Objectives This study evaluated the pause-dependency of the J-wave to characterize this phenomenon in idiopathic ventricular fibrillation (VF). Background The J-wave can be found in apparently ...healthy subjects and in patients at risk for sudden cardiac death, and risk stratification is therefore needed. Methods Forty patients with J-wave–associated idiopathic VF were studied for J waves with special reference concerning pause-dependent augmentation. J waves were defined as those ≥0.1 mV above the isoelectric line and were compared with 76 non-VF patients of comparable age and sex. Results The J-wave was larger in patients with idiopathic VF than in the controls: 0.360 ± 0.181 mV versus 0.192 ± 0.064 mV (p = 0.0011). J waves were augmented during storms of VF (n = 9 22.5%), which was controlled by isoproterenol; they disappeared within weeks in 5 patients. In addition, sudden prolongation of the R-R interval was observed in 27 patients induced by benign arrhythmia, and 15 patients (55.6%) demonstrated pause-dependent augmentation (from 0.391 ± 0.126 mV to 0.549 ± 0.220 mV; p < 0.0001). In the other 12 experimental subjects and in the 76 control subjects, J waves remained unchanged. Pause-dependent augmentation of J waves was detected in 55.6% (sensitivity) but was specific (100%) in the patients with idiopathic VF with high positive (100%) and negative (86.4%) predictive values. Conclusions Pause-dependent augmentation of J waves was confirmed in about one-half of the patients with idiopathic VF after sudden R-R prolongation. Such dynamicity of J waves was specific to idiopathic VF and may be used for risk stratification.
Abstract Background Patients with repetitive ventricular tachyarrhythmias — so-called electrical storm — frequently require antiarrhythmic drugs. Amiodarone is widely used for the treatment of ...electrical storm but is ineffective in some patients. Therefore, we investigated the efficacy of stepwise administration of nifekalant, a pure potassium channel blocker, and mexiletine for electrical storm. Methods This study included 44 patients with repetitive ventricular tachyarrhythmias who received stepwise therapy with nifekalant and mexiletine for electrical storm. Nifekalant was initially administered, and mexiletine was subsequently added if nifekalant failed to control ventricular tachyarrhythmias. Results Nifekalant completely suppressed recurrences of ventricular arrhythmias in 28 patients (64%), including 6 patients in whom oral amiodarone failed to control arrhythmias. In 9 of 16 patients in whom nifekalant was partially effective but failed to suppress ventricular arrhythmias, mexiletine was added. The addition of mexiletine prevented recurrences of ventricular tachyarrhythmias in 5 of these 9 patients (56%). There was no death associated with electrical storm. In total, the stepwise treatment with nifekalant and mexiletine was effective in preventing ventricular tachyarrhythmias in 33 of 44 patients (75%). There was no difference in cycle length of the ventricular tachycardia, QRS interval, QT interval, or left ventricular ejection fraction between patients who responded to antiarrhythmic drugs and those who did not. During follow-up, 8 patients had repetitive ventricular tachyarrhythmia recurrences, and the stepwise treatment was effective in 6 of these 8 patients (75%). Conclusions The stepwise treatment with nifekalant and mexiletine was highly effective in the suppression of electrical storm.
Catheter ablation of the renal artery can be performed without apparent angiographic stenosis. This suggests that renal nerve function can be attenuated with minor structural damage to the renal ...artery.
To clarify this hypothesis, we examined the relationship between electrical nerve stimulation (ENS)-induced blood pressure (BP) response and severity of histological injury of the renal artery using an acute canine model of renal artery ablation.
An irrigation catheter was inserted into the renal arteries of 8 dogs, and radiofrequency current was delivered at 15, 20, or 25 W. ENS was applied to each artery before and after ablation.
Before ablation, ENS increased the BP and heart rate from 145 ± 15/86 ± 13 to 189 ± 21/111 ± 19 mm Hg and from 116 ± 9 to 130 ± 6 beats/min, respectively. Heart rate variability indices and serum catecholamine levels were elevated concomitantly. After ablation, the ENS-induced increase in BP and heart rate were markedly attenuated after 15 W ablation and those were nearly completely inhibited after 20 or 25 W ablation. An increase in heart rate variability indices and serum catecholamine levels became insignificant regardless of the applied energy. Renal artery angiograms revealed stenotic lesions only after 25 W ablation procedures. Histological studies showed mild to moderate injury of the arterial wall and autonomic nerves caused by 20 and 25 W ablation procedures, whereas only minor changes caused by 15 W ablation.
Functional renal autonomic nerve ablation is potentially performable with the guidance of ENS.
