes mellitus (odds ratio, 1.79; 95% confidence interval, 1.08-3.87; P < .01). The results of this study show that current smoking is associated with an increased level of urinary albumin excretion, suggesting that smoking was a risk factor in the development of increased urinary albumin excretion in these patients.

Adult↗

PubMed2006

Homocysteine levels are associated with the results of 123I-metaiodobenzylguanidine myocardial scintigraphy in type 2 diabetic patients.

PURPOSE: Elevated total plasma homocysteine (tHcy) levels and cardiovascular autonomic dysfunction are associated with a high mortality in type 2 diabetic patients. We tested the hypothesis that hyperhomocysteinemia is associated with insulin resistance and cardiovascular autonomic dysfunction in type 2 diabetic patients not receiving insulin treatment. METHODS: The study group consisted of 17 type 2 diabetic patients with high tHcy levels (>15 mmol/l, age 58+/-5 years, high tHcy group). The control group consisted of 23 age-matched type 2 diabetic patients with normal tHcy levels (<or=15 mmol/l, age 58+/-9 years, normal tHcy group). Cardiovascular autonomic function was assessed by baroreflex sensitivity, heart rate variability, plasma norepinephrine concentrations, and cardiac (123)I-metaiodobenzylguanidine (MIBG) scintigraphy. RESULTS: Early and delayed (123)I-MIBG myocardial uptake values were lower (p<0.005 and p<0.01, respectively) and the percent washout rate of (123)I-MIBG was higher (p<0.001) in the high tHcy group than in the normal tHcy group. The fasting plasma insulin concentrations (p<0.0001) and the homeostasis model assessment (HOMA) index values (p<0.0001) were higher in the high tHcy group than in the normal tHcy group. Multiple regression analysis revealed that the level of tHcy was independently predicted by the HOMA index values and the myocardial uptake of (123)I-MIBG at the delayed phase. CONCLUSION: Our results demonstrate that high levels of tHcy are associated with depressed cardiovascular autonomic function and insulin resistance in patients with type 2 diabetes mellitus.

3-Iodobenzylguanidine↗

PubMed2006

Diazoxide-induced cardioprotection via DeltaPsim loss depending on timing of application.

Although the role of mitochondrial ATP-sensitive potassium (mitoKATP) channels in cardioprotection is widely accepted, it remains unclear when their opening is critical for protection. We tested the hypothesis that the mitoKATP channel acts as a trigger or mediator of protection against apoptosis through loss of mitochondrial inner membrane potential (DeltaPsim). Exposure of neonatal rat cardiomyocytes to H2O2 (0.5 mmol/L) resulted in apoptosis associated with severe DeltaPsim loss. Pretreatment with diazoxide (20 to 100 micromol/L) prevented H2O2-induced apoptosis and DeltaPsim loss at 2 but not 18 h after exposure, while the latter was prevented by cotreatment with diazoxide. Lack of protection by pretreatment with diazoxide was observed in cardiomyocytes cultured in a medium containing H2O2 for 2 h and then not containing for 16 h. The slopes of the regression lines of the relationship between the proportion of apoptotic cells and DeltaPsim loss (y = -0.89 vs. -0.42) and the proportion of cells with high side scatter signal differed between cardiomyocytes exposed H2O2 for 2 and 18 h. Diazoxide per se caused a transient DeltaPsim loss (within 30 min) with a recovery followed by persistent DeltaPsim loss (after 6 h). Inhibition of the former by 5-hydroxydecanoate (5-HD, 0.5 mmol/L) abolished protection of pretreatment with diazoxide (trigger phase), while that of the latter prevented the protection of cotreatment with diazoxide (mediator phase). Our results suggest that mitoKATP channels act as a trigger and mediator of cardioprotection through a transient or persistent DeltaPsim loss depending on phenotypic consequence in response to oxidants.

Animals↗

PubMed2006

Hyperhomocysteinemia is a significant risk factor for silent cerebral infarction in patients with chronic renal failure undergoing hemodialysis.

