ifekalant hydrochloride (NIF) is the first class III anti-arrhythmic agent for intravenous use covered by National Health Insurance in Japan for refractory ventricular tachycardia and fibrillation (VT/VF). NIF blocks the delayed rectifier K + channels, especially the IKr channels. NIF also has some potential to block the inward rectifier K + current IK1 and transient outward K + channel Ito. Thus it prolongs the action potential duration (APD) and stops VT/VF by extending the refractory period. 1,2 However, amiodarone (AMD) is a known K-channel blocker that also has Na blocking action and blocking action. The properties of NIF differ greatly from those of AMD.In 1999, our coworkers Tanabe et al investigated the effect of NIF (MS-551) on the effective refractory period (ERP) in the epicardium and endocardium in a canine model of acute myocardial infarction (AMI), and reported that NIF significantly prolonged the ERP in both the normal zone (NZ) and ischemic zone (IZ) of the ischemic myocardium; however, the dispersion of the ERP in the epicardium and endocardium increased in the NZ but decreased in the IZ. 3 Recently, our coworkers Amino et al conducted a comparative investigation of the 90% APD (APD90) prolonging effect of NIF on the surface of the left ventricle (LV) and APD90 dispersion (APDD) in isolated perfused rabbit hearts at basic cycle lengths (BCLs) of 400 ms and 250 ms. APD90 was prolonged with the efficacy of a reverse use dependent block without increasing the APDD at either BCL, and as a result NIF decreased VT/VF vulnerability. 4 These study results suggest that NIF may stop VT/VF by improving epicardial surface and transmural dispersion of repolarization (TDR) in the LV, in addition to its refractory-period-prolonging action.In a clinical study, we used NIF to treat lidocaine-resistant VT/VF in patients with out-of-hospital cardiopulmonary arrest (OHCPA), and reported that it exerted excellent anti-arrhythmic efficacy. 5 In a study in which we compared OHCPA patients with acidosis and in-hospital cardiopulmonary arrest (IHCPA) patients without acidosis, NIF was Background Because nifekalant hydrochloride (NIF) displayed a superior defibrillating effect on ventricular tachycardia/fibrillation (VT/VF) in cardiopulmonary arrest (CPA) patients, despite some QT prolongation, its effect on transmural dispersion of repolarization (TDR) in the left ventricle (LV) in an animal model of CPA was investigated. Methods and ResultsEight beagle dogs were created with a myocardial infarction under anesthesia, and then VT/VF induction by continuous stimulation and cardiopulmonary resuscitation (CPR) were repeated. NIF (0.3 mg/kg) was administered under acidotic conditions (pH 7.26). The QTc interval measured by Y-lead ECG showed no significant prolongation before and after NIF. The activation recovery interval (ARI) measured by 64-lead LV surface mapping showed minimum ARI prolongation (40%) by NIF without maximum ARI prolongation, and as a result the ARI dispersion decreased by 67%. The repolarization time (RPT)...

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The patient, a 48-year-old womanwith cardiac fibroma, is the second oldest patient with this disease in Japan. Her electrocardiogram showed findings compatible with old high lateral, posterior and possibly lateral myocardial infarction, regions which corresponded to the tumor site. In patients whose electrocardiogram suggests a previous myocardial infarction (pseudo myocardial infarction), the possibility of intramyocardial tumor should be taken into consideration. (Internal Medicine 33: 10-12, 1994)

A 9-lead Holter monitor using the lead-switching technique (9-lead DCG) and conventional 12-lead electrocardiograph (12-lead ECG) were simultaneously used for recording during treadmill exercise testing (Td-test) in 140 patients with coronary artery disease. Coronary arteriography was performed in 118 of the 140 patients, and the correlation between coronary stenosis and anterior or inferior projection of ST depressions occurring during the Td-test was investigated. Additionally, 10 patients with acute myocardial infarction (AMI) were studied to test ST elevation detection by the 9-lead DCG. The CM5 lead demonstrated ST depressions in 92 of the 109 patients showing ST depressions in one or more leads. High lateral (HL) and/or low lateral leads detected all ST depressions occurring in the I and aVL leads of the 12-lead ECG. Leads CM1, CM2 and CM3 exhibited low sensitivity (0-32%) and high specificity (56-100%), while leads CM4, CM5, and CM6 provided greater sensitivity (66-95%), but less specificity (3-32%) in detecting diseases of the left anterior descending artery, left circumflex artery and/or right coronary artery (RCA). In contrast, the low back (LB) lead demonstrated high sensitivity (88%) and high specificity (86%) in detecting RCA disease. Lead CM3 detected ST elevations in all 6 patients with anterior AMI, while the LB lead did so in all 4 patients with inferior AMI. With a Holter monitor, 4 leads are needed: CM5 like, CM3 like, lateral (such as HL) and inferior (such as LB). The LB lead is useful in detecting inferior ischemia.

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