Osamu Fujimura

Epicardial ablation of ventricular tachycardia: An institutional experience of safety and efficacy

BACKGROUNDnEpicardial ablation has been shown to be a useful adjunct for treatment of ventricular tachycardia (VT).nnnOBJECTIVEnTo report the trends, safety, and efficacy of epicardial mapping and ablation at a single center over an 8-year period.nnnMETHODSnPatients referred for VT ablation (June 2004 to July 2011) were divided into 3 groups: ischemic cardiomyopathy (ICM), nonischemic cardiomyopathy (NICM), and idiopathic ventricular arrhythmias (VA). Patients with scar-mediated VT who underwent combined epicardial and endocardial (epi-endo) mapping and ablation were compared with those who underwent endocardial-only (endo-only) ablation with regard to patient characteristics, acute procedural success, 6- and 12-month clinical outcomes.nnnRESULTSnAmong 144 patients referred for VT ablation, 95 patients underwent 109 epicardial procedures (94% access rate). Major complications were seen in 8 patients (8.8%) with pericardial bleeding (>80 cm(3)) in 6 cases (6.7%), although no tamponade, surgical intervention, or procedural mortality was seen. Patients with ICM who underwent a combined epi-endo ablation had improved freedom from VT compared with those who underwent endo-only ablation at 12 months (85% vs 56%; P = .03). In patients with NICM, no differences were seen between those who underwent epi-endo ablation and those who underwent endo-only ablation at 12 months (36% vs 33%; P = 1.0). In idiopathic VA, only 2 of 17 patients were successfully ablated from the epicardium.nnnCONCLUSIONSnIn this large tertiary single-center experience, complication rates are acceptably low and improved clinical outcomes were associated with epi-endo ablation in patients with ICM. Patients with NICM represent a growing referred population, although clinical recurrence remains high despite epicardial ablation. Epicardial ablation has a low yield in idiopathic VA.

Termination of acute atrial fibrillation in the Wolff-Parkinson-White syndrome by procainamide and propafenone: Importance of atrial fibrillatory cycle length

The effects of intravenous procainamide (n = 30) or propafenone (n = 25) were evaluated in 55 patients with acute atrial fibrillation and the Wolff-Parkinson-White syndrome. All patients received either procainamide (12 to 15 mg/kg body weight) or propafenone (1 to 2 mg/kg) during sustained (greater than 10 min) atrial fibrillation or after termination of nonsustained atrial fibrillation. Termination of atrial fibrillation was attributed to a drug if it occurred less than or equal to 15 min after infusion. Measurements included mean cycle length of fibrillatory electrograms (mean AA interval) as measured at the high right atrium and shortest RR interval between pre-excited cycles during atrial fibrillation. Atrial fibrillation terminated more frequently after procainamide administration (65%) than after propafenone (46%), although this difference was not significant. Procainamide prolonged the shortest pre-excited RR interval (228 +/- 41 to 339 +/- 23 ms, p = 0.0001) as did propafenone (215 +/- 40 to 415 +/- 198 ms, p = 0.0001) and the magnitude of increase was greater for propafenone (p = 0.048). Patients with sustained atrial fibrillation had shorter mean AA intervals than did their counterparts with nonsustained atrial fibrillation (123 +/- 25 versus 186 +/- 35 ms, p = 0.0001). Termination of sustained atrial fibrillation by either drug was accompanied by prolongation of the mean AA interval but not necessarily by the shortest pre-excited RR interval. Termination of atrial fibrillation was heralded by a 68% increase in the mean AA interval after procainamide administration compared with a 30% increase when the arrhythmia persisted. For propafenone the increases were 90% and 68%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Relationship Between Sinus Rhythm Late Activation Zones and Critical Sites for Scar-Related Ventricular Tachycardia Systematic Analysis of Isochronal Late Activation Mapping

Background—It is not known whether the most delayed late potentials are functionally most specific for scar-related ventricular tachycardia (VT) circuits. Methods and Results—Isochronal late activation maps were constructed to display ventricular activation during sinus rhythm over 8 isochrones. Analysis was performed at successful VT termination sites and prospectively tested. Thirty-three patients with 47 scar-related VTs where a critical site was demonstrated by termination of VT during ablation were retrospectively analyzed. In those who underwent mapping of multiple surfaces, 90% of critical sites were on the surface that contained the latest late potential. However, only 11% of critical sites were localized to the latest isochrone (87.5%–100%) of ventricular activation. The median percentage of latest activation at critical sites was 78% at a distance from the latest isochrone of 18 mm. Sites critical to reentry were harbored in regions with slow conduction velocity, where 3 isochrones were present within a 1-cm radius. Ten consecutive patients underwent ablation prospectively guided by isochronal late activation maps, targeting concentric isochrones outside of the latest isochrone. Elimination of the targeted VT was achieved in 90%. Termination of VT was achieved in 6 patients at a mean ventricular activation percentage of 78%, with only 1 requiring ablation in the latest isochrone. Conclusions—Late potentials identified in the latest isochrone of activation during sinus rhythm are infrequently correlated with successful ablation sites for VT. The targeting of slow conduction regions propagating into the latest zone of activation may be a novel and promising strategy for substrate modification.

Value of a revised procainamide test in the Wolff-Parkinson-White syndrome

A shortest preexcited RR interval less than 250 ms during atrial fibrillation identifies the patient with Wolff-Parkinson-White syndrome potentially at risk for ventricular fibrillation. Loss of preexcitation after infusion of up to 10 mg/kg of procainamide during sinus rhythm has been reported to correlate with a slow ventricular response during atrial fibrillation and has been proposed as a noninvasive test to establish risk of sudden death in these patients. Others have failed to establish this relation and have questioned the usefulness of the procainamide test. Such conflicting results were hypothesized to be a result of differing dosages and methodology. Consequently, this study tested the effect of incremental doses of procainamide (to a cumulative dose of 1 g) on the anterograde effective refractory period of the accessory pathway and related the reliability of the procainamide test to the dose at which preexcitation was lost. The effect of procainamide on the anterograde effective refractory period of the accessory pathway was dose dependent; patients who lost preexcitation had a steeper dose-response curve. Loss of preexcitation by a cumulative dose of 550 mg provided the best balance for sensitivity (60%) and specificity (89%) in identifying patients with preexcited shortest RR greater than 250 ms. Specificity fell steeply after this dosage and higher doses were not useful. The diagnostic accuracy of the procainamide test is critically related to dosage and method of infusion.

Acute effect of disopyramide on atrial fibrillation in the Wolff-Parkinson-White syndrome☆

Disopyramide was administered intravenously to 54 patients during atrial fibrillation and predominantly pre-excited QRS configuration at the time of electrophysiologic study. All patients had Wolff-Parkinson-White syndrome and no patient had coexistent heart disease. The drug was given during sustained atrial fibrillation (n = 45) or during sinus rhythm before induction of atrial fibrillation for patients whose atrial fibrillation was self-terminating in the control state (n = 9). Atrial fibrillation converted to sinus rhythm within 15 min after disopyramide in 37 (82%) of the 45 patients. The shortest RR intervals between two pre-excited cycles increased from 208 +/- 42 to 293 +/- 117 ms (p less than 0.0001). The average RR interval of all cycles prolonged from 332 +/- 60 to 396 +/- 117 ms(n = 45, p less than 0.0001). The 9 patients in whom pre-excitation was abolished after the drug had a significantly longer initial shortest RR interval than that of the 36 patients in whom pre-excitation persisted (246 +/- 47 versus 199 +/- 36 ms, p = 0.0022). No patients developed significant hemodynamic or other adverse effects after disopyramide. These data support the intravenous use of disopyramide in patients with normal ventricular function who have atrial fibrillation and a predominant ventricular response over an accessory atrioventricular pathway.

