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Biomedical subjects

Shunichi Homma

Publications and source records attributed to Shunichi Homma.

At least 55 records · Page 3Linked to original sources
PubMed2004

Effect of aspirin and warfarin therapy in stroke patients with valvular strands.

BACKGROUND: Valvular strands are associated with ischemic stroke. The recurrent rate of adverse events in stroke patients with valvular strands has not been defined and, importantly, there are no randomized studies to evaluate efficacy of antithrombotic therapies in these patients. METHODS: Patent Foramen Ovale in Cryptogenic Stroke Study (PICSS) enrolled 630 stroke patients, of whom 312 (49.5%) were randomized to warfarin and 318 (50.5%) were randomized to aspirin; 265 patients experienced cryptogenic stroke and 365 experienced stroke with known subtypes. Endpoints were recurrent ischemic stroke or death from any cause. All transesophageal echocardiography studies were blindly, centrally analyzed and all endpoints were blindly adjudicated. RESULTS: Overall, of 619 studies analyzed, valvular strands were present in 39.4% of the patients (244/619), 5.8% (36/619) on the aortic valve and 27.8% (172/619) on the mitral valve, and 5.8% (36/619) on both valves. In an intention-to-treat analysis, there was no significant difference in the time to primary endpoints between patients with and without strands in the overall population (P=0.82; hazard ratio: 1.05; 95% CI: 0.70 to 1.57; 2-year event rates: 16.4% versus 15.5%). Among the patients with strands, there was no significant difference in the time to primary endpoints between those treated with warfarin or aspirin (P=0.21; hazard ratio: 0.67; 95% CI: 0.36 to 1.26; 2-year event rates: 13.5% versus 19.6%). CONCLUSIONS: While on medical therapy, valvular strands do not significantly increase recurrent adverse event rates in patients with ischemic stroke. Furthermore, the study does not provide evidence to support an advantage of warfarin or aspirin for this purpose.

Adult↗
PubMed2004

Relation between socioeconomic status, race-ethnicity, and left ventricular mass: the Northern Manhattan study.

Increased left ventricular mass (LVM) and lower socioeconomic status (SES) are predictors of cardiovascular morbidity and mortality. Blacks and Hispanics are more likely to have higher LVM and lower SES. The relation between SES, race-ethnicity, and LVM has not been fully explored. Data were used from the NOMAS population-based sample of 1916 subjects living in Northern Manhattan. SES was characterized on the basis of educational attainment and divided into 4 categories. Echocardiography-defined LVM was indexed according to height at the allometric power of 2.7 and analyzed as a continuous variable. LVM varied by race in our cohort (blacks 48.9 g/m2.7, Hispanics 48.4 g/m2.7, whites 45.6 g/m2.7; P=0.004). Using ANCOVA, there was a significant inverse and graded association between mean LVM and SES for the total cohort. Mean LVM was 48.4 g/m2.7, 48.6 g/m2.7, 47.1 g/m2.7, and 45.3 g/m2.7 for the lowest to the highest educational level category (P trend=0.0004). This relationship remained among normotensives (P trend=0.0005) and was present for blacks (P trend=0.009), but not for whites (P trend=0.86) or Hispanics (P trend=0.47). The difference in mean LVM between the highest and lowest categories of education was 5.3 g/m2.7 for blacks, 0.0 g/m2.7 for whites, and 1.0 g/m2.7 for Hispanics. Lower SES is an independent predictor of increased LVM among hypertensive and normotensive blacks.

Black or African American↗
PubMed2004

Management of patients with stroke and a patent foramen ovale.

Observational studies have established a strong association between the presence of patent foramen ovale (PFO) and increased risk of ischemic stroke. The mechanism involved is presumed to be a paradoxical embolism from a venous thrombus that travels via the PFO to the systemic circulation. The best treatment modality to prevent recurrent stroke in patients with PFO remains undefined. There are four major choices: 1) medical therapy with anticoagulants, 2) medical therapy with antiplatelet agents, 3) surgical closure, and 4) percutaneous device closure. The Patent Foramen Ovale in Cryptogenic Stroke Study has demonstrated that antiplatelet and anticoagulant therapies are of equal benefit in preventing recurrent neurologic events in stroke patients with a PFO. Medical therapy should remain as the initial choice of secondary prophylactic therapy. PFO closure, either surgical or percutaneous, may further reduce event rates; however, this remains to be demonstrated because no randomized trial to date has compared PFO closure with medical therapy.

Anticoagulants↗
PubMed2004

Management of patients with stroke and a patent foramen ovale.

