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Biomedical subjects

Toshiyuki Ishikawa

Publications and source records attributed to Toshiyuki Ishikawa.

At least 19 recordsLinked to original sources
PubMed2007

Reverse perfusion-metabolism mismatch predicts good prognosis in patients undergoing cardiac resynchronization therapy: a pilot study.

BACKGROUND: Cardiac resynchronization therapy (CRT) improves glucose metabolism in the septum of patients with heart failure, so in the present study the predictive value of combined fluorodeoxyglucose (FDG)-positron emission tomography (PET) and metoxy-isobutyl isonitrile (MIBI)-single photon emission computed tomography (SPECT) for the prognosis of patients undergoing CRT was investigated. METHODS AND RESULTS: Fourteen patients (70.3+/-8.2 years) who underwent FDG-PET and MIBI-SPECT before implantation of a biventricular pacemaker were enrolled. The total number of matches, mismatches, reverse mismatches, summed difference score (SDS: sum total of FDG - MIBI scores) and SDS per segment (%SDS) in each of 5 areas of myocardium (septum, anterior, lateral, inferior area, apex) was calculated and compared between the survival groups (all survival: survival group; survival without ischemic heart disease (IHD): non-IHD survival group) and non-survival group. Both the number of reverse mismatch segments and the %SDS in the septum in the non-IHD survival group were significantly greater than in the non-survival group (3.2+/-1.6 vs 0.5+/-0.6, p<0.05; 0.62+/-0.61 vs -0.11+/-0.19, p<0.05). The receiver-operating characteristics curves for prognosis showed that the area under the curve for the number of reverse mismatch segments in the septum (0.93; confidence interval 0.61-0.98) was significantly greater. CONCLUSION: A reverse mismatch pattern in the septum can predict a good prognosis for patients treated with CRT.

Aged↗
PubMed2006

Combined prognostic utility of ST segment in lead aVR and troponin T on admission in non-ST-segment elevation acute coronary syndromes.

Many studies have shown that ST-segment depression is a strong predictor of poor outcomes in patients with non-ST-segment elevation acute coronary syndromes (NSTE-ACSs); however, lead aVR was not considered in these studies. The present study examined the prognostic usefulness of the 12-lead electrocardiogram in combination with biochemical markers in 333 patients with NSTE-ACS. ST-segment deviation of > or =0.5 mm was considered clinically significant. Coronary angiography was performed a median of 3 days after admission in all patients. The primary end point was the composite of death, myocardial infarction, and urgent revascularization at 90 days. ST-segment elevation in lead aVR (odds ratio 13.8, 95% confidence interval 1.43 to 100.9, p = 0.03) and increased troponin T (odds ratio 7.9, 95% confidence interval 1.22 to 123.8, p = 0.04) were the only independent predictors of restricted events (death or myocardial infarction) at 90 days. ST-segment elevation in lead aVR (odds ratio 12.8, 95% confidence interval 4.80 to 33.9, p < 0.0001) and increased troponin T (odds ratio 2.03, 95% confidence interval 1.20 to 4.29, p = 0.04) were also the only independent predictors of adverse events (death, myocardial infarction, or urgent revascularization) at 90 days. When ST-segment status in lead aVR was combined with troponin T, patients with ST-segment elevation in lead aVR and increased troponin T had the highest rates of left main or 3-vessel coronary disease (62%) and 90-day adverse outcomes (47%). In conclusion, our findings suggest that ST-segment status in lead aVR combined with troponin T on admission is a simple and useful clinical tool for early risk stratification in patients with NSTE-ACS.

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PubMed2006

Correlation between plasma brain natriuretic peptide concentration and lung thallium-201 uptake on exercise thallium perfusion images.

