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Biomedical subjects

Mafumi Owa

Publications and source records attributed to Mafumi Owa.

10 recordsLinked to original sources
PubMed2005

A critical increase in right-to-left shunt after acute myocardial infarction in a 68-year-old male with tetralogy of Fallot.

A male patient with tetralogy of Fallot accompanied by aortic regurgitation had maintained sufficient exercise capacity for a number of decades with the status of acyanotic tetralogy of Fallot. When he was 67 years old, he suffered a posterior wall acute myocardial infarction and direct percutaneous coronary angioplasty successfully revascularised the target lesion in the left circumflex artery. However, a few months after the onset of the myocardial infarction, his shortness of breath became clinically significant and was associated with increased right-to-left shunt and increased right ventricular end-diastolic pressure, as well as hypoxia. At 68 years old, therefore, total corrective repair of the tetralogy with replacement of the aortic and pulmonary valves was performed. The patient was asymptomatic after the successful operation. This report suggests that coronary artery disease can be one of the potential factors in inducing critical hemodynamic changes in aging patients with congenital heart disease, especially those who have a shunt between the right and left chambers. The unique clinical course is described with some discussion of the repair of tetralogy in adults.

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PubMed2003

The influence of spontaneous termination of atrial fibrillation on P wave-triggered signal-averaged electrocardiogram.

BACKGROUND: Prolongation of total filtered P wave duration (Ad) and low root mean square voltages for the last 20 ms of the P wave (LP20) on a P wave-triggered signal-averaged electrocardiogram (PSAECG) are typically observed in paroxysmal atrial fibrillation (PAF) patients. A shortening of atrial refractoriness and intra-atrial conduction delay (atrial remodeling) have been shown to occur in response to PAF. We, therefore, investigated the effects of spontaneous termination of PAF on the parameters of PSAECG. METHODS: We measured the Ad, LP20 and left atrial (LA) diameter by ultrasonic echocardiography before, within 1 h after, and 3 and 12 months after PAF termination in patients with no structural heart disease (n=11). RESULTS: The PAF duration was 16+/-5 h. The Ads before, within 1 h after, and 3 and 12 months after PAF were 137+/-4, 148+/-4, 137+/-6, and 135+/-7 ms, respectively. The Ad within 1 h after PAF was significantly (P<0.01) longer than at the other three acquisition points. Although the LP20 within 1 h after PAF termination was not significantly different from the other three points, the change in LP20 (within 1 h after PAF-before PAF, -1.1+/-0.4 microV) in the long PAF duration group was significantly (P<0.05) greater than that of the short PAF duration group. LA diameter was unchanged at all points. CONCLUSION: These data suggest that PAF results in prolongation of Ad after termination of PAF.

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PubMed2003

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

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. METHODS AND RESULTS: Twenty-three patients (65 +/- 2 years) who underwent 24-hour ambulatory monitoring, had one or more episodes of PAF (>30 min), and had maintained normal sinus rhythm for >60 min before/after PAF were enrolled in this study. Mean duration of PAF was 6.2 +/- 1.2 hours. HRV parameters were analyzed in a 10-minutes section at 60 minutes, 20 minutes, and immediately before the onset of PAF and after its termination. PAF began at night in 14 patients (group N) and during the daytime in 9 patients (group D). In group N, the high-frequency (HF) component and low-frequency (LF) component showed a significant decrease after PAF; PAF was preceded by a gradual increase in HF and LF. Changes in the LF/HF ratio, however, did not occur before or after PAF. Conversely, group D showed a significant increase in the LF/HF ratio before PAF and a decrease in LF and the LF/HF ratio after PAF, but no changes in HF. These changes in HRV parameters were not influenced by the duration or termination time of PAF. CONCLUSION: This study suggests that the autonomic nervous system plays an important role in both the initiation and termination of PAF. Furthermore, the time of PAF onset influences the autonomic tone at the initiation and termination of PAF.

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PubMed2003

Percutaneous cardiopulmonary support aids resuscitation from sustained ventricular tachycardia.

A 67-year-old man was transferred to hospital because of acute circulatory failure resulting from sustained left ventricular tachycardia (LVT) and dysfunction. Transthoracic echocardiography revealed severely impaired left ventricular contraction and dyskinesis of the apical wall. Neither anti-arrhythmic agents nor direct current cardioversion was effective; the patient was resuscitated by immediate use of percutaneous cardiopulmonary support and intraaortic balloon counterpulsation. Ventricular contraction returned to normal following restoration of normal sinus rhythm with amiodarone and cibenzoline. The pathogenesis of LVT accompanied by transient ventricular dyskinesis is discussed with regard to the efficient use of a mechanical circulatory support system in resuscitation.

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PubMed2003

Effects of angiotensin-converting enzyme inhibition on changes in left ventricular myocardial creatine kinase system after myocardial infarction: their relation to ventricular remodeling and function.

