It is definitely accepted that the pulmonary vein premature beats are the most frequent AF triggers.
Cardiac fibrillation—challenges and evolving solutions | Nature Reviews Cardiology
However, the substratum is poorly known. Why do pulmonary vein ectopic premature beats cause AF in some patients while in others they may persist the whole life without causing any additional arrhythmia? Why may young people without any apparent cardiopathy have isolated AF? Why can many severe diseased atria survive without AF? These questions suggest the presence of a consistent AF substratum apart from pulmonary vein triggers, which is common both in sick and in apparently normal heart.
To develop the present invention, 40 pts. Mitral regurgitation was mild in 16 pts. There was no significant coronary disease or dilated cardiomyopathy. All patients were taking high antiarrhythmic doses of amiodarone 21 pts. None of these cases had had a history of a thromboembolic episode.
Before the procedure, all AF patients were studied by magnetic resonance in order to evaluate the pulmonary veins anatomy. All pts. All patients provided a written informed consent. The procedure began with endovenous general anesthesia being the ventilation controlled by Drager Cicero E M. In 8 pts. Four electrophysiological catheters were placed coronary sinus, His bundle, right atrium and right ventricle through subclavian and femoral venous punctures, carrying out the conventional electrophysiological study.
Finally, one spiral lead from St. Jude Medical, Inc. Paul, Minn. Systemic anticoagulation was achieved with intravenous , IU heparin and additional 1, IU each according to the coagulation activated time.
US5840025A - Apparatus and method for treating cardiac arrhythmias - Google Patents
The study began at the endocardial surface of the left atrium near the left pulmonary veins insertion, with the ablation of all the potentials that presented right-Fourier-shift AF nests during sinus rhythm and during pacing of the distal coronary sinus. The same procedure was repeated for the left atrium roof, for the left atrium wall near the right pulmonary veins insertion, for the left atrium posterior wall and, finally, for the left surface of the interatrial septum. Similar procedure was repeated for the right atrium eliminating all AF nests, taking special care to avoid lesions in the sinus and AV nodes.
The spiral catheter was used only for checking the frequent pulmonary vein isolation during the ablation of the AF nests near the pulmonary vein insertion showing its relation with the venous myocardium. Intentional electrical venous isolation was not intended.
The procedure was suspended as soon as no more AF nests could be found. Oral anticoagulation was maintained for 3 months. The effect of the present invention can be seen from the results of the Spectral Analysis of the Compact and Fibrillar Myocardium. The compact myocardium presented a homogeneous spectrum with a fundamental frequency ranging between 50 Hz and 75 Hz mean Most AF nests fibrillar myocardium presented a fractionated spectrum with 3 to 6 significant components mean 3. The fundamental frequency ranged from 15 Hz to 87 Hz mean of The remaining harmonics presented mean frequencies of After ablation, the fibrillar myocardium showed remarkable reduction of the harmonics but only moderate reduction in the amplitude of the fundamental frequency, resulting in a left frequency shifting, with the final spectral curve similar to that of compact myocardium, FIG.
In the control group no typical AF nests were found except in one patient. AF induction was possible only in this case despite having no history of spontaneous AF. They were treated a mean of They were located mainly in the following places:. Near the left superior pulmonary vein insertion in 31 Near the right superior pulmonary vein in 30 Left surface of the interatrial septum in 31 Left atrium posterior wall in 20 Right surface of the interatrial septum in 15 Right atrial wall near the insertion of the veins cava except the sinus node area in 21 Non-intentional electrical isolation of 35 pulmonary veins, 6 superior and 3 inferior vena cava were observed during the ablation of the AF nests on the atrial wall near the venous insertion.
At ablation, two atypical left atrial flutter were observed, one case was abolished by RF application and the other reverted by cardioversion.
Another 3 cases of atypical flutter were observed on the first and second post-ablation days, and were treated with endovenous amiodarone 2 and external cardioversion. They were solved with temporary low doses of amiodarone lasting one to three days of treatment. All these arrhythmias were no longer observed after the healing phase.
The mean follow-up was 9. After the healing phase, 32 paroxysmal or persistent AF patients are in sinus rhythm with no episode of AF Only two patients presented AF relapse 5. Holter monitoring was performed in 28 patients. The most significant finding was the presence of frequent atrial premature beats in 6 and rare atrial premature beats in 26 patients. Furthermore, very short episodes of non sustained atrial tachycardia were observed in 5 cases.
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Despite the very low significance of the arrhythmias, 14 Two pericardial effusions occurred in cases with difficult transseptal puncture due to anatomical variation being one clinically treated and the other solved with pericardial drainage. No other complications were observed. The mean time of radiation, including the transseptal puncture, was In this study, using the spectral analysis through the fast Fourier transform FFT , it was possible to clearly identify 2 kinds of atrial myocardium with very important electrophysiological differences, which we have named as compact and fibrillar, FIG.
