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Featured researches published by Mafumi Owa.


Journal of the American College of Cardiology | 2001

Transient left ventricular apical ballooning without coronary artery stenosis : a novel heart syndrome mimicking acute myocardial infarction

Kazufumi Tsuchihashi; Kenji Ueshima; Tatsuro Uchida; Nobuhiro Ohmura; Kazuo Kimura; Mafumi Owa; Minoru Yoshiyama; Shunichi Miyazaki; Kazuo Haze; Hisao Ogawa; Takashi Honda; Mamoru Hase; Ryuichi Kai; Isao Morii

Abstract OBJECTIVES To determine the clinical features of a novel heart syndrome with transient left ventricular (LV) apical ballooning, but without coronary artery stenosis, that mimics acute myocardial infarction, we performed a multicenter retrospective enrollment study. BACKGROUND Only several case presentations have been reported with regard to this syndrome. METHODS We analyzed 88 patients (12 men and 76 women), aged 67 ± 13 years, who fulfilled the following criteria: 1) transient LV apical ballooning, 2) no significant angiographic stenosis, and 3) no known cardiomyopathies. RESULTS Thirty-eight (43%) patients had preceding aggravation of underlying disorders (cerebrovascular accident [n = 3], epilepsy [n = 3], exacerbated bronchial asthma [n = 3], acute abdomen [n = 7]) and noncardiac surgery or medical procedure (n = 11) at the onset. Twenty-four (27%) patients had emotional and physical problems (sudden accident [n = 2], death/funeral of a family member [n = 7], inexperience with exercise [n = 6], quarreling or excessive alcohol consumption [n = 5] and vigorous excitation [n = 4]). Chest symptoms (67%), electrocardiographic changes (ST elevation [90%], Q-wave formation [27%] and T-wave inversion [97%]) and elevated creatine kinase (56%) were found. After treatment of pulmonary edema (22%), cardiogenic shock (15%) and ventricular tachycardia/fibrillation (9%), 85 patients had class I New York Heart Association function on discharge. The LV ejection fraction improved from 41 ± 11% to 64 ± 10%. Transient intraventricular pressure gradient and provocative vasospasm were documented in 13/72 (18%) and 10/48 (21%) of the patients, respectively. During follow-up for 13 ± 14 months, two patients showed recurrence, and one died suddenly. CONCLUSIONS A novel cardiomyopathy with transient apical ballooning was reported. Emotional or physical stress might play a key role in this cardiomyopathy, but the precise etiologic basis still remains unclear.


American Journal of Cardiology | 1984

Augmentation of atrial contribution to left ventricular inflow with aging as assessed by intracardiac Doppler flowmetry.

Kunio Miyatake; Mitsunori Okamoto; Naokazu Kinoshita; Mafumi Owa; Izuru Nakasone; Hiroshi Sakakibara; Yasuharu Nimura

The influence of aging on the left ventricular (LV) function in diastole was investigated from the aspect of the mitral inflow pattern using 2-dimensional Doppler echocardiography. The subjects for the investigation were 69 persons who were diagnosed as healthy by a checkup examination. The peak velocity in the rapid filling phase and that in the atrial contraction phase tended to decrease and to increase with aging, respectively. However, these tendencies were not statistically significant. However, the ratio of the atrial contraction phase to the rapid filling phase showed a significant increase with aging (r = 0.82, p less than 0.001). Therefore, it is considered that the mitral flow conditions are influenced by aging. The result obtained is also interpreted to mean that the LV distensibility in early diastole is impaired with aging and that the contribution of the atrial contraction to LV filling is compensatorily augmented.


American Journal of Cardiology | 1984

Clinical applications of a new type of real-time two-dimensional Doppler flow imaging system

Kunio Miyatake; Mitsunori Okamoto; Naokazu Kinoshita; Shiro Izumi; Mafumi Owa; Seiichi Takao; Hiroshi Sakakibara; Yasuharu Nimura