In patients with chronic renal failure undergoing hemodialysis (HD), the presence of silent cerebral infarction (SCI) is associated with high mortality. Plasma total homocysteine (tHcy), which increases with renal dysfunction, has been flagged as a novel predictor for cerebrovascular events. We tested the hypothesis that the presence of SCI correlates with tHcy in HD patients. Based on brain magnetic resonance imaging findings, 44 patients undergoing HD were divided into a with-SCI group (61+/-9 years [mean+/-SD]; n=24) and a without-SCI group (60+/-8 years, n=20), in whom 24-hour ambulatory blood pressure monitoring was performed. The number of patients with diabetes or hypertension was not different between the 2 groups. We made the following observations: (1) the percentage of smokers was higher in the with-SCI group than in the without-SCI group (P<.05); (2) plasma levels of high-density lipoprotein cholesterol were lower and tHcy was higher in the with-SCI group than in the without-SCI group (P<.05 and P<.0001, respectively); (3) and systolic ambulatory blood pressure and mean heart rate during nighttime were higher in the with-SCI group than in the without-SCI group (P<.05). Multivariate logistic analysis identified hyperhomocysteinemia as an independent and significant risk factor for SCI (odds ratio, 1.22; 95% CI, 1.10-1.36; P<.01). Our findings indicate that plasma tHcy may be a novel useful predictor for SCI in patients with chronic renal failure undergoing HD.

Blood Pressure Monitoring, Ambulatory↗

PubMed2006

Influence of menstrual cycle on QT interval dynamics.

OBJECTIVES: The aim of this study was to investigate the effects of the menstrual cycle on QT interval dynamics and the autonomic tone in healthy women. METHODS: Holter ECGs were recorded in 11 healthy women aged 18-32 years during the follicular and luteal phases of their regular menstrual cycle. The interval from QRS onset to the apex (QaT) and to the end of the T-wave (QeT), the interval between the apex and the end of the T-wave (Ta-e), and RR intervals were measured automatically in the course of 24 hours by Holter ECGs. The QeT/RR, QaT/RR, and Ta-e/RR relationships were evaluated in each subject. The autonomic tone was assessed by the serum catecholamine level at rest and heart rate variability was measured by Holter ECGs. RESULTS: (1) The follicular and luteal phases did not differ significantly with respect to the slopes of the QeT/RR, QaT/RR, and Ta-e/RR relationships. However, QeT and QaT intervals were significantly shorter for all RR intervals in the luteal than in the follicular phase (P < 0.0001). (2) The serum progesterone concentration was significantly higher in the luteal than in the follicular phase (P < 0.001). (3) Noradrenaline was significantly higher in the luteal than in the follicular phase (P < 0.05). There was no significant difference in the follicular and luteal phases with respect to heart rate variability measurements. CONCLUSIONS: Our results suggest that the menstrual cycle affects the QT intervals. The observed shorter QT interval during the luteal than the follicular phase may be attributable to the increase in serum progesterone and sympathetic tone.

Adolescent↗

PubMed2006

Phosphatidylinositol 3-kinase-dependent activation of akt, an essential signal for hyperthermia-induced heat-shock protein 72, is attenuated in streptozotocin-induced diabetic heart.

We tested the hypothesis that phosphatidylinositol 3-kinase (PI 3-kinase)-dependent activation of Akt is essential for the expression of cardiac heat-shock protein 72 (HSP72) and that this pathway is impaired in the streptozotocin (STZ)-induced diabetic heart. STZ-induced male diabetic rats were treated with insulin (STZ-insulin group, n = 26) or vehicle (STZ-vehicle group, n = 61) for 3 weeks. Whole-body hyperthermia (43 degrees C for 20 min) was applied, and the heart was isolated 24 h later. Compared with control heart, hyperthermia-induced HSP72 expression and phosphorylation of Akt were attenuated in the STZ-vehicle heart. Pretreatment with wortmannin attenuated hyperthermia-induced HSP72 expression and phosphorylation of Akt. In isolated perfused heart experiments, the hyperthermia-treated STZ-vehicle heart showed poor left ventricular functional recovery during reperfusion after no-flow global ischemia compared with hyperthermia-treated control heart. Insulin treatment restored HSP72 expression and reperfusion-induced functional recovery. In cultured neonatal rat cardiomyocytes, hyperthermia-induced HSP72 expression was enhanced by insulin, together with tolerance against hypoxia-reoxygenation injury. Wortmannin and LY294002 inhibited hyperthermia-induced HSP72 expression and phosphorylation of Akt. Our results indicate that activation of Akt, in a PI 3-kinase-dependent manner, is essential for hyperthermia-induced HSP72 expression in association with cardioprotection, suggesting impairment of this signaling pathway in the STZ-induced diabetic heart, probably due to insulin deficiency.