The former, normal and predominant, shows a homogeneous spectral shape around the fundamental frequency, FIG. In contrast, the latter shows lower amplitude, segmented and heterogeneous spectrum, FIG. Since the harmonics are gathered in 2 to 5 groups of relative high amplitude, the fibrillar myocardium is characterized by a rightshift of the spectrum. The FFT allows us to conclude that the fibrillar myocardium may be composed of several myocardium strands with few lateral connections, presenting dispersion of the conduction speed.
Thanks to the conexins, the compact myocardium—which is the predominant pattern—is composed of tightly connected cells, Table 2. This very well organized structure works like one cell due to the intercalated discs. Its conduction is homogeneous with a predominant wave front and, in absence of barriers presents similar speed in any direction isotropy , FIG.
As a rule, the resulting potential is fast, bi or triphasic, FIG. The cells work in-phase, reacting in a organized sequence that results in a uniform spectral pattern, FIG. The fibrillar myocardium is much less frequent and is located in some specific regions in the atrial wall AF nests , Table 2. Apparently, a fibrillar mycardium is more primitive, and seems to have transitional features between nervous, vascular walls and atrial myocardium. In contrast to the compact, a fibrillar myocardium works like a bunch of loose cells. Probably the lateral connections are scarce promoting a longitudinal conduction speed higher than the transversal one anisotropy , and heterogeneous wave front conduction.
High speed filaments are side by side with others of less speed, FIG. The spectrum of this tissue is typically very fractioned, suggesting it is composed of relatively independent fascicles. We conclude it has much less conexins than the compact FIG. The electrophysiological features of this tissue permit the highest response rate among the cardiac cells being the most probably substratum for the AF maintenance.
Location of the Compact and Fibrillar Myocardium By means of spectral analysis, the narrow areas of fibrillar myocardium—AF nests—could be found easily. Although there was a significant variation among patients, these places were usually found in the atrial wall near the pulmonary veins insertion, more frequent in the superior ones. Frequently it was observed inside the pulmonary veins. In these cases, numerous AF nests were found in the whole left surface of the interatrial septum, being less frequent in the right.
This finding suggests that the distention of the atrial myocardium likely converted the compact into fibrillar myocardium, probably by detaching inter-cellular connections. Less frequent AF nests were found in the right atrium. The more commonly involved places were the junction of superior vena cava and right atrium, the right surface of the interatrial septum in the posterior area and near fossa ovalis and the crista terminalis. An essential trait is that both the sinus and the AV nodes areas present frequency spectrum very similar to the fibrillar myocardium probably due to the nervous origin being necessary special attention for not damage them.
Our main purpose was to find and abolish the AF substratum without line blocks. In this sense, the following observations suggest the fibrillar myocardium and the AF nests are the real AF substratum:. In FIG. It may be clearly observed that the AF nest presents the highest frequency and the most out-of-phase and disorganized activation. The shortest interval between two consecutive near-fields shows that the refractory period of the AF nest is much smaller than that of the compact myocardium. These data match with the findings of Haissaguerre et al who have demonstrated the very short refractory period of muscular pulmonary vein sleeves less than ms.
Oral et al. We have observed similar behavior of the AF nests in the atrial wall. The elimination of AF nests or the isolation by creating line blocks make the AF maintenance more difficult;. We have observed that the AF nests tend to present relatively delayed high amplitude in the 3rd channel with characteristic polyphasic high frequency potentials in the 2nd and in the 3rd channel. Typically, the 3rd channel potential lasts more than 30 ms when measured from the beginning of the 1st channel, FIG.
The location and the treatment of the AF nests were accomplished with the same catheter. The spiral catheter, placed in pulmonary veins, was used to demonstrate that the elimination of the AF nests near pulmonary veins resulted in many veins isolation, FIG. This fact suggests that the natural muscular fibers dispersion in the atrium-vein transition probably favors the appearance of fibrillar myocardium building up congenital or natural AF nests. The purpose was to get the elimination or significant attenuation of the high frequency AF nest potentials in the 3rd channel.
The low frequency presents only a discrete amplitude reduction, left shifting the resulting spectrum towards the normal shape. The Fourier transform shows that, after ablation, the great amount of segmented harmonics above 80 Hz from the AF nests is strongly reduced or eliminated being the fundamental frequency less affected.
As a result, the partial RF ablation of the fibrillar myocardium tends to convert its spectrum into that of the compact, FIG. Stimulating the atrium with progressive high frequency energy we have found a very interesting difference in the compact and fibrillar myocardium behavior. This physiopathology understanding allows us to ablate the AF during the arrhythmia. As the compact myocardium does not present this state it represents one AF Nest. Thus, after ablating several resonant areas during AF we eliminate the AF reverting it to the sinus rhythm. This method allows AF ablation with high probability of cure or AF control without seeking for pulmonary vein premature beats.
Besides being less time-consuming, it seems to be highly effective, regardless of the erratic presence of pulmonary ectopic activity.