Shigetaka Kanda

Two Cases in Which Myocardial Injury Could Be Only Evaluated by Nuclear Medicine Studies on Electric Shock Patients Whose Electrocardiogram and Myocardial Enzyme Levels Were Normal

Heart injury due to electric shock is currently diagnosed based on electrocardiogram (ECG) changes or elevated levels of myocardial enzymes or both. However, the rate at which ECG detects abnormalities is very low; thus, the estimated rate of the diagnosis of myocardial damage due to electric shock is lower than the actual rate. The method of nuclear medicine study of the heart is superior with regard to evaluating transient ischemia, such as angina pectoris, in patients whose ECG and myocardial enzyme levels are normal. Therefore, we attempted to diagnose transient myocardial damage in electric shock patients by using nuclear medicine study of the heart.

Systematic review of the use of intravenous amiodarone and nifekalant for cardiopulmonary resuscitation in Japan

Intravenous amiodarone is considered to be the first‐line drug for the treatment of ventricular tachycardia or fibrillation. However, in Japan, nifekalant had been used before the introduction of amiodarone; therefore, most clinical studies on amiodarone use have been small‐scale studies. The aim of the present study was to review the literature concerning the actual use of amiodarone and nifekalant in order to evaluate the effects of both drugs and the most appropriate mode of administration.

Longitudinal analysis of the depressive effects of intravenous amiodarone on depolarization and repolarization: A case report

Intravenous amiodarone (AMD) induces multiple antiarrhythmic effects via blocking of Na(+), Ca(2+), and IKr channels, and beta receptors. A patient on chronic dialysis was administered AMD for nonsustained ventricular tachycardia after successful cardiopulmonary resuscitation. QT prolongation occurred 5 h after AMD administration. AMD was withdrawn at 24 h because of prolonged QTc interval (716 ms), which persisted for a further 48 h (661 ms). Ventricular premature contraction (VPC) was significantly decreased at 7h; however, VPC increased again after discontinuing AMD. Depolarization changes induced by the Na(+)-channel blocking action of AMD were analyzed. There was increasing filtered QRS-duration and duration of low-amplitude signals at voltage <40 µV, and decreasing root-mean-square voltage of signals in the last 40 ms of ventricular late potentials (LPs) within 7 h. However after stopping AMD, LPs were reversed. The blood concentration of AMD reached the effective level within 10 min but decreased immediately to an ineffective level. Onset and disappearance of the VPC-inhibiting effect corresponded to the depressive effect on depolarization but not with the increase in the prolonged repolarization effect and blood concentration. Even if the QT interval is sufficiently prolonged, the Na(+)-channel blocking action is required for AMD to induce the antiarrhythmic effect.

Changes in arrhythmogenic properties and five‐year prognosis after carbon‐ion radiotherapy in patients with mediastinum cancer

Carbon‐ion irradiation of rabbit hearts has improved left ventricular conduction abnormalities through upregulation of gap junctions. However, to date, there has been no investigation on the effect of carbon‐ion irradiation on electrophysiological properties in human. We investigated this effect in patients with mediastinum extra‐cardiac cancer treated with carbon‐ion radiotherapy that included irradiating the heart.

Arrhythmogenic Substrates in Sleep-Disordered Breathing with Arterial Hypertension

Sleep‐disordered breathing (SDB) is highly associated with arterial hypertension (HT). Sympathetic hypertonia increases the risk of sudden cardiac death in patients with sleep apnea. This study aims to noninvasively investigate the electrophysiological features in SDB patients with and without arterial HT.

Implant Characteristics of Quadripolar and Bipolar Left Ventricular Leads for Cardiac Resynchronization Therapy: Results from the Attain Success Japan Study