Observational studies have established a strong association between the presence of patent foramen ovale (PFO) and increased risk of ischemic stroke. The mechanism involved is presumed to be a paradoxical embolism from a venous thrombus that travels via the PFO to the systemic circulation. The best treatment modality to prevent recurrent stroke in patients with PFO remains undefined. There are four major choices: 1) medical therapy with anticoagulants, 2) medical therapy with antiplatelet agents, 3) surgical closure, and 4) percutaneous device closure. The Patent Foramen Ovale in Cryptogenic Stroke Study has demonstrated that antiplatelet and anticoagulant therapies are of equal benefit in preventing recurrent neurologic events in stroke patients with a PFO. Medical therapy should remain as the initial choice of secondary prophylactic therapy. PFO closure, either surgical or percutaneous, may further reduce event rates; however, this remains to be demonstrated because no randomized trial to date has compared PFO closure with medical therapy.

Anticoagulants↗
PubMed2004

Measurement of coronary vasomotor function: getting to the heart of the matter in cardiovascular research.

Measurement of endothelial function in patients has emerged as a useful tool for cardiovascular research. Although no gold standard for the measurement of endothelial function exists, the measurement of flow-mediated dilation in the brachial artery, assessed with Doppler ultrasonography, is the most studied method. However, the assumption that endothelial dysfunction detected in brachial arteries is a manifestation of systemic endothelial dysfunction including the coronary circulation may not be entirely valid. Brachial and myocardial circulations differ in terms of the microvascular architecture, the pattern of blood flow and vascular resistance (e.g. shunt vessels occur in the hand but not in the myocardium), their metabolic regulation, type of receptors that contribute to humoral regulation and the pathways that are activated to induce hyperaemia. In this context, measuring coronary vasomotor function may be more useful than brachial artery measures to predict and assess potential myocardial damage related to limited vascular responsiveness. This review aims to provide an overview of the basic concept of coronary flow reserve and its different modalities of measurement, as well as its utility in cardiovascular research.

Brachial Artery↗
PubMed2004

Central role for aldose reductase pathway in myocardial ischemic injury.

Aldose reductase (AR), a member of the aldo-keto reductase family, has been implicated in the development of vascular and neurological complications of diabetes. Recently, we demonstrated that aldose reductase is a component of myocardial ischemic injury and that inhibitors of this enzyme protect rat hearts from ischemia-reperfusion injury. To rigorously test the effect of aldose reductase on myocardial ischemia-reperfusion injury, we used transgenic mice broadly overexpressing human aldose reductase (ARTg) driven by the major histocompatibility complex I promoter. Hearts from these ARTg or littermate mice (WT) (n=6 in each group) were isolated, perfused under normoxic conditions, then subjected to 50 min of severe low flow ischemia followed by 60 min of reperfusion. Creatine kinase (CK) release (a marker of ischemic injury) was measured during reperfusion; left ventricular developed pressure (LVDP), end diastolic pressure (EDP), and ATP were measured throughout the protocol. CK release was significantly greater in ARTg mice compared with the WT mice. LVDP recovery was significantly reduced in ARTg mice compared with the WT mice. Furthermore, ATP content was higher in WT mice compared with ARTg mice during ischemia and reperfusion. Infarct size measured by staining techniques and myocardial damage evaluated histologically were also significantly worse in ARTg mice hearts than in controls. Pharmacological inhibition of aldose reductase significantly reduced ischemic injury and improved functional recovery in ARTg mice. These data strongly support key roles for AR in ischemic injury and impairment of functional and metabolic recovery after ischemia. We propose that interventions targeting AR may provide a novel adjunctive approach to protect ischemic myocardium.

Adenosine Triphosphate↗
PubMed2004

Simvastatin preserves cardiac function in genetically determined cardiomyopathy.

Endothelial dysfunction characterizes heart failure (HF). Simvastatin (Sim) increases endothelial nitric oxide (NO) independent of lipid-lowering. We evaluated the effect of Sim on cardiac function, apoptosis, and NO availability in HF. Five-month-old cardiomyopathic (CM) hamsters were divided into 2 groups: Sim (20 mg/kg, 6 weeks, n = 6) and Untreated (n = 6). Age-matched normal hamsters served as controls (n = 6). Serial echocardiograms were performed to measure LV function. Myocardial apoptosis, eNOS, and capillary density were measured at 6 weeks. Cardiomyopathic hamsters had lower LV shortening fraction (SF) compared with controls (17 +/- 3% vs 59 +/- 2%), higher LV end-diastolic volume (30 +/- 3 vs 6 +/- 2 mL/m2), and lower LV mass/volume ratio (0.5 +/- 0.04 vs 0.72 +/- 0.02 mg/ml, P < 0.001). During follow-up, SF decreased (9 +/- 2%) and LV volume increased (38 +/- 1 mL/m2) in untreated hamsters (P < 0.05 from baseline) but did not change significantly in the Sim group (P < 0.05 vs untreated). Myocardial caspase-3 activity was higher and apoptotic nuclear density was lower in Sim compared with untreated CM hamsters (0.072 +/- 0.02% vs 0.107 +/- 0.03%, P < 0.01). Myocardial capillary density was highest in the Sim group (P < 0.05). eNOS expression was not different between groups. Sim retards the progression of HF in CM hamsters. This may be related to an increase in coronary microvasculature, increase in NO availability, and decreased apoptosis.

