In experimental studies and/or human body surface mapping, the activation - recovery interval (ARI) is used as a parameter to estimate local repolarization. However, it has not been clarified whether the ARI calculated from the intracardiac unipolar electrogram of humans reasonably represents the local effective refractory period (ERP). Measurement of ARIs at multiple ventricular sites can be helpful in assessing the dispersion of ventricular refractoriness of humans, so we examined the relationship between ERP and ARI in the control state and under treatment with dl-sotalol during clinical electrophysiologic studies (EPS). Of 19 patients, an EPS was performed in the control state in 12 and during treatment with dl-sotalol in the other 7. Quadripolar electrode catheters with an interelectrode distance of 5 mm were placed at the right atrium and in the right ventricle. Using atrial pacing, the heart rate was increased incrementally by 10 beats/min, and ERP and ARI were measured for each pacing rate. The ERP at the right ventricle was measured by single extrastimulation between the first and third distal electrodes of the catheter in the right ventricle, and the ARI was calculated from the second distal unipolar electrode of the same catheter as the interval between the minimum derivative of the intrinsic deflection and the maximum derivative of the T wave. In all patients, the unipolar electrogram was stable during the entire EPS, and 83 data points in the control group and 50 in the dl-sotalol group were analyzed. At each pacing rate, the beat-to-beat difference of ARI was less than 10 ms. As the atrial pacing rate increased, the ERP and ARI were progressively shortened, and linear regression analysis revealed an excellent correlation between ERP and ARI. At the same pacing rate, the ERP and ARI in the dl-sotalol group were longer than those in the control group, but no difference was observed in the slope (close to 1.0) and in the intercept of the regression lines between ERP and ARI. In the human ventricle, the ARI calculated from the intracardiac unipolar electrogram represents the local ERP both in the control state and under treatment with dl-sotalol. The ARI can be used as a parameter of local refractoriness and used to study the distribution of refractoriness in the human ventricle. (Jpn Circ J 2001; 65: 702 - 706)

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It is unknown whether the pathogenetic mechanisms underlying acute myocardial infarction (AMI) differ according to the clinical presentation of preinfarction angina, so the present study measured plasma levels of C-reactive protein (CRP) in 280 patients with AMI in whom serum creatine kinase levels were normal on admission and increased subsequently. Patients were classified into 3 groups according to the type of preinfarction angina: no angina (n=95), stable angina (n=48), and unstable angina (n=137). Patients with unstable angina were subdivided according to the Braunwald classification: class IB (n=39), class IIB (n=22), and class IIIB (n=76). There were no differences among the 5 groups in baseline characteristics. CRP on admission was significantly higher and the level of physical activity at symptom onset was significantly lower in the Braunwald class IIIB group than in the other groups, but no differences were observed among the other groups. Patients with preinfarction Braunwald class IIIB unstable angina had higher CRP levels on admission and symptom onset at a lower level of physical activity. In such patients, the pathogenetic mechanisms may differ from those in other subsets of patients with AMI and active inflammation may play a more important role in AMI onset. (Jpn Circ J 2001; 65: 707-710)

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Mechanical alternans has been observed in patients with severe congestive heart failure, and the phenomenon is considered to be a terminal sign. Therapeutic strategies for chronic heart failure have significantly developed, but it is uncertain whether patients with mechanical alternans can be effectively treated or not. Seventeen consecutive patients with dilated cardiomyopathy were enrolled: 11 were treated with β-blockers on conventional therapeutic regimens and 6 patients were not indicated for or were unable to continue β-blockade. Mechanical alternans was detected during cardiac catheterization in the patients under physiologic tachycardia (110 beats/min) and stepwise dobutamine loading. In the initial study, mechanical alternans occurred in 70.6% of the patients: 8 of the 11 being treated with β-blockers and 4 of the 6 without β-blockade therapy. In the second study, none of the patients taking β-blockers showed mechanical alternans under the same protocol; the occurrence of mechanical alternans did not change in the patients who were not being treated with β-blockers. The left ventricular ejection fraction increased in patients whose mechanical alternans could not be induced during the follow up, but decreased in the patients in whom mechanical alternans was repeatedly inducible. It is concluded that mechanical alternans is associated with the failing myocardium and may be potentially correctable. (Jpn Circ J 2001; 65: 711 - 716)

