Alejandro A. Ventura, Lisandro Soriano, Marisa G. López
Servicio de Arritmias. Cordis-Instituto del Corazón.
(3500) Resistencia, Chaco E-mail
Recibido 04-FEB-13 – ACEPTADO después de revisión el25-MAYO-14.
The authors declare not having conflicts of interest
Rev Fed Arg Cardiol. 2014; 43(3): 150-154
Introduction: Radiofrequency ablation procedures are usually guided by fluoroscopy, however the use of X rays is potentially harmful for both the patient and the medical and paramedical staff. Objectives: To compare the results of radiofrequency ablation performed exclusively for the navigation systems, with those made with conventional techniques in patients with typical atrial flutter Methods: Five patients with typical atrial flutter were ablated only with the assistance of the navigation systems (group I), and compared retrospectively with 21 similar cases, made with the conventional technique (group II). The endpoint of the procedure was the confirmation of bidirectional block of the cavo-tricuspid isthmus and non-inducibility of atrial flutter. We analyzed the recurrence of clinical arrhythmia and holter until 6 months after the ablation procedure. Results: No significant differences between groups with respect to the success of the procedure: Gr I = 5p (100%) vs. Gr II = 20p (95.2%). In Gr I there were no complications, and Gr II a hematoma on the puncture site. The average fluoroscopy time in the Gr II was 15 ± 8 min, not requiring the use of it in group I. The incidence of recurrence was similar in both groups (0% vs. 4.7% Gr I Gr II). Conclusions: In patients with typical atrial flutter, radiofrequency ablation exclusively with navigation systems is a feasible and safe technique, with results comparable to the conventional technique.
INTRODUCTION The ablation procedures by radiofrequency (RFA) are usually guided by fluoroscopy; however, the use of X-rays is potentially harmful, both for the pt and for the medical and paramedical staff. RFA of different arrhythmogenic substrates exclusively with navigation systems, has been previously described, proving to be a safe technique and comparable to conventional methods [1,2]. It could be beneficial for such technique, besides being mandatory in pregnant women, to extend it to other patients, in order to prevent their exposition and of the sanitary staff to radiation. The way we see it, there is no history in our country of publications where this technique was compared to the conventional method.
In the present paper, we present our experience in 5 patients with typical atrial flutter (TAF), that were ablated exclusively with the assistance of the navigator, and compared in a retrospective way with 21 cases of similar characteristics, made with the conventional technique. We also made a review on the potential deleterious effects of radiations on health.
Since November 2012, all the pts that were admitted into our institution with diagnosis of TAF, underwent procedures of RFA without fluoroscopy, exclusively guided with the assistance of the navigator (group I). In a retrospective fashion, 21 patients were analyzed with TAF and similar clinical characteristics, that were ablated since November 2010 until November 2012, with the conventional method (group II). In Table 1, the characteristics in both groups are indicated.
Table 1. Clinical characteristics and results of the procedures
of ablation without fluoroscopy (G-I) and ablation by conventional method (G-II)
Group I (N=5 p)
Group II (N=21 p)
Left atrium diameter
Left atrium area
Rhythm during ablation:
Time of fluoroscopy
Group I (ablation without fluoroscopy) and Group II (ablation by conventional method)
Description of the procedure of ablation without fluoroscopy
The patients received anticoagulation treatment (INR 2-3) for 3 weeks before the procedure. In 1 patient in whom the values of INR were not reliable, transesophageal echo was performed to rule out the presence of thrombi.
Threedimensional electroanatomic mapping was made by an EnSite Navx navigator (St Jude Medical, Minnesota, USA). The angiography equipment was turned off and the medical and paramedic staff did not use lead protection. Under sedation/analgesia with midazolam/fentanyl, right femoral venous punctures were made. Three catheters were introduced, which guided by the navigator images, were made to advance through the inferior vena cava (IVC) until the right atrium (RA). A skin patch was used as a reference parameter for the EnSite. First, anatomical cartography of the RA was made with a 7F quadripolar deflectable catheter, defining the SVC, the IVC, tricuspid annulus (TA), appendage, His bundle, with a special definition of the cavo-tricuspid isthmus (CTI). Next, the mentioned catheter was introduced into the coronary sinus, the anatomical image of which was added to the RA. A second 8F duodecapolar halo deflectable catheter, was placed in the lateral side of the RA around the TA. A third deflectable catheter of 8 mm (Blazer 8F) was used to apply radiofrequency.
