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In predicting the origin of focal atrial arrhythmias, a precise analysis of the P-wave morphology in the 12-lead electrocardiogram is essential. In this report, we demonstrate a unique ectopic atrial rhythm and discuss its origin by analyzing the P-wave morphology., (© 2016 Wiley Periodicals, Inc.)

Ectopic foci arising from pulmonary veins (PVs) are the predominant sources for the initiation and maintenance of atrial fibrillation (AF) in a vast majority of cases. However, ectopic foci also exist in the non-PV areas like superior vena cava (SVC) in 10-20% of the cases. We report the significance of SVC isolation in a patient with persistent AF and anomalous pulmonary venous connection of the right superior pulmonary vein into the SVC., (©2012, The Authors. Journal compilation ©2012 Wiley Periodicals, Inc.)

Characterization of ultrasound detected fetal arrhythmias is generally performed by means of M-mode and pulsed Doppler echocardiography (fECHO), sonographic techniques that allow only indirect and approximate reconstruction of the true electrophysiological events that occur in the fetal heart. Several studies demonstrated the ability of fetal magnetocardiography (fMCG) to identify fetal arrhythmias. We report on three women, studied after the 32nd gestational week, who were referred for fMCG because of unsatisfying fetal cardiac visualization with fECHO due to maternal obesity, fetus in constant dorsal position hiding the fetal heart, intrauterine growth retardation, and oligohydramnios. Minor pericardial effusion was present in the third patient and digoxin therapy was given. FMCG were recorded with a 77-channel MCG system working in a shielded room. Independent Component Analysis (FastICA algorithm) was used to reconstruct fetal signals. The good quality of the retrieved fetal signals allowed real-time detection of arrhythmias and their classification as supraventricular extrasystoles (SVE), with/without aberrant ventricular conduction and/or atrioventricular block. The time course of the fetal cardiac rhythm was reconstructed for the entire recording duration; hence, fetal heart rate variability could be studied in time and frequency. Since isolated extrasystoles may progress to more hazardous supraventricular tachycardias, the noninvasive antenatal characterization of, even transient, fetal arrhythmias and their monitoring during pregnancy can be of great clinical impact.

We have shown that pacemapping from each of the pulmonary veins reveals unique surface ECG characteristics. However, application of these criteria to spontaneous atrial premature complexes is often difficult because of obscuration by the prior T wave. We hypothesized that the pulmonary vein of origin of spontaneous atrial premature complexes can be determined by measuring characteristics of the P wave whether or not the P wave was superimposed on the prior T wave. We analyzed 58 spontaneous atrial premature complexes of known pulmonary vein origin in 30 patients referred for atrial fibrillation ablation. The origin of all the atrial premature complexes was documented by detailed, intracardiac multipolar catheter mapping. Based on previous work, the criteria for distinguishing right-sided from left-sided pulmonary vein origin of atrial premature complex includes: (1) P wave duration < 120 ms; (2) P wave amplitude in lead I > 0.05 mV; and (3) P wave amplitude in leads II/III > 1.25. The criteria to separate superior from inferior pulmonary veins included the sum of the P wave amplitude in all the inferior leads greater than 0.3 mV. The combination of the P wave duration < 120 ms and the ratio of the P wave amplitude in leads II/III > 1.25, distinguished right-sided from left-sided pulmonary vein origin of spontaneous atrial premature complexes with a sensitivity of 82% and specificity of 100%. The sum of the P wave amplitude in leads II, III, and aVF > 0.3 mV distinguished superior from inferior pulmonary vein of origin with a sensitivity of 39% and specificity of 73%. The pulmonary vein origin of spontaneous atrial premature complexes can often be localized using careful quantitative analysis of the surface ECG despite superimposition of the P wave upon the T wave. Separation of right-sided from left-sided pulmonary vein origin of spontaneous atrial premature complexes can be determined with good specificity and sensitivity, while the ability to distinguish inferior from superior pulmonary vein origin is limited.