Androstadienes↗

PubMed2006

Pioglitazone but not glibenclamide improves cardiac expression of heat shock protein 72 and tolerance against ischemia/reperfusion injury in the heredity insulin-resistant rat.

We tested the hypothesis that pioglitazone could restore expression of heat shock protein (HSP)72 in insulin-resistant rat heart. At 12 weeks of age, male Otsuka Long-Evans Tokushima Fatty (OLETF) rats and control (LETO) rats were treated with pioglitazone (10 mg x kg(-1) x day(-1)) or glibenclamide (5 mg x kg(-1) x day(-1)) for 4 weeks. Thereafter, hyperthermia (43 degrees C for 20 min) was applied. In response to hyperthermia, the activation of serine/threonine kinase Akt depending on phosphatidylinositol 3 (PI3) kinase was necessary for cardiac expression of HSP72. Hyperthermia-induced activation of Akt and HSP72 expression were depressed in OLETF rat hearts. Pioglitazone but not glibenclamide improved insulin sensitivity in OLETF rats, which was associated with the restoration of Akt activation and HSP72 expression. In experiments with isolated perfused heart, reperfusion-induced cardiac functional recovery was suppressed in OLETF rat hearts, which was improved by pioglitazone but not glibenclamide. Our results suggest that PI3 kinase-dependent Akt activation, an essential signal for HSP72 expression, is depressed in the heart in insulin-resistant OLETF rats, and the results suggest also that the restoration of HSP72 expression and tolerance against ischemia/reperfusion injury by treatment with pioglitazone might be due to an improvement of insulin resistance, leading to restoration of impaired PI3 kinase-dependent Akt activation in response to hyperthermia.

Animals↗

PubMed2006

[Evaluation of autonomic function using posture change].

There are several examinations to evaluate cardiac autonomic function. Autonomic neuropathy is a common complication of diabetes mellitus and is associated with increased mortality. Baroreflex sensitivity (BRS) is a marker for the ability to augment vagal activity. Several studies have shown that BRS is impaired in diabetes with autonomic neuropathy. The head-up tilt test is the most useful tool to diagnose the neurally mediated syncope. We have developed a new non-invasive method to evaluate the baroreflex using downward tilting (DT-BRS). In our previous study conducted in healthy volunteers and diabetic patients, we demonstrated a strong correlation between systolic blood pressure increase and corresponding RR interval lengthening during downward tilting, which yielded DT-BRS values that correlated well with the BRS value obtained by the phenylephrine method (Phe-BRS). Heart rate responses observed after both squatting and standing (squatting test) are assumed to be a simple and useful tool to assess autonomic activity. We reported that indices of the squatting test showed a significant correlation with BRS assessed by Phe-BRS in diabetes. DT-BRS and the squatting test may provide promising information for the assessment of reflex vagal activity in diabetes.

Autonomic Nervous System↗

PubMed2005

Brain natriuretic peptide and cardiac autonomic function in type 2 diabetic patients.

The present study tested the hypothesis that increased plasma brain natriuretic peptide (BNP) levels are related to cardiac autonomic dysfunction in type 2 diabetic patients. A total of 32 consecutive Japanese patients with type 2 diabetes were assigned to either a high-BNP (>or=18 pg/ml) group (n=12; age 57+/-13 years, mean+/-S.D.) or a normal-BNP (<18 pg/ml) group (n=20; 59+/-10 years). No patient had any overt structural heart disease. Cardiac autonomic function was assessed by measurements of baroreflex sensitivity (BRS), heart rate variability (HRV) and cardiac (123)I-metaiodobenzylguanidine (MIBG) scintigraphic findings. BRS was lower (p<0.005) in the high-BNP group than in the normal-BNP group. However, the components of HRV, and the early and delayed myocardial uptake of (123)I-MIBG and percentage washout rate of (123)I-MIBG were not significantly different between the groups. The plasma level of BNP negatively correlated with BRS (r=0.35, p=0.049). These findings suggest that increased plasma BNP levels were related to cardiac reflex parasympathetic dysfunction in our Japanese type 2 diabetic patients.

3-Iodobenzylguanidine↗

PubMed2005

Effects of valsartan and perindopril combination therapy on left ventricular hypertrophy and aortic arterial stiffness in patients with essential hypertension.

