Introduction: Atrial fibrillation (AF) is the most frequently occurring atrial arrhythmia. Fibrillation intervals are used to characterize AF and have a potential to determine the strategy for AF therapy regardless of its etiology. However, measuring local fibrillation intervals requires an extensive period of time when using visual methods, and such methods are also subject to data bias. Recently several methods for measuring the atrial fibrillation cycle length (AFCL) using computers have been developed. Atrial activation during AF was considered to be random or chaotic. From recent studies, however, it was found that AF has various degrees of organization, and therefore activation during AF can be analyzed by spectral analysis. Several kinds of spectral analysis have become available for characterization of AF, and fast Fourier transform analysis is most frequently used. Autocorrelation function also can be used for analysis of AF intervals and could give us further information, such as minimum AFCL. Further, the frequency analysis of AF may be useful to predict the effect of antiarrhythmic drugs, cardioversion and catheter ablation for AF. This review was designed to investigate the analysis of AF intervals and to assess methods, interpretation and clinical implications.

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Atrial fibrillation (AF) is an arrhythmia associated with increased morbidity and mortality. The pulmonary veins (PVs) play an important role not only in the onset but also the maintenance of AF. Therefore, the goal of present AF ablation is to electrically disconnect the PVs from the rest of the atrium by ablating around the origin of the PVs. Several groups using ablation of all 4 PVs outside the tubular portion have reported that the success rate without antiarrhythmic drugs is much more consistent, at 75 to 95%. A further 10% to 20% of patients may become responsive to previously ineffective antiarrhythmic drugs. Although the success rate of AF ablation appears high, a very low incidence of complications has been reported including cardiac tamponade, embolism, esophageal injury, PV stenosis, and proarrhythmia resulting from reentrant tachycardias. However, the complication rates can be decreased by more recent modifications to the technique and presently available technologies. Thus, AF ablation is an effective, safe, and established treatment for AF that offers an excellent chance for a lasting cure.

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Introduction: In a case of pacemaker and/or implantable cardioverter defibrillator (ICD) implantations, there is the possibility of infections related to the device. In such case, the removal of the total system is desirable, however, the lead extraction can sometimes be difficult. Methods: Among 756 subjects who underwent a device implantation procedure, we experienced 19 cases with a device infection or skin problems requiring a surgical procedure such as thinning or inflammation of the skin over the pocket or lead. We divided these 19 cases into three groups as cases with neither systemic nor local infections (N group), cases with regional but systemic infections (R group), and cases with systemic infections (S group). And the prognoses of these cases were investigated. Results: Out of the 19 cases, 12 cases were classified into N group, 5 cases were classified into R group, and the remaining 2 cases were classified into S group. The lead extractions were performed in one case each in the N, R and S groups. None of the cases in the N group developed a systemic infection over an average observation period of 31 months. Four cases in the R group remain been free from systemic infection over an average observation period of 39.5 months. Conclusion: Lead extractions are the ideal treatment in cases with device implantation site complications, but are not necessary if the extraction is difficult.

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Cardiac resynchronization therapy (CRT) improves symptoms and cardiac function in patients with heart failure and prolongs QRS duration on an electrocardiogram. However, additional effects of concomitant CRT in patients who undergo cardiac surgery are unclear. We assessed the clinical efficacy of this therapy when it is performed concomitantly with primary cardiac surgery.
METHODS: We evaluated four patients who underwent primary surgery and CRT between February 2002 and December 2003, and compare clinical data with four patients who underwent conventional primary surgery without CRT.
RESULTS: Primary surgeries were CABG (n=2), aortic valve replacement (n=1), mitral valve plasty (n=1) and mitral annular plication (n=4). After the operation, symptoms associated with congestive heart failure were improved in all patients. The average NYHA class improvement was from 3.3±0.5 before the operation to 1.7±0.6 after the operation. All patients were discharged after surgery. Only one patient needed re-hospitalization for congestive heart failure one month after the operation. The mean QRS duration (190±47.6 ms vs 160±16.3 ms), cardiothoracic ratio (60.7±5.7% vs 58.5±2.9%) and ejection fraction (28.5±8.8% vs 50.0±0.0%) were also improved after surgery.
CONCLUSION: In patients with poor left ventricular function and impaired cardiac conduction, CRT performed concomitantly with primary surgery may improve the postoperative course. Further study on indications for implantation of a CRT device during primary surgery is needed.