This study evaluated the incidence of atrial premature beats (APBs) and the impact of various provocative maneuvers in patients with focally initiated AF. Fifty patients (39 men, 57 +/- 0.4 years) with focally initiated, paroxysmal AF underwent Holter recording and a standardized protocol of provocative maneuvers: vagomechanical stimulation, adenosine 12 mg i.v., esmolol 500 ng/kg i.v., orciprenaline i.v. 5 mg/50 mL saline 0.9%, and atropine 0.01 mg/kg i.v. A surface ECG was recorded for 20 minutes at baseline and following each part of the protocol. High focal activity was defined as > or = 1 APB/minute. During Holter ECG, 29 (58%) patients had an amount of < 200 APBs, 12 (24%) patients < 700 > or = 200, and 9 (18%) patients > or = 700 APBs. Less than 1 hour of high focal activity was observed in 34 (68%) of the 50 patients. Before starting provocative maneuvers 15 (30%) patients had high focal activity whereas 35 (70%) presented < 1 APB/minute. In 29 (58%) patients APBs increased by > or = 1/min during provocative maneuvers: by vagomechanical stimulation in 11 patients, after adenosine in 15, esmolol in 12, orciprenaline in 15, and after atropine in 9 patients. In all patients with > or = 1 APB/min at baseline, focal activity decreased or disappeared during some single provocative maneuvers. AF occurred in eight patients under provocative maneuvers. No predictive factors of a successful provocative maneuver were detected with regard to the baseline patients characteristics and Holter results. In conclusion, patients with focally initiated AF have a low incidence of spontaneous APBs. Various provocative maneuvers successfully increase APBs in more than half of the patients; orciprenaline had the highest efficacy. Some provocative maneuvers may suppress APBs in the setting of high focal activity at baseline.

The spatial resolution (SR) of the body surface Laplacian map (BSLM) was assessed using a three-dimensional, realistically shaped, heart-torso model. The BSLMs were estimated from the body surface potential maps (BSPMs) generated by pacing different sites of the ventricle of a three-dimensional computer heart model using a novel three-dimensional spline Laplacian algorithm. Pacing was performed at a total of 88 myocardial units in five regions of the AV ring (anterior, left wall, posterior, right wall, and septum) and three regions adjacent to the AV ring in the middle anterior and posterior of the ventricles. The SR of the BSPMs and BSLMs were investigated by means of the correlation coefficient (CC) of maps. When 5 microV and 10 microV Gaussian white noises were added into the simulated BSPMs, the SR, at 36 ms after the onset of pacing, was about 5.0 +/- 1.2 mm and 5.4 +/- 1.3 mm for the BSPMs, and 3.3 +/- 0.8 mm and 4.0 +/- 0.9 mm for the BSLMs, respectively. The results of the present simulation study suggest that the BSLM has higher SR and may provide a more accurate means than the BSPMs for differentiating between the accessory pathways or the sites of other ectopic cardiac beats along the AV ring and in its neighboring regions.

Atrial premature depolarizations (APDs) originating from focal sites, particularly the pulmonary veins (PV), may become triggers of atrial fibrillation (AF). Accurate mapping of APDs with conventional methods may be time consuming and expose the patient to unnecessary instrumentation of the left atrium. We hypothesized that the atrial activation sequence recorded using a simple system that includes an esophageal catheter and a custom-made 16-electrode catheter with two sets of floating electrodes eight in the coronary sinus and eight in the high right atrium) could be sufficient to localize the APDs. The study included 29 patients with frequent APDs and AF refractory to antiarrhythmic medications. The APD site of origin was confirmed with single-point sequential mapping techniques using the CARTO system ten patients) or by placement of multielectrode catheters in the right and left PV (19 patients). Of the 29 patients, 20 patients had a single APD focus; 8 patients had two different APD morphologies; and 1 patient had three APD foci. Mapping for ablation of the APD foci showed earliest activation in the left superior PV in 12 patients, right superior PV in 15 patients, right middle PV in 4 patients, right inferior PV in 1 patient, the lingular branch of the left superior PV in 2 patients, left inferior PV in 2 patients, and right atrium along the crista terminalis in 3 patients. The activation sequence and relative timing of the recordings obtained with our catheter configuration was highly predictive of right and left atrial origin and, more importantly, of right and left PV foci.