Abstract We determined the prevalence of J waves in the electrocardiograms (ECG) of 120 patients with Wolff-Parkinson-White syndrome in comparison with J-wave prevalence in a control group of 1936 ...men and women with comparable demographic and ECG characteristics and with normal atrioventricular conduction. J waves were present only during manifest preexcitation in 22 of 120 patients (18.3%), disappearing after catheter ablation and suggesting that J waves were associated with the presence of preexcitation. J waves were present in 19 (15.8%) of 120 patients only after ablation, apparently having been masked by early depolarization of the preexcited myocardial region, and in 22 patients (18.3%), J waves were not altered significantly by preexcitation. Thus, the overall J-wave prevalence was 52.5% (63/120) and, excluding those apparently due to preexcitation, 34.8% (41/120), both substantially higher than the prevalence (11.5%) in the control group ( P < .001 for both). The patients with J waves appearing only during preexcitation were younger, predominantly females. The presence of J waves after ablation was associated with a history of atrial fibrillation and shorter ventricular effective refractory period. It is concluded that the prevalence of J waves is high in patients with Wolff-Parkinson-White syndrome and is influenced by manifest preexcitation.
Abstract Ventricular tachycardia (VT) may occur in patients after corrective surgery for tetralogy of Fallot (ToF), and this can be a cause of sudden cardiac death. Macroreentrant VT is a unique ...mechanism in these patients, although other mechanisms are involved in VT development. Owing to advances in electrophysiological knowledge and medical technology, macroreentrant VT after corrective surgery for ToF can be treated by catheter ablation. In the macroreentrant circuit of VT, several critical isthmuses (types 1–4) could be included, and these are supported by anatomical obstacles and operative interventions in the right ventricle. Linear radiofrequency (RF) application through the critical isthmus can terminate and prevent the recurrence of macroreentrant VT. Among the critical isthmuses, the type 1 isthmus (between the right ventricular outflow scar and tricuspid annulus) is the most common, but compared with the other types of isthmuses, it is longer so and has a thicker myocardium. Therefore, higher-energy RF application using irrigation and/or large-tip ablation catheters is usually required to complete the linear conduction block. Since other isthmuses may simultaneously work as critical components of the macroreentrant circuit, detailed mapping is encouraged before starting RF application in the type 1 isthmus. Since long-term evidence of the effectiveness of catheter ablation for VT in patients after ToF repair is limited, hybrid treatment with implantable cardioverter defibrillators (ICDs) would be a reasonable strategy for secondary prevention of cardiac events, such as that in patients with other underlying heart diseases. Indications of electrophysiological study, catheter ablation, and/or ICD therapy for primary prevention of sudden cardiac death should be further examined in high-risk patients after ToF repair.
Abstract It is not known if J waves of early repolarization can be affected by depolarization or not. We report 2 cases in whom J waves were unmasked by preexcitation. A 59-year-old woman with ...Wolff-Parkinson-White syndrome who had frequent episodes of tachycardia underwent radiofrequency catheter ablation. The 12-lead electrocardiogram on admission showed delta waves and a notch in leads II, III, and aVF (J waves), which disappeared after the elimination of preexcitation. A 56-year-old man with Wolff-Parkinson-White syndrome was admitted for catheter ablation for supraventricular tachycardia. His electrocardiogram showed delta waves in I, II, aVL, V2 to V6 , and J waves in the inferior leads and V3 through V6 with ST elevation and ST elevation in V2 . After ablation, J waves disappeared and were replaced by S waves. However, ST elevation remained in the precordial leads. The 2 cases suggest that J waves may be affected by the depolarization process: preexcitation.
A Post-QRS Potential in Brugada Syndrome Aizawa, Yoshifusa, MD; Chinushi, Masaomi, MD; Tagawa, Minoru, MD ...
Journal of the American College of Cardiology,
04/2008, Letnik:
51, Številka:
17
Journal Article
Previous studies have showed that the interval between the peak and the end of the T wave (Tp-e) is a marker of transmural dispersion of ventricular repolarization.
We studied the relationship ...between (a) the Tp-e on local pseudo transmural electrograms (pseudo transmural Tp-e) or limb leads of body surface electrocardiogram (surface Tp-e) and (b) the intracardiac left ventricular (LV) repolarization during a drug-induced QT-interval prolongation.
Using open-chested canine intact hearts treated by anthopleurin-A, transmural LV electrograms were recorded via needle electrodes placed in the basoanterior, midanterior, apicoanterior, basolateral, midlateral, and apicolateral LV wall. Recovery time (RT) was calculated as an index of local repolarization at each transmural unipolar electrode.
This model showed slower heart rate-dependent heterogeneous distribution of ventricular repolarization both along the basal to apical axis and along the transmural axis. RT was longer at the LV apex than at the base and longer in the lateral than in the anterior wall during the slower heart rate. A high correlation was found between surface Tp-e and total LV dispersion. In contrast, pseudo transmural Tp-e correlated with transmural RT dispersion. The shortest RT in the heart roughly corresponded to the peak, as did the longest RT with the end of the T wave on the surface electrocardiogram.
During drug-induced QT-interval prolongation with a large apicobasal and anterolateral dispersion of ventricular repolarization, the Tp-e in the limb leads expresses spatial (total) distribution of repolarization in the whole left ventricle.
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