Makiyoshi Shima

Comparative Study of Nifekalant Versus Amiodarone for Shock-Resistant Ventricular Fibrillation in Out-of-Hospital Cardiopulmonary Arrest Patients

Background: In Japan, intravenous nifekalant (NIF) was often used for direct current cardioversion-resistant ventricular fibrillation (VF), until the use of intravenous amiodarone (AMD) was approved in 2007. The defibrillatory efficacy of NIF and AMD has thus far not been compared for resuscitation. Methods and Results: Between August 2007 and April 2009, 403 consecutive out-of-hospital patients with cardiopulmonary arrest were transferred to the Emergency Medical Service of Tokai University. Of these, 30 patients with first defibrillation failure or VF recurrence were enrolled for this NIF/AMD study. The final defibrillation success (and hospital survival rate) was 67% (10/15) in the AMD and 47% (7/15) in the NIF group. The discharge survival rate was 53% (8/15) in the AMD and 21% (4/15) in the NIF group (P = 0.06). Notably, all 4 survivors in the NIF group could take up normal daily life again, whereas this was restricted to only 2 patients from the 11 survivors in the AMD group. The difference is probably partly attributable to longer time from AMD administration to defibrillation success compared with NIF. In the cases of defibrillation failure, VF continued in 4/8 by NIF, however, asystole or pulseless electrical activity occurred in 4/5 patients by AMD. Conclusions: AMD may be borderline superior over NIF to facilitate defibrillation in out-of-hospital patients with cardiopulmonary arrest. However, from the view point of preservation of brain function, NIF is not inferior to AMD for CPR.

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 AMD was withdrawn at 24 h because of prolonged QTc interval (716 ms), which persisted for a further 48 h (661 ms).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.

Incidence of Positive Ventricular Late Potentials Differs in Postural Changes among Supine, Left, and Right Lateral Decubitus, and Prone and Sitting Positions in Brugada Syndrome

High‐risk patients with Brugada syndrome (BrS) have inherent late potential (LP) fluctuations that might be explained by autonomic activity, electrolyte abnormality, and body temperature changes. However, the correlation between postural changes and LP determinates remains unknown.