OBJECTIVE: To compare the effects of combined therapy of an angiotensin II receptor blocker (ARB; valsartan) and an angiotensin converting enzyme inhibitor (ACEI; perindopril) on blood pressure (BP), metabolic profiles, plasma brain natriuretic peptide (BNP) levels, echocardiographic findings, and aortic pulse wave velocity (PWV) with those of respective monotherapy in never-treated patients with essential hypertension. METHODS: This was a prospective randomized trial, in which there were 31 patients with essential hypertension and left ventricular hypertrophy (LVH) who visited the outpatient clinic of Oita Red Cross Hospital (14 women and 17 men; mean+/-SD age, 59+/-5 years). Each patient was randomly assigned to receive valsartan (160 mg/day, V group, n=10), perindopril (8 mg/day, P group, n=11), or a combination of valsartan (80 mg/day) and perindopril (4 mg/day, V+P group, n=10) for 40 weeks. Ambulatory BP monitoring (ABPM), echocardiographic findings, metabolic findings, plasma BNP levels, and brachial-ankle PWV (baPWV) were evaluated before and after the 40-week therapy. RESULTS: The baseline and post-therapeutic BP levels were similar among the three groups. At baseline ABPM, non-dipping was observed in 80, 82, and 80% in the V, P, and V+P groups, respectively. Each 40-week therapy regimen comparably reduced ABP. The plasma BNP levels (P<0.0001 for each), left ventricular mass index (LVMI) (P<0.01 for each), and PWV values (P<0.0001 for each) were also reduced. However, when compared with either V or P group, the percentage reduction in LVMI (P<0.05 and P<0.005, respectively), BNP (P<0.05 for each), and baPWV values (P<0.005 and P<0.001, respectively) was greater in the V+P group. CONCLUSIONS: Our findings suggest that, when compared with each monotherapy, perindopril and valsartan combination therapy exerts greater beneficial effects regarding the regression of LVH, reduction in BNP, and improvement of PWV in a selected group of essential hypertensive patients with LVH and high prevalence of non-dipping patterns.

Aged↗

PubMed2005

Heterogeneous expression of connexin 43 in the myocardium of rabbit right ventricular outflow tract.

The right ventricular outflow tract (RVOT) has been demonstrated as an important focus in idiopathic ventricular arrhythmias. However, the role of the gap junction in this region in arrhythmic events has not been fully investigated. The purpose of this study was to evaluate the expression and distribution of the gap junction protein connexin 43 (Cx43) in the myocardium of the RVOT area of normal adult rabbits. Tissue samples were obtained from 6 regions of normal rabbit heart, i.e. the left ventricle (LV) free wall, the LV papillary muscle, the RVOT free wall, and the RVOT septum which was subdivided into the RV side, the central layer, and the LV side. Immunohistochemical analysis was performed to investigate the characteristics of Cx43 distribution in the RVOT area. In the LV free wall and papillary muscle, Cx43 was abundantly, homogeneously, and approximately equally expressed in end-to-end- and side-to-side intercellular connections. In the free wall of the RVOT, Cx43 expression was poor compared to both these LV regions and side-to-side cell connections were predominant. Cx43 was as richly and homogeneously distributed in the central layer and LV side of the RVOT septum as in the two LV regions. However, in the RV side of the RVOT septum, its distribution was scant and an unstained area was noted. The heterogeneous expression of Cx43 in the RVOT area may serve as substrate for idiopathic ventricular arrhythmia.

Animals↗

PubMed2005

High-sensitivity C-reactive protein is associated with insulin resistance and cardiovascular autonomic dysfunction in type 2 diabetic patients.

We tested the hypothesis that elevated levels of plasma high-sensitivity C-reactive protein (HSCRP) are associated with insulin resistance/hyperinsulinemia and cardiovascular autonomic dysfunction in type 2 diabetic patients without insulin treatment. The study group consisted of 17 type 2 diabetic patients with high HSCRP (0.3-1.0 mg/dL; age, 59+/-8 years, mean+/-SD; high HSCRP group). The control group consisted of 18 age-matched type 2 diabetic patients with low HSCRP (<0.3 mg/dL; 59+/-7 years; low HSCRP group). Cardiovascular autonomic function was assessed by baroreflex sensitivity, heart rate variability, plasma norepinephrine concentration, and cardiac metaiodobenzylguanidine (MIBG) labeled with iodine 123 scintigraphic findings. Baroreflex sensitivity was lower in the high HSCRP group than in the low HSCRP group (P<.05). Early and delayed 123I-MIBG myocardial uptake values were lower (P<.05 and P<.005, respectively) and the percent washout rate of 123I-MIBG was higher (P<.01) in the high HSCRP group than in the low HSCRP group. Fasting plasma insulin concentration (P<.01) and the homeostasis model assessment index (P<.01) were higher in the high HSCRP group than in the low HSCRP group. Multiple regression analysis revealed that the level of HSCRP was independently predicted by fasting plasma insulin concentration and myocardial uptake of 123I-MIBG at a delayed phase. Our results suggest that high levels of HSCRP are associated with depressed cardiovascular autonomic function and hyperinsulinemia and that fasting plasma insulin concentration and myocardial uptake of 123I-MIBG at a delayed phase are independent predictors of HSCRP level in our Japanese patients with type 2 diabetes mellitus.