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The diastolic deceleration slope of coronary flow velocity is steeper in patients with substantial `no reflow' phenomenon than in those without it. This study investigated whether functional outcomes in patients with anterior wall acute myocardial infarction (AMI) can be predicted by analyzing the coronary flow velocity pattern recorded with transthoracic Doppler (TTD) echocardiography. Coronary blood flow velocity in the distal left anterior descending coronary artery was recorded with TTD at day-2 after primary percutaneous transluminal coronary angioplasty/Stent in 51 patients with anterior AMI and the diastolic deceleration half time (DHT, ms) was measured. The wall motion score index (WMSI) was measured at day-1 and -21. In the retrospective study, the DHT was much shorter in those with a poor outcome than in those with good outcome (152±109 vs 395±128 ms, p<0.05). Receiver-operating characteristic analysis documented that DHT ≥300 ms is a suitable cut-off point (sensitivity of 83% and specificity of 93%). In the prospective study (n=30), ΔWMSI(d1-d21) was significantly higher in those with a DHT ≥300 ms than those without (0.3±0.5 vs 1.6±0.7, p<0.001). DHT correlated significantly with ΔWMSI(d1-d21) (r=0.76, p<0.001). Patients with a shorter DHT of diastolic coronary flow velocity have a poorer functional outcome among patients with anterior AMI. The TTD-determined DHT is a useful predictor of myocardial viability after an anterior AMI. (Jpn Circ J 2001; 65: 717 - 722)

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The present study investigated the incidence and ECG characteristics of ventricular tachycardias (VTs) originating from the left ventricular (LV) epicardium. Thirty-one consecutive patients with VT or premature ventricular contraction originating from the outflow tract (OT-VT) underwent catheter ablation. Twenty-one OT-VTs were ablated from the endocardium in the right ventricular (RV) OT and 3 were ablated from the endocardium in the LVOT. In the remaining 7 patients, 4 (13%) OT-VTs were LV epicardial in origin, and 1 of these was ablated from the left sinus of Valsalva. The ECG characteristics of OT-VT of epicardial origin included prominent tall R-waves in the inferior leads, an R-wave in V₁ and an S-wave in V₂, precordial R-wave transition in V_2-4, a deep QS-wave in aV_L, and no S-wave in V₆. In addition, there was an atypical left bundle branch block morphology with an inferior axis. These findings were observed during pacing from several sites in the LV epicardium. Furthermore, pacing from the left sinus of Valsalva caused a relatively tall R in V₁, deep S-wave in V₂ and a tall R-wave with a shallow S-wave in V₃, as well as tall R-waves in the inferior leads, which represented intermediate characteristics between RV endocardial OT-VT and LV endocardial OT-VT. In conclusion, OT-VT originating from the LV epicardium is not uncommon and has characteristic ECG findings. Some of them can be ablated from the left sinus of Valsalva. (Jpn Circ J 2001; 65: 723 - 730)

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The present study evaluated the effect of hypertension (HT), dyslipidemia and diabetes mellitus (DM) on the development of coronary atherosclerosis in the Japanese population, using a cross-sectional study of 433 patients (254 men and 179 women) aged 30 years or older who underwent coronary angiography for suspected or known coronary heart disease angina at 5 cardiology departments in the Fukuoka area between September 1996 and August 1997. Patients with a disease duration of 6 months or more were excluded. The main outcome measure was angiographically defined coronary artery stenosis and was found to a significant degree in 146 patients (33.7%). HT, DM, low levels of high-density lipoprotein cholesterol (HDL-C) and hypertriglyceridemia remained as significant coronary artery disease (CAD) risk factors even after controlling for age, sex, hospital, smoking, alcohol use, body mass index and leisure time physical activity. However, hypercholesterolemia was not a significant risk factor after adjusting for these variables. After controlling for these variables, DM, low HDL-C and hypertriglyceridemia were significant CAD risk factors for men, but only DM was a significant CAD risk factor in women. These results indicate that in Japan DM, low HDL-C and hypertriglyceridemia may be more important CAD risk factors than hypercholesterolemia. (Jpn Circ J 2001; 65: 731 - 737)

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To test the hypothesis that hypoxia and hypercapnia have different effects on the genesis of respiratory sinus arrhythmia (RSA), the magnitude of RSA to these stimuli was compared in 3 unanesthetized dogs. Respiration was continuously monitored through a permanent tracheostomy, and the electrocardiogram and blood pressure were also monitored. The magnitude of RSA was assessed as an instantaneous amplitude of the R-R interval oscillation in the high-frequency band of 0.15-0.80 Hz by means of complex demodulation. In a total of 47 runs with hypoxia, heart rate, mean arterial pressure, respiratory rate and tidal volume increased, but RSA magnitude decreased even after adjusting for the effects of respiratory rate and tidal volume. In a total of 39 runs with hypercapnia, heart rate and mean arterial pressure did not change, despite the increased respiratory rate and tidal volume. In contrast to hypoxia, RSA magnitude increased even after adjusting for the effects of respiratory rate and tidal volume. The different effects of the two respiratory stimuli on RSA magnitude were noted at any level of ventilation and support the original hypothesis. (Jpn Circ J 2001; 65: 738 - 742)

