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E Ikeno

Publications and source records attributed to E Ikeno.

11 recordsLinked to original sources
PubMed1996

Reverse redistribution of technetium-99m-sestamibi following direct PTCA in acute myocardial infarction.

UNLABELLED: A pattern of reverse redistribution (RR) has not been documented in myocardial 99mTc-sestamibi imaging. The purpose of the study was to clarify the time-related changes in myocardial distribution of 99mTc-sestamibi in patients with acute myocardial infarction. METHODS: Myocardial SPECT with 99mTc-sestamibi was performed in 27 patients with acute myocardial infarction within 1 wk after the onset. Twenty-three patients received direct percutaneous transluminal coronary angioplasty (PTCA) and 4 patients did not. Myocardial images were obtained 1 hr (early) and 3 hr (delayed) after the injection of 99mTc-sestamibi. Regional myocardial uptake of 99mTc-sestamibi was scored from 4 (normal) to 0 (no activity), and the RR pattern was defined as a decrease of more than 1 in the regional score at the 3-hr delayed images. Regional myocardial uptake and clearance of 99mTc-sestamibi was also assessed quantitatively. Coronary arteriography and left ventriculography were performed 1 mo later. RESULTS: Out of 22 patients with successful PTCA, RR of 99mTc-sestamibi was observed in 15 patients (68%). Persistent defects (PD) were seen in 12 patients (7 patients with successful PTCA, 1 patient with unsuccessful PTCA, and 4 patients who did not receive angioplasty). In patients with RR, regional uptake of 99mTc-sestamibi in the area of myocardial infarction decreased from 54% +/- 10% in the early images to 43% +/- 8% in the delayed images (p < 0.01). Technetium-99m-sestamibi clearance from the myocardium was faster in the infarct area than in the normal area (26% +/- 7% versus 9% +/- 6%, p < 0.01). Coronary arteriography performed 1 mo later revealed that the patency of the infarct related artery was 100% (15/15) in patients with RR and 50% (6/12) in those with PD (p < 0.01). The extent and severity of a wall motion abnormality were less in patients with RR than in those with PD (extent: 24 +/- 10 versus 36 +/- 9 chord, p < 0.01; severity: -2.7 +/- 0.4 versus -3.4 +/- 0.6 s.d./chord, p < 0.01). CONCLUSION: The RR of 99mTc-sestamibi was observed in 68% of patients after successful direct PTCA and was associated with the accelerated clearance of 99mTc-sestamibi from the myocardium. The presence of RR in 99mTc-sestamibi imaging indicates the patency of the infarct-related artery and predicts the preserved left ventricular function.

Aged↗
PubMed1995

Diagnostic usefulness of activation-recovery interval for reciprocal ECG changes. Effects of regional myocardial cooling, warming, or coronary occlusion on epicardial electrograms in dogs.

The proximal left circumflex coronary artery (LCx) was cannulated and perfused with blood from the carotid artery in nine open-chest dogs. Perfused blood temperature was modulated by immersing a bypass tube in a temperature-controlled water tank. Two epicardial electrodes were placed, one at the LCx area and one at the left anterior descending coronary artery (LAD) area. The temperature of the autoperfused blood was set at 23 degrees C and was gradually elevated to 42 degrees C during 30 minutes. The QRS, ST-T, and QRST areas, and the activation-recovery interval of the electrode at the LCx area, changed unidirectionally in relation to elevation of the blood temperature. Although the QRS, ST-T, and QRST areas of the electrode at the LAD area changed in proportion to changes in the electrode at the LCx area, the activation-recovery interval of the electrode at the LAD area remained constant in all dogs. During 2-minute occlusion of the proximal LCx (n = 7), the activation-recovery interval of the electrode at the LAD area also remained constant despite the presence of reciprocal electrocardiographic changes. The activation-recovery interval is a useful index for defining whether a change in ST-T in a unipolar electrogram is due to a local electrophysiologic effect or a reciprocal effect.

Action Potentials↗
PubMed1993

Role of ATP-sensitive K+ channel on ECG ST segment elevation during a bout of myocardial ischemia. A study on epicardial mapping in dogs.

BACKGROUND: ATP-sensitive K+ channels are activated when the myocardium becomes ischemic. However, the role of the ATP-sensitive K+ current in the emergence of ECG ST changes during ischemia remained unclarified. METHODS AND RESULTS: The left anterior descending coronary artery (LAD) was cannulated and perfused with arterial blood from the carotid artery through a bypass tube in 8 anesthetized, open-chest dogs. An array of 60 unipolar electrodes mounted on a sock was used to record epicardial electrograms of the whole heart. Pinacidil (10 micrograms.kg-1 x min-1), an ATP-sensitive K+ channel opener, was infused into the bypass tube for 2 minutes, and the electrograms were recorded before and after the infusion. The elevation of the ST segment and the increase of QRST area were observed spatially over the LAD-perfused region. At the electrode showing the largest ST segment elevation, the activation recovery interval, an index of action potential duration, was shortened from 202 +/- 9 to 111 +/- 18 milliseconds (P < .001). These electrographic changes were similar to those noted in 2-minute coronary occlusion (n = 8). The extent of ST segment elevation during coronary occlusion was attenuated after the intravenous pretreatment with glibenclamide (0.3 mg/kg), a blocker of the KATP channel (n = 5). CONCLUSIONS: The findings of this study suggest that the activation of ATP-sensitive K+ channels during a bout of acute myocardial ischemia plays an important role in the emergence of ECG ST elevation.

Action Potentials↗
PubMedDate not supplied

Prolonged repolarization during hypoxemia in epicardial electrogram: difference from ischemia and a competitive action of cyclic AMP.

The effects of regional hypoxemia and ischemia on epicardial electrogram were studied in anesthetized, open-chest dogs. The left circumflex artery (LCx) was cannulated and perfused with either arterial blood or hypoxic solution. A contact electrode for recording monophasic action potential (MAP) was applied to the epicardial site of the LCx area. Epicardial electrograms and MAP in the LCx perfusion territory were recorded 1) just before and at the end of a 2-min coronary occlusion (ischemia) and 2) just before and at the end of a 2-min perfusion of hypoxic solution (hypoxemia). The activation-recovery interval (ARI), defined as an interval from the minimum derivative of the QRS complex to the maximum derivative of the T-wave in the unipolar electrogram, changed linearly with MAP duration during above interventions. The ARI decreased by 29% from 189 +/- 14 to 134 +/- 30 ms during ischemia (p < .001), and it increased by 39% from 183 +/- 11 to 254 +/- 31 ms during hypoxemia (p < .001). Hypoxemia produced a giant negative T-wave whose pattern was not modified by pretreatments with autonomic nerve blockers (propranolol and atropine), a Ca2+ channel blocker (verapamil), an ATP-sensitive K+ channel (KATP blocker (5-hydroxydecanoate or transient outward K+ current (I(to) blocker (4-aminopyridine). Isoproterenol, forskolin or aminophylline inhibited both the appearances of giant negative T and the ARI prolongation. Accordingly, unlike ischemia, hypoxemia prolongs repolarization process and this prolongation is inhibited by the augmentation of intracellular cyclic AMP.

Action Potentials↗