3-Iodobenzylguanidine↗

PubMed2005

Gender differences in autonomic modulation of ventricular repolarization in humans.

BACKGROUND: Gender differences in the incidence of ventricular arrhythmias have been reported and torsades de pointes associated with long QT syndrome are more common in women than men. Although increased sympathetic tone has an important role in vulnerability to arrhythmia, little is currently known regarding gender differences in the dynamic electrophysiological response to sympathetic stimulation. Therefore, we investigated whether there is a gender difference in humans with respect to the dynamic response of ventricular repolarization to beta-adrenergic stimulation and to autonomic blockade. METHODS: Twelve-lead ECGs were continuously recorded during isoproterenol infusion (protocol 1) and autonomic blockade with propranolol and atropine infusion (protocol 2) in 24 healthy volunteers (12 men, 23 +/- 2 years; 12 women, 23 +/- 5 years). QT (QTc) intervals were measured at the baseline and at a heart rate of 75, 100, and 120 beats/min. RESULTS: (1) The morphology of the T wave dynamically and transiently changed to bifid or biphasic during the acute phase of isoproterenol infusion. The incidence of these morphologic changes was higher in women than men (P < 0.05). (2) The QTc interval was initially prolonged and then shortened in both men and women during isoproterenol administration. However, QTc prolongation was significantly greater in women (0.44 +/- 0.02 to 0.55 +/- 0.03 sec) than men (0.42 +/- 0.03 to 0.51 +/- 0.04 sec; P < 0.05). (3) The QTc interval was significantly prolonged under autonomic blockade and the intrinsic QTc interval was longer in women than men (P < 0.05). CONCLUSION: While sympathetic stimulation and autonomic blockade modulated the dynamics of ventricular repolarization in both sexes, it was more pronounced in women. This gender difference may partially account for the susceptibility of women to arrhythmogenesis.

Adult↗

PubMed2005

[Study of the antibodies against measles, rubella, mumps and varicella-zoster viruses in sera from the medical staffs].

For infection control against measles, rubella, mumps and varicella-zoster viruses in the hospital, it is important to assess the immunity of the medical staff against those viruses and to achieve high immunocompetence in the medical staff by vaccination. We estimated the specific antibodies against measles, rubella, mumps and varicella-zoster viruses by ELISA in 686 care workers (240 men, 446 women) of Yamagata University Hospital. The members (frequencies) without antibodies for each virus were 59 (8.6%) for measles virus, 68 (9.9%) for rubella virus, 104 (18.2%) for mumps virus and 5 (0.7%) for varicella-zoster virus. The ratios of positive antibodies, especially against rubella and mumps viruses, were higher among women than men. To see the relationship between the immunity and age, we studied the numbers without antibodies by dividing the persons by age. The numbers of negative IgG for measles virus were 45 (17.5%) in the persons age of 21-30, 8 (4.3%) in 31-40, 4 (2.4%) in 41-50 and 2 (2.7%) in over 51. The numbers of negative IgG for rubella virus were 21 (8.2%) in the persons age of 21-30, 22 (11.7%) in 31-40, 22 (13.2%) in 41-50 and 3 (4.1%) in over 51. The numbers of negative IgG for mumps virus were 35 (13.6%) in the persons age of 21-30, 39 (20.7%) in 31-40, 22 (13.2%) in 41-50 and 8 (10.8%) in over 51. The numbers of negative IgG for varicella-zoster virus were 4 (1.6%) in the persons age of 21-30 and 1 (0.5%) in 31-40. The rate of the persons without antibodies but who had received vaccination in the past were the following: 46% for measles virus, 21% for rubella virus and 21% for mumps. The results of antibodies were informed individually and the persons without antibody against each virus were recommended to receive a vaccination for each virus.