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A number of isolated adult cardiomyocytes dies within a few days of culture and the mode of death has recently been suggested to be apoptosis, based on its association with the appearance of DNA fragmentation. However, morphological evidence is still lacking and precise analysis, including quantification, has not been performed. Adult rat ventricular cardiomyocytes isolated by enzymatic dissociation were incubated for 7 days in a serum-free medium (the rapid attachment model) and after various incubation periods, both attached and floating cells were counted and classified based on combined criteria of morphology and membrane permeability (dye exclusion): type 1, rod cells with intact membranes; type 2, non-rod cells with intact membranes; and type 3, non-rod cells with ruptured membranes. The number of both rod-shaped and dye-excluding cells decreased with the incubation period. After 7 days culture, the number of residual cells decreased to 12% of the initial value. Electron microscopy identified type 1 cells as viable, type 2 cells as viable or apoptotic, and type 3 as undergoing oncosis (primary necrosis) or secondary post-apoptotic necrosis. Ultrastructural morphometry revealed that oncotic cell death occurred predominantly during the early phase of culture whereas the more abundant apoptotic cell death occurred throughout the culture period. In conclusion, although both apoptotic and oncotic death occur in the natural course of adult rat cardiomyocytes in short-term culture, apoptosis is more predominant. Because of the high incidence of spontaneous cell death predominantly via apoptosis, this information is important for the interpretation of studies using this cell type in culture. (Jpn Circ J 2001; 65: 743 - 748)

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The conductance catheter is widely used for the continuous measurement of the left ventricular (LV) pressure - volume loops. Cyclical change of the right ventricular (RV) volume may alter the parallel conductance volume, thereby affecting the LV mechanical parameters. Using 8 open-chest adult mongrel dogs, multiple LV pressure - volume loops were obtained by 2 methods: first with a vena cava occlusion (VCO) method, which involved RV volume alteration, and second with a right-heart-bypass (RHB) preparation, which decompressed the right ventricle completely. The slope of the end-systolic pressure - volume relation (E_es), the end-systolic volume associated with the end-systolic pressure of 100 mmHg (V_100,es), stiffness constant (β), and the end-diastolic volume associated with the end-diastolic pressure of 9 mmHg (V_9,ed) were calculated from each loop. There was minimal influence from RV volume alteration on systolic-phase indices [E_es (VCO method, 6.37±1.91 mmHg/ml; RHB preparation, 6.60±1.66 mmHg/ml; p=0.356), and V_100,es (VCO method, 18.4±9.3 ml; RHB preparation, 17.8±9.0 ml; p=0.681)], but there was a significant influence on diastolic-phase indices [β (VCO method, 0.0599±0.0152; RHB preparation, 0.0839±0.0150; p=0.007), and V_9,ed (VCO method, 35.6±11.3 ml; RHB preparation, 31.9±12.3 ml; p=0.001)]. The increase in the RV volume in the diastolic phase increased the parallel conductance volume, causing overestimation of the LV diastolic volume measured by the conductance catheter. (Jpn Circ J 2001; 65: 749 - 752)

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A unique case of left internal mammary artery-to-circumflex coronary artery collateral pathway, which was conceivably encouraged to develop by coronary occlusion. The pathway provided sufficient collateral perfusion to preserve the local myocardial performance. (Jpn Circ J 2001; 65: 753 - 754)

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Patients with acute pulmonary embolism and venous thromboembolism are usually treated with anticoagulant therapy for at least 3 months as the optimum duration. A patient with recurrent idiopathic venous thromboembolism at the eighth month during anticoagulation (warfarin to target international normalized ratio of 2.0-3.0) is described. The case suggests that patients with idiopathic venous thromboembolism have a high risk of recurrence, even if a strict anticoagulant regimen is followed. (Jpn Circ J 2001; 65: 755 - 756)

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The patient was a 46-year-old man with a history of syncope attack after diarrhea. Nonsustained polymorphic ventricular tachycardia (PVT) initiated by short-coupled premature ventricular complex was detected by Holter monitoring. No organic heart disease was found, and the QT interval during sinus rhythm was normal. It was thought that the PVT might be related to hypokalemia, so electrophysiological studies were performed under the condition of hypokalemia (K = 3.4 mmol/L), after potassium loading (K = 4.2 mmol/L) and after oral amiodarone therapy. Under the condition of hypokalemia, nonsustained PVT occurred spontaneously, and the monophasic action potential duration at 90% repolarization (MAPD₉₀) at the right ventricular apex was very short (175 ms). The MAPD₉₀ returned to normal after loading potassium (230 ms) and after oral amiodarone therapy (240 ms), and PVT no longer occurred. With continued oral amiodarone and spironolactone therapy, the patient has been free of syncope attack over a follow-up period of 5 years. (Jpn Circ J 2001; 65: 757 - 760)

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A 49-year-old female presented with a 1-month history of cough and low-grade fever. Echocardiography showed a large mass in the right ventricle and percutaneous right ventricular endomyocardial biopsy provided the histologic diagnosis. Despite radiotherapy and chemotherapy, the patient died. At autopsy, the metastatic deposit in the heart was larger than the primary cervical carcinoma. (Jpn Circ J 2001; 65: 761 - 763)

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