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In a new drug development, regulatory authorities recommend the “thorough QT/QTc study”, in which the use of a positive control group was recommended for evaluating assay sensitivity that allows the detection of a QT/QTc interval prolongation about 5 msec. The effects of postural change on the QT/QTc intervals were examined to determine its potential usefulness as a nonpharmacological positive control. Standard 12-lead electrocardiograms of 72 healthy male subjects (mean age: 22.6±2.0 years) were recorded in the morning and evening in 6 positions (supine, 30-degree semisitting, standing, supine, 90-degree sitting, and standing). The QT-RR relationships during postural changes seemed to be similar in the morning and the evening. The QTc interval calculated by the Fridericia’s or Framingham’s formula shortened in the sitting (7 to 10 msec) and the standing position (11 to 14 msec) compared to that in the supine position. On the other hand, the QTc interval calculated by the Bazett’s formula prolonged by nearly 4 msec in the sitting position and by nearly 9 msec in the standing position. The results suggest that the difference in QTc interval during postural change, especially from supine to sitting position, could be useful as a nonpharmacological positive control.

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Left atrial tachycardia (AT) has been reported to occur after pulmonary vein isolation (PVI) for the treatment of atrial fibrillation (AF). We treated 3 patients who developed AT of different mechanisms following PVI. In case 1, focal AT originating at the ostium of the left superior PV was demonstrated and focal radiofrequency ablation was performed at the breakthrough point at the ostium of the left superior PV terminated the AT. In case 2, AT was shown to be counterclockwise macroreentrant AT around the left inferior PV through the conduction gap of the left sided posterior wall for which linear ablation was performed between left superior and inferior PVs. Focal ablation at the conduction gap terminated the AT. In case 3, a macroreentrant AT propagating around the mitral annulus was demonstrated and linear ablation between left inferior pulmonary vein and mitral annulus (mitral isthmus) terminated the AT.

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A 49-year-old male was referred to the hospital because of syncope caused by ventricular tachycardia (VT) with a pulse of 240 bpm and QRS morphology with a LBBB configuration and superior axis. The patient had been on a long-term regimen of steroids to treat his scleroderma. Satisfying 2 major criteria (QRS widening and an epsilon wave in the right chest leads) and 3 minor criteria (a slight enlargement and akinesis of the right ventricle, positive late potential in the signal averaged electrocardiogram and left bundle branch block-type VT) he was diagnosed with arrhythmogenic right ventricular cardiomyopathy. A voltage map of his right ventricle (RV) during sinus rhythm was obtained using an electroanatomical mapping system (CARTO, Biosense-Webster, Diamond, CA, USA). Two islet-like low voltage areas were found and linear double potentials were recognized between areas in the lateral wall of the right ventricle (RV) very close to the tricuspid annulus. The earliest activation of the double potential line during VT was 70 msec prior to the QRS onset. We applied radiofrequency energy at that point during the VT and it successfully slowed and terminated the VT. Thereafter the VT could not be induced by any stimulation from multiple RV sites.

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We report an unexpected sudden cardiac death due to variant angina complicated by ventricular fibrillation occurring during routine ambulatory electrocardiographic monitoring. The patient had one previous episode of ventricular fibrillation before the lethal event. He had no significant coronary artery disease and was asymptomatic throughout his illness. In clinical practice, when an episode of ventricular fibrillation is noted, one should be aware of the risk of sudden cardiac death, even if the patient’s vasospastic angina is relatively stable and asymptomatic.

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The patient was a 78-year-old man with dilated cardiomyopathy. His cardio-thoracic ratio was 60.4% and left ventricular ejection fraction (LVEF) was 33%. He had been repeatedly admitted for congestive heart failure. He underwent implantation of an implantable cardioverter-defibrillator (ICD) for ventricular fibrillation. We compared the values of BNP and shock impedance stored by the ICD. The correlation coefficient (p-value) between BNP and shock impedance was −0.700 (p<0.0005), increase of BNP and shock impedance was −0.778 (p<0.0001), percent increase of BNP and shock impedance was −0.767 (p<0.0005). In conclusion, there is an inverse relation between BNP and shock impedance, and measurements of shock impedance may be useful in the management of congestive heart failure.

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During implantation of a pacemaker into a 15-year-old male (height: 155 cm, weight: 65 kg) suffering from complete atrioventricular block, it was difficult to exteriorize the myocardium by approaching from below the xiphoid process so an operative field was obtained by using a heart stabilizer. A myocardial electrode was fixed after confirming stable circulatory dynamics with no arrhythmia and good R wave amplitude and pacing thresholds. As the heart stabilizer is now a vital device for off-pump coronary artery bypass (OPCAB), we consider that it will also become a useful device for procedures other than OPCAB in the field of cardiac surgery.

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