In the patients admitted to the procedure with TAF (3 patients), an Activation Sequence Map (Figure 1) was made: the precocity of bipolar electrograms, obtained in each contact point of the exploring catheter with the RA endocardium, are illustrated by a color scale, so that the earliest adopts the white color, and the latest the lilac color. Such colors are applied on the 3D anatomical cartography of the RA.
Figure 1. TAF activation sequence map: the precocity of the bipolar electrograms obtained
in each contact point of the exploring catheter with the RA endocardium (yellow points) are expressed in a color scale (left lateral border of the figure). Such colors are applied on the
3D anatomical mapping of the RA: in the LA appendage projection (B), you may see how
from the CTI (white color), the circuit of the arrhythmia rotates in a clockwise manner around the VT, in an ascending way through the septum and later in a descending way through the lateral side of the RA (A).
In the patients with TAF present, entrainment was also conducted from the CTI with the goal of confirming the participation of it in the circuit (return cycle-tachycardia cycle ≤20 ms).
In the 2 patients that were admitted in sinus rhythm, pacing was made from the PCS to evaluate the activation sequence in the halo catheter and the conduction time through the CTI in a clockwise direction, measured from the PCS until the halo distal pole (HD). Next, pacing from the HD, the conduction time through the CTI in a counterclockwise direction (HD-PCS) was analyzed. In these patients, initially there were no attempts of induction of TAF made.
Next, with the ablation catheter, a line of RF applications was made, point by point, at the level of the 6th hour of the CTI, from its ventricular side until the IVC, using a power of 70 Watts, and a maximum temperature of 65°C (Figure 2). In the case of patients with TAF present, the application continued until the reversion of it. In the patients that were admitted in sinus rhythm, the line of RF applications was made while the PCS was being stimulated, controlling the activation sequence in the halo catheter, with the aim of determining the time of change of it (CTI block). In both cases, a verification of the bidirectional block of the CTI was made. It was considered that the CTI was blocked in a clockwise manner, if during the pacing from the PCS, the activation sequence in the halo catheter was decreasing and the PCS-HD time >120 ms. The counterclockwise block was confirmed with a PCS-HD time >120 ms.
Figure 2. Application of RF on the CTI (dark brown dotted line) and the time of the reversion of arrhythmia (electrograms strips in the inferior part). The ablation catheter (green tip) and the duodecapolar halo catheter are observed in the RA lateral side (yellow). RA anatomy images in the RA appendage (A) and LA appendage (B).
The procedure was considered successful if the patient left the room in sinus rhythm and with evidence of bidirectional block of CTI and the TAF was not inducible with programmed atrial stimulation. The patients were discharged the day after the procedure, with ACO medication, and no antiarrhythmic medication.
RFA procedures in the control group
In the 21 patients in the control group, the procedure was made with a technique similar to the one described, but the catheters were placed under fluoroscopic control (conventional technique).
Follow-up The patients were controlled clinically and by 12-lead ECG at one week after the procedure and later monthly. A control Holter study was made at 3 and 6 months. The record of flutter in the tracings was considered recurrence.
The RFA procedure was successful in all patients in Group I (100%) and in 20 patients of Group II (95.2%). There were no complications recorded in Group I. One patient in Group II (5%) presented a minor complication (hematoma in the puncture site). A patient in Group II (5%) presented RAF recurrence detected in Holter at 3 months; this patient was ablated again successfully. There were no recurrences detected in the patients in Group I during follow-up, until 6 months after the ablation.
