Michiko Yukinaka

Brugada syndrome associated with an autonomic disorder

A 44 year old man with Brugada syndrome and ventricular fibrillation had an autonomic disorder, shown by spectral analysis of heart rate variability and 123I-MIBG myocardial scintigraphy. Periodic variation of the ST segments was detected by Holter ECG. Increased high frequency power (0.15–0.40 Hz), an index of parasympathetic nerve activity, was observed just before ST segment elevation. In addition, local dysfunction of sympathetic nerves in the left ventricle was detected by 123I-MIBG myocardial scintigraphy. Unbalanced autonomic nerve function plays an important role in inducing Brugada-type ECG signs.

Mismatch between myocardial accumulation of 123 I-MIBG and 99m Tc-MIBI and late ventricular potentials in patients after myocardial infarction: Association with the development of ventricular arrhythmias

BACKGROUND Late ventricular potentials are widely used to predict life-threatening arrhythmias, although the predictive value is low. To improve prediction, we correlated the incidence of ventricular arrhythmias with mismatches in myocardial 99mTc-methoxyisobutylisonitrile (MIBI)/(123)I-metaiodobenzylguanidine (MIBG) accumulation and late ventricular potentials (LP). METHODS AND RESULTS Fifty patients with old myocardial infarctions were divided into an LP-positive group (n = 19) and an LP-negative group (n = 31). On bulls-eye single photon emission computed tomographic MIBI and MIBG images, the heart was divided into 9 segments to evaluate the accumulation of the 2 nuclides. There was no difference in total defect score (TDS) for MIBI between the LP-positive and LP-negative groups. However, TDS for MIBG and differences TDS between MIBI and MIBG (ATDS) were significantly greater in the LP-positive group. CONCLUSIONS The incidence of severe ventricular arrhythmias was greater among patients with an increased ATDS in the LP-positive group. Thus the combination of these two methods may improve the prediction of ventricular arrhythmias after myocardial infarction.

Assessment of autonomic nervous activity during gastrointestinal endoscopy: Analysis of blood pressure variability by tonometry

We continuously measured blood pressure by tonometry in 30 patients during endoscopy to determine the influence of upper gastrointestinal endoscopy on cardiac events. Patients were divided into two groups: one group treated with scopolamine butylbromide as premedication (SB group) and another group without premedication (C group). Time‐ and frequency domain analyses of beat‐to‐beat systolic blood pressure variability were performed for 128 consecutive beats. For time‐domain analysis, we calculated the coefficient of variation of systolic blood pressure (CVBP). For the frequency domain analysis, we determined the low‐frequency (LFBP; 0.04–0.15 Hz) and high‐frequency (HFBP; 0.15–0.40 Hz) powers of the variation in systolic blood pressure and the ratio of LFBP to HFBP (LFBP/HFBP) during endoscopy. The CVBP and HFBP, indicators of parasympathetic tone, increased in the early phase of endoscopy but decreased significantly in the middle and late phases compared with the pre‐endoscopy value. The ratio of LFBP/HFBP, an indicator of indirect sympathetic tone, increased throughout the endoscopic procedure. Moreover, premedication with scopolamine butylbromide prevents the excessive parasympathetic nervous reflex when an endoscope passes through the upper digestive tract and also brings both decreased parasympathetic tone and increased sympathetic tone at the late phase of endoscopic procedure. Our results indicate that gastrointestinal endoscopy induced an autonomic nervous abnormality, which may contribute to the occurrence of cardiac events during endoscopic procedures.

Evaluation of autonomic nervous function in patients with essential hypertension complicated with peptic ulcer

Background and Aims : The relationship between peptic ulcer, autonomic activity and the incidence of Helicobacter pylori infection in untreated hypertensive patients complicated with peptic ulcer were evaluated.