Several studies have reported that the left ventricular (LV) lead implant success rate ranges between 88.0% and 92.4%. Coronary venous anatomy differs among patients thus, necessitating multiple types of leads. To date, the implant success rate among Japanese patients utilizing a pre-specified family LV leads (including bipolar and quadripolar) is not well known. The Attain Success Japan Study enrolled patients indicated for a de novo or an upgrade cardiac resynchronization therapy implant. Patients were followed for 3 months, and the implant success rates with Medtronic Attain family LV leads as well as the incidence of complications related to the LV lead were evaluated.Three hundred 53 patients were enrolled from 29 sites in Japan; 346 patients had LV lead implant attempts. The LV lead was successfully implanted in 336 patients (97.1%). Bipolar and quadripolar LV lead implants were successful in 97.2% and 99.2% of patients, respectively (P = 0.43). Four complications (1.2%) related to the LV leads were reported; all of which occurred in patients receiving bipolar LV leads. The quadripolar LV leads were more frequently implanted in the apical segment compared with bipolar leads (21.6% versus 3.8%, P < 0.01). This study demonstrated a high implant success rate and a low LV lead-related complication rate, regardless of bipolar, or quadripolar in a Japanese cohort of patients.

Normal 123 I-MIBG uptake areas may be associated with hyperinnervation and arrhythmia risk in phenol model rabbit hearts: AMINO et al .

Iodine‐123 metaiodobenzylguanidine (123I‐MIBG) is useful for detecting sympathetic innervation in the heart, and has been closely associated with fatal arrhythmias. However, such imaging is typically calibrated to the area of highest uptake and thus is unable to identify areas of hyperinnervation. We hypothesized that normal 123I‐MIBG uptake regions in the denervated heart would demonstrate nerve sprouting and correlate with the potential for arrhythmogenesis.

Erratum to “Systematic review of the use of intravenous amiodarone and nifekalant for cardiopulmonary resuscitation in Japan” [J. Arrhythm. 30 (2014) 180–185]

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Radiofrequency Catheter Ablation from the Epicardial Sites for Ventricular Arrhythmias Originating from the Left Ventricular Summit—Two Case-Reports—

Introduction: We report 2 cases of ventricular arrhythmias (VAs) originating from the left ventricular summit (LVS) which required radiofrequency energy (RF) application in the great cardiac vein (GCV) and/or the epicardium for treating VAs. Case 1: Sixty-five year-old female with idiopathic VAs underwent RF-catheter ablation (CA). The earliest activation site of VAs was observed in GCV, to which left descending coronary artery (LAD) run close. Sufficient RF delivery could not be performed due to the concerns about the injury to LAD, and the procedure resulted in a transient therapeutic effect. Case 2: Fifty-one year-old male suffering from VAs associated with non-ischemic cardiomyopathy underwent RF-CA. In 1st session, the earliest activation site of VAs was recognized in GCV, however, RF-CA application in GCV failed to abolish VAs. In 2nd session with the subxiphoidal pericardial approach, the earliest site was located at LVS extremely close to LAD. Despite the multiple RF applications in the vicinity sites of that portion, we were unable to abolish VAs. Conclusion: In sporadic cases, epicardial approach is required to eliminate VAs. However, the discretion and attention have to be paid in order to avoid the serious complications for treating VAs originating from LVS.

Successful Catheter Ablation of Mitral Isthmus Related Multiple and Unstable Ventricular Tachycardias after Myocardial Infarction

Catheter ablation in patients with multiple and unstable postinfarction ventricular tachycardias (VTs) by placing lines of radiofrequency lesions with using 3D electroanatomical mapping is still challenging. We report a case of 69-years-old male with such VTs in which a linear lesion across the mitral isthmus successfully eliminated tachycardias. Four distinct unstable VTs were induced: three with a left bundle (LB) and one with a right bundle (RB) morphology. The analysis of the ventricular activation sequence along the posterior aspect of the mitral annulus (coronary sinus) revealed that the direction of wavefront propagation during the LB-VTs was opposite to that during the RB-VT. Electroanatonical mapping demonstrated a wide inferior infarct region. Then pace mapping was performed along the infarct border to assume the putative exit sites of the induced VTs. Each pacemaps performed along the septal and lateral aspects of the infarct border reproduced the QRS morphology of LB- and RB-VT, respectively. Based on these data, all four VTs were considered to be “mitral isthmus related”. Placement of a linear lesion across the isthmus rendered all VTs noninducible. Mitral isthmus plays a role in the genesis of unstable VT. Even when treating patients with multiple and unstable postinfarction VTs, catheter ablation can be feasible if a critical isthmus is identified in the mitral isthmus.