The development over the last 30 years of diagnostic and therapeutic invasive procedures in electrophysiology, has meant one of the most impressive advancements in medicine. They were based on the positioning of catheters in the different chambers of the heart under fluoroscopic control. However, the use of fluoroscopy is potentially dangerous for the health of the patients and the sanitary staff. The advent of the electroanatomic mapping by the use of digital navigators represented an invaluable supplement for such procedures, increasing its effectiveness; however, we still don’t have randomized studies that show typical flutter ablation is more efficient with a navigator than without it. RFA of different arrhythmogenic substrates exclusively with navigation systems, has been previously described [1,2]. Its use was initially forced in patients that could not be exposed to fluoroscopy, as for instance pregnant women. However, as long as it proves to be a safe technique, comparable to conventional methods, it starts to appear as an alternative that could become a routine practice, due to its advantage of preventing the deleterious effects of radiation.
When performing a review on the deleterious effects of radiation, the following should be taken into account: the characteristics of radiation produced by X-rays tubes , the effects of radiation on the organism , the mechanisms of action of radiation on biological material , that the damage caused depends on the amount of energy absorbed, of the area exposed, of the velocity of absorption, and of the mechanism followed by this, and that the damage is accumulative along extended intervals of time [6,7].
Interventionist radiology and cardiology contribute in a significant way in the exposition to ionizing radiation both in patients and in the medical staff . According to what was published by the United Nation’s Scientific Committee on the Effects of Atomic Radiation , the radiological interventionist procedures represent 1% of the use of radiation in the medical field in general, while they contribute with 10% of the collective dose .
The way to measure radiation in the exposed staff should be taken into account : the time of radioscopy , the dose of radiation by the area of radiation of the ray, the effective dose received to estimate the risk of the effects of radiation, and the proper methods of protection both for the patients and the medical staff .
In cardiac interventionism, the procedures with greater risk are angiography and coronary angioplasty (each separately or jointly) , followed by radiofrequency ablation. The electrophysiology study in general is the one that presents a lower rate of exposition to radiation, as long as radioscopy is used without uptake of images . Radiofrequency ablation however, is the procedure with a greater rate of doses by area and effective dose, due to the extended time of radioscopy . In average, a coronary angiography implies a radiation dose equivalent to 300 chest X-rays; an angioplasty plus implantation of endovascular prosthesis corresponds to 1000 chest X-rays , and finally a radiofrequency ablation procedure is equivalent to 1500 chest X-rays.
Feasibility and effectiveness of the procedure of RFA without radioscopy
In our experience, the management of catheters guided exclusively by the navigator did not present major difficulties. In all cases it was possible to place without problems, the coronary sinus catheter, which we consider the greatest challenge. When planning this project, we took into account the possibility of occasionally using the radioscopy equipment before extreme difficulties, an unnecessary condition in any case.
Until we have randomized studies that would show the benefits of using a navigator over the ablation technique of typical atrial flutter by the conventional method, this technique continues being the indication adopted internationally and that is in the international guidelines of ablation by catheter.
The knowledge of the effects of radiation could be suboptimal in the medical community; however, it is strongly recommended by the professional guidelines and reinforced by the European law, which states that it is the responsibility of all the physicians to reduce to a minimum the risk of impairment that the radiation may cause in the patients, the professional staff and themselves .
Limitations of the study
We should highlight and remind that although 2 groups of patients with similar characteristics were compared, this is not a randomized or prospective study, which considerably limits the assessment when comparing efficacy. The second great limitation is the number of patients (n=5) of the group being studied, which does not allow drawing conclusions of any kind.
In this initial experience, in a series of cases of 5 patients with typical atrial flutter (TAF), radiofrequency ablation (RFA) only with navigation systems was a feasible and safe technique, with encouraging and comparable results to those of the conventional technique.
The procedure of RFA of TAF depending on the isthmus, is properly regulated and it showed a high effectiveness and efficacy to prevent the recurrence of arrhythmia.
The possibility of extending this technique to other arrhythmias originating in the right chambers that would not require transseptal puncture is being considered, and possibly to left arrhythmias too.
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