Electrograms for identification of the atrial ablation site during catheter ablation of accessory pathways.

BACKGROUND: Catheter ablation of accessory pathways using radiofrequency current has been shown to be effective in patients with Wolff-Parkinson-White syndrome, by using either the ventricular or atrial approach. However, the unipolar electrogram criteria for identifying a successful ablation at the atrial site are not well established. METHODS AND RESULTS: One hundred patients with Wolff-Parkinson-White were treated by delivering radiofrequency energy at the atrial site. Attempts were considered successful when ablation (disappearance of the delta wave) occurred in < 10 seconds. In eight patients with concealed pathway, the accessory pathway location was obtained by measuring the shortest V-A interval either during ventricular pacing or spontaneous or induced reciprocating tachycardia. In 92 patients both atrioventricular valve annuli were mapped during sinus rhythm, in order to identify the accessory pathway (K) potential before starting the ablation procedure. When a stable filtered (30-250 Hz) "unipolar" electrogram was recorded, the following time intervals were measured: (1) from the onset of the atrial to the onset of the K potential (A-K); (2) from the onset of the delta wave to the onset of the K potential (delta-K); and (3) from the onset of the K potential to the onset of the ventricular deflection (K-V). During unsuccessful versus successful attempts, A-K (51 +/- 11 ms vs 28 +/- 8 ms, P < 0.0001 for left pathways [LPs]; and 44 +/- 8 ms vs 31 +/- 8 ms, P < 0.02 for right pathways [RPs]) and delta-K intervals (2 +/- 9 ms vs -18 +/- 10 ms, P < 0.0001 for LPs; and 13 +/- 7 ms vs 5 +/- 8 ms, P < 0.02 ms for RPs) were significantly longer. CONCLUSIONS: Short A-K interval (< 40 ms), and a negative delta-K interval recorded from the catheter positioned in the atrium are strong predictors of successful ablation of LPs and RPs. Therefore, the identification of the K potential appears to be of paramount importance for positioning of the ablation catheter, followed by analysis of A-K and delta-K unipolar electrogram intervals. However, it appears that the mere recording of K potential is not, per se, predictive of successful outcome, but rather the A-K and delta-K interval.

Electrophysiologic effects of amlodipine vs. diltiazem in patients with coronary artery disease and beta-blocking therapy.

This study compares the electrophysiologic effects of amlodipine and diltiazem in patients with coronary artery disease concomitantly treated with background beta-blocking therapy. Thirty patients were included in an open-label parallel study in two phases. During phase 1, patients were screened and placed on maintenance atenolol therapy at 50 or 100 mg/day, while phase 2 consisted of right-sided catheterization and randomization of patients to either amlodipine (10 mg i.v.) or diltiazem (10 mg i.v.). Following treatment with amlodipine, no significant alteration in markers of electrophysiological activity was observed. Treatment with diltiazem resulted in a significant lengthening of sinus cycle length (SCL, p < 0.04), AH interval (p < 0.02), and Wenckebach CL (WCL, p < 0.001), and a trend towards an increase in sinus node recovery time (SNRT, p = 0.057). No effects were observed with regard to HV interval and corrected SNRT. The results of this study indicate that 10 mg intravenous amlodipine has no significant electrophysiological action on sinus or AV node function in patients receiving beta-blocker therapy with atenolol, suggesting that amlodipine can be added to beta-blockers to treat patients with myocardial ischemia and/or hypertension without any significant increase in the risk of bradyarrhythmias.

Effects of thrombolysis and atenolol or metoprolol on the signal-averaged electrocardiogram after acute myocardial infarction. Late Potentials Italian Study (LAPIS).