The clinical significance of a newly developed real-time 2-dimensional (2-D) Doppler flow imaging technique was assessed. In the instrumentation of the echocardiograph, the pulsed Doppler mechanism was incorporated in a wide-angle, phased-array system. The Doppler flow signals obtained from the cardiac chamber were processed on the basis of the autocorrelation principle. The direction, velocity and variance of the intracardiac blood flow were calculated in real time and displayed in the color-coded mode on the television screen, and were superimposed on the 2-D echocardiographic image of the heart. The technique was used in 20 healthy subjects and 100 cardiac patients. The new technique clearly visualized the whole aspect of intracardiac blood flow by the cine mode in real time; thus, the technique may be called Doppler cineangiocardiography. The mitral inflow and the aortic ejection flow were clearly demonstrated. A regurgitant jet from the valve orifices was dynamically visualized as seen in the cineangiogram. The spatial orientation and extent of the regurgitant jet were easily assessed. The jet stream through the stenotic mitral orifice was well imaged in the left ventricular cavity, showing a variety of stream directions. Intracardiac shunts in ventricular septal defect and atrial septal defect were clearly visualized. The defect could be localized on the interventricular septum on the basis of the site where the shunt flow spurted, although the echocardiographic interruption was not demonstrated in the 2-D echocardiographic image of the cardiac structure. Although some technical problems remain, our new technique greatly improves the diagnostic efficacy of ultrasound.


Journal of Cardiovascular Electrophysiology | 2003

Role of autonomic tone in the initiation and termination of paroxysmal atrial fibrillation in patients without structural heart disease

Takeshi Tomita; Manabu Takei; M T Yuko Saikawa; Takeshi Hanaoka; Shin-Ichiroh Uchikawa; Hiroshi Tsutsui; Masakazu Aruga; Toyohisa Miyashita; Yoshikazu Yazaki; Hiroshi Imamura; Osamu Kinoshita; Mafumi Owa; Keishi Kubo

Introduction: Previous studies have suggested that paroxysmal atrial fibrillation (PAF) of vagal origin often occurs at night and PAF of sympathetic origin occurs during the daytime; however, autonomic tone after spontaneous termination of PAF has not been determined. The aim of this study was to evaluate by heart rate variability (HRV) analysis the relationship between the time of PAF onset and autonomic tone before and after PAF.


Vascular Medicine | 1997

Soluble form of selectins in blood of patients with acute myocardial infarction and coronary intervention.

Shumpei Sakurai; Atsushi Inoue; Chang-Sung Koh; Mafumi Owa; Nobuo Yanagisawa

Soluble (s) P-selectin, sE-selectin, sL-selectin and soluble intercellular adhesion molecule-1 (sICAM-1) levels were examined by monoclonal antibody-based enzyme immunoassay on serum samples taken from nine patients with acute myocardial infarction (AMI) and eight patients with stable angina pectoris (SAP) before and after the successful percutaneous transluminal coronary angioplasty (PTCA). In patients with acute phase of AMI, the levels (mean ± SEM) of sP-selectin (110 ± 18 ng/ml) and sE-selectin (54 ± 15 ng/ml) before PTCA, were significantly higher than those in the SAP group, the values being 44 ± 27 and 21 ± 4 ng/ml (p<0.05), respectively. After recanalization, the levels of sE-selectin and sL-selectin were significantly decreased (sE-selectin 54 ± 15 to 42 ± 11 ng/ml, sL-selectin 1104 ± 106 to 891 ± 59 ng/ml, P < 0.05, respectively). These findings suggest that the presence of activated and/or injured endothelial cells, which may be involved in the plaque disruption or intraluminal thrombosis in AMI region and that the inflammatory process may be altered after reperfusion therapy.


American Journal of Cardiology | 2000

Relation between vascular morphologic changes during stent implantation and the magnitude of in-stent neointimal hyperplasia.

Jun Koyama; Mafumi Owa; Shumpei Sakurai; Hirohide Shimada; Hiroyuki Hikita; Takeo Higashikata; Shu-ichi Ikeda