Angiogenesis Inducing Agents↗
PubMed2004

Macrophage inhibitor, semapimod, reduces tumor necrosis factor-alpha in myocardium in a rat model of ischemic heart failure.

Pharmaceutical agents aimed at reducing tumor necrosis factor-alpha (TNF-alpha) levels appeared to be attractive possibilities in the medical management of heart failure, as heart failure was shown to be associated with high TNF-alpha levels. However, therapies specifically targeting TNF-alpha failed to show any survival benefit. We examined whether a broad inhibition of inflammatory cytokine production secondary to macrophage inhibition would be more effective at improving cardiac function in the setting of heart failure. To this end, we studied Semapimod (formerly known as CNI-1493), a synthetic guanylhydrazone that inhibits macrophage activation and the production of several inflammatory cytokines. Left anterior descending coronary ligation surgery was performed on each animal to induce a myocardial infarction. After confirming heart failure by echocardiography, the animals were randomly assigned to one of four groups: (1) rats with myocardial infarct receiving high-dose Semapimod, 10 mg/kg/d (MI-H, N = 13); (2) rats with myocardial infarct receiving low-dose Semapimod, 3 mg/kg/d (MI-L, N = 9); (3) rats with myocardial infarct receiving vehicle treatment, 2.5% mannitol in water (MI-0, N = 9); and (4) control rats with sham operation and vehicle treatment (Sham, N = 10). Both Semapimod and vehicle treatments were administered by daily tail vein injections over a course of five days. Echoes were repeated at 2, 5, and 9 weeks following treatment. At 9 weeks, hemodynamic data were collected and the animals were euthanized. Trichrome staining was done to assess infarct, and immunohistochemistry was performed to assess TNF-alpha levels. Prior to drug administration, serum was taken from 5 random rats. No detectable level of TNF-alpha was seen (lower limit of detection for the assay used = 12.5 pg/mL). Also prior to any treatment, echocardiography confirmed significant cardiac impairment of rats undergoing LAD ligation as compared with sham. Over the course of the 9 weeks, there were 4 deaths, all in the MI-H group. There was no difference between Semapimod-treated animals and vehicle-treated MI animals in any echocardiographic or hemodynamic parameter. TNF-alpha staining in the noninfarcted region was evident only in the MI groups, not the sham group. When blindly compared on a semiquantitative scale (ie, 0 = no visible staining to 3 = marked staining), a significant difference in staining was observed between MI-0 versus MI-H (1.19 +/- 0.32 versus 0.33 +/- 0.14; P = 0.03) and between MI-0 and MI-L (1.19 +/- 0.32 versus 0.39 +/- 0.22; P = 0.05). In this setting, despite the fact that Semapimod treatment decreased tissue TNF-alpha levels, it did not improve cardiac function, and at high doses it was associated with higher mortality. These results in a rodent model confirm the results of clinical trials with etanercept and infliximab (ie, that decreasing TNF levels in plasma or tissues does not improve cardiac function and may actually increase mortality).

Animals↗
PubMed2004

Hypopharyngeal perforation near-miss during transesophageal echocardiography.