The plasma brain natriuretic peptide (BNP) concentration at rest correlates with left ventricular end-diastolic pressure (LVEDP), left ventricular ejection fraction (LVEF), and pulmonary capillary wedge pressure (PCWP). High lung thallium-201 uptake has been reported to be associated with hemodynamic variables such as LVEDP, LVEF, and PCWP. However, there is no study that has investigated the correlation of plasma BNP concentration with lung thallium-201 uptake. We examined whether the plasma BNP concentration was related to lung thallium-201 uptake. Before exercise, venous blood samples were obtained from 39 patients with old myocardial infarction. We investigated the correlations between plasma BNP concentration and lung thallium-201 uptake, and whether they were related to LVEF, extent of nonviable myocardium, and ischemic myocardium, respectively, with thallium-201 exercise stress testing. The plasma BNP concentration significantly correlated with lung thallium-201 uptake (P < 0.05), nonviable segments (P < 0.01), and LVEF (P < 0.01). Lung thallium-201 uptake correlated with nonviable segments (P < 0.01). Our results suggest that increased secretion of BNP is related to increased lung thallium-201 uptake, and they are related to the extent of nonviable myocardium and decreased left ventricular function. Plasma BNP concentration and lung thalium-201 uptake may reflect the extent of myocardial fibrosis causing myocyte stretch.

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PubMed2006

Adenosine concentration in great cardiac vein is increased in non-ventricular fibrillation dogs.

This study was conducted to clarify the relationship between myocardial endogenous adenosine concentration in the great cardiac vein during ischemia and reperfusion-induced ventricular fibrillation (VF) and the occurrence rate of ischemia and reperfusion-induced VF. Sixty anesthetized mongrel dogs were subjected to 10-min left anterior descending artery occlusion and reperfusion. Blood from the great cardiac vein was sampled for the determination of adenosine and catecholamine concentrations. Hemodynamic parameters (blood pressure, lift ventricular dp/dt, left ventricular end-diastolic pressure, and cardiac output) were monitored throughout the experimental period. During coronary occlusion and reperfusion, VF occurred in 25 dogs (VF group). Ventricular fibrillation did not occur in 35 other dogs (non-VF group). Adenosine concentration in the great cardiac vein before the coronary occlusion did not differ between the two groups. However, the adenosine concentration in the great cardiac vein of the non-VF group significantly increased compared with that of the VF group (2,343 vs 65 pmol/ml, P = 0.026) during coronary occlusion and reperfusion. In contrast, hemodynamic parameters did not differ between the two groups. The study results demonstrated that adenosine concentration in the great cardiac vein was higher in the non-VF group than in the VF group, suggesting that myocardial endogenous adenosine may have a role in the suppression of ischemia and reperfusion-induced VF in dogs.

Adenosine↗
PubMed2006

Evaluation of myocardial glucose metabolism before and after recovery of myocardial function in patients with tachycardia-induced cardiomyopathy.

BACKGROUND: We assessed left ventricular (LV) function and myocardial glucose metabolism by fluoro-18-deoxyglucose (18F-FDG) positron emission tomography (PET) in patients with tachycardia-induced cardiomyopathy (TC). METHODS: The subjects were 42 patients with heart disease, consisting of 7 patients with TC (61.4 +/- 19.0 years, LVEF 34.1%+/- 10.6%) and 35 with ischemic heart disease (IHD) (63.1 +/- 10.8 years, LVEF 49.9%+/- 13.5%). Five volunteers with normal ECG were the control group. All of the patients underwent 18F-FDG PET and echocardiography, and all of the patients with TC underwent 18F-FDG PET and echocardiography before and 6 months after antitachycardia therapy. Six patients underwent radiofrequency catheter ablation (RFCA) and 1 patient was medically treated with antitachycardia therapy. Myocardial glucose metabolism was assessed semiquantitatively by using the % dose uptake of 60 kg of BW (% dose uptake). RESULTS: Mean % dose uptake of the control group was 5.52 +/- 0.54%. After antitachycardia therapy, LVEF significantly improved (34.1 +/- 10.6% vs 54.3 +/- 13.6%, P < 0.01), and % dose uptake also significantly improved (1.26 +/- 0.55% vs 1.49 +/- 0.62%, P < 0.05). Patients with IHD showed higher % dose uptake than those with TC before antitachycardia therapy (3.18 +/- 1.36 vs 1.26 +/- 0.55%, P < 0.01), controls showed higher value of % dose uptake than TC before antitachycardia therapy (5.52 +/- 0.54% vs 1.26 +/- 0.55%, P < 0.01). CONCLUSION: Semiquantitative analysis of 18F-FDG PET showed that antitachycardia therapy improved myocardial glucose metabolism in patients with TC.