Intimal hyperplasia usually occurs after balloon overstretch injury or wire coil stimuli to coronary arteries. We examined whether the degree of vessel wall stretch during coronary stent placement could predict the amount of in-stent neointimal hyperplasia after a 6-month follow-up. Serial (preintervention, postballooning, poststent implantation, and a follow-up after 6 months) intravascular ultrasound (IVUS) was used to study 457 consecutive cross-sectional areas in 28 patients. IVUS imaging, using a motorized pullback system at 0.5 mm/s, allowed 1-mm axial increment measurements of the total vascular, stent, and lumen cross-sectional areas. The mean total vascular area changed from 10.89 +/- 2.50 mm2 before to 11.27 +/- 2.49 mm2 after ballooning, to 12.80 +/- 2.59 mm2 after stenting, and to 12.58 +/- 2.41 mm2 at follow-up (p < 0.0001). The mean lumen area changed from 3.36 +/- 1.95 mm2 before to 4.21 +/- 1.65 mm2 after ballooning, to 5.16 +/- 1.09 mm2 after stenting, and to 3.57 +/- 1.23 mm2 at follow-up (p < 0.0001). The mean stent area decreased from 5.25 +/- 1.17 mm2 after stenting to 5.09 +/- 0.90 mm2 at follow-up (p < 0.0001). Stepwise logistic regression analysis showed that delta total vascular area (after stent implantation - before intervention) was a strong predictor of the amount of intimal hyperplasia (r = 0.57, p < 0.0001). Vascular overstretch caused by the stenting procedure promotes intimal hyperplasia in proportion to the degree of sectional vascular stretch.


American Journal of Cardiology | 1996

Delayed improvement in skeletal muscle metabolism and exercise capacity in patients with mitral stenosis following immediate hemodynamic amelioration by percutaneous transvenous mitral commissurotomy

Takanori Yasu; Takaaki Katsuki; Nobuhiro Ohmura; Ikuko Nakada; Mafumi Owa; Mikihisa Fujii; Akira Sakaguchi; Muneyasu Saito

The abrupt improvement in hemodynamics after successful percutaneous transvenous mitral commissurotomy (PTMC) does not immediately enhance exercise capacity. Improved exercise capacity several months after PTMC has been reported. We hypothesized that the delayed improvement in exercise capacity is due partly to the slow improvement in the metabolism of skeletal muscle. This study examined the short- and long-term effects of PTMC on exercise capacity and skeletal muscle metabolism in patients with mitral stenosis. Treadmill exercise testing with respiratory gas analysis was performed in 11 patients with symptomatic mitral stenosis before and 3, 30, and 90 days after successful PTMC. On the same schedule, forearm metabolism of high-energy phosphates was measured by magnetic resonance spectroscopy during and after handgrip exercise. Ten healthy volunteers were examined. PTMC resulted in an immediate symptomatic improvement. However, exercise capacity and skeletal muscle metabolism remained unchanged 3 days after PTMC. At 30 days after PTMC, there were significant improvements in peak oxygen consumption (p <0.05), intracellular pH at end-exercise (p <0.05), and time constant for phosphocreatine recovery (mean +/- SD 88.9 +/- 11.3 vs 106.3 +/- 11.7 seconds, p <0.01) compared with these baseline values. These improvements remained even at 90 days after PTMC. Exercise capacity improved with some time delay after immediate hemodynamic amelioration by PTMC. Long-term improvement in exercise capacity depends partly on the slowly progressing improvement in skeletal muscle metabolism after long-standing mitral stenosis.


International Journal of Cardiology | 2000

Intravascular lymphomatosis presenting as reversible severe pulmonary hypertension

Mafumi Owa; Jun Koyama; Kiyoshi Asakawa; Hiroshi Hikita; Keishi Kubo; Shu-ichi Ikeda