OBJECTIVES/HYPOTHESIS: The traditional blind passage of a transesophageal echocardiography probe transorally through the hypopharynx is considered safe. Yet, severe hypopharyngeal complications during transesophageal echocardiography at several institutions led the authors to investigate whether traditional probe passage results in a greater incidence of hypopharyngeal injuries when compared with probe passage under direct visualization. STUDY DESIGN: Randomized, prospective clinical study. METHODS: In 159 consciously sedated adults referred for transesophageal echocardiography, the authors performed transesophageal echocardiography with concomitant transnasal videoendoscopic monitoring of the hypopharynx. Subjects were randomly assigned to receive traditional (blind) or experimental (optical) transesophageal echocardiography. The primary outcome measure was frequency of hypopharyngeal injuries (hypopharyngeal lacerations or hematomas), and the secondary outcome measure was number of hypopharyngeal contacts. RESULTS: No perforation occurred with either technique. However, hypopharyngeal lacerations or hematomas occurred in 19 of 80 (23.8%) patients with the traditional technique (11 superficial lacerations of pyriform sinus, 1 laceration of pharynx, 12 arytenoid hematomas, 2 vocal fold hematomas, and 1 pyriform hematoma) and in 1 of 79 patients (1.3%) with the optical technique (superficial pyriform laceration) (P =.001). All traumatized patients underwent flexible laryngoscopy, but none required additional intervention. Respectively, hypopharyngeal contacts were more frequent with the traditional than with the optical technique at the pyriform sinus (70.0% vs. 10.1% [P =.001]), arytenoid (55.0% vs. 3.8% [P =.001]), and vocal fold (15.0% vs. 3.86% [P =.016]). CONCLUSION: Optically guided trans-esophageal echocardiography results in significantly fewer hypopharyngeal injuries and fewer contacts than traditional, blind transesophageal echocardiography. The optically guided technique may result in decreased frequency of potentially significant complications and therefore in improved patient safety.

Adult↗
PubMed2004

Left ventricular mobile thrombus associated with ventricular assist device: diagnosis by transesophageal echocardiography.

Ventricular assist devices (VADs) have been used as a bridge to cardiac transplantation in patients with end-stage congestive heart failure. Despite adequate anticoagulation, thromboembolism is a major complication and in particular, a left ventricular (LV) thrombus associated with VADs has been reported as an important cause of thromboembolic complications. The frequency of LV thrombus formation in the patients with VAD support using LV apical cannulation is reported to be low. A 61-year-old woman supported with VAD with LV apical cannulation had a mobile LV thrombus adjacent to the inflow cannula diagnosed by transesophageal echocardiography.

Echocardiography, Transesophageal↗
PubMed2003

Apolipoprotein B production reduces lipotoxic cardiomyopathy: studies in heart-specific lipoprotein lipase transgenic mouse.

Lipid accumulation is associated with cardiac dysfunction in diabetes and obesity. Transgenic mice expressing non-transferable lipoprotein lipase (LpL) with a glycosylated phosphatidyl-inositol (GPI) anchor in cardiomyocytes have dilated cardiomyopathy. However, the mechanisms responsible for lipid accumulation and cardiomyopathy are not clear. Hearts from 3-month-old mice expressing GPI-anchored human LpL (hLpLGPI) mice had increased fatty acid oxidation and heart failure genes and decreased glucose transporter genes. 6-month-old mice had increased mRNA expression and activation of the apoptosis marker caspase-3. Moreover, hLpLGPI hearts had significant cytochrome c release from mitochondria to cytosol. Low density lipoprotein uptake was greater in hLpLGPI hearts, and this was associated with more intracellular apolipoprotein B (apoB). To test whether lipid accumulation in the hLpLGPI heart is reduced by cardiac expression of apoB, hLpLGPI mice were bred with transgenic human apoB (HuB)-expressing mice. Hearts of HuB/hLpLGPI mice had less triglyceride (38%) and free fatty acids (19%), secreted more apoB, and expressed less atrial natriuretic factor (ANF) and brain natriuretic peptide (BNP) and more glucose transporter 4 (GLUT4). The increased mortality of the mice was abrogated by the transgenic expression of apoB. Therefore, we hypothesize that cardiac apoB expression improves cardiomyopathy by increasing lipid resecretion from the heart.

Animals↗
PubMed2003

Atrial anatomy in non-cardioembolic stroke patients: effect of medical therapy.

OBJECTIVES: The purpose of the study was to assess the mechanism responsible for increased stroke risk in patients with atrial septal aneurysm (SA) and patent foramen ovale (PFO), and to determine the efficacy of medical therapy for preventing stroke recurrence or death. BACKGROUND: Atrial septal aneurysm and PFO are associated with stroke. However, the mechanism for this association is undefined, and the efficacy of medical therapy has not been investigated in a randomized fashion. METHODS: The Patent foramen ovale In Cryptogenic Stroke Study (PICSS) evaluated transesophageal echocardiography findings in patients enrolled in the Warfarin-Aspirin Recurrent Stroke Study, a randomized double-blind trial to evaluate the efficacy of warfarin compared with aspirin. RESULTS: Large PFO and prominent eustachian valve (EV) or right atrial (RA) filamentous strands were found more frequently in patients with SA compared with those without SA (37.7% vs. 10.9%, p < 0.001 and 59.4% vs. 43.1%, p = 0.02). Patients with SA and PFO had no significant difference in time to recurrent stroke or death compared with those having neither (hazard ratio [HR] 1.08, 95% confidence interval [CI] 0.49 to 2.38, p = 0.84; two-year event rates 15.9% vs. 14.5%). Patients with SA, PFO, and RA anatomy predisposing to paradoxical embolization also had no difference compared with those without these findings (HR 1.22, 95% CI 0.43 to 3.47, p = 0.71; two-year event rates 18.2% vs. 14.2%). There was no significant difference in time to recurrent stroke or death between the patients treated with warfarin or aspirin (HR 1.00, 95% CI 0.22 to 4.47, p = 1.0; two-year event rates 16.0% vs. 15.8%). CONCLUSIONS: Atrial septal aneurysm is associated with the presence of large PFO and prominent EV or RA filamentous strands. On medical therapy, patients with SA and PFO did not experience increased risk of adverse events, and there was no difference between treatment results for warfarin and for aspirin.