Cardiomyopathies↗
PubMed2006

Assessment of atrial regional wall motion using strain Doppler imaging during biatrial pacing in the bradycardia-tachycardia syndrome.

INTRODUCTION: Biatrial pacing is expected to have preventive effects on atrial fibrillation. METHODS: We evaluated atrial regional wall motion by strain Doppler imaging (SDI) in 6 patients (62.5 +/- 11.3 [SD] years), who suffered from atrial fibrillation, with an implanted biatrial pacemaker. SDI was performed and atrial regional wall motion was estimated during biatrial (BiA) and right atrial appendage (RAA) pacing. RESULTS: There was no significant difference in the interval from the pacing spike to the peak strain of the atrium in the lateral right atrium (LRA) between BiA and RAA pacing. However, there was a significant difference in the septal atrium (SA) between BiA and RAA pacing (225.0 +/- 19.9 vs 267.2 +/- 15.7 ms, P < 0.0001) and in the lateral left atrium (LLA) between BiA and RAA pacing (216.7 +/- 21.6 vs 275.0 +/- 16.2 ms, P < 0.0001). There were significant differences in the time difference of peak strain between BiA and RAA pacing in each atrial segment (LRA-AS: 2.2 +/- 5.9 vs 45.0 +/- 11.9 ms, P = 0.0016, SA-LLA: -8.3 +/- 5.5 vs 7.8 +/- 2.7 ms, P < 0.0011, LRA-LLA: -6.1 +/- 3.9 vs 52.8 +/- 13.2 ms, P = 0.0002). There was no significant difference in the interval from the pacing spike to the inflection point of atrial strain (S-I) of LRA. However, there were significant differences in S-I of SA (83.9 +/- 24.1 vs 129.9 +/- 30.6 ms, P = 0.0086) and LLA (102.2 +/- 37.9 vs 166.1 +/- 13.4 ms, P = 0.0028). CONCLUSION: BiA pacing improved the synchronicity of regional wall motion of both atrium.

Adult↗
PubMed2006

Suppression of atrial fibrillation by atrial pacing.

BACKGROUND: Atrial fibrillation (AF) is a common arrhythmia in patients with an implanted pacemaker, but the role of atrial pacing in preventing AF is still unclear. METHODS AND RESULTS: Sixty-six patients (67.8+/-12.1 years) were enrolled: 54 with sick sinus syndrome (SSS), 11 with atrioventricular blocks (AVB), and 1 with SSS and AVB. The prevalence of AF was investigated. In 22 patients with AF, the AF burden was estimated under "back-up pacing" (40-50 beats/min), then under "atrial pacing" (60-85 beats/min). The prevalence of AF in the SSS group tended to be higher than that in the AVB group (48.1% vs 18.2%, p=0.06). The AF burden in patients with a percentage of atrial pacing (% atrial pacing) <50% was significantly greater than that in patients with % atrial pacing >or=50% (12.5+/-21.1% vs 4.2+/-10.3%, p<0.05). AF disappeared immediately after "atrial pacing" in 4 patients (18.2%). In 9 patients (40.9%), the AF burden decreased gradually, and AF disappeared in 6 patients (27.3%) after 207.9+/-130.2 days. CONCLUSION: The prevalence of AF may be higher in patients with SSS than in those with AVB. Atrial pacing has a preventive effect on AF, and the effect of atrial pacing is not always immediate but is progressive in some patients.

Aged↗
PubMed2006

Daily shock impedance measured by implantable cardioverter defibrillator is useful in the management of congestive heart failure.