We investigated the usefulness of the time- and frequency-domain analysis of the P wave triggered signal-averaged ECG (P-SAECG) for detecting patients with paroxysmal atrial fibrillation (Paf). In previous studies, the usefulness of the time domain of the P-SAECG to detect patients with Paf was described but that of the frequency domain is unknown. We analyzed the P-SAECG in the time and frequency domain in 23 patients with Paf and 19 controls. The 32-unipolar chest lead ECGs and the standard bipolar limb lead ECGs were obtained. The time-domain analysis showed that the filtered P duration (fPd) was significantly longer (P < 0.01) in patients with Paf than controls: the predictive accuracy of Paf with fPd > 120 ms was 69%. The frequency domain analysis showed that the area ratio of power spectrum area of 0-20 Hz to 20-100 Hz (AR20) was significantly higher (P < 0.01) and the magnitude ratio at 30 Hz (%Mag.30) calculated by dividing the magnitude at 30 Hz by the maximal magnitude was significantly (P < 0.01) lower in patients with Paf than controls in the left lateral chest leads. The predictive accuracy of Paf with AR20 > or = 1.5 and that with %Mag.30 < 40% was 83% and 73%, respectively. Our results indicate that the frequency-domain analysis of P waves in lateral leads is useful as is the time-domain analysis to detect patients with Paf. The AR20 > or = 1.5 and %Mag.30 < 40% provides accurate predictability of Paf.

The ability of single paced ventricular beats during tachycardia to penetrate the tachycardia circuit and reset the subsequent atrial depolarization (atrial preexcitation), enabling calculation of the "preexcitation index," can be helpful in analyzing supraventricular tachycardias. However, the ventricular refractory period often prevents ventricular capture of beats with the necessary prematurity to demonstrate atrial preexcitation, particularly in atrioventricular nodal reentrant tachycardia (AVNRT). We hypothesized that the use of double premature stimuli could overcome this limitation. In 25 consecutive patients with either AVNRT or atrioventricular reciprocating tachycardia (AVRT) we attempted to demonstrate atrial preexcitation with single and double ventricular extrastimuli. Whereas atrial preexcitation with a single extrastimulus could only be achieved in 3 of 11 patients with AVNRT, all but 1 patient demonstrated atrial preexcitation with the use of double ventricular extrastimuli. On the other hand, in all but 1 patient with AVRT, atrial preexcitation could be achieved with single and double extrastimuli. A formula was derived for obtaining a preexcitation index with double extrastimuli and shown to correspond closely with the preexcitation index obtained with a single extrastimulus in the 16 patients in whom atrial preexcitation could be achieved with single and double extrastimuli. Thus, this technique significantly enhances the ability to achieve atrial preexcitation and to calculate the preexcitation index in patients with AVNRT, and thus may be useful in deciphering tachycardia mechanism in some patients, as well as being a useful technique in studying the electrophysiological properties of the antegrade and retrograde limbs of AVNRT.

Unexplained syncope is the main indication for the implantation of a diagnostic pacemaker. Studies on those implanted have shown that in patients with unexplained syncope, the diagnosis of paroxysmal bradycardia was feasible and reliable. The present study was designed to evaluate a new bradycardia diagnosis algorithm, loaded in a dual chamber pacemaker, in 24 patients considered as candidates for diagnostic pacemakers. During a mean follow-up of 153 days, at least one bradycardia episode was recorded in 13 patients. The mean number of detected bradycardias was 6 and the median was 3. The mean delay between the algorithm activation and the first bradycardia episode was 67 days. The mechanism of bradycardia was atrioventricular block in 6 patients, sinus node dysfunction in 6 patients, and consecutive blocked atrial premature beats in 1 patient, as indicated by the event markers. In 11 patients bradycardia was recorded during the daytime only or day and night. In two patients the episodes were recorded only at night. Overall, the algorithm was well-tolerated; however, some mild symptoms were observed due to the method of bradycardia determination, allowing bradycardia. Three patients were symptomatic as a direct result of the algorithm operation, and four patients had symptoms related to the single chamber operation of the pacemaker while functioning in the diagnosis mode (VDI). These symptoms were relieved with DDD pacing.