Early diagnosis of interferon-induced myocardial disorder in patients with chronic hepatitis C: evaluation by myocardial imaging with 123I-BMIPP

Abstract: Interferon (IFN) therapy for chronic hepatitis C is sometimes associated with cardiac complications. In the present study, we performed myocardial imaging with 123I-labeled β-methyl-p-iodophenylpentadecanoic acid (123I-BMIPP) in order to evaluate myocardial disorders caused by IFN. We studied 40 healthy subjects (H group) and 25 patients with chronic hepatitis C who had been treated with IFN (IFN group). A Holter electrocardiogram (ECG) was performed and the autonomic nervous function was assessed by analyzing the spectral variability and 1/f fluctuation of heart rate. Myocardial planner imaging with 123I-BMIPP was performed to obtain the time activity curve for 20 min immediately after administration of 123I-BMIPP (dynamic study). Early and delayed myocardial single photon emission computed tomography (SPECT) images were expressed as Bulls eyes and the myocardium was divided into four segments to calculate the washout rate for each segment on early and late SPECT images (early and late SPECT study). No significant differences in autonomic nervous function were observed between the two groups in heart rate variability. In a dynamic study, the reduction rate from the time activity curve was significantly higher in the IFN group compared with the H group (reduction rate, IFN group, 5.3 ± 3.7% vs H group, 1.2 ± 3.3%; P < 0.05). In the early and delayed myocardial SPECT study, the washout rate for the IFN group was significantly increased in all myocardial areas compared to that in the H group. However, the metabolic disorder of fatty acids caused by IFN was reversed on the se-cond 123I-BMIPP myocardial scintigraphy examination several months after IFN therapy. These results indicate that metabolic disorders of fatty acids caused by IFN therapy can be detected before abnormalities are observed by Holter-ECG or echocardiography.

Is autonomic dysfunction a necessary condition for chronic peptic ulcer formation

Background: The relationship between 1/f fluctuation of the heart rate variability and Helicobacter pylori infection was evaluated, in order to clarify whether autonomic nervous dysfunction is a necessary condition for chronic peptic ulcer formation.

Age-related changes in the magnitude of ventricular depolarization vector: analyses by magnetocardiogram.

The magnetocardiogram has the beneficial feature that permits the strength and location of the current dipole to be estimated. This study examines the issue of whether the magnitude of the heart current during depolarization phase was influenced by the age of healthy subjects. The magnetocardiograms were recorded by means of a second-derivative SQUID (superconducting quantum interference device) magnetometer (BT Corp, Model BMP, San Diego, CA) in 150 healthy subjects. The subjects were subgrouped into 5 age-based categories according to the age. The current dipole of the maximum QRS complex was determined from isofield contour maps during the ventricular depolarization phase, and no significant differences were observed in the magnitude in the current source for any age category. However, the amplitudes of the RV5 and SV1 + RV5 in the standard electrocardiogram were larger in 65 to 74-year-old women than other age groups, and the SV1 + RV5 was smaller for the 45 to 74-year-old men than for the men aged 25 to 44 years. These findings suggest that the age-associated changes in the QRS complex observed by the electrocardiogram are caused by increased electric resistance and not by the heart current itself. The results additionally suggest that no effects of aging were observed in the actual heart current of the heart during the depolarization phase.

Source Localization of Initial QRS Vector in Patients with Idiopathic Cardiomyopathy: Comparison with Normal Subjects and Patients with Anterior Myocardial Infarction

The magnetocardiographic three-dimensional (3-D) source localization using superconducting quantum interference device (SQUID) gradiometer has an excellent spatial and temporal resolution. Abnormal Q wave is frequently seen in the electrocardiogram (ECG) in patients with idiopathic cardiomyopathy, even in those without myocardial infarction. In the present study, to assess the origin of abnormal Q wave in the idiopathic cardiomyopathy, current sources were analyzed by the magnetocardiograms (MCGs), and the results were to that of compared with abnormal Q wave in patients with anterior myocardial infarction.