BACKGROUND: Clinical data suggest that changes in intrathoracic impedance and fluid accumulation in the lung are inversely related. METHODS AND RESULTS: Daily shock impedance (S-IMP) was evaluated in 29 patients in whom a Ventak Prizm 2 was implanted (61+/-14 years old). The mean follow-up period was 45+/-18 weeks, during which 6 patients had episodes of decompensated heart failure (DHF group) and the others did not (NHF group). There was no significant difference between the DHF group and NHF group in the mean value of the S-IMP (46.4 +/-3.3 vs 45.4+/-5.4 Omega). The range of S-IMP in individual patients in the DHF group was significantly greater than that in the NHF group (13.8+/-0.38 vs 7.0+/-3.1 Omega, p<0.0001). Mean weekly change of S-IMP in individual patients in the DHF group was significantly greater than that in the NHF group (1.583+/-0.630 vs 1.092+/-0.361 Omega, p<0.0176). When the cut-off value was set at >1.242 Omega, sensitivity was 100% and specificity was 69.6% for a diagnosis of DHF. There was a significant negative correlation between the percent increases in brain natriuretic peptide (BNP) and S-IMP (correlation coefficient: -0.775 p<0.0001) in the DHF group. There was an inverse relation between BNP and S-IMP. CONCLUSIONS: Measurement of shock impedance may be useful in the management of congestive heart failure.

Aged↗
PubMed2006

Differences between men and women in terms of clinical features of ST-segment elevation acute myocardial infarction.

BACKGROUND: Many studies have examined sex-related differences in the clinical features of acute myocardial infarction (AMI). However, prospective studies are scant, and sex-related differences in symptoms of AMI remain unclear. We examined differences between men and women in terms of the clinical features of ST-segment elevation AMI. METHODS AND RESULTS: We studied 457 patients (106 women and 351 men) with ST-segment elevation AMI who were admitted within 24 h after symptom onset. The same cardiologist interviewed all patients within 48 h after admission. Women were older than men (72 vs 62 years, p<0.001) and had higher rates of hypertension (70 vs 56%, p=0.010), diabetes mellitus (36 vs 26%, p=0.047), and hyperlipidemia (51 vs 38%, p=0.019). Women were more likely than men to have non-specific symptoms (45 vs 34%, p=0.033), non-chest pain (pain in the jaw, throat, neck, shoulder, arm, hand, and back), mild pain (20 vs 7%, p<0.001), and nausea (49 vs 36%, p=0.013). On coronary angiography, the severity of coronary-artery lesions was similar in both sexes. In-hospital mortality was significantly higher in women than in men (6.6 vs 1.4%, p=0.003). CONCLUSIONS: Clinical profiles and presentations differ between women and men with AMI. Women have less typical symptoms of AMI than men.

Acute Disease↗
PubMed2006

Prognostic significance of inverted T waves in patients with acute pulmonary embolism.

BACKGROUND: The significance of inverted T waves remains unclear in patients with acute pulmonary embolism (PE). METHODS AND RESULTS: The relationship of the number of leads with inverted T waves to the severity of PE in 40 patients with acute PE was studied. Patients were classified into 3 groups according to the number of leads with inverted T waves on the admission electrocardiogram (ECG): 15 patients, or=7 leads (group H). In groups L, M and H, the rates of right ventricular dysfunction on echocardiography were 47%, 92% and 100% (p<0.01), respectively, and the rates of in-hospital complicated events (including death or the need for catecholamine support, cardiopulmonary resuscitation or mechanical cardiovascular support because of hemodynamic instability) were 0%, 8% and 46% (p=0.004), respectively. On multivariate analysis, arterial hypotension at presentation (odds ratio (OR) 8.96, p=0.049) and inverted T waves in >or=7 leads on the admission ECG (OR 16.8, p=0.037) were the only independent predictors of in-hospital complicated events. CONCLUSIONS: The number of leads with inverted T waves may be a useful and simple marker of increased risk for early complications in patients with acute PE.

Acute Disease↗
PubMed2006

[Improvement of central sleep disordered breathing with severe congestive heart failure by biventricular pacing therapy: a case report].

A 74-year-old man with ischemic cardiomyopathy was repeatedly admitted for congestive heart failure. His left ventricular ejection fraction was 21% and diastolic left ventricular dimension was 73.5mm by echocardiography. He was treated with biventricular pacing and heart failure improved from New York Heart Association class III to II. Before the treatment, brain natriuretic peptide was 600.5 pg/ml. Apnea hypopnea index was 23.8 and all events were central type. After biventricular pacing, apnea hypopnea index was improved to 21.9 after 11 days, 14.0 after 33 days, and 4.8 after 48 days. His left ventricular ejection fraction was 36%, diastolic left ventricular dimension was 71.4mm, and brain natriuretic peptide was 383.8 pg/ml. In this patient, central sleep disordered breathing was improved by biventricular pacing therapy after only 48 days.