Intravascular lymphomatosis commonly affects the chest roentgenogram showed a ground-glass-likevessels of the skin and central nervous system, shadow in the lower lung fields. Chest computed although blood vessels in other organs may be tomogram showed diffuse ground-glass attenuation, occluded. Primary presentation in the lungs is disfine centrilobular nodules in bilateral lung fields and tinctly uncommon [1]. In this report, we describe a bilateral hilar mild lymph node swellings. The eleccase with intravascular lymphomatosis, mainly pretrocardiogram showed sinus tachycardia and T wave senting severe hypoxia and pulmonary hypertension. inversion in the V1 to V3 chest leads. A continuous A 44-year-old woman was transferred to our wave Doppler suggested a systolic pressure gradient hospital with a history of low-grade fever about 1 of 79 mmHg between the right ventricle and right year prior to admission. Recently, progressive dyspatrium. Microscopic examination of a transbronchial nea had developed and persistent high serum lactate lung biopsy specimen demonstrated thickened alveodehydrogenase (LDH) was noted. At first, thrombolar septae and neoplastic cells that had partially embolism was suspected because of hypoxemia, aggregated and occluded the small vessels of the lung pulmonary hypertension and patchy pulmonary perfu(Fig. 1). Immunohistochemical examination revealed sion defects seen on perfusion scintigraphy, but that these abnormal cells were positive for leukocyte urokinase did not lessen her symptoms. On physical common antigen and L26, indicating a B cell origin. examination reticular erythema localized on the abAfter six weeks with the CHOP regimen (cyclodomen, and decreased superficial sensations in the phosphamide, doxorubicin, vincristine and predareas of the bilateral ulnar and tibial nerves were nisolone), her dyspnea and hypoxemia remarkably noted. Laboratory findings included a platelet count improved, and laboratory findings became normal. 2 of 100 000/mm , CRP of 5.4 mg/dl, an elevated Doppler study suggested a systolic pulmonary presLDH level (2,584 U/ l, normal ,220 U/ l), beta-2 sure of 20|25 mmHg. The elevated LDH level microglobulin of 7.18 mg/ l, Ferritin of 242.2 ng/ml persisted, however, and consequently oral Etoposide and elevated liver function tests (GOT 177U/ l, GPT administration was started as salvage chemotherapy. 126U/ l). and arterial blood gas levels were pH 7.467, Six months later she died of recurrent lymphoma with P 47.8 mmHg, P 33.9 mmHg in room air. The advanced respiratory failure. O CO 2 2 Lung involvement in intravascular lymphomatosis can be demonstrated pathologically at autopsy in approximately 60% of patients, although predominant *Corresponding author. E-mail address: [email protected] (M. Owa). manifestation in lung is extremely rare. It is im-


Prehospital and Disaster Medicine | 2007

Medical care for a mass gathering: the Suwa Onbashira Festival.

Kazuyuki Yazawa; Yukihiro Kamijo; Ryuichi Sakai; Masahiko Ohashi; Mafumi Owa

INTRODUCTION The Suwa Onbashira Festival is held every six years and draws approximately one million spectators from across Japan. Men ride the Onbashira pillars (logs) down steep slopes. At each festival, several people are crushed under the heavy log. During the 2004 festival, for the first time, a medical care system that coordinated a medical team, an emergency medical service, related agencies, and local hospitals was constructed. OBJECTIVE The aims of this study were to characterize the spectrum of injuries and illness and to evaluate the medical care system of this festival. METHODS The festival was held 02 April-10 May 2004. The medical records of all of the patients who presented to an on-site medical tent or who were treated at the scene and transported to hospitals over a 12-day period were reviewed. The following items were evaluated: (1) the emergency medical system at the festival; (2) the environmental circumstances; and (3) patient data. RESULTS All medical usage rates are reported as patients per 10,000 attendees (PPTT). A total 1.8 million spectators attended the festival during the 12-day study period; a total of 237 patients presented to the medical tent (1.32 PPTT), and 63 (27%) were transferred to hospitals (0.35 PPTT). Of the total, 135 (57%) suffered from trauma--two were severely injured with pelvic and cervical spine fractures; and 102 (43%) had medical problems including heat-related illness. CONCLUSIONS Comprehensive medical care is essential for similar mass gatherings. The appropriate triage of patients can lead to efficient medical coverage.


Pacing and Clinical Electrophysiology | 1999

Percutaneous Cephalic Vein Approach for Permanent Pacemaker Implantation

Hirohide Shimada; Kazuo Hoshino; Masayoshi Yuki; Shumpei Sakurai; Mafumi Owa

Implantation of permanent pacemaker leads into the cephalic vein within the deltopectoral groove is enhanced by introduction of a flexible guidewire into the brachial vein at the antecubital fossa, which is then advanced to the subclavian vein. The cephalic vein within the deltopectoral groove is easily found by incision with the guidewire as a marker. A pacing lead or leads can be inserted along the guidewire or by using a sheath advanced over the guidewire. The procedure was performed on 32 patients and the pacing leads of 28 procedures (DDD 15, VDD 9 and VVI 4) were inserted using the cephalic vein without complications.

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Kazuo Kimura

Yokohama City University Medical Center

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Teruo Inoue

Dokkyo Medical University

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