We assessed the effects of angiotensin-converting enzyme (ACE) inhibition on changes in the myocardial intracellular creatine kinase (CK) system in relation to left ventricular (LV) remodeling and function in heart failure after myocardial infarction (MI) in rats. We compared the findings at 4 weeks after MI to those at 12 weeks after MI. LV weight and chamber size were significantly increased and percent fractional shortening (%FS) was decreased in untreated MI rats compared with normal control animals both at 4 and 12 weeks after MI. Animals with MI and treated with the ACE inhibitor temocapril showed significantly reduced LV weight and chamber size and increased %FS compared with untreated MI rats at 12 weeks after MI, but not at 4 weeks after MI. At 4 weeks after MI, no significant changes were found in the total creatine and relative distribution of each CK isoenzyme in either the temocapril-treated or untreated animals with MI compared with the normal controls. In contrast, at 12 weeks after MI, untreated MI rats showed significant reductions in the total creatine and mitochondrial and MM-CK fractions and increases in the MB- and BB-CK fractions compared with the controls. The alterations in the mitochondrial and MB-CK fractions were significantly attenuated after 12 weeks of ACE inhibition. Thus, LV myocardial energy metabolism is progressively impaired and its alteration is not related to the magnitude of geometric changes and LV dysfunction after MI. Most of the beneficial effects of ACE inhibition were observed at 12 weeks after MI. Our results may provide an insight into the therapeutic strategy of ACE inhibition in chronic heart failure after MI.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2002

Quantification of cardiac stress during EGD without sedation.

BACKGROUND: Although the complication rate of endoscopy is low, EGD may induce cardiac stress. The aim of this study was to quantify cardiac stress during EGD. METHODS: Heart rate, blood pressure, cardiac output, and peripheral oxygen saturation were measured during endoscopy without sedation in 7 volunteers. Cardiac output was measured with an automated echocardiographic technique. Cardiac index, left ventricular work index, and rate-pressure product were calculated. Serum catecholamine concentrations were measured before and after the examination. RESULTS: Heart rate increased significantly when the endoscope was located in the esophagus compared with the rate before insertion (p < 0.05). No significant changes in cardiac index and left ventricular work index were observed during endoscopy. Rate-pressure product increased significantly at the point of esophageal observation compared with that before insertion (p < 0.05). The rate-pressure product was maximally increased during esophageal observation at 66% over baseline (95% CI [45%, 86%]). Serum concentration of norepinephrine rose significantly after the examination (p < 0.05). CONCLUSIONS: Cardiac output did not increase during EGD without sedation in healthy male volunteers. Cardiac stress increased during EGD as indicated by a 66% increase in rate-pressure product. The cardiac stress was approximately equal to that observed in 3.3 to 5 metabolic equivalents of treadmill exercises.

Adult↗
PubMed2002

Iodine-123 metaiodobenzylguanidine scintigraphic analysis of myocardial sympathetic innervation in patients with AL (primary) amyloidosis.

BACKGROUND: Although a high incidence of myocardial adrenergic denervation has been reported in patients with familial amyloid polyneuropathy, assessment of cardiac sympathetic nerve function has not been available in patients with AL (primary) amyloidosis. METHODS: To test the hypothesis that myocardial sympathetic nerve innervation might be impaired and variable according to the presence or absence of clinical autonomic abnormalities and congestive heart failure in AL amyloidosis, we examined 25 patients by use of iodine-123 metaiodobenzylguanidine (MIBG) scintigraphy. RESULTS: Ten of the 16 patients without autonomic symptoms and 5 of the 9 patients with autonomic neuropathy showed congestive heart failure. The heart/mediastinal activity (H/M) ratio (1.53 +/- 0.06 vs 1.29 +/- 0.05 at 3 hours, P <.001) and myocardial washout ratio (41.5% +/- 4.8% vs 30.8% +/- 4.0%, P <.001) of MIBG were significantly increased in patients without autonomic symptoms compared with patients showing autonomic neuropathy. In patient groups with and without autonomic dysfunction, patients demonstrating congestive heart failure exhibited a significantly decreased H/M ratio and increased washout compared with patients with no heart failure, and left ventricular fractional shortening was positively correlated with the H/M ratio and inversely correlated with the washout ratio. There were significant correlations between the low-frequency component of the heart rate variability and the H/M ratio and washout ratio in the entire patient population. CONCLUSIONS: Patients with AL amyloidosis and no autonomic dysfunction showed variable degrees of enhanced cardiac adrenergic neuronal activity with presynaptic sympathetic dysfunction. In contrast, patients with AL amyloidosis and autonomic neuropathy exhibited prominent myocardial adrenergic denervation with normal or impaired sympathetic neural function of the heart. This study demonstrates that myocardial uptake and turnover of MIBG in patients with AL amyloidosis are heterogeneous and dependent on the presence or absence of congestive heart failure and cardiac autonomic dysfunction.

3-Iodobenzylguanidine↗
PubMed2002

Aortic dissection complicating failed coronary stenting.

We present a case of coronary dissection with retrograde extension to the sinus of Valsalva and ascending aorta after transradial percutaneous coronary intervention. Sealing the entry port of the coronary dissection with a stent resulted in failure. We made careful observation of the patient s course because the dissection did not seem to progress. Abnormal staining of the false lumen disappeared within an hour and the dissection repaired itself spontaneously in a day.

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