Aged↗
PubMed2005

Predictors of left main or three-vessel disease in patients who have acute coronary syndromes with non-ST-segment elevation.

To identify an early, simple, noninvasive predictor of left main (LM) or 3-vessel disease (3-VD), we retrospectively studied clinical variables on admission in 310 patients with acute coronary syndromes with non-ST-segment elevation. Univariate analysis indicated that many factors were related to LM/3-VD. Multivariate analysis showed that ST-segment elevation in lead aVR of >/=0.5 mm was the strongest predictor of LM/3-VD, followed by positive troponin T (odds ratio 19.7, p <0.001, and odds ratio 3.08, p = 0.048, respectively). ST-segment elevation in lead aVR of >/=0.5 mm and positive troponin T identified LM/3-VD with sensitivities of 78% and 62%, specificities of 86% and 59%, positive predictive values of 57% and 26%, and negative predictive values of 95% and 87%, respectively (p <0.05). Our findings suggest that in patients with non-ST-segment elevation acute coronary syndromes, ST-segment elevation in lead aVR of >/=0.5 mm and positive troponin T on admission (especially the former) are useful predictors of LM/3-VD.

Adult↗
PubMed2005

Long-term follow-up of atrioventricular delay optimization in patients with biventricular pacing.

BACKGROUND: Atrioventricular (AV) delay optimization may be important in patients with biventricular pacing and the optimal AV delay can be predicted using Doppler echocardiography and the formula: optimal AV delay = AV delay-the interval between the end of A wave and complete closure of the mitral valve when the AV delay is set at slightly prolonged AV delay. METHODS AND RESULTS: In the present study the efficacy of this method was evaluated in 5 patients (67.4+/-8.0 (SD) years old) with biventricular pacing. Cardiac output (CO) and diastolic filling time were measured by Doppler echocardiography. When the AV delay was set at the predicted optimal AV delay -25 ms, the predicted optimal AV delay (133+/-66 ms) and predicted optimal AV delay + 25 ms, the respective CO were 4.5+/-0.9, 5.3+/-1.0, 4.8+/-1.0 L/min (p<0.05, ANOVA) and the diastolic filling times were 364 +/-100, 373+/-105, 335+/-84 ms (p<0.05, ANOVA). Congestive heart failure improved from New York Heart Association class 3.6+/-0.5 to 1.4+/-0.5 (p<0.001). CONCLUSIONS: AV delay optimization is important in patients with biventricular pacing and can be easily achieved by the new method.

Aged↗
PubMed2005

Persistent hyperglycemia is associated with left ventricular dysfunction in patients with acute myocardial infarction.

BACKGROUND: The relationship of changes in blood glucose concentrations after admission to left ventricular (LV) dysfunction in patients with recanalized anterior acute myocardial infarction (AMI) remains unclear. METHODS AND RESULTS: Blood glucose concentrations were measured on admission and 24 h after symptom onset in 210 patients with recanalized anterior AMI within 6 h of symptom onset. Of them, 142 had hyperglycemia on admission, defined as a blood glucose >or=8.9 mmol/L, and 68 patients did not. Among the patients with admission hyperglycemia, 49 had persistent hyperglycemia, defined as a blood glucose >or=8.9 mmol/L 24 h after onset, and 93 did not. The incidences of myocardial blush grade of 0/1 after recanalization indicating impaired myocardial perfusion (71%), and peak creatine kinase concentration (5,631+/-2,855 mU/ml) were higher and predischarge LV function (43+/-11%) was lower in patients with persistent hyperglycemia than in those without (p<0.01). Multivariate analysis showed that persistent hyperglycemia was independently associated with LV dysfunction, defined as a predischarge LV ejection fraction <or=40% (odds ratio 7.38, p=0.001). CONCLUSIONS: Persistent hyperglycemia at 24 h after symptom onset is associated with LV dysfunction before discharge in patients with recanalized anterior AMI.

Adult↗
PubMed2005

Beneficial effects of biatrial pacing on cardiac function in patients with bradycardia -- tachycardia syndrome.

