<i>Background:</i> External cardioversion is effective to terminate persistent atrial flutter. Biphasic shocks have been shown to be superior to monophasic shocks for ventricular defibrillation and atrial fibrillation cardioversion. The purpose of this trial was to compare the efficacy of rectilinear biphasic versus standard damped sine wave monophasic shocks in symptomatic patients with typical atrial flutter. <i>Methods:</i> 135 consecutive patients were screened, 95 (70 males, mean age 62 ± 13 years) were included. Patients were randomly assigned to a monophasic or biphasic cardioversion protocol. Forty-seven patients randomized to the monophasic protocol received sequential shocks of 100, 150, 200, 300 and 360 J. Forty-eight patients with the biphasic protocol received 50, 75, 100, 150 or 200 J. <i>Results:</i> First-shock efficacy with 50-Joule, biphasic shocks (23/48 patients, 48%) was significantly greater than with the 100-Joule, monophasic waveform (13/47 patients, 28%, p = 0.04). The cumulative second-shock efficacy with the 50- and 75-Joule, biphasic waveform (39/48 patients, 81%) was significantly greater than with the 100- and 150-Joule, monophasic waveform (25/47 patients, 53%, p < 0.05). The cumulative efficacy for the higher energy levels showed naturally no significant difference between the two groups. The amount of the mean delivered energy was significantly lower in the biphasic group (76 ± 39 J) compared to the monophasic one (177 ± 78 J, p < 0.05). <i>Conclusions:</i> For transthoracic cardioversion of typical atrial flutter, biphasic shocks have greater efficacy and the mean delivered current is lower than for monophasic shocks. Therefore, biphasic cardioversion with lower starting energies should be recommended.
Background Multiple strategies for ablation of monomorphic ventricular tachycardia (VT) remote after myocardial infarction have been proposed. Definition of the most relevant isthmus site remains a common therapeutic problem.
Methods and Results 7 pts with documented recurrent and inducible or incessant monomorphic VT have been included in the study. Noncontact maps were obtained using the Ensite-Array® system during VT, programmed right ventricular stimulation (PVS) and sinus rhythm (SR). Geometry creation and ablation was performed with a 7F, 4mm irrigated tip catheter (50W, 60°, 17ml/s flow).
In all pts multiple, median 4 (3-6), VT morphologies were inducible by PVS or overdrive stimulation. In 6 pts an endocardial origin was associated with the clinical VT. In 4 pts the clinical VT isthmus was identified by late activation during SR and concurrent left ventricular (LV) activation via the isthmus in addition to the septal activation wave during PVS (fig.). This was not the observed for any other than the clinical VT isthmus. Short ablation lines of 8 (5-12) radiofrequency current applications perpendicular to the direction of activation at the isthmus exit site rendered the clinical VT noninducible in all pts with endocardial reentries. Additional linear lesions were employed for the treatment of further inducible, predominantly faster, VTs.
Conclusion Late and simultaneous activation of the LV can readily be identified by noncontact mapping and is indicative for the dominant isthmus. Short ablation lines at this site are effective for the treatment of the dominant VT. ![Graphic][1] [1]: /embed/graphic-1.gif
The present study sought to investigate the electrophysiological properties of isolated pulmonary veins following successful radiofrequency (RF) catheter ablation in patients with paroxysmal atrial fibrillation (PAF). Overall, 71 pulmonary veins in 37 consecutive patients (age: 56 +/- 9 years) with recurrent PAF were targeted for RF ablation at the ostial region in order to achieve a complete functional block. Following disconnection, the incidence of dissociated pulmonary vein (PV) activity and its response to orciprenalin were studied. RF ablation abolished conduction in 67 (94%) of 71 potentially arrhythmogenic PVs after a mean of 10.7 +/- 6.4 RF applications for each PV. After ablation, spontaneous dissociated automatic activity (9 to 52 beats/min, median 27) was found in 6 out of 67 isolated PVs (left superior: n = 1, left inferior: n = 1, right superior: n = 2, common left PV: n = 2). Slight acceleration (13 to 68 beats/min, median 29) of dissociated PV activity was observed during infusion of orciprenalin. Following isolation, initiation of sustained or nonsustained local fibrillation was recorded in only two cases of the common left sided PV with preceding automatic activity. In one patient PV fibrillation occurred during orciprenalin infusion following a repetitive response to a dissociated automatic rhythm with increasing duration as well as destabilization. In the other patient, PV fibrillation occurred immediately after the occurrence of PV automaticity. Slow dissociated automatic rhythms are detectable within 9% of disconnected PVs. The unique anatomic substrate of common left PVs seem to favor the occurrence of local fibrillation following isolation. The initiation pattern of fibrillation within the isolated PV has pathophysiological implications and underlines the contribution of multiple factors to the onset and sustenance of PAF.