Adult↗

PubMed2005

Progressive facilitation of antegrade conduction via an accessory pathway in a patient with Wolff-Parkinson-White syndrome and permanent atrial fibrillation.

The case of a 64-year-old man with Wolff-Parkinson-White syndrome and permanent atrial fibrillation (AF) is reported. The patient was admitted due to electrocardiographic feature of AF with rapid conduction over the left-sided accessory pathway. Administration of pirmenol effectively suppressed the ventricular response via an accessory pathway. A transesophageal echocardiography detected an uncertain thrombus in the left atrial appendage. During the 33-month follow-up period, the ventricular response via an accessory pathway was progressively facilitated. Radiofrequency catheter ablation using a transseptal approach was performed during AF, resulting in complete elimination of the antegrade accessory pathway conduction.

Anti-Arrhythmia Agents↗

PubMed2004

Patients with mild hypertensive heart disease and left ventricular outflow tract obstruction: treatment with angiotensin II antagonists.

Systolic anterior motion of the mitral leaflet (SAM) combined with obstruction at the left ventricular (LV) outflow tract is often observed on echocardiography in elderly hypertensive patients with severe concentric LV hypertrophy. We experienced, however, two patients with mild hypertension who had an ejection systolic murmur, SAM, and LV outflow tract obstruction with a pressure gradient of 46 and 45 mmHg, respectively, despite very mild symmetric hypertrophy of LV wall (12 mm) by echocardiography. Treatment with angiotensin II type 1 receptor blocker improved intraventricular obstruction and LV hypertrophy in both patients. Left ventricular outflow tract obstruction should be suspected in hypertensive patients with mild LV hypertrophy, particularly in those with an ejection systolic murmur. Angiotensin II antagonists could be considered as the treatment of choice for such patients.

Aged↗

PubMed2004

Regulation of QT indices mediated by autonomic nervous function in patients with type 2 diabetes.

Both the QT interval and QT dispersion in diabetic patients have been reported to increase with the progression of cardiac autonomic neuropathy and to have a prognostic value. We assessed the cardiac autonomic influences on QT indices using the measurements of baroreflex sensitivity, heart rate variability, and cardiac (123)I-metaiodobenzylguanidine scintigraphic findings in patients with type 2 diabetes mellitus. Forty-two consecutive patients with type 2 diabetes (mean+/-SD: 54+/-10 years, 22 women and 20 men) were studied. Baroreflex sensitivity negatively correlated with the maximum and minimum QTc intervals as well as QT/QTc dispersion. However, the high-frequency power and the ratio of low-frequency power to high-frequency power of heart rate variability did not correlate with any QT indices. The percent washout rate of (123)I-metaiodobenzylguanidine positively correlated with QT/QTc dispersion, but not with maximum and minimum QTc intervals. Our findings suggest that cardiac vagal dysfunction is related to QT interval prolongation while both sympathetic and vagal dysfunctions are related to increased QT dispersion in type 2 diabetic patients. Baroreflex sensitivity and percent washout rate of (123)I-metaiodobenzylguanidine may be useful parameters indicating the abnormalities of the cardiac ventricular repolarization in this population.

3-Iodobenzylguanidine↗

PubMed2004

Characteristics of new-onset ventricular arrhythmias in pregnancy.

The characteristics and underlying mechanisms of new-onset ventricular arrhythmia during pregnancy have not been adequately investigated. We studied 11 pregnant women aged 35.4 +/- 3.1 years who experienced new-onset ventricular arrhythmias during pregnancy. The onset of their first episode of ventricular arrhythmia was distributed equally over the 3 trimesters. Ventricular premature contractions (VPCs) and ventricular tachycardia (VT) exhibited a monomorphic configuration in all patients; in 8 (73%) they originated from the right ventricular outflow tract. The frequency of VPCs decreased by more than 95% in 83% of the patients; couplets and VTs disappeared completely in all patients during the postpartum period. All parameters of heart rate variability were significantly lower during pregnancy than postpartum (P < .05). QT and QTc intervals were normal during pregnancy in all patients. The slope and the intersect of the QT/RR relationship obtained from Holter ECGs were not significantly different during pregnancy and in the postpartum period. New-onset ventricular arrhythmias in pregnancy manifest characteristics similar to those of idiopathic VT. Our findings suggest that various hemodynamic and neurohormonal changes associated with pregnancy play an important role in ventricular arrhythmogenesis.

Adult↗