BACKGROUND: Biatrial (BiA) pacing prevents atrial fibrillation. By an unknown mechanism. The purpose of this study was to use Doppler echocardiography to evaluate the hemodynamic effects during BiA pacing. METHODS AND RESULTS: The subjects were 7 patients with bradycardia - tachycardia syndrome with an implanted pacemaker. Atrial pacing sites were the right atrial appendage (RAA) and coronary sinus. P wave duration during BiA pacing (123 +/-16 ms) was significantly shorter than during either RAA pacing (167+/-19 ms, p<0.05) or sinus rhythm (148+/-12 ms, p<0.05). Doppler echocardiography revealed a greater cardiac output during BiA pacing than during RAA pacing (4.1+/-1.1 vs 3.5+/-0.7 L/min, p=0.042). The Doppler waveform of transmitral flow indicated that the left ventricular contraction interrupted the atrial filling wave during RAA pacing. The interval between the end of the atrial filling wave of transmitral flow and the mitral valvular closing sound was significantly increased by BiA pacing compared with RAA pacing (56+/-65 vs 40+/-57 ms, p=0.047). CONCLUSION: Cardiac hemodynamics were improved by BiA pacing and reduction of left atrial load may be one of the mechanisms.

Aged↗
PubMed2005

ST-segment depression in lead aVR: a useful predictor of impaired myocardial reperfusion in patients with inferior acute myocardial infarction.

STUDY OBJECTIVE: During inferior acute myocardial infarction (AMI), the ECG lead aVR is frequently ignored, and therefore its clinical significance remains unclear. We examined the relation between ST-segment deviation seen in lead aVR on ECGs obtained at hospital admission and myocardial reperfusion in patients who have experienced recanalized inferior AMIs. DESIGN AND SETTING: Retrospective study. PATIENTS: A total of 225 patients with inferior AMIs in whom Thrombolysis in Myocardial Infarction grade 3 flow was achieved within 6 h after symptom onset. MEASUREMENTS AND RESULTS: Patients were classified as follows according to ST-segment deviation in lead aVR on an ECG obtained at hospital admission: group A, 103 patients with no ST-segment depression; group B, 80 patients with ST-segment depression of < or = 1.0 mm; and group C, 42 patients with ST-segment depression of > 1.0 mm. There were no differences in time from symptom onset to hospital admission or in the culprit lesion among the three groups. The degree of ST-segment elevation in leads II, III, aVF, V5, or V6, the degree of ST-segment depression in leads V1 to V4, and the sum of ST-segment deviation in these leads were lowest in group A and highest in group C. In groups A, B, and C, the incidence of impaired myocardial reperfusion, defined as myocardial blush grade 0/1, was 2%, 23%, and 67%, respectively (p < 0.001). The sensitivity and negative predictive values of ST-segment depression in lead aVR for impaired myocardial reperfusion were higher than those based on other ECG variables. Multivariate analysis showed that the degree of ST-segment depression in lead aVR was an independent predictor of impaired myocardial reperfusion (odds ratio 8.41; 95% confidence interval, 2.96 to 23.9; p < 0.001). CONCLUSIONS: We conclude that the degree of ST-segment depression in lead aVR is a useful predictor of impaired myocardial reperfusion in patients who have experienced inferior AMIs.

Electrocardiography↗
PubMed2005

[Successful defibrillation by disconnection of superior vena cava electrode for high defibrillation threshold: a case report].

A 72-year-old man with dilated cardiomyopathy and sustained ventricular tachycardia was treated with amiodarone. He visited another hospital because of loss of consciousness. Electrocardiography showed 2: 1 atrioventricular block. Ambulatory electrocardiography showed total heart beats were 59,700 per day. He was referred to our hospital to evaluate his heart. Several types of ventricular tachycardia and ventricular fibrillation were induced by program stimulation during the electrophysiological study. Therefore, an implantable cardioverter-defibrillator was introduced. During defibrillation threshold tests, ventricular fibrillation could not be terminated by the maximal output of 31J. Despite changing the polarity and lead position, stable defibrillation could not be obtained. Finally, successful defibrillation could only be achieved by disconnection of the superior vena cava electrode.

Aged↗