Clinical significance of electrocardiography recordings from a higher intercostal space for detection of the brugada sign.

BACKGROUND: The significance of higher intercostal space electrocardiography (HICS ECG) for the detection of the Brugada sign was investigated. METHODS AND RESULTS: The subjects consisted of 113 cases (108 males, 5 females; mean age, 57+/-17 years) with incomplete right bundle branch block type QRS morphology and ST-segment elevation (>0.10 mV) in the right precordial leads. Obvious structural heart disease was not observed in any of the subjects. The V(1-3) leads of the standard 12-lead ECG and the HICS ECG were recorded in the supine position, and the amplitude of the terminal portion of the QRS (J-point) and ST-segment (80 ms from the J-point) were measured. In the HICS ECG, there was an increase in the area in which the Brugada sign was detectable (47 leads to 66 leads), and in cases with the Brugada sign, the amplitude of the J-point increased. CONCLUSIONS: The HICS ECG may be helpful for the detection of the Brugada sign.

Anti-lipid deposition effect of HMG-CoA reductase inhibitor, pitavastatin, in a rat model of hypertension and hypercholesterolemia.

Since the rat is an atherosclerosis-resistant species, the study of atherosclerosis using rats is limited. The present study was undertaken to develop an atherosclerotic model in rats, to investigate the effect of nitric oxide (NO) inactivation and hyperlipidemia, and to evaluate the effect of pitavastatin, a 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoA reductase) inhibitor, on NO inactivation and on hyperlipidemia-induced changes in the cardiovascular system. Four-month-old male spontaneously hypertensive hyperlipidemic rats (SHHR) and Sprague-Dawley (SD) rats were used to study 1) the effect of the period of treatment with N(G)-nitro-L-arginine methyl ester (L-NAME, 100 mg/L) on high fat diet (HFD)-treated SHHR and SD rats, and 2) the effect of pitavastatin (Pit, 0.3 mg/kg/day) on the changes in the aorta of L-NAME- and HFD-treated SHHR and SD rats. L-NAME administration for 1 month then HFD feeding for 2 months markedly increased the deposition of lipids and the thickness of the endothelium in SHHR. Continuous L-NAME treatment with HFD produced severe injury and stripped of endothelium in both strains. The plasma total cholesterol of L-NAME + HFD-treated and L-NAME + HFD + Pit-treated SHHR was significantly higher than that of control SHHR. Lipid deposition, however, was comparatively less in the aorta of L-NAME + HFD + Pit-treated SHHR. The concentration of cholesterol in the aorta of control SHHR was significantly lower than that in the aorta of L-NAME + HFD-treated SHHR, whereas that of L-NAME + HFD + Pit-treated SHHR was the same as that in control SHHR. These data indicated that Pit blocked lipid deposition in the aorta of L-NAME + HFD treated SHHR without changing plasma lipid profiles. In conclusion, NO inactivation and HFD induce lipid deposition in the endothelium, and the HMG-CoA reductase inhibitor blocks the deposition in SHHR.

Congenital absence of the left circumflex coronary artery associated with acute myocardial infarction: a case report.

Among the congenital anomalies of the coronary arteries, a left circumflex artery (LCX) defect is extremely rare. A 49-year-old man who developed an acute anterior infarction underwent coronary angiography, which revealed complete occlusion of the left main trunk, but the territory usually supplied by the LCX had been perfused by the superdominant right coronary artery. Treatment of the left main trunk by percutaneous coronary intervention produced a favorable result. Accurate evaluation of the principal vessels and the extent of compensatory perfusion is important when diagnosing ischemic heart disease accompanied by anomalous coronary arteries and for choosing the best treatment modality.

Influence of mobile magnetic resonance imaging on implanted pacemakers.

PURPOSE: Mobile magnetic resonance imaging (MRI) systems will be widely used in Japan. When traveling, mobile MRI generate alternating electromagnetic waves which may cause electromagnetic interference (EMI). This study was designed to determine whether this may influence the function of implanted pacemakers (PM). METHODS AND RESULTS: The influence of the static magnetic fields was tested in the first method using a PM-human model (Phantom). Magnetic force was simultaneously measured. The PM was switched to the magnet mode within 90 cm from the vehicle, where the magnetic force was = 2 mT. In the second method, six phantoms were placed on the side of the road, facing in three different directions in X-Y-Z axis orientations, at 1.3 m and 2.0 m above the ground. The mobile MRI passed by at a distance of 1 m from the phantoms at the speed of 20 or 40 km/h. In these experiments, magnet mode switch of the PM was observed for 2 seconds when the vehicle passed close to the phantoms, though no electrical noise was recorded. CONCLUSION: Mobile MRI vehicles can switch a PM to magnet mode when the distance between patient and vehicle is < 90 cm, regardless of whether the vehicle is moving or at a stop. Patients with implanted PM should not approach within < 1 m of a mobile MRI. No other EMI-induced PM dysfunction was detected.

Experimental study on the effectiveness and safety of radiofrequency catheter ablation with the cooled ablation system.

Experimental in vitro and in vivo studies were performed to assess the effectiveness and safety of the cooled-tip catheter and the Cooled Ablation System, which enables the creation of deeper and wider burn lesions in the myocardial tissue using radiofrequency current. This system was confirmed to consistently create large burns by cooling the catheter tip with circulating water within the catheter, even under unfavorable conditions. On the other hand, unfavorable effects, as a result of over burning, such as explosive vaporization within the tissue (the 'pop' phenomenon), tissue carbonization, coronary artery injury and lung injury were identified. 'Pop' was difficult to predict, but it is important to know how it can be avoided. No 'Pop' was seen without first observing an impedance decrease, thus it was considered safe to decrease the radiofrequency current if the impedance began to decrease. This system will be very effective for ablation of refractory arrhythmias, such as ventricular tachycardia or atrial flutter, but it is recommended that only experienced electrophysiologists use this system to avoid serious complications.

Relationship between infarction location and size to QT dispersion in patients with chronic myocardial infarction.

The relationship between the location and size of an infarction and QT dispersion was investigated in 84 Japanese patients with chronic myocardial infarction (54 with anteroseptal infarction and 30 with inferior infarction). The control group consisted of 23 subjects without ischemic heart disease (13 normal subjects and 10 hypertensive patients). Corrected QT dispersion (maximum corrected QT interval minus minimum corrected QT interval: QTc dispersion), was significantly larger in the anterior infarction group than in the control group (69.9+/-21.5 msec vs 53.0+/-17.6 msec), while the inferior infarction group showed no significant difference from control subjects. QTc dispersion was significantly greater in the patients with large anterior infarcts than in those with small anterior infarcts (80.5+/-20.5 msec vs 61.9+/-18.8 msec). In patients with chronic myocardial infarction, QT dispersion is influenced by the infarct location and size. Accordingly, interpretation of QT dispersion data should take these factors into consideration.