Late potentials (LPs) detected on the signal-averaged (SA) electrocardiogram (ECG) predict arrhythmic events after acute myocardial infarction (AMI). The effect of thrombolysis on the incidence of LPs after AMI is controversial and its impact on subsequent arrhythmic events is not known. Moreover, the effects of beta blockers on the SAECG have not been studied. Six hundred eighteen patients with AMI were studied; thrombolysis was given to 228 (37%). In comparison with patients treated conventionally, those receiving thrombolysis were significantly younger and more frequently male, had higher peak values of creatine kinase, a lower prevalence of non-Q-wave AMI, and a higher incidence of ventricular fibrillation in the acute phase, and more frequently received beta blockers. An SAECG obtained 6 to 8 days after AMI showed LPs in 24% of patients receiving and in 25% not receiving thrombolysis (p = NS). On admission, intravenous beta blockers were administered to 110 patients (18%); those receiving beta blockers were younger, had lower peak values of creatine kinase and more frequently received thrombolysis. LPs were less frequently found in patients treated than in those not treated with beta blockers (15 vs 27%; p = 0.007); however, this effect was found only in those with an ejection fraction > or = 40%. Independent predictors of LPs by multivariate analysis were an ejection fraction < 40% (p = 0.007), ventricular fibrillation in the acute phase (p = 0.02), and absence of beta-blocking therapy (p = 0.03). During a mean follow-up of 12 +/- 7 months, there were 39 cardiac deaths (6%), 13 of which were sudden (2%), and 9 sustained ventricular tachycardias.(ABSTRACT TRUNCATED AT 250 WORDS)

[Results of surgical treatment in supraventricular tachycardias]. / Risultati del trattamento chirurgico delle tachicardie sopraventricolari.

From May 1989 to May 1992, 44 patients (mean age 41 years, range 15-66) underwent surgery for supraventricular tachycardias: in 35 patients with atrioventricular reentrant tachycardia or atrial fibrillation associated with accessory pathway and refractory to medical treatment, the epicardial approach was used; in 8 with atrioventricular nodal reentrant tachycardia, a perinodal cryosurgery of the atrioventricular node was used, and in 1 patient with atrial flutter a cryosurgical ablation around the orifice of the coronary sinus and surrounding tissues was performed. All 38 accessory pathways were successfully ablated in 35 patients and no recurrences of delta wave or tachycardia were observed during a mean follow-up of 17 +/- 10 months. Atrial perforation during surgery and pericarditis were the only complications observed. All 8 patients with atrioventricular nodal reentrant tachycardia were successfully treated: in 2 patients dual pathways persisted after surgery but tachycardia was no longer inducible. No recurrences were observed during a mean follow-up of 15 +/- 4 months. Since surgery (15 months), the patient with atrial flutter has been free of recurrent episodes of atrial flutter. In conclusion, surgical treatment of supraventricular tachycardias is highly successful, with no mortality and very low morbidity. Should transcatheter ablation fail, surgery should be the treatment of choice in patients with frequent and symptomatic supraventricular tachycardias.

[Right accessory pathway simulating a nodo-ventricular pathway: an electrophysiologic study and intraoperative mapping]. / Via accessoria destra che simula una via nodo-ventricolare: studio elettrofisiologico e mappaggio intraoperatorio.

We report a case of a patient with episodes of wide QRS tachycardia and syncope. During the electrophysiologic study, a wide QRS tachycardia (200 b/m) with left bundle branch block morphology was reproducibly induced by incremental atrial pacing with progressive shortening of the HV interval and lengthening of the AV interval, suggesting the presence of a nodoventricular accessory pathway (Mahaim fiber). The intraoperative mapping performed during tachycardia showed the earliest ventricular activation to be over the right antero-lateral AV groove, different from the usual epicardial activation previously described. According to the earliest epicardial breakthrough point, we performed an epicardial AV fat pad dissection which produced irreversible disappearance of preexcitation, confirmed at the postoperative electrophysiologic study. No recurrence of tachycardia was observed during a follow-up of 11 months. This case further confirms previous data that the "so-called" Mahaim fibers could be a right accessory pathway with decremental properties.