Anticoagulants↗
PubMed2003

Left ventricular mass and geometry and the risk of ischemic stroke.

BACKGROUND AND PURPOSE: Left ventricular hypertrophy (LVH) is a risk factor for cardiovascular events, but its effect on ischemic stroke risk is established mainly in whites. The effect of LV geometry on stroke risk has not been defined. The aim of the present study was to evaluate whether LVH and LV geometry are independently associated with increased ischemic stroke risk in a multiethnic population. METHODS: A population-based case-control study was conducted on 394 patients with first ischemic stroke and 413 age-, sex-, and race-ethnicity-matched community control subjects. LV mass was measured by transthoracic echocardiography. LV geometric patterns (normal, concentric remodeling, concentric or eccentric hypertrophy) were identified. Stroke risk associated with LVH and different LV geometric patterns was assessed by conditional logistic regression analysis in the overall group and age, sex, and race-ethnic strata, with adjustment for established stroke risk factors. RESULTS: Concentric hypertrophy carried the greatest stroke risk (adjusted odds ratio [OR], 3.5; 95% confidence interval [CI], 2.0 to 6.2), followed by eccentric hypertrophy (adjusted OR, 2.4; 95% CI, 2.0 to 4.3). Concentric remodeling carried slightly increased stroke risk (adjusted OR, 1.7; 95% CI, 1.0 to 2.9). Increased LV relative wall thickness was independently associated with stroke after adjustment for LV mass (OR, 1.6; 95% CI, 1.1 to 2.3). CONCLUSIONS: LVH and abnormal LV geometry are independently associated with increased stroke risk. LVH is strongly associated with ischemic stroke in all age, sex, and race-ethnic subgroups. Increased LV relative wall thickness imparts an increased stroke risk after adjustment for LV mass and is of additional value in stroke risk prediction.

Age Distribution↗
PubMed2003

Race-ethnic differences in patent foramen ovale, atrial septal aneurysm, and right atrial anatomy among ischemic stroke patients.

BACKGROUND AND PURPOSE: Stroke remains a substantial cause of mortality and morbidity in the United States. Racial differences in stroke incidence and mortality persist with well-known excesses among blacks. Information on stroke among Hispanics is limited. In particular, little is known about whether patent foramen ovale (PFO), atrial septal aneurysm (ASA), and other atrial anomalies associated with cryptogenic stroke differ among minority populations. METHODS: As a part of the PFO in Cryptogenic Stroke Study, transesophageal echocardiography was performed in a cohort of 630 ischemic stroke patients (mean age, 59+/-12 years; 44% women; 45% whites, 35% blacks, 17% Hispanics, 3% other). The prevalences of PFO, ASA, and right atrial (RA) anatomy favoring paradoxical embolization were compared among race-ethnic groups. Statistical analyses used analysis of variance for continuous variables and logistic regression for dichotomous variables with adjustments for age and sex. RESULTS: Age- and sex-adjusted prevalences of PFO and ASA were similar across race-ethnic subgroups. However, large PFO was significantly less prevalent among blacks than among whites (odds ratio, 0.47; 95% confidence interval, 0.24 to 0.91; P=0.02). RA anatomy favoring paradoxical embolization was also significantly less prevalent among blacks compared with whites (odds ratio, 0.62; 95% confidence interval, 0.43 to 0.91; P=0.01). There were no significant differences in prevalence between whites and Hispanics. CONCLUSIONS: Although the frequency of PFO did not vary among race-ethnic groups, a large PFO and RA anatomy favoring paradoxical embolization were significantly more prevalent among whites and Hispanics compared with blacks. These may be relatively more important risk factors for stroke among whites and Hispanics than among blacks.

Age Distribution↗