Multiple strategies for ablation of monomorphic ventricular tachycardia (VT) remote after myocardial infarction have been proposed. Definition of the most relevant isthmus site remains a common therapeutic problem. 7 pts with documented recurrent and inducible or incessant monomorphic VT have been included in the study. Noncontact maps were obtained using the Ensite-Array® system during VT, programmed right ventricular stimulation (PVS) and sinus rhythm (SR). Geometry creation and ablation was performed with a 7F, 4mm irrigated tip catheter (50W, 60°, 17ml/s flow). In all pts multiple, median 4 (3-6), VT morphologies were inducible by PVS or overdrive stimulation. In 6 pts an endocardial origin was associated with the clinical VT. In 4 pts the clinical VT isthmus was identified by late activation during SR and concurrent left ventricular (LV) activation via the isthmus in addition to the septal activation wave during PVS (fig.). This was not the observed for any other than the clinical VT isthmus. Short ablation lines of 8 (5-12) radiofrequency current applications perpendicular to the direction of activation at the isthmus exit site rendered the clinical VT noninducible in all pts with endocardial reentries. Additional linear lesions were employed for the treatment of further inducible, predominantly faster, VTs. Late and simultaneous activation of the LV can readily be identified by noncontact mapping and is indicative for the dominant isthmus. Short ablation lines at this site are effective for the treatment of the dominant VT.
Three-dimensional electroanatomic (CARTO) activation mapping of the cavotricuspid isthmus can be helpful to guide atrial flutter ablation, but to date has not been investigated in comparison to conventional strategies. The aim of the present study was to assess the efficacy of the CARTO navigation system, especially with respect to the fluoroscopy time required for successful atrial flutter ablation.Eighty patients with recurrent common-type atrial flutter were randomly assigned to temperature-controlled radiofrequency (RF) catheter ablation, either guided by conventional criteria (group 1) or additionally oriented on electroanatomic mapping (group 2). In all patients, similar multipolar catheters were inserted into the coronary sinus and placed at the tricuspid annulus, respectively. In group 2, positioning of the mapping electrode and delivery of RF pulses within the cavotricuspid isthmus was mainly oriented on the CARTO map to achieve the most linear and continuous RF lesions. Abolition of intra-atrial conduction verified by conventional criteria (group 1) and electroanatomic mapping (group 2) could be verified in all patients. The overall number of RF pulses (group 1: 16.7+/-6.5; group 2: 13.2+/-5.3) and mean procedure duration (group 1: 172.5+/-47.4 min; group 2: 169.3+/-47.3 min) were not different between the two groups, but mean fluoroscopy time was significantly shorter when the CARTO technology was used (group 1: 29.2+/-9.4 min; group 2: 7.7+/-2.8 min; P = 0.0001). Recurrence of atrial flutter was observed in 3 (9%) patients in each group after a mean follow-up of 8.5+/-2.8 months.Atrial flutter can be abolished effectively using the conventional technique as well as oriented on electroanatomic mapping. However, overall X-ray exposure can be significantly reduced by the CARTO-guided approach without prolongation of procedure duration.
Introduction: Pulmonary veins (PVs) are the predominant location of triggers for atrial fibrillation (AF), but little is known about the electrophysiologic properties of PVs. In addition, the influence of amiodarone on the electrophysiologic properties of PVs has not been elucidated. Methods and Results: Fifty‐five patients with symptomatic and drug‐resistant AF were divided into two groups: group 1 patients (n = 29) without antiarrhythmic drug therapy at the time of electrophysiologic study (EPS), and group 2 patients (n = 26) undergoing continuous long‐term treatment with amiodarone. EPS including programmed stimulation of both atria and within the PVs was performed in both groups. In group 1, the effective refractory period (ERP) of all PVs (174 ± 62 msec) was significantly shorter than the ERP of the left atrium ([LA] 254 ± 30 msec, P = 0.0001) and right atrium ([RA] 221 ± 29 msec, P = 0.0001). The same pattern was observed in group 2 (PV: 210 ± 58 msec; LA: 259 ± 35 msec, P = 0.0001; RA: 246 ± 37 msec, P = 0.0255). The ERP of all stimulated PVs was significantly lower in group 1 (174 ± 62 msec) than in group 2 (210 ± 58 msec; P = 0.0001). The ERP of the left superior and right superior PVs and RA but not the left inferior PV and LA were significantly increased in patients treated with amiodarone. Decremental conduction properties were observed in all stimulated PVs, and there were no significantly differences between the maximal decrement of both groups. Conclusion: The distinctive electrophysiologic properties of PVs are emphasized by amiodarone therapy. Long‐term amiodarone treatment is responsible for heterogeneous alteration of the PV electrophysiology, which may account for the individual antiarrhythmic responses in a subset of patients with paroxysmal AF.