Tissue voltage discordance during tachycardia versus sinus rhythm: Implications for catheter ablation

BACKGROUNDnElectroanatomic mapping systems are an important tool to identify cardiac chamber voltage and assess channels of slow conduction.nnnOBJECTIVEnTo assess the correlation between electroanatomic mapping voltage maps obtained during macroreentrant tachycardia compared to sinus rhythm (SR) with a contact mapping system.nnnMETHODSnWe retrospectively evaluated patients with atrial flutter (AFL) referred for radiofrequency ablation with electroanatomic voltage maps obtained during AFL and SR. The atrium was divided into predetermined segments. Overall atrial and segmental peak-to-peak bipolar voltages in AFL and SR were assessed. To directly compare a region within the same patient, tissue voltage differences during AFL and SR were assessed on the basis of mean voltage difference.nnnRESULTSnSixteen patients (87% men) had available voltage maps. Eighty-one percent had typical cavotricuspid isthmus-dependent right AFL. A mean of 441.7±153.9 vs 398.1±125.4 total points (P = .22) were sampled during AFL and SR, with a mean of 99.5±58.9 vs 91.2±60.4 points (P = .45) sampled per region. Overall right atrial mean voltage was significantly higher during AFL than SR (0.554±0.092mV vs 0.473±0.079mV; P≤.001), with the lateral wall (0.707±0.120mV vs 0.573±0.097mV; P = .0004) and the cavotricuspid isthmus (0.559±0.100mV vs 0.356±0.066mV; P<.0001) also showing higher mean voltage during AFL. When compared within an individual patient, 19% (14 of 75) of the patient regions had a>0.5mV mean voltage difference and 40% (30 of 75) had a>0.25mV mean voltage difference.nnnCONCLUSIONSnThese data suggest that voltage maps performed during macroreentrant atrial arrhythmias often vary significantly from maps obtained during SR.

Ventricular asystole due to atrial oversensing by a VVI pacemaker: VVT mode as a simple solution

We report a rare case of atrial oversensing by a VVI pacemaker that caused ventricular asystole. Changing the programming to VVT mode not only eliminated the problem but also provided atrioventricular synchrony and rate responsiveness.

Selection of Ablation Catheters, Energy Sources, and Power Delivery

The primary purpose of lesion-forming technologies in atrial fibrillation is to create safe and effective myocardial lesions in a reasonable time frame while avoiding collateral damage. The complex anatomy of the left atrium creates unique difficulties for any lesion-forming technology employed in the ablation of atrial fibrillation. Unfortunately, the ideal energy source for the treatment of atrial fibrillation has yet to be developed, and thus multiple different technologies are still used. Lesion-forming technologies currently employed in the treatment of atrial fibrillation include radio-frequency energy, cryothermal energy, and high-intensity focused ultrasound. This review touches on the basic principles behind each of these technologies and highlights the advantages and limitations of their use in the treatment of atrial fibrillation. Finally, we briefly review some evolving strategies for the treatment of atrial fibrillation, including the use of lasers, microwaves, and Beta-irradiation as well as the injection of autologous fibroblasts.

A case of an incision-related single-loop intra-atrial reentrant tachycardia showing an eccentric atrial activation sequence and widely separate potentials resembling a double-loop reentry; its mechanism and analysis

Introduction A supraventricular reentrant tachycardia (SVT) appearing after cardiac surgery is known to have a complicated reentrant circuit, such as a figure-8 pattern based on a double-loop reentry using both an incisional line and the cavotricuspid isthmus (CTI). In order to determine the reentrant circuit of the SVT, detailed mapping using a 3-dimensional (3-D) electroanatomical mapping system during the tachycardia is essential. We present an incision-related single-loop reentrant SVT, resembling a double-loop reentry, which was correctly diagnosed by analyzing the special positional relationship between the multipolar electrode catheter and the incision.

INFLUENCE OF VENTRICULAR PACING WAVEFRONTS ON MYOCARDIAL SCAR DETECTION DURING ELECTROANATOMIC VOLTAGE MAPPING

The effects of varying pacing wavefronts on left ventricular scar characterization has not be systematically assessed.nnPatients referred for ablation of scar-related ventricular tachycardia underwent substrate-based ablation where bipolar voltage maps were